Updated on 2022/05/19

写真a

 
SAITO, Kiyoshi
 
Affiliation
Faculty of Science and Engineering, School of Fundamental Science and Engineering
Job title
Professor

Concurrent Post

  • Faculty of Science and Engineering   Graduate School of Fundamental Science and Engineering

  • Affiliated organization   Global Education Center

Research Institute

  • 2020
    -
    2022

    理工学術院総合研究所   兼任研究員

  • 2020
    -
    2022

    リサーチイノベ オープンイノベーション推進セクション   兼任センター員

  • 2020
    -
    2022

    高等研究所   兼任研究所員

Education

  •  
    -
    1997

    Waseda University   Graduate School, Division of Science and Engineering   Mechanical engineering  

  •  
    -
    1992

    Waseda University   Faculty of Science and Engineering   mechanical engineering  

Degree

  • Waseda University   Dr. Engineering

Research Experience

  • 2022.04
    -
    Now

    Waseda University

  • 2019.04
    -
    Now

    Waseda University

  • 2008.04
    -
    Now

    Present Professor

  • 2014
    -
     

    Adjunct professor, University of Indonesia

  • 2011
    -
     

    Visiting professor, University of the philippines

  • 2002
    -
     

    Associate professor, Waseda University

  • 2000
    -
     

    National Institute for Resources and Environment

  • 1999
    -
    2000

    Domestic research fellow,

  • 1996
    -
    1998

    Research associate, Waseda University

▼display all

Professional Memberships

  •  
     
     

    日本エネルギー学会

  •  
     
     

    ASHRAE

  •  
     
     

    IIR

  •  
     
     

    日本冷凍空調学会

  •  
     
     

    日本機械学会

 

Research Areas

  • Earth resource engineering, Energy sciences

  • Control and system engineering

  • Transport phenomena and unit operations

  • Thermal engineering

  • Mechanics and mechatronics

  • Robotics and intelligent system

▼display all

Research Interests

  • Dynamics, Robotics, Energy saving, Air conditioning, Environmental engineering

Research Seeds

Papers

  • Variational formulation of stationary two-phase flow distribution

    Niccolo Giannetti, Mark Anthony Redo, Kiyoshi Saito, Hiroaki Yoshimura

    Case Studies in Thermal Engineering   26   101082 - 101082  2021.08

    DOI

  • Absorption heat transformer - state-of-the-art of industrial applications

    Falk Cudok, Niccolò Giannetti, José L. Corrales Ciganda, Jun Aoyama, P. Babu, Alberto Coronas, Tatsuo Fujii, Naoyuki Inoue, Kiyoshi Saito, Seiichi Yamaguchi, Felix Ziegler

    Renewable and Sustainable Energy Reviews   141   110757 - 110757  2021.05

    DOI

  • Semitheoretical formulation of annular flow void fraction using the principle of minimum entropy production

    Niccolò Giannetti, Seiichi Yamaguchi, Kiyoshi Saito, Hiroaki Yoshimura

    International Journal of Thermal Sciences   158  2020.12

     View Summary

    © 2020 Elsevier Masson SAS The two-phase flow void fraction is a critical parameter for characterising the pressure drop as well as heat and mass transfer capability of the working fluid within thermal systems, the accurate estimation of which drives heat exchanger design and control optimisation. A semitheoretical expression for the void fraction of two-phase flows, also applicable to small-sized channels, is obtained from an analytical study based on the principle of minimum entropy production and the introduction of empirical coefficients to be fitted to experimental data available in the open literature. These coefficients embody the importance of the simplified physical terms of this formulation while recovering the accuracy loss owing to nonlinear phenomena, heat and mass transfer, and three-dimensional effects. By accounting for surface tension, this model generalises previous theories and describes the influence of smaller-sized channels in terms of the stable void fraction. This mathematical framework can be used to summarise data covering different refrigerants, channel diameters, and operating conditions.

    DOI

  • A cost effective and non-intrusive method for performance prediction of air conditioners under fouling and leakage effect

    Sholahudin, Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito, Katsuhiko Tanaka, Hiroto Ogami

    SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS   42  2020.12

     View Summary

    Realistic performance predictions are required for efficient operation strategy of air conditioners. In this study, the application of a cost effective and non-intrusive black box model utilizing artificial neural networks (ANN) to predict the cooling capacity of air conditioning systems is investigated, while considering the effect of fouling and leakage that may occur after prolonged operation. The effect of various leakage and fouling combinations on the output cooling capacity were numerically simulated. The training data set is first generated for a system that is ideally operating without any fouling or leakage. The developed ANN model is tested to predict cooling capacity in "faulty" systems. The results indicated that, as long as leakage and fouling are limited below 10% and 4% respectively, the ANN model trained by the data generated with the ideal system, can predict cooling capacity with a relative averaged cooling capacity difference (Delta(Q) over bar (e,rel)) of approximately 13%. Moreover, the inclusion of data with different leakage and fouling combinations in the training set enables accurate predictions of the cooling capacity of the air conditioning system during the entire timespan of its operation. It suggests that cooling capacity under the fouling and leakage phenomena can be predicted using limited input information.

    DOI

  • Experimental implementation of artificial neural network for cost effective and non-intrusive performance estimation of air conditioning systems

    Sholahudin, Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito, Yoichi Miyaoka, Katsuhiko Tanaka, Hiroto Ogami

    APPLIED THERMAL ENGINEERING   181  2020.11

     View Summary

    Owing to the high variability of operating conditions and the complexity of dynamic phenomena occurring within air conditioning cycles, the realistic performance estimation of these systems remains an open question in this field. This paper demonstrates the applicability of a cost-effective estimation method based on an artificial neural network exclusively using four refrigerant temperatures as the network input. The experimental datasets are collected from a reference experimental facility. The system is operated with variable cooling load, outdoor temperature, and indoor temperature settings, as representative of the actual operation. The artificial neural network structure was optimized by considering the effect of previous time step inputs, number of neurons, sampling time, and number of training data. The results reveal that the developed model can successfully estimate the cooling capacity of an air conditioning system during on-off, continuous unsteady, and steady operation, using four temperature inputs with relative averaged error below 5%.

    DOI

  • Prediction of two-phase flow distribution in microchannel heat exchangers using artificial neural network

    Niccolo Giannetti, Mark Anthony Redo, Sholahudin, Jongsoo Jeong, Seiichi Yamaguchi, Kiyoshi Saito, Hyunyoung Kim

    International Journal of Refrigeration   111   53 - 62  2020.03

     View Summary

    © 2019 Due to the intrinsic complexity of two-phase flow distribution and the limited mathematical flexibility of conventional formulations of the phenomenon, previous attempts generally fall short in the accuracy and applicability of their prediction. To address these issues, this study focuses on methods with higher mathematical flexibility. Specifically, the construction and training of Artificial Neural Network (ANN) is presented for the identification of this complex phenomenon. The interaction of the numerous physical phenomena, occurring at different scales, is thus represented by the network structure, offering a formulation capable of achieving higher accuracy. Experimental data from a full-scale heat exchanger of an air-conditioning system operating over a wide range of conditions are used to train and test the ANN. The network optimisation with Bayesian regularisation against experimental data leads to a structure featuring 4 inputs, 3 hidden layers, and 3 neurons for each layer, which demonstrates deviations on the single output mostly lower than ± 10% and a correlation index higher than 98%, when the whole data set is used for training the ANN. The analysis of the network optimisation for different shares of data used for the network testing, shows higher training and testing accuracy as the number of training data increases, along with no apparent overfitting.

    DOI

  • Formulation of steady-state void fraction through the principle of minimum entropy production

    Niccolo GIANNETTI, Kiyoshi SAITO, Hiroaki YOSHIMURA

    Journal of Thermal Science and Technology   15 ( 3 ) JTST0025 - JTST0025  2020

    DOI

  • Film rupture and partial wetting over flat surfaces with variable distributor width

    Niccolo Giannetti, Piyatida Trinuruk, Seiichi Yamaguchi, Kiyoshi Saito

    Science and Technology for the Built Environment   25 ( 10 ) 1313 - 1324  2019.11

    DOI

  • Dynamic modeling of room temperature and thermodynamic efficiency for direct expansion air conditioning systems using Bayesian neural network

    Sholahudin, Keisuke Ohno, Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito

    APPLIED THERMAL ENGINEERING   158  2019.07

     View Summary

    In this paper, dynamic performance identification for a direct expansion (DX) air conditioning (AC) system is proposed using Bayesian artificial neural network (ANN). The input and output datasets are generated by a dedicated AC simulator by varying the compressor speed in various signal amplitudes and including dynamic cooling load and ambient temperature. The exergy destruction, which represents the work potential losses in the system and room temperature indicating the thermal comfort are selected as the output variables. The key parameters of an ANN model, including the number of neurons and tapped delay lines, are optimized to improve the prediction accuracy. The results show that the dynamic response of the exergy destruction and room temperature can be predicted accurately by the optimized ANN model using three neurons, a Bayesian regularization algorithm, five delayed inputs for the compressor speed and room temperature, and six delayed inputs for the cooling load and ambient temperature. The validation of the multi-step-ahead prediction showed satisfying results with respect to the root mean squared errors (RMSEs) and coefficient of variations (CVs) of the room temperature (RMSE: 0.18 degrees C and CV: 0.85%) and exergy destruction (RMSE: 1.79 W and CV: 0.4%). Accordingly, the identification of the AC system behavior presented in this paper could be further implemented to control the DX AC system operation to achieve a desired thermal comfort with low exergy destruction.

    DOI

  • Semi-theoretical model of the wetting characteristics of aqueous ionic liquid on an aluminium finned-tube desiccant contactor

    Niccolo Giannetti, Richard Jayson Varela, Hifni Ariyadi, Seiichi Yamaguchi, Kiyoshi Saito, Xin Ming Wang, Hiroshi Nakayama

    Refrigeration Science and Technology   2019-August   4616 - 4623  2019

     View Summary

    © 2019 International Institute of Refrigeration. All rights reserved. A new design of an internally cooled desiccant contactor which uses a new ionic liquid (IL) solution as sorptive medium is targeted. To optimise its operative performance, a semi-theoretical model based on a variational thermodynamic principle is developed to predict the film rupture and wetting ability of the IL solution for different values of the IL mass fraction over a comprehensive range of liquid spray density. The minimum Reynolds number Reb allowing the film-like flow configuration and, below this value, the wetted fraction of the solid substrate are firstly formulated on an analytical basis. Successively, the theoretical formulation is used as a reference to minimise deviations between predicted results and measured data by calibrating dedicated characteristic coefficients. Predicted film rupture, wetting ability and wetting hysteresis behaviour are strongly affected by the IL mass fraction and found in good agreement with the measurements.

    DOI

  • Performance and Application of Combined System of Liquid Desiccant and R718 Centrifugal Heat Pump

    Hajime Yabase, Seiichi Yamaguchi, Kiyoshi Saito, Hiroshi Hasuike, Hayato Sakamoto, Satoru Matsumoto, Masatoshi Harada

    10TH INTERNATIONAL MEETING OF ADVANCES IN THERMOFLUIDS (IMAT 2018): SMART CITY: ADVANCES IN THERMOFLUID TECHNOLOGY IN TROPICAL URBAN DEVELOPMENT   2062  2019

     View Summary

    The air-conditioning system for buildings and facilities is required that the room temperature and the humidity are kept in a predetermined range for comfortable air-conditioning. For achieving the above only by a heat pump, the room condition should be heated till the preset temperature after cooling till the temperature from which the request humidity is obtained, and this operation is inefficient.To overcome such inefficiency, separation of latent heat and sensible heat has been proposed. This is a two-step process in which temperature and humidity are adjusted separately in two steps by combining desiccant dehumidifier and heat pump. Theoretically, the system is known to be effective in reducing energy consumption, but in practical application, this technology can be further improved.In this research, we combined the liquid desiccant equipment which can perform low temperature regeneration and R718 centrifugal heat pump suitable for high efficiency for this application. Based on this concept, we have developed a highly efficient air-conditioning system by improving element equipment and optimizing operating conditions. The performance of this system is reported here.

    DOI

  • Assessment of thermal and transport properties of ionic liquids as suitable absorbent for absorption cooling applications

    H. M. Ariyadi, S. Yamaguchi, K. Saito

    IOP Conference Series: Materials Science and Engineering   539  2019.01

     View Summary

    © Published under licence by IOP Publishing Ltd. Ionic liquids, salts which have liquid phase at temperature below 100°C, have been widely introduced in engineering applications, including absorption cooling systems. The application of ionic liquids in absorption cooling systems is intended to remove the disadvantages of conventional working fluids such as corrosion and crystallization. In terms of thermodynamic performances, theoretical investigation based on solubility behavior of ionic liquids in natural refrigerants show a competitive performance in comparison with conventional working fluid. Nevertheless, heat transfer performance, which is also an important key in absorption cooling systems, particularly in terms of system design and size, needs to be deeply explored and investigated. This study aims to assess the thermal and transport properties of ionic liquids as absorbent in relation to the heat and mass transfer characteristics of these working fluids. The thermal and transport properties of ionic liquids proposed as absorbent for absorption cooling systems are collected, and heat and mass transfer characteristic of these ionic liquids based on their thermal and transport properties are investigated and analyzed. Finally, the most suitable ionic liquids for absorption machines, both in terms of thermodynamics and heat and mass transfer performances can be proposed.

    DOI

  • Semitheoretical Prediction of the Wetting Characteristics of Aqueous Ionic Liquid Solution on an Aluminum Finned-Tube Desiccant Contactor

    Niccolo Giannetti, Richard Jayson Varela, Hifni Ariyadi, Seiichi Yamaguchi, Kiyoshi Saito, Xin-Ming Wang, Hiroshi Nakayama

    Journal of Fluids Engineering   140 ( 12 )  2018.12

     View Summary

    This study involves exploring a new design of an internally cooled/heated desiccant contactor by using a new ionic liquid (IL) solution as the sorptive solution. In order to optimize its operative performance, a semitheoretical model based on the principle of minimum energy is developed to predict the film rupture and wetting ability of the IL solution over a comprehensive range of IL mass fraction and flow rates. A first experimental validation of the fundamental equations of the theoretical model is presented and used as a reference to minimize deviations between predicted results and measured data by calibrating dedicated characteristic coefficients. The noteworthy quantitative and qualitative agreement in the whole range of IL mass fractions and flow rates is promising for contributing to the design of optimized system configurations and control strategies.

    DOI

  • Development and validation of an analytical formulation of the Nusselt and Sherwood numbers on a partially wetted absorber tube

    Niccolo Giannetti, Ryosuke Moriwaki, Seiichi Yamaguchi, Kiyoshi Saito

    Science and Technology for the Built Environment   24 ( 8 ) 850 - 860  2018.09

    DOI

  • Numerical simulation of Marangoni convection within absorptive aqueous Li-Br

    Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito

    International Journal of Refrigeration   92   176  2018.08  [Refereed]

    DOI

  • Simplified expressions of the transfer coefficients on a partially wet absorber tube

    Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito

    International Journal of Refrigeration    2018.07  [Refereed]

    DOI

  • General correlations for the heat and mass transfer coefficients in an air-solution contactor of a liquid desiccant system and an experimental case application

    Richard Jayson Varela, Seiichi Yamaguchi, Niccolo Giannetti, Kiyoshi Saito, Masatoshi Harada, Hikoo Miyauchi

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER   120   851 - 860  2018.05

     View Summary

    This paper presents general types of correlation for the heat and mass transfer coefficients inside an air solution contactor as expressions of Reynolds-Prandtl numbers and Reynolds-Schmidt numbers, respectively. These general equations summarize the physical and thermophysical properties of the air, the solution, and the contactor, which make them capable to be used for parametric studies provided they are fitted in a wide range of experimental data that include all the properties involved. In this work, a liquid desiccant system with an adiabatic structured packed bed as contactor and an aqueous lithium chloride as solution was constructed. The experimental data taken at various air superficial velocities and solution flow rates were fitted to the general correlations, and comparisons between the predicted and experimental results for both coefficients are within +/- 10%, for both dehumidification and regeneration processes. In addition, the calculated values of the outlet air humidity ratio and temperature agree well with the experimental data for both processes. The particular equations for the heat and mass transfer coefficients can be used to perform parametric studies at different air superficial velocities and solution flow rates with very good accuracy. Results from this study can help improve the system design and operation methods of air-solution contactors. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

  • Experimental investigation of the wetting characteristics of an aqueous ionic liquid solution on an aluminum fin-tube substrate

    Richard Jayson Varela, Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito, Xin-Ming Wang, Hiroshi Nakayama

    INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID   88   472 - 482  2018.04  [Refereed]

     View Summary

    In falling film liquid desiccant systems, finding a suitable pair of liquid desiccant and contact surface is of primary engineering interest. This requires knowledge on the wetting characteristics of the liquid on the solid substrate, which consequently requires intensive experimental investigation. In this study, the wetting characteristics of a new ionic liquid aqueous solution in an aluminum fin-tube substrate were experimentally investigated. Then, a simple method for estimating the wetted area on the substrate through image processing was developed. Visual analysis of the surface wetting was also conducted, and three types of wetting patterns are discussed. Experimental results on the static contact angle and contact angle hysteresis suggest that the ionic liquid solution is mostly wetting, and the aluminum surface is slightly to moderately rough. It was found that the wettability of the ionic liquid solution increases as the ionic liquid mass fraction increases. The wetting hysteresis phenomenon and the factors contributing to its occurrence were also clarified. The results from this study would be useful for the development of a new model or improvement of existing wetting models, which can help improve the prediction and control of the heat and mass transfer performance in internally cooled/heated fin-tube contactors. (C) 2018 Elsevier Ltd and IIR. All rights reserved.

    DOI

  • DEVELOPMENT OF HIGH PERFORMANCE AIR-CONDITIONING SYSTEM COMBINED LIQUID DESICCANT AND R718 CENTRIFUGAL HEAT PUMP

    Hajime Yabase, Seiichi Yamaguchi, Kiyoshi Saito, Hiroshi Hasuike, Hayato Sakamoto, Satoru Matsumoto, Masatoshi Harada

    13TH IIR GUSTAV LORENTZEN CONFERENCE ON NATURAL REFRIGERANTS     1345 - 1352  2018

     View Summary

    General implementation of air conditioning in buildings and facilities is such that in order to keep room temperature and humidity within predetermined range, heat pump is used to lower the air temperature to achieve desired humidity and then the air is heated to the specified temperature. From energy-saving perspective, this process is inefficient.To overcome such inefficiency, separation of latent heat and sensible heat has been proposed. This is a two-step process in which temperature and humidity are adjusted separately in two steps by combining desiccant dehumidifier and heat pump. Theoretically, the system is known to be effective in reducing energy consumption, but in practical application, this technology can be further improved.For this research, we have chosen liquid desiccant dehumidifier as the desiccant can be regenerated at low temperature. For heat pump system, we have chosen R718 centrifugal as it is suited for increasing efficiency for such combination of desiccant and heat pump. By improving each element of the system and seeking optimization of operating conditions, we aim to develop a high efficiency air-conditioning system. The result is reported here.

    DOI

  • Annular flow stability within small-sized channels

    Niccolo Giannetti, Daisuke Kunita, Seiichi Yamaguchi, Kiyoshi Saito

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER   116   1153 - 1162  2018.01  [Refereed]

     View Summary

    An analytical study based on a variational thermodynamic principle is presented to evaluate the influence of surface tension on the stability of annular flow within small-sized channels. The model introduces phenomenological assumptions in the interfacial structure of the flow regime and theoretically draws the equilibrium transition line from an annular regime to the initiation of the partial wetting condition on the inner surface. By including surface tension, this model expands previous theories and identifies the stable flow configuration in terms of void fraction and interfacial extension. The significant influence of a higher surface tension and smaller diameter (i.e. lower Weber number) are responsible for a lower stable void fraction and higher slip ratio. A complete screening of the main influential parameters is conducted to explore the descriptive ability of the model. This analysis aims at contributing to the understanding of the stability of two-phase flow regimes and can be extended to the transition between other neighbouring regimes, including wall friction as well as liquid entrainment phenomena. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

  • MODELLING OF WATER VAPOR ABSORPTION BY AQUEOUS IONIC LIQUID FLUIDS IN A VERTICAL-TUBE FALLING FILM ABSORBER

    Ariyadi Hifni Mukhtar, Giannetti Niccolò, Yamaguchi Seiichi, Saito Kiyoshi

    Grand Renewable Energy proceedings   1 ( 0 )  2018

     View Summary

    Due to their unique characteristics, recently ionic liquids have been proposed as a novel absorbent for absorption systems to eliminate the drawbacks of conventional water/LiBr working fluids, particularly crystallization and corrosion. Studies on the cycle performance of absorption cooling systems using water/ionic liquid working pairs have been published in many literatures. However, specific studies on the absorption characteristics of these new working pairs still remains open. Present study theoretically analyses the absorption characteristics of water vapor by aqueous ionic liquid solutions in a vertical tube falling film absorber. The model is developed by employing three ordinary differential equations describing the absorption process and is validated. The results are analyzed and the performances of water/ionic liquid are compared with those of conventional water/LiBr working fluid.

    CiNii

  • Experimental performance of a double-lift absorption heat transformer for manufacturing-process steam generation

    Arnas Lubis, Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito, Naoyuki Inoue

    ENERGY CONVERSION AND MANAGEMENT   148   267 - 278  2017.09  [Refereed]

     View Summary

    As widely known, some industrial processes produce a large amount of waste heat while others require a large amount of steam to heat the process flow. The main difference involves the temperature level of these heat quantities. Absorption heat transformers play a strategic role in waste heat recovery and heat supply to manufacturing processes due to their ability to utilize heat at a certain temperature level and release the enthalpy of mixing of the refrigerant at a different temperature level with a negligible amount of mechanical work input. However, given the lack of examples that find application as operative plants, the feasibility of the technology is questioned in academic and technical domains. In this study, the operability of a double-lift absorption heat transformer that generates pressurized steam at 170 degrees C is studied across a full range of operative conditions. The results demonstrate and clarify the manner in which the system can operate steadily and efficiently when driven by hot water temperature at approximately 80 degrees C while safely generating steam at a temperature exceeding 170 degrees C. The conditions yielding maximum system efficiency and capacity are identified, and the obtained experimental results are used to define an optimal control strategy. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

  • Analytical solution of film mass-transfer on a partially wetted absorber tube

    Niccolo Giannetti, Andrea Rocchetti, Seiichi Yamaguchi, Kiyoshi Saito

    INTERNATIONAL JOURNAL OF THERMAL SCIENCES   118   176 - 186  2017.08  [Refereed]

     View Summary

    This work presents a two-dimensional analytical solution of the governing differential equation for falling film vapour-absorption around a plain horizontal tube. The solution of the species transport equation gives the LiBr mass fraction distribution within the liquid absorptive film flowing along the tube surface and can be used to characterize the mass transfer performance of falling film absorbers or generators. By means of the inclusion of partial wetting effects at reduced solution mass flowrates, this study obtains an analytical expression of the mass transfer coefficient of these devices applicable over an extended range of operative conditions. The hypotheses of small penetration for physical absorption and constant heat flux condition are applied at the film interface to reach a closed-form solution. Fourier method is used to solve the problem and the eigenvalues obtained from the characteristic equation depend on Lewis number, Biot number and the dimensionless heat of absorption. Given the boundary condition at the wall, the two-dimensional mass fraction field of the laminar film can be expressed analytically as a function of Schmidt, Reynolds numbers, the tube dimensionless diameter and the ratio of the wetted area to the total exchange surface. Finally, mass transfer coefficient and absorbed mass flux are locally and globally investigated as functions of the influent dimensionless groups to clarify their effects on the physical process and screen the potentiality of the model. Results show notable qualitative and quantitative agreement with previous numerical solutions and experimental results from previous literature. This model constitutes a widely applicable and time-saving tool for actual system simulations, design and control. (C) 2017 Elsevier Masson SAS. All rights reserved.

    DOI

  • Transient operation characteristics and control method in combined air-conditioning systems

    Jongsoo Jeong, Kiyoshi Saito, Sarngwoo Karng, Seoyoung Kim, Kwangho Kim

    SCIENCE AND TECHNOLOGY FOR THE BUILT ENVIRONMENT   23 ( 4 ) 567 - 581  2017  [Refereed]

     View Summary

    This study examines, using actual driving and simulations, transient operation characteristics and control methods for a combined system. It consists of both single-stage compression-type and single-effect absorption-type refrigerators and is driven by the shaft power and waste heat from a gas engine. Given the complicated nature of the system, determining the unsteady-state performance and control characteristics of the entire system is difficult. Hence, it must be equipped with an adequate control system to maintain acceptable system performance. Our results reveal that this system is controlled, as predicted, under unsteady-state conditions by using a novel control method. The unsteady-state simulation model is validated by comparing the driving results with the simulated results. Thus, gas-engine-driven combined air-conditioning systems possess a response time similar to absorption-type refrigerators. This indicates that the transient response of the entire system is governed by the absorption-type refrigerator, although the cooling capacity of the absorption-type refrigerator is only 13% of the entire cooling capacity. Therefore, when designing the control system of the combined system, the fact that the entire combined system is mainly governed by the absorption-type refrigerator should be considered despite its low cooling capacity.

    DOI

  • Wetting behavior of a liquid film on an internally-cooled desiccant contactor

    Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER   101   958 - 969  2016.10  [Refereed]

     View Summary

    Heat and mass transfer processes performed by using thin liquid films are recurrent in a series of technical applications. The circumstances under which dry spots appear on the exchange surface for the film breakage, as well as the extent of the wetted part of the surface and the liquid vapor interface, are critical to predict and control the performances of these devices. To characterize the wetting behavior of liquid films on internally-cooled desiccant contactors, this paper originates from an experimental study and, adopting a standpoint useful for a practical interpretation of wettability measurements, introduces a corresponding theoretical model based on the principle of minimum energy. Both the estimation of the wetted area by image processing of the test section and the theoretical model highlight a hysteresis phenomenon of the film wetting behavior for gradually increasing and decreasing liquid flowrates. The modeling approach, experimental results and a first comparison are hereby presented and discussed. Quantitative and qualitative agreement appears promising for a further employment of the model in actual system design and control. (C) 2016 Elsevier Ltd. All rights reserved.

    DOI

  • High Efficiency Air Conditioning System for Data Centers Part 1 : Characteristic Analysis of the Pump cycle

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2014   21 - 24  2016

    DOI CiNii

  • High Efficiency Air Conditioning System for Data Centers Part 2 : Control of the Pump cycle

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2014   25 - 28  2016

    DOI CiNii

  • Entropy parameters for falling film absorber optimization

    Niccolo Giannetti, Andrea Rocchetti, Arnas Lubis, Kiyoshi Saito, Seiichi Yamaguchi

    APPLIED THERMAL ENGINEERING   93   750 - 762  2016.01

     View Summary

    A local entropy generation analysis, for water vapor absorption in LiBr-H2O solution, is performed referring to velocity, temperature and concentration fields obtained from the numerical solution of mass and energy transport equations. The hydrodynamic description is based on Nusselt boundary layer assumption and the actual amount of irreversibility introduced is determined for an absorptive falling film over a cooled horizontal tube inside the absorber. Results are explored in different operative conditions in order to examine the impact of the various irreversibility sources in a wide operative range. A least irreversible solution mass flow-rate can always be identified. Furthermore, a simple and general thermodynamic analysis, carried out regarding a refrigerating and a heat boosting applications, makes evidence of a dimensionless group "Q/sigma T" that separates the weight of the irreversibilities and gives the way to an optimization criterion applied to the absorber in order to improve the whole system efficiency. Both thermodynamic equilibrium and sub-cooling conditions of the solution at the inlet are considered for typical temperature and concentration of refrigerators' absorbers and heat transformers' absorbers. Results suggest the importance to work at reduced mass flow-rates with a thin uniform film. In practice, tension-active additives are required to realize this condition. Also, it is highlighted that the two parameters defined with reference to the dimensionless group "Q/sigma T" can be maximized by specific values of the tube radius, operative Reynolds number, solution sub-cooling and temperature difference between the wall and the inlet solution. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

  • SOLAR AIR-CONDITIONING SYSTEM AT THE UNIVERSITY OF INDONESIA

    Hajime Yabase, Kiyoshi Saito, Arnas Lubis, Idrus Alhamid, Nasruddin

    INTERNATIONAL JOURNAL OF TECHNOLOGY   7 ( 2 ) 212 - 218  2016

     View Summary

    Indonesia's economic growth has continued at a steady rate of approximately 5% to 6% annually, and energy consumption in the entire country has been increasing year by year. Demand for air conditioning in buildings is expanding. In line with this expansion, a 239 kW solar air-conditioning system using a single-double effect combined absorption chiller was installed in a building at the University of Indonesia's Faculty of Engineering located in Depok city, near Jakarta, with the aim of reducing greenhouse gas emissions. We collected and analyzed data from this air-conditioning system to better comprehend its performance. We report the outline and the performance of the chiller and the air-conditioning system.

    DOI

  • Thermodynamic optimization of three-thermal irreversible systems

    Niccolo Giannetti, Andrea Rocchetti, Kiyoshi Saito

    International Journal of Heat and Technology   34   S83 - S90  2016.01

     View Summary

    Multi-temperature-level systems enlarge the prospects and degrees of freedom for an effective design and an environment-friendly use of energy. Based on a general thermodynamic model of three-thermal cycles and finite thermal capacity of the heat sources, this paper aims at the analysis and the performance optimization of these systems by considering the influence of irreversibility. Suitable dimensionless parameters for an overall optimization are introduced and their influence on the cycle efficiency is investigated. This approach identifies the limitations imposed to the physical processes by accounting for the inevitable dissipation due to their constrained duration and intensity, and constitutes a general thermodynamic criterion for the optimization of three-thermal irreversible systems. Dependence on the main factors is highlighted in a way that shows how to change them in order to improve the overall efficiency. Under this point of view, the analysis evaluates COP improvements and can be used to perform plant diagnostics, besides predicting the system performance. The use of this criterion is exemplified for the absorption chiller application case.

    DOI

  • Irreversibility analysis of falling film absorption over a cooled horizontal tube

    Niccolo Giannetti, Andrea Rocchetti, Kiyoshi Saito, Seiichi Yamaguchi

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER   88   755 - 765  2015.09

     View Summary

    Based on a numerical study of the water vapour absorption process in LiBr-H2O solution, for a laminar, gravity driven, viscous, incompressible liquid film, flowing over a horizontal cooled tube, irreversibilities related to fluid friction, heat transfer, mass transfer and their coupling effects have been locally and globally examined. The hydrodynamic description is based on Nusselt boundary layer assumptions. The tangential and normal velocity components, respectively obtained from momentum and continuity equations, have been used for the numerical solution of mass and energy transport equations in the two-dimensional domain defined by the film thickness and the position along the tube surface. Local entropy generation calculation can be performed referring to the calculated velocity, temperature and concentration fields. Results have been explored in different operative conditions, in order to examine comprehensively the impact of the various irreversibility sources and to identify the least irreversible solution mass flow-rate for the absorber. As a parallel, a refined understanding of the absorption process can be obtained. Considering absorption at the film interface and cooling effect at the tube wall, the analysis thermodynamically characterises the absorption process which occurs inside actual falling film heat exchangers and establishes a criterion for their thermodynamic optimisation. Results suggest the importance to operate at reduced mass flow rates with a thin uniform film. Meanwhile, tension-active additives are required to realise this condition. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

  • Thermodynamic Analysis of Irreversible Heat-transformers

    Niccolo Giannetti, Arnas, Andrea Rocchetti, Kiyoshi Saito

    MAKARA JOURNAL OF TECHNOLOGY   19 ( 2 ) 90 - 96  2015.08

     View Summary

    Absorption heat transformers extend the possibilities for efficient and environment-friendly energy conversion processes. Based on a general thermodynamic model of three-thermal cycles with finite thermal capacity of the heat sources, this paper is intent upon analyzing and optimizing the performance of absorption heat transformers, by including the influence of irreversibility in the analytical expression of the system efficiency. Dimensionless parameters for an overall optimization are defined and a first screening is performed to clarify their influence. Dependence on the main factors is highlighted to suggest how to change them in order to enhance the whole system performance. Under this point of view, the analysis evaluates coefficient of performance (COP) improvements and can be used to perform existing plant diagnostics, besides predicting the system performance. The use of this criterion is exemplified for specific heat transformers data from literature. This approach identifies the limitations imposed to the physical processes by accounting for the inevitable dissipation due to their constrained duration and intensity, and constitutes a general thermodynamic criterion for the optimization of three-thermal irreversible systems.

    DOI

  • Entropy parameters for desiccant wheel design

    Niccolo Giannetti, Andrea Rocchetti, Kiyoshi Saito, Seiichi Yamaguchi

    APPLIED THERMAL ENGINEERING   75   826 - 838  2015.01  [Refereed]

     View Summary

    In this work a thermodynamic analysis of a desiccant wheel is proposed to investigate and identify the optimum size and operating regime of this device. A steady state entropy generation expression, based on effectiveness parameters suitable for desiccant wheels operability, is obtained applying a control volume approach and assuming perfect gas behaviour of the binary air-vapour mixture. A new entropy generation number N-L, is defined using a minimum indicative value of the entropy generation S-L,S-min and investigated in order to obtain useful criteria for desiccant wheels optimization. The effectiveness-NTU design method is employed by combining solution of thermal exchange efficiency for rotary heat exchanger with the characteristic potential method, under the conditions of heat and mass transfer analogy. The analysis is applied to a specific desiccant wheel and N-L, variation with NTU is explored under various operative conditions and wheels characteristics in terms of dimensionless velocity and flow unbalance ratio. (C) 2014 Elsevier Ltd. All rights reserved.

    DOI

  • Comparison of heat transfer coefficient during evaporation of natural refrigerants and R-1234yf in horizontal small tube

    Kwang-Il Choi, Jong-Taek Oh, Kiyoshi Saito, Jong Soo Jeong

    INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID   41   210 - 218  2014.05  [Refereed]

     View Summary

    An experimental data comparison of evaporation heat transfer coefficient of R-744(CO2), R717(NH3), R-290(C3H8) and R-1234yf in horizontal small tubes was conducted under some various flow conditions. The experimental data were obtained over a heat flux range of 5 -60 kW m(-2), mass fluxes from 50 to 600 kg m(-2) S-1, saturation temperatures from 0 to 10 degrees C, and quality up to 1.0. The test section made of stainless steel tubes with inner diameters of 1.5 mm and 3.0 mm, and a length of 1000 and 2000 mm, respectively, was heated uniformly by applying an electric power to the tubes directly. Effects of mass flux, heat flux, saturation temperature and inner tube diameter on heat transfer coefficient are reported in the present study. Among the present working refrigerants, R-744 has a highest heat transfer coefficient. Laminar flow was observed in the evaporative small tubes and considered in the modification of evaporation heat transfer coefficient correlations. (C) 2013 Elsevier Ltd and IIR. All rights reserved.

    DOI

  • :Design Method for Solar Single-Double Effect Combined Absorption Chiller

    YABASE Hajime, SAITO Kiyoshi, JEONG Jongsoo

    Trans.JSRAE     431 - 437  2014

     View Summary

    Solar single-double effect combined absorption chiller has come into wide use compared with other types of solar absorption system because it is equipped with high-efficient double effect apparatus of helping solar heat. This paper reports the machine design to enhance the performance by solar heat. So far, thermal conductance KAs of elements composed in absorption chillae have been often limited in machine design because the change of KAs means remanufacture of the test machine. Hence, easily to realize the machine design with the most efficient performance COP in the objected system, we evaluated the performance with KAs designed by simulation, which is a good way to evaluate system performance easily without empirical method and leads to design to save time. Each KA needs to be concluded under the conditions of common parameter, for example, evaporator temperature, condensation temperature, pinch temperatures of heat exchangers, etc. In the simulation result, it is clarified that the reverse flow type can be the highest performance among several types of single-double effect absorption cycle suggested.

    DOI CiNii

  • Intermittent Driving Simulation of Compression type Heat Pump : 1st Report : Mathematical model and simulation of single-stage vapor compression type heat pump

    OHNO Keisuke, SAITO Kiyoshi, YAMAGUCH Seiichi, KISHIMOTO Tetsuro, MATSUMOTO Kuniyasu

    Trans.JSRAE   30 ( 2 ) 107 - 122  2013.06

     View Summary

    Compression-type heat pumps have been employed in many fields of refrigeration and air conditioning for achieving energy savings. In addition, the system operates at high efficiency under a variety of operating conditions throughout the year through various innovative components, such as the inverter, and the annual performance improvement. However, the running time of the system over the year under low load conditions is very long, and under such conditions, the system operates intermittently because of the difficulty in the continuous running of the compressor. Of course, because intermittent driving is made under such an operating condition, the performance can estimate that it decreases greatly easily, but it is the present conditions that field operation performance does not become clear almost. Therefore, the key goals of this study were to clarify the intermittent driving performance of the compression-type heat pump and to devise a way to improve its performance and develop an optimum operation method. As the first step, we constructed a mathematical model that can predict intermittent driving characteristics at the time of low load of the pump, which are crucial to investigation of the performance. The constructed model was validated experimentally. In summary, a mathematical model of the compression-type heat pump was constructed, and its validity was demonstrated via comparison of its results with those obtained experimentally.

    DOI CiNii

  • Numerical and experimental performance analysis of rotary desiccant wheels

    Seiichi Yamaguchi, Kiyoshi Saito

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER   60   51 - 60  2013.05  [Refereed]

     View Summary

    In air-conditioning field, a dehumidification has become increasingly important for human health and comfort especially in hot and humid climates. However, a conventional mechanical dehumidification with a vapor compression refrigerator has some problems. Therefore, much attention has been paid recently to a desiccant air-conditioning system as an alternative to the conventional system. In this paper, we focus on a rotary desiccant wheel which is the main component of the desiccant air-conditioning system and develop and validate the mathematical model by comparison with experimental results. The validation is conducted under various operating conditions. The mathematical model discussed in this paper includes, for example, the entrance region effect in air channel, detailed diffusion phenomenon in porous solid. In experiments, effects of the regeneration air temperature, air superficial velocity, wheel thickness and wheel rotational speed on the desiccant wheel performance are investigated. In addition, the temperature and humidity distribution at the outlet of the desiccant wheel are measured. As a result, an average relative error between the predicted and the measured humidity ratio difference distribution is 3.3% and temperature difference distribution 10.8%. Moreover, the effect of the regeneration air inlet temperature, the air superficial velocity, wheel thickness and wheel rotational speed on the desiccant wheel performance are clarified and the predicted results are totally in good agreement with the measured results. (C) 2013 Elsevier Ltd. All rights reserved.

    DOI

  • Thermodynamic performance of a hybrid air cycle refrigeration system using a desiccant rotor

    Kyudae Hwang, Chan Ho Song, Sung Ki Kim, Kiyoshi Saito, Sunao Kawai

    HEAT AND MASS TRANSFER   49 ( 3 ) 359 - 367  2013.03  [Refereed]

     View Summary

    Due to the concern on global warming, the demand for a system using natural refrigerant is increasing and many researches have been devoted to develop systems with natural refrigerants. Among natural refrigerant systems, an air cycle system has emerged as one of alternatives of Freon gas system due to environmentally friendly feature in spite of the inherent low efficiency. To overcome the technical barrier, this study proposed combination of multiple systems as a hybrid cycle to achieve higher efficiency of an air cycle system. The hybrid air cycle adopts a humidity control units such as an adsorber and a desorber to obtain the cooling effect from latent heat as well as sensible heat. To investigate the efficacy of the hybrid air cycle, the cooling performance of a hybrid air cycle is investigated analytically and experimentally. From the simulation result, it is found that COP of the hybrid air cycle is two times higher than that of the conventional air cycle. The experiments are conducted on the performance of the desiccant system according to the rotation speed in the system and displayed the feasibility of the key element in the hybrid air cycle system. From the results, it is shown that the system efficiency can be enhanced by utilization of the exhausted heat through the ambient heat exchanger with advantage of controlling the humidity by the desiccant rotor.

    DOI

  • Operation Characteristics of Heat Transportation System Using CO2

    Jongsoo Jeong, Kiyoshi Saito, Jongtaek Oh, Kwangil Choi

    2011 2ND INTERNATIONAL CONFERENCE ON ADVANCES IN ENERGY ENGINEERING (ICAEE)   14   1601 - 1606  2012  [Refereed]

     View Summary

    Recently, information and communications technologies (ICT) have been widely used in the air-conditioning field, and high-performance and density ICT facilities have been rapidly growing. At the same time, the heat generated per unit area of a normal data center, where the servers and routers are concentrated, in an ICT facility is an extremely serious problem. Therefore, this study aims to investigate the performance and characteristics of the server spot cooling heat transportation system adopting CO2 as the working fluid to prevent the occurrence of hot spots and decrease the power consumed by a conventional overall air conditioning system installed at a data center with experiments and simulations. In the result, we determined the optimum CO2 circulation rate that maximizes the rejected heat flow rate, and minimizes power consumption. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of organizing committee of 2nd International Conference on Advances in Energy Engineering (ICAEE).

  • Development of General Purpose Energy System Simulator

    Kiyoshi Saito, Jongsoo Jeong

    2011 2ND INTERNATIONAL CONFERENCE ON ADVANCES IN ENERGY ENGINEERING (ICAEE)   14   1595 - 1600  2012  [Refereed]

     View Summary

    Smart energy system is very large energy system that consists of the windmill, solar panel, heat pump, air-conditioning system, solar thermal panel and so on. To develop efficient smart energy system, it is very important to investigate how to manage the total energy utilization of the total smart energy system. But it is difficult to examine the energy management only with experiment. The simulation is promising technology for the development of the energy management of the smart energy systems. But as this system is too large, we can't analyze this system, unless we analyze this system rationally. Therefore we have established the modular analysis theory that can analyze the large scale energy system. This paper introduces this theory and using this theory, we have developed the energy system analyzing simulator that is called "Energy Flow +M". This simulator has been already opened for the worldwide through Internet. This simulator is expected to be used for the energy saving of the total energy systems. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the organizing committee of 2nd International Conference on Advances in Energy Engineering (ICAEE).

  • Hybrid liquid desiccant air-conditioning system: Experiments and simulations

    Seiichi Yamaguchi, Jongsoo Jeong, Kiyoshi Saito, Hikoo Miyauchi, Masatoshi Harada

    APPLIED THERMAL ENGINEERING   31 ( 17-18 ) 3741 - 3747  2011.12  [Refereed]

     View Summary

    This study focuses on a hybrid liquid desiccant air-conditioning system consisting of a conventional liquid desiccant system and a vapour compression heat pump. The hybrid liquid desiccant air-conditioning system is expected to enhance the system efficiency of a conventional liquid desiccant system. In this study, the liquid desiccant is aqueous solution of lithium chloride and the refrigerant of the vapour compression heat pump is R407C. The main feature of this system is that the absorber and regenerator are integrated with the evaporator and condenser respectively. The performance evaluation test is conducted to obtain the primary data. Additionally, the improvement method for the system efficiency is discussed by the mathematical calculations. As a result, the system can dehumidify 5.9 g/kg(DA) under the conditions of summer in Tokyojapan. Then, the calculation results show that COPs can become higher by improving the compressor isentropic efficiency and the temperature efficiency of solution heat exchanger. (C) 2011 Elsevier Ltd. All rights reserved.

    DOI

  • Performance analysis of desiccant dehumidification systems driven by low-grade heat source

    Jongsoo Jeong, Seiichi Yamaguchi, Kiyoshi Saito, Sunao Kawai

    INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID   34 ( 4 ) 928 - 945  2011.06  [Refereed]

     View Summary

    If a desiccant dehumidification system can be driven by a heat source whose temperature is below 50 degrees C, exhaust heat from devices such as fuel cells or air conditioners can be used as its heat source, thereby saving energy. Therefore, in this study, we used a previously validated simulation model to determine the minimum heat source temperature for driving a desiccant dehumidification system. We considered four desiccant dehumidification systems that can be driven by waste heat-conventional desiccant-type systems (wheel type and batch type with only desiccant), a system with a precooler, double-stage-type systems (a type with two desiccant wheels and a four-partition desiccant wheel type), and a batch-type system with an internal heat exchanger. We found that among these systems, the last system can be driven by the lowest heated air temperature-approximately 33 degrees C-which is considerably lower than that of the conventional system. (C) 2010 Elsevier Ltd and IIR. All rights reserved.

    DOI

  • Static characteristics and efficient control of compression- and absorption-type hybrid air conditioning system

    Jongsoo Jeong, Kiyoshi Saito, Sunao Kawai

    INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID   34 ( 3 ) 674 - 685  2011.05  [Refereed]

     View Summary

    A gas engine driven hybrid air conditioning system was constructed; it consisted of a gas engine, a single-stage compression-type refrigerator, and a single-effect absorption-type refrigerator that can be driven by shaft power and waste heat, respectively, from the gas engine. Its efficiency is greatly enhanced as compared to a conventional gas engine heat pump because it utilizes waste heat from the gas engine. This study used simulation and experiments to elucidate the static characteristics of this air conditioning system and develop a control system to drive this combined system efficiently. In the simulation results, the system COP at the design point was about 1.87 and, at 50% partial load operation, the performance increased by 14% because of the simultaneous manipulation of the input gas flow rate and hot water flow rate. The validity of the simulation was confirmed by experiments carried out using the actual constructed machine. (c) 2011 Elsevier Ltd and IIR. All rights reserved.

    DOI

  • Development and validation of static simulation model for CO2 heat pump

    Seiichi Yamaguchi, Daisuke Kato, Kiyoshi Saito, Sunao Kawai

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER   54 ( 9-10 ) 1896 - 1906  2011.04  [Refereed]

     View Summary

    A simulation model for the CO2 heat pump water heater was developed and validated in this study. Component models of the gas cooler, evaporator, compressor, and expansion valve were constructed with careful consideration for the heat transfer performances. To validate the simulation model, experiments were carried out using an actual CO2 heat pump water heater (water heating capacity: 22.3 kW; hot-water temperature: 90 degrees C). In simulations and experiments, the effects of the inlet water temperature and outside air temperature on the system characteristics were discussed. As a result, the average difference in COP between the simulation results and experimental results is 1.5%. (C) 2011 Elsevier Ltd. All rights reserved.

    DOI

  • Ammonia Boiling Heat Transfer in Minichannels

    Satoshi Takabayashi, Kiyoshi Saito, Kimitaka Kadowaki, Masashi Kato

    PROCEEDINGS OF ISHTEC2012, 4TH INTERNATIONAL SYMPOSIUM ON HEAT TRANSFER AND ENERGY CONSERVATION     371 - 375  2011

     View Summary

    Nowadays new types of heat exchangers which utilize small channel tubes with ammonia refrigerant have been widely considered due to the high energy efficiency and environmental issues. This study carries out experiment in evaporation temperature of -10 degrees C to +5 degrees C at 10 to 40 kW/m(2) heat flux and 40 to 120 kg/m(2)s in mass flux with 1.0 mm and 3.0 mm inner diameter tubes. The test results showed high heat transfer coefficient for 1.0 mm tube. The Kandlikar model predicted both 1.0mm and 3.0mm tube's heat transfer coefficient well. For recording the flow patterns inside the tube, we used a high speed video camera and found the annular flow dominated at the low vapor quality region for 1.0mm tube. Accordingly the annular flow seemed to be the cause of the high heat transfer. Also we measured pressure drop in both of the tubes and found that there was not much difference between 1.0 mm and 3.0 mm tubes under the same experimental conditions. A separated model with the Mishima Hibiki parameter predicted the pressure drop of 1.0mm results well, but couldn't predict that of the 3.0mm results.

  • FRICTIONAL PRESSURE DROP AND VOID FRACTION DURING EVAPORATION OF C3H8, NH3 AND CO2 IN SINGLE CIRCULAR SMALL TUBES

    Kwang-Il Choi, Agus S. Pamitran, Jong-Taek Oh, Kiyoshi Saito, Jong Soo Jeong

    23RD IIR INTERNATIONAL CONGRESS OF REFRIGERATION   23   1834 - +  2011  [Refereed]

     View Summary

    An experimental study of evaporation pressure drop in single circular small tubes was conducted for flow of C3H8, NH3 and CO2 under some various flow conditions. The test matrix encompasses the entire quality range from 0.0 to 1.0, mass fluxes from 50 to 600 kg m(-2) s(-1), heat fluxes from 5 to 70 kW m(-2) and saturation temperatures from 0 to 10 degrees C. The test section was made of circular stainless steel tubes with inner diameters of 1.5 mm and 3.0 mm, and a length of 2000 mm in horizontal orientation. The test section was heated uniformly by applying an electric power to the tubes directly. The effects of mass flux, heat flux, saturation temperature and inner tube diameter are presented in this study. The pressure drop of CO2 is the lowest among the working refrigerants. The experimental pressure drop was compared with some existing pressure drop correlations. Existing void fraction prediction methods were evaluated for the present experimental pressure drop. A modified pressure drop correlation using homogenous void fraction model is developed.

  • Experimental study on titanium heat exchanger used in a gas fired water heater for latent heat recovery

    Kyudae Hwang, Chan Ho Song, Kiyoshi Saito, Sunao Kawai

    APPLIED THERMAL ENGINEERING   30 ( 17-18 ) 2730 - 2737  2010.12  [Refereed]

     View Summary

    In general, latent heat recovery is usually accompanied by the corrosion of the heat exchanger, which is caused by the strongly acidic condensate when the temperature of the flue gas is lowered below the acid dew point. The present study has been conducted to investigate the heat and mass transfer characteristics in a titanium heat exchanger with excellent corrosion resistance used for waste heat recovery with the condensation arranged in a gas fired water heater. In addition, the thermal efficiency of the gas fired water heater was evaluated based on the net calorific value at the maximum rated output during latent heat recovery from the exhaust flue gas. Parametric studies were conducted for the flue gas flow rate, inlet temperature and mass flow, rate of the supplied water, respectively. Different arrangements of the tubes of the heat exchanger including in-line and staggered configurations were investigated. The experimental results indicate that the thermal efficiency of the gas fired water heater with a latent heat recovery (LHR) heat exchanger was enhanced by about 10% compared with conventional instantaneous water heaters, i.e., water heaters without heat recovery. In addition, in terms of the Nusselt number and the Sherwood number, the heat and mass transfer performance of the staggered tube bank type were approximately 50% and 10% higher than that on the in-line tube bank type when the Reynolds number of the flue gas was 10(3). (C) 2010 Elsevier Ltd. All rights reserved.

    DOI

  • Performance analysis of four-partition desiccant wheel and hybrid dehumidification air-conditioning system

    Jongsoo Jeong, Seiichi Yamaguchi, Kiyoshi Saito, Sunao Kawai

    INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID   33 ( 3 ) 496 - 509  2010.05

     View Summary

    A desiccant dehumidification system with air can decrease energy consumption because it can be driven by low-grade waste heat below 80 degrees C. If this system can be driven by low-temperature heat sources whose temperature is below 50 degrees C, exhausted heat from fuel cells or air conditioners that exist everywhere can be used as heat sources. This could lead to considerable energy saving. This study provides a detailed evaluation of the performance of a four-partition desiccant wheel to make a low-temperature driving heat source possible and achieve considerable energy saving by the simulation and experiment. Further, the study investigates the in-depth performance of a hybrid air-conditioning system with a four-partition desiccant wheel by simulation. As a result, it was clear that there exists an optimum rotational speed to maximize the dehumidification performance and that the hybrid air-conditioning system improves COP by approximately 94% as compared to the conventional vapour compression-type refrigerator. (C) 2009 Elsevier Ltd and IIR. All rights reserved.

    DOI

  • PERFORMANCE EVALUATION OF SILICA GEL DESICCANT WHEEL BY SIMULATION AND EXPERIMENT

    Seiichi Yamaguchi, Kiyoshi Saito, Sunao Kawai

    PROCEEDINGS OF THE INTERNATIONAL SYMPOSIUM ON INNOVATIVE MATERIALS FOR PROCESSES IN ENERGY SYSTEMS 2010 (IMPRES2010): FOR FUEL CELLS, HEAT PUMPS AND SORPTION SYSTEMS     161 - 168  2010

     View Summary

    In this paper, we have developed a simulation model of a desiccant wheel to use the investigation of the optimum design and operation. For this usage, the high precision model has to be constructed for the global design and operating conditions. Heat and mass transfer phenomenon inside the desiccant wheel are divided into the convection heat and mass transfer inside air channels and heat and mass diffusions inside desiccant walls. Therefore, the simulation model is developed separately divided into the air channel and the desiccant wall. In the desiccant wall, the model is constructed by considering the diffusion in the porous solid. On the other hand, in the air channel, the convective heat and mass transfer coefficients are derived from the CFD analysis. To validate the model, we examined the effect of the air superficial velocity on the pressure drop and the effect of the regeneration air inlet temperature on the outlet humidity and temperature. As a result, The simulation results are in good agreement with the experimental results and the validity of this simulation model was confirmed.

    DOI

  • Heat and mass transfar of zeolite desiccant wheel with simulation and experiment

    Seiichi YAMAGUCHI, Kiyoshi SAITO, Sunao KAWAI

    International Workshop on Environment&Enpineering2009    2009.11

  • Development of General-purpose Energy System Analysis Software“ENERGY FLOW+M"-Static analysis of Co2 heat pump system

    Jong-Soo Jeong, Kiyoshi Saito

    2009 WINTER ANNUAL CONFERENCE    2009.11

  • サイクル再熱除湿方式ルームエアコンにおける除湿性能向上

    中村啓夫, 舟越砂穂, 横山英範, 森本素生, 齋藤潔

    日本冷凍空調学会論文集2009   Vol.26,No.4   405 - 416  2009.09

    DOI

  • サイクル再熱除湿方式における室温・湿度制御方法の検討

    中村啓夫, 舟越砂穂, 横山英範, 森本素生, 齋藤潔

    日本冷凍空調学会論文集2009   Vol.26,No.4   417 - 427  2009.09

    DOI

  • 単効用吸収冷凍機の断続運転特性解析

    大野慶祐, 西山教之, ガス, 齋藤潔

    日本機械学会第19回環境工学総合シンポジウム2009論文集    2009.07

  • リキッドデシカントシステムにおける除湿・再生用充鎮層における熱・物質移動特性と圧力損失

    伊藤卓, 山口誠一, 齋藤潔, 河合素直

    日本機械学会第19回環境工学総合シンポジウム2009論文集    2009.07

  • ゼオライト系デシカントローターの性能評価実験と静特性解析

    山口誠一, 齋藤潔, 早, 恩田直樹

    日本機械学会第19回環境工学総合シンポジウム2009論文集    2009.07

  • シリカゲル系デシカントローターの高精度シュミレーションモデルの構築

    山口 誠一, 齋藤 潔, 河合 素直, 恩田 直樹

    第43回空気調和・冷凍連合講演会講演論文集    2009.04

  • FLOW BOILING HEAT TRANSFER CHARACTERISTICS OF R-22 AND R-134a IN 0.5, 1.5 AND 3.0 mm TUBES

    Kwang-Il Choi, A. S. Pamitran, Jong-Taek Oh, Hoo-Kyu Oh, Kiyoshi Saito

    ACRA 2009: PROCEEDINGS OF THE 4TH ASIAN CONFERENCE ON REFRIGERATION AND AIR-CONDITIONING     28 - 34  2009  [Refereed]

     View Summary

    An experimental study of R-22 and R-134a two-phase vaporization in horizontal minichannel was reported. In order to obtain the local heat transfer coefficients, the test was ran under heat flux range of 10 to 40 kW m(-2), mass flux range of 200 to 600 kg m(-2) s(-1), saturation temperature range of 5 to 10 degrees C, and quality up to 1.0. The test section, which was made of stainless steel tube and heated uniformly by applying an electric current to the tube directly, has inner tube diameters of 0.5, 1.5 and 3.0 mm, and lengths of 0.33 and 2.0 m. The effects on heat transfer coefficient of mass flux, heat flux and inner tube diameter were presented. The experimental heat transfer coefficients were compared with the predictions using existing heat transfer coefficient correlations. A. new boiling heat transfer coefficient correlation based on the superposition model, with considering the laminar flow, was developed.

  • 汎用熱システム解析手法の確立への試み -第5報 圧縮式冷凍機の起動・停止解析への適用-

    大野 慶祐, 齋藤 潔, 中村 啓夫

    2008年度日本冷凍空調学会年次大会講演論文集    2008.10

  • リキッドデシカントシステムの吸収・再生器用充填層における熱・物質移動特性の解明

    山口 誠一, 齋藤 潔, 河合 素直

    2008年度日本冷凍空調学会年次大会講演論文集    2008.10

  • デシカントローターにおける熱・物質移動特性の検討と静特性解析

    山口 誠一, 齋藤 潔, 河合 素直, 恩田 直樹

    2008年度日本冷凍空調学会年次大会講演論文集    2008.10

  • エネルギーシステム汎用解析ソフト“ENERGY FLOW+M”の開発 -第2報 デシカント空調システムの静特性解析-

    平松 雅弘, 齋藤 潔, 中村 英明(アサンキャ

    2008年度日本冷凍空調学会年次大会講演論文集    2008.10

  • エネルギーシステム汎用解析ソフト“ENERGY FLOW+M”の開発 -第1報 圧縮式冷凍機の静特性解析-

    大野 慶祐, 齋藤 潔, 中村 英明(アサンキャ

    2008年度日本冷凍空調学会年次大会講演論文集    2008.10

  • シリカゲル系デシカントローターの性能評価と特性解析

    山口 誠一, 齋藤 潔, 河合 素直, 恩田 直樹

    日本機械学会・第18回環境工学総合シンポジウム2008 CD-ROM論文集    2008.07

  • WIDE RANGE UNSTEADY-STATE SIMULATION OF COMPRESSION TYPE REFRIGERATOR WITH MODULAR ANALYSIS

    K.OHNO, H.NAKAMURA, K.SAITO

    IIR 2008 HVAC energy efficiency best practice conference,Melbourne    2008

  • STATIC SIMULATION AND EXPERIMENT OF CO2 HEAT PUMP WATER HEATER

    D.KATO, S.YAMAGUCHI, K.SAITO, S.KAWAI

    8th IIR Gustav Lorentzen Conference on Natural Working Fluids,Copenhagen,2008    2008

  • PERFORMANCE EVALUATION OF DESICCANT DEHUMIDIFICATION SYSTEMS WITH LOW-GRADE HEAT SOURCE

    Jongsso.JEONG, Seiichi.YAMAGUCHI, Kiyoshi.SAITO, Sunao.KAWAI, Naoki.ONDA

    HVAC energy efficiency best practice conference,Melbourne in Australia,2008    2008

  • PERFORMANCE ENHANCEMENT OF COMPRESSION TYPE REFRIGERATOR WITH FOUR-PARTITION DESICCANT WHEEL

    M.Hiramatsu, S.Yamaguchi, K.Saito, S.Kawai

    IIR 2008 HVAC energy efficiency best practice conference,Melbourne    2008

  • PERFORMANCE ANALYSIS OF MULTI-PARTITION DESICCANT WHEEL

    J.JEONG, S.YAMAGUCHI, K.SAITO, S.KAWAI

    8th IIR Gustav Lorentzen Conference on Natural Working Fluids,Copenhagen,2008    2008

  • EFFECT OF DESIGN AND OPERATING CONDITIONS ON PERFORMANCE OF DESICCANT WHEELS

    Kenichi Tsutsui, Seiichi Yamaguchi, Kiyoshi Saito, Naoki Onda

    IIR 2008 HVAC energy efficiency best practice conference,Melbourne    2008

  • Pressure drop and heat transfer during two-phase flow vaporization of propane in horizontal smooth minichannels

    Kwang-Il Choi, A.S.Pamitran, Jong-Taek Oh, Kiyoshi Saito

    Elsevier   no.32   837 - 845  2008

  • 汎用熱システム解析手法の確立への試み 第5報 吸収式冷凍機の動特性解析への適用

    木暮 悠樹, 齋藤 潔, 岡 雅博, 佐々木 裕文, 河合 素直

    2007年度日本冷凍空調学会年次大会講演論文集    2007.10

  • 吸収ヒートポンプ式蒸気発生装置の開発

    梶山 啓輔, 岡 雅博, 東京ガス, 福住 幸大, 入江 毅一, 河合 素直, 齋藤 潔

    2007年度日本冷凍空調学会年次大会講演論文集    2007.10

  • 開放型吸収式除湿機の性能試験とシュミレーション

    井出 順, 山口 誠一, 齋藤 潔, 河合 素直

    2007年度日本冷凍空調学会年次大会講演論文集    2007.10

  • 開放型吸収式除湿機の除湿・再生器における圧力損失と熱・物質移動特性

    山口 誠一, 齋藤 潔, 河合 素直

    2007年度日本冷凍空調学会年次大会講演論文集    2007.10

  • デシカントローターの占有体積を最小化する最適設計手法に関する検討

    山口 誠一, 齋藤 潔, 河合 素直, 佐々木 裕文, 恩田 直樹

    2007年度日本冷凍空調学会年次大会講演論文集    2007.10

  • Static analysis of desiccant wheel 2nd report

    Seiichi Yamaguchi, Kiyoshi Saito, Sunao Kawai, Masahiro Oka

    nternational congress of refrigeration, Beijing    2007.08

  • Static analysis of desiccant wheel 1st report

    Seiichi Yamaguchi, Kiyoshi Saito, Sunao Kawai, Masahiro Oka

    International congress of refrigeration Beijing    2007.08

  • STUDY ON OPTIMUM DESIGN METHOD OF ABSORPTION REFRIGERATOR 2ND REPORT:APPLICATION TO DOUBLE EFFECT ABSORPTION CYCLE

    J.JEONG, K.SAITO, S.KAWAI

    PROCEEDINGS The 22nd International Congress of Refrigeration 2007,Beijing.    2007.08

  • STATIC ANALYSIS OF DESICCNAT WHEEL 2ND REPORT:PERFORMANCE ANALYSIS AND OPTIMUM DESIGN OF THE DESICCANT WHEEL

    S.YAMAGUCHI, K.SAITO, S.KAWAI, M.OKA, T.MURAKAMI, H.SASAKI

    PROCEEDINGS The 22nd International Congress of Refrigeration 2007,Beijing.    2007.08

  • STATIC ANALYSIS OF DESICCNAT WHEEL 1ST REPORT :CONSTRUCTION OF SIMULATION MODEL AND INVESTIGATION OF VALIDITY OF THE MODEL

    S.YAMAGUCHI, K.SAITO, S.KAWAI, M.OKA, T.MURAKAMI, H.SASAKI

    PROCEEDINGS The 22nd International Congress of Refrigeration 2007,Beijing.    2007.08

  • 第2種吸収式ヒートポンプの性能試験と特性解析

    木暮悠樹, 齋藤 潔, 河合素直, 福住幸大, 梶山啓輔

    第41回空気調和・冷凍連合講演会講演論文集    2007.04

  • 4分割デシカントローターの性能評価

    柴尾 雄人, 山口 誠一, 齋藤 潔, 河合 素直

    第41回空気調和・冷凍連合講演会講演論文集    2007.04

  • 除・加湿プロセスの多段化によるデシカント空調システムの駆動熱源温度の低温化に関する検討

    柴尾 雄人, 山口 誠一, 齋藤 潔, 河合 素直

    2006年度日本冷凍空調学会年次大会講演論文集    2006.10

  • 三重効用吸収冷凍機のフローによる性能比較

    大谷 真人, 齋藤 潔, 河合 素直

    2006年度日本冷凍空調学会年次大会講演論文集    2006.10

  • デシカントローターの静特性解析 第1報 デシカントローターの数値解析モデルの構築とその妥当性の検証

    森 博孝, 山口 誠一, 齋藤 潔, 河合 素直, 岡 雅博, 村上 高, 東京, 佐々木 裕文, 恩田 直樹

    2006年度日本冷凍空調学会年次大会講演論文集    2006.10

  • デシカントローターの静特性解析 第2報 構造および運転条件がデシカントローターの性能に与える影響の検討

    山口 誠一, 森 博孝, 齋藤 潔, 河合 素直, 岡 雅博, 村上 高, 東京, 佐々木 裕文, 恩田 直樹

    2006年度日本冷凍空調学会年次大会講演論文集    2006.10

  • Licl 水溶液を用いた開放型吸収式除湿機の実運転状況における特性解析

    井出 順, 松下 俊一郎, 山口 誠一, 齋藤 潔, 河合 素直

    2006年度日本冷凍空調学会年次大会講演論文集    2006.10

  • Efficiency enhancement of absorption refrigerator with two phase flow ejector

    Jeongsoo Jeong, Kiyoshi Saito, Choiku Yoshikawa, Sunao Kawai

    7th Gustav Lorentzen Conference on NWF, Trondheim, Norway    2006.05

  • 水冷媒ハイブリッド冷凍機の高性能化に向けた制御手法の検討

    並木 晴史, 山口 誠一, 鄭 宗秀, 稲垣 勝之, トーセ, 齋藤 潔, 河合 素直

    第40回空気調和・冷凍連合講演会講演論文集    2006.04

  • 2段除湿・2段再生によるデシカントロータの高性能化

    柴尾 雄人, 山口 誠一, 鄭 宗秀, 稲垣 勝之, トーセ, 齋藤 潔, 河合 素直

    第40回空気調和・冷凍連合講演会講演論文集    2006.04

  • Characteristics evaluation of absorption type dehumidifier using aqueous LiCl solution

    Seiichi Yamaguchi, Shunnichiro Matsushita, Jongsoo Jeong, Kiyoshi Saito, Sunao Kawai, Katsuyuki Inagaki, Ken Hongo

    PROCEEDINGS OF THE 3RD ASIAN CONFERENCE ON REFRIGERATION AND AIR-CONDITIONING VOLS I AND II     345 - +  2006

     View Summary

    Sorption dehumidification of air has become the. focus of attention as an alternative to conventional dehumidification process by air cooling below the dew point. Liquid desiccant using LiCl solution has advantages over conventional solid desiccants, because the energy loss per hydration-dehydration process cycle is smaller for liquid desiccant than it is for typical solid desiccant. An open cycle absorption type dehumidifier using LiCl solution in this paper is can be driven by low grade waste heat and is effective for saving energy. However, a detailed analysis of the characteristics of the system has not been clearly investigated.The purpose of this paper is to evaluate a performance of the dehumidifier using LiCl solution on condition that air conditioning is driven in hot and high humid summer climate in Japan. In this paper, first, a packed bed as a part of absorption type dehumidifier is evaluated in which heat and mass transfer occur simultaneously, and secondary, the characteristics of dehumidifier is investigated as the whole system.As a simulation result, in case of performance evaluation of the system, when the heat source (hot water) tmperature is 70 degrees C, COPD (the efficiency of dehumidification) is 0.7 at design point. And, when the heat source temperature is about 80 degrees C, LiCl crystallizes by physical property of LiCl solution cooled in solution cooler that the cycle can not be driven. Therefore, heat source temperature must be carefully designed to keep the solution concentration below crystallization line.

  • 水冷媒を用いたハイブリッド冷凍機の特性解析

    鄭 宗秀, 稲垣 勝之, トーセ, 齋藤 潔

    2005年度日本冷凍空調学会年次大会講演論文集    2005.10

  • 圧縮・吸収ハイブリッド空調システムの起動特性解析

    寺島 陽生, 齋藤 潔, 河合 素直, 鄭 宗秀, 竹内 由実, 刑部 尚樹

    2005年度日本冷凍空調学会年次大会講演論文集    2005.10

  • Licl 水溶液を用いた開放型吸収式除湿機の特性評価 第1報 除湿部および再生部の特性解析

    山口 誠一, 松下 俊一郎, 鄭 宗秀, 齋藤 潔, 稲垣 勝之, トーセ, 本郷 賢

    2005年度日本冷凍空調学会年次大会講演論文集    2005.10

  • Licl 水溶液を用いた開放型吸収式除湿機の特性評価 第2報 システムの特性解析

    山口 誠一, 松下 俊一郎, 鄭 宗秀, 齋藤 潔, 稲垣 勝之, トーセ, 本郷 賢

    2005年度日本冷凍空調学会年次大会講演論文集    2005.10

  • Performance evaluation of open type absorption dehumidifier using LiCl solution as liquid desiccant

    Shumichiro Matsushita, Seiichi Yamaguchi, Kiyoshi Saito, Sunao Kawai

    International sorption conference, Denver, CO, USA    2005.06

  • Performance Evaluation of Latent Heat Recovery Heat Exchanger Using Enhanced Titanium Tubes for Gas Fired Water Heater

    Kyudae Hwang, Kiyoshi Saito, Sunao Kawai, Katsuyuki Inagaki, RYuji Ozawa

    TEFC6, JEJU, KOREA    2005.03

  • Efficiency enhancement of absorption chiller using NH3-H2O with two phase flow ejector

    Jongsoo Jeong, Kiyoshi Saito, Sunao Kawai, Choiku Yoshikawa, Kazuhiro Hattori

    TFEC6, JEJU, Korea    2005.03

  • Dynamic characteristics of absorption and compression type hybrid air conditioning system

    Haruo Terashima, Kiyoshi Saito, Jeongsoo Jeong

    TFEC6, JEJU, Korea    2005.03

  • Performance enhancement on gas fired water heater using titanium heat exchanger for latent heat recovery

    Kyudae Hwang, Sunggun Hyun, Kiyoshi Saito, Sunao Kawai, Katsuyuki Inagaki, Ryuji Ozawa

    Journal of the Japan Institute of Energy   84 ( 1 ) 62 - 67  2005

     View Summary

    The performance of natural gas (13A) fired water heater with titanium heat exchanger for latent heat recovery was evaluated. In the terms of thermal efficiency, the performance of the water heater was evaluated based on the net calorific value at maximum rated output. The thermal efficiency of gas fired water heater with latent heat recovery heat exchanger was ≈ 10% higher than that of the conventional instantaneous water heater. The overall heat conductance of the heat exchanger with staggered tube rows was more efficient than that of the inline tube rows.

    DOI

  • プラズマ親水性表面処理による蒸発伝熱促進に関する実験的研究

    黄 奎大, 齋藤 潔, 河合 素直, 姜 炳夏

    2004年度日本冷凍空調学会年次大会講演論文集    2004.10

  • NAS電池排熱を利用したCO2給湯機の性能評価

    和田 知記, 齋藤 潔, 草鹿 仁, 河合 素直, 荻須 吉洋, 山下 牧夫, 黒本 英智

    2004年度日本冷凍空調学会年次大会講演論文集    2004.10

  • Licl 水溶液を用いた開放型吸収式除湿機の性能評価 第1報:シュミレーションによる性能評価

    稲垣 勝之(トーセツ, 久保田 薫(トーセツ, 本郷 賢, 高橋 英信, 鄭 宗秀, 齋藤 潔, 荻須 吉洋, 河合 素直

    2004年度日本冷凍空調学会年次大会講演論文集    2004.10

  • 排ガス駆動吸収例温水機の開発(第2報)

    井上修行, 遠藤哲也, 齋藤潔, 河合素直

    日本冷凍空調学会論文集/日本冷凍空調学会   21 ( 2 ) 109 - 120  2004.09

    DOI

  • 排ガス駆動吸収例温水機の開発(第1報)

    井上修行, 遠藤哲也, 齋藤潔, 河合素直

    日本冷凍空調学会論文集/日本冷凍空調学会   21 ( 2 ) 97 - 108  2004.08

    DOI

  • 高設定温度,高換気量に対応可能な次世代空調方式に関する研究

    稲垣勝之, トーセツ, 中川安明(トーセツ, 齋藤 潔, 河合 素直

    第38空気調和・冷凍連合講演会講演論文集    2004.04

  • 自然冷媒を用いた冷凍機・ヒートポンプのエジェクターによる高効率化に関する研究(第3報)

    吉川朝郁, 鄭宗秀, 服部一裕, 齋藤潔, 河合素直

    日本冷凍空調学会論文集/日本冷凍空調学会   21 ( 1 ) 23 - 31  2004.03

    DOI

  • 自然冷媒を用いた冷凍機・ヒートポンプのエジェクターによる高効率化に関する研究(第2報)

    吉川朝郁, 鄭宗秀, 服部一裕, 齋藤潔, 河合素直

    日本冷凍空調学会論文集/日本冷凍空調学会   21 ( 1 ) 13 - 22  2004.03

    DOI

  • 自然冷媒を用いた冷凍機・ヒートポンプのエジェクターによる高効率化に関する研究(第1報)

    吉川朝郁, 鄭宗秀, 服部一裕, 齋藤潔, 河合素直

    日本冷凍空調学会論文集/日本冷凍空調学会   21 ( 1 ) 1 - 12  2004.03

    DOI

  • Study on absorption and compression hybrid air conditioning system - Performance analysis and efficient control method of hybrid air conditioning system whose absorption cycle is single effect

    J Jeong, K Saito, S Kawai, N Nishiyama, M Kataoka

    2ND ASIAN CONFERENCE ON REFRIGERATION AND AIR-CONDITIONING, PROCEEDINGS     406 - 413  2004  [Refereed]

     View Summary

    A hybrid air conditioning system consists of a gas engine as a driving source and a single-stage compression and single-effect absorption type refrigerator that can be driven by a motive power and a waste heat from the gas engine simultaneously. It can improve the efficiency of the gas engine heat pump greatly because it uses the waste heat from the gas engine. This paper aims to estimate the performance and construct the control systems to drive this hybrid air conditioning system efficiently by the simulation. The static simulation models of the hybrid air conditioning system were constructed and the performance was investigated using the model. As a result of the simulation, system COP of the design point is about 1.87. And one of the actual control methods to achieve efficient partial load is manipulating two parameters - rotational speed and the hot water flow rate simultaneously. At 50% partial load operation, the performance is 14% higher than that of the design point.

  • Heat and mass transfer characteristics in gas fired water heater with titanium heat exchanger for latent heat recovery

    Kyudae Hwang, Sunggun Hyun, Kiyoshi Saito, Sunao Kawai, Katuyuki Inagaki, Ryuji Ozawa

    6th international symposium on Heat Transfer     790 - 795  2004

  • Efficiency Enhancement of Chiller and Heat Pump Using Natural Working Fluids with Two-phase Flow Ejector, 3rd report

    Choiku Yoshikawa, Jeongsoo Jeong, Kazuhiro Hattori, Kiyoshi Saito, Sunao Kawai

    Japan Society of Refrigerating and Air Conditioning Engineers   21 ( 1 ) 23 - 31  2004

    DOI

  • Efficiency Enhancement of Chiller and Heat Pump Using Natural Working Fluids with Two-phase Flow Ejector, 2nd report

    Choiku Yoshikawa, Jeongsoo Jeong, Kazuhiro Hattori, Kiyoshi Saito, Sunao Kawai

    Japan Society of Refrigerating and Air Conditioning Engineers   21 ( 1 ) 13 - 21  2004

    DOI

  • Efficiency Enhancement of Chiller and Heat Pump Using Natural Working Fluids with Two-phase Flow Ejector, 1st report

    Choiku Yoshikawa, Jeongsoo Jeong, Kazuhiro Hattori, Kiyoshi Saito, Sunao Kawai

    Japan Society of Refrigerating and Air Conditioning Engineers   21 ( 1 ) 1 - 12  2004

    DOI

  • Heat transfer and pressure drop characteristics of enhanced titanium tubes

    Kyudae Hwang, Jongsoo Jeong, Sunggun Hyun, Kiyoshi Saito, Sunao Kawai, Katsuyuki Inagaki, Ryuji Ozawa

    Desalination   159 ( 1 ) 33 - 41  2003.09

     View Summary

    The present study investigated the characteristics of heat transfer and pressure drop for various types of enhanced titanium tubes. The heat transfer experiments were conducted using a steam-condensing flow facility at a constant inlet temperature of cooling water, and the Reynolds number range varied from 15,000 to 65,000. The heat transfer coefficients were determined using a modified version of the Wilson plot technique and the friction factors were calculated from pressure drop measurements. The experimental results reported enable practical design to be achieved for the heat exchanger using enhanced titanium tubes and optimization of tube geometry for specific conditions.

    DOI

  • Heat transfer and pressure drop characteristics of enhanced titanium tubes

    K Hwang, J Jeong, S Hyun, K Saito, S Kawai, K Inagaki, R Ozawa

    DESALINATION   159 ( 1 ) 33 - 41  2003.09

     View Summary

    The present study, investigated the characteristics of heat transfer and pressure drop for various types of enhanced titanium tubes. The heat transfer experiments were conducted using a steam-condensing flow facility at a constant inlet temperature of cooling water, and the Reynolds number range varied from 15,000 to 65,000. The heat transfer coefficients were determined using a modified version of the Wilson plot technique and the friction factors were calculated from pressure drop measurements. The experimental results reported enable practical design to be achieved for the heat exchanger using enhanced titanium tubes and optimization of tube geometry for specific conditions.

    DOI

  • 吸収サイクルの動特性解析

    齋藤潔

    日本冷凍空調学会 冷凍   78 ( 909 ) 41 - 47  2003.07

  • Study on the Efficient Drive of a Desiccant Air Conditioning System

    Jong-Soo Jeong, Kiyoshi Saito, Sunao Kawai

    日本冷凍空調学会論文集/日本冷凍空調学会   20 ( 2 ) 257 - 264  2003.05

    DOI

  • 汎用熱システム解析手法の確立への試み(第4報:圧縮式冷凍機の動特性解析への適用)

    鄭 宗秀, 尾崎 純也, 齋藤 潔, 河合 素直

    第37回空気調和・冷凍連合講演会講演論文集    2003.04

  • 汎用熱システム解析手法の確立への試み(第3報:動特性解析の基本的な考え方)

    齋藤 潔, 尾崎 純也, 鄭 宗秀, 河合 素直

    第37回空気調和・冷凍連合講演会講演論文集    2003.04

  • 多重効用サイクルによる吸収冷凍機の高効率化(第2報)

    井上修行, 齋藤潔, 河合素直

    日本冷凍空調学会論文集/日本冷凍空調学会   20 ( 4 ) 473 - 484  2003.04

    DOI

  • 多重効用サイクルによる吸収冷凍機の高効率化(第1報)

    井上修行, 入江智芳, 齋藤潔, 河合素直

    日本冷凍空調学会論文集/日本冷凍空調学会   20 ( 4 ) 461 - 472  2003.04

    DOI

  • Optimum Design Method of an Absorption Refrigerator(-1st report : Single Effect Absorption Cycle -)

    Jeongsoo Jeong, Sunggun Hyun, Kiyoshi Saito, Sunao Kawai

    The 6th ASME-JSME Thermal Engineering Joint Conference, Hawaii, USA    2003.03

  • Thermal Efficiency Enhancement on Gas-Fired Water Heater Using Titanium Heat Exchanger for Latent Heat Recovery

    Kyudae Hwang, Sunggun Hyun, Jongsoo Jeong, Kiyoshi Saito, Sunao Kawai, Katuyuki Inagaki, Ryuji Ozawa

    22nd World Gas Conference, Tokyo, Japan    2003

  • Performance Analysis of Advanced Air Cycle Refrigeration System

    Kyudae Hwang, Sunggun Hyun, Takao Ando, Kiyoshi Saito, Sunao Kawai, Junji Matuda, Hirokazau Yoneda

    Proc. of 21st IIR International Congress of Refrigeration, Washington D.C., USA    2003

  • Optimum Design Method for an Single Effect Absorption Refrigerator Based on the First and Second Law Analysis

    Jeongsoo Jeong, Kiyoshi Saito, Sunao Kawai

    Proc. of ,21st IIR International Congress of Refrigeration, Washington D.C., USA     1 - 9  2003

  • Characteristic analysis of an efficient hybrid air conditioning system (1st report, performance analysis of compression and absorption hybrid cycle)

    Jongsoo Jeong, Kiyoshi Saito, Sunggun Hyun, Sunao Kawai, Noriyuki Nishiyama, Choiku Yoshikawa

    Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   69 ( 685 ) 2114 - 2121  2003

     View Summary

    A gas engine heat pump (GHP) is the type of compression heat pump that is driven by the motive power from the gas engine. To improve the performance of this GHP greatly, it is necessary to add the heat pump driven by the waste heat from the gas engine to the GHP. This paper suggests the new hybrid heat pump in which the waste heat driven heat pump is combined with the compression heat pump. This system can be driven by the motive power and the waste heat from the gas engine simultaneously. In this paper, the hybrid heat pump whose waste heat driven heat pump is the absorption heat pump is adopted. The working-fluids are ammonia and water. The performance of this hybrid heat pump is analyzed with the simulation. As a result, it was found that gas engine hybrid air conditioning system with the new hybrid heat pump can realize the very high efficiency-primary energy ratio is about 2.4.

    DOI

  • Study on the Efficient Drive of a Desiccant Air Conditioning System

    Jong Soo Jeong, Kiyoshi Saito, Sunao Kawai

    Japan Society of Refrigerating and Air Conditioning Engineers   20 ( 2 ) 147 - 154  2003

    DOI

  • Characteristic analysis of an Efficient Hybrid Air Conditioning System

    Jongsoo Jeong, Kiyoshi Saito, Sunggun Hyun, Sunao Kawai, Noriyuki Nishiyama, Choiku Yoshikawa

    Japan Society of Mechanical Engineers   69 ( 685 ) 130 - 137  2003

  • The Performance analysis of absorption heat pump which can supply the hot and the chilled water simultaneously

    Sunggun Hyun, Toshiaki Kajitani, Jongsoo Jeong, Kiyoshi Saito, Sunao Kawai

    Second International Conference on Energy Research & Development     207 - 216  2002

  • Study on the Efficient Drive of a Desiccant Air Conditioning System

    Jongsoo Jeong, Yuji Horiuchi, Sunggun Hyun, Kiyoshi Saito, Sunao Kawai

    Proc. of the Asian Conference on Refrigeration and Air Conditioning 2002, Kobe, Japan     203 - 210  2002

  • Performance and characteristic analysis of a super efficient hybrid air-conditioning system

    JS Jeong, SG Hyun, K Saito, S Kawai

    PROCEEDINGS OF THE INTERNATIONAL SORPTION HEAT PUMP CONFERENCE     246 - 254  2002

     View Summary

    A gas engine heat pump, is the type of compression heat pump which is driven by motive power from the gas engine. To improve the performance of the gas engine heat pump greatly, it is necessary to add the heat pump driven by the waste heat from the gas engine. Therefore, in this paper a new hybrid heat pump in which the waste heat driven heat pump is combined with the compression heat pump is suggested, and a super efficient hybrid air conditioning system using this heat pump with gas engine is constructed. The performance of this hybrid heat pump is analyzed by the simulation. Then, some control techniques to drive this hybrid air conditioning system are introduced. The working-fluids are ammonia and water. As a result, it was found that this new hybrid air-conditioning system can realize extremely efficient drive primary energy ratio is about 2.4. And the control system in which hot water flow rate and solution flow rate, and rotational frequency are manipulated simultaneously can realize efficient part load.

  • Performance Analysis of a Super Efficient Hybrid Air-Conditioning System(first report: a Compression and Absorption Hybrid Cycle)

    Jongsoo Jeong, Sunggun Hyun, Kiyoshi Saito, Sunao Kawai, Noriyuki Nishiyama, Choiku Yoshikawa, Hiroyuki Suzuki, Syuji Fukano

    CIAR     386 - 395  2001.08

  • Study on the start-up characteristics of double-effect absorption refrigerator driven by waste steam

    Kiyoshi Saito, Sunao Kawai, Noriyuki Nishiyama

    Heat Transfer - Asian Research   29 ( 5 ) 427 - 445  2000.07

     View Summary

    Absorption refrigerators can be driven by waste heat. In particular, the double-effect type of absorption refrigerator, which is highly efficient, is drawing a great deal of attention as a waste heat recovery system. This research examines the double-effect absorption refrigerator driven by steam, assuming waste heat from the fuel cells is applied. In the start-up of the double-effect absorption refrigerator, the solution temperature is almost equal to the temperature of the air. Due to the large temperature difference between the solution and the heat sources, the solution is overheated. In the worst case, it will be crystallized. Additionally, some solution is circulated due to the existence of a pressure difference between the heat exchangers. If the solution pump is started before an adequate pressure difference is obtained, the absorption refrigerator cannot be started normally. To investigate these problems, a simulation model is constructed. An experiment is conducted to investigate the performance of this model. As a result, the validity of this model is confirmed and the detailed start-up characteristics are clarified. (C) 2000 Scripta Technica, Heat Trans Asian Res, 29(5): 427-445, 2000.

    DOI

  • Study on the start-up characteristics of double-effect absorption refrigerator driven by waste steam

    Kiyoshi Saito, Sunao Kawai, Noriyuki Nishiyama

    Heat Transfer - Asian Research   29 ( 5 ) 427 - 445  2000.07

     View Summary

    Absorption refrigerators can be driven by waste heat. In particular, the double-effect type of absorption refrigerator, which is highly efficient, is drawing a great deal of attention as a waste heat recovery system. This research examines the double-effect absorption refrigerator driven by steam, assuming waste heat from the fuel cells is applied. In the start-up of the double-effect absorption refrigerator, the solution temperature is almost equal to the temperature of the air. Due to the large temperature difference between the solution and the heat sources, the solution is overheated. In the worst case, it will be crystallized. Additionally, some solution is circulated due to the existence of a pressure difference between the heat exchangers. If the solution pump is started before an adequate pressure difference is obtained, the absorption refrigerator cannot be started normally. To investigate these problems, a simulation model is constructed. An experiment is conducted to investigate the performance of this model. As a result, the validity of this model is confirmed and the detailed start-up characteristics are clarified. (C) 2000 Scripta Technica, Heat Trans Asian Res, 29(5): 427-445, 2000.

    DOI

  • New Business Development Evaluation of Farm-Corporations in Japan

    SAITO Kiyoshi

    Japanese Journal of Farm Management   37 ( 4 ) 29 - 37  2000.03

    DOI CiNii

  • Static Characteristics of WMVR Hybrid Absorption Refrigerator Driven by Waste Heat and Motive Power:1st report:Suggestion of Cycle and Model Construction for WMVR Hybrid Absorption Refrigerator

    HYUN Sunggun, SAITO Kiyoshi, KAWAI Sunao

    Transactions of the Japan Society of Refrigerating and Air Conditioning Engineers   17 ( 3 ) 297 - 305  2000

     View Summary

    Absorption refrigerator driven by waste heat can realize the energy savings. But if only waste heat is used as a heat source, the surplus of the waste heat or the shortage of the cooling capacity occur due to the change of the cooling capacity or the waste heat. In these cases, it is effective to back up this refrigerator with that driven by the stable source such as motive power. But using two refrigerators costs too much. This research suggests the WMVR hybrid refrigerator which can be operated using motive power and waste heat simultaneously. For this refrigerator, the simulation model was constructed and detailed characteristics were clarified. And based on these results, the effect of the design parameters such as the solution concentration and the pressure in the MVR generator on COP was revealed.

    DOI CiNii

  • Static Characteristics of WMVR Hybrid Absorption Refrigerator Driven by Waste Heat and Motive Power

    Sungun Hyun, Kiyoshi Saito, Sunao Kawai

    Japan Society of Refrigerating and Air Conditioning Engineers   17 ( 3 ) 297 - 305  2000

    DOI

  • DYNAMIC CHARACTERISTICS OF GENERATOR FOR AN ABSORPTION REFRIGERATOR(The Pool Boiling and The Falling Film Type Generator)

    SungGun HYUN, Kiyoshi SAITO, Hiroshi OSHITANI, Sunao KAWAI

    Twentieth International Congress of Refrigeration    1999.09

    DOI

  • 吸収冷凍機用再生器の動特性解析(第1報:プール沸騰式再生器)

    玄成建, 齋藤潔, 河合素直

    日本機械学会論文集   65 ( 631B ) 256 - 263  1999.03

    DOI

  • Dynamic characteristics of generator for absorption refrigerator

    Suggun Hyun, Kiyoshi Saito, Hiroshi Oshitani, Sunao Kawai

    20th international congress of refrigeration, Sydney, Australia    1999

  • Dynamic characteristics of the generator for absorption refrigerator (2nd report, falling film type generator)

    Sunggun Hyun, Kiyoshi Saito, Hiroshi Oshitani, Sunao Kawai

    Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   65 ( 638 ) 3447 - 3454  1999

     View Summary

    A falling film type heat exchanger is expected as the generator for the absorption refrigerator because of its capability to improve the speed of response and to drive the absorption refrigerator with lower temperature of the waste heat sources than the pool boiling type. In the latest research, we constructed the dynamic model of the pool boiling type generator and clarified the dynamic characteristics. This research aims to build the dynamic model of the falling film type generator for investigation of its dynamic characteristics in detail. First, dynamic model of the falling film type generator considering both heat and mass transfer is constructed. Then, the validity of this model is examined with the experiment of generator element installation. As a result, the validity was confirmed by the correspondence between the simulation results and experimental data.

    DOI

  • Dynamic characteristics of the generator for absorption refrigerator (2nd report, falling film type generator)

    Sunggun Hyun, Kiyoshi Saito, Hiroshi Oshitani, Sunao Kawai

    Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   65 ( 638 ) 3447 - 3454  1999

     View Summary

    A falling film type heat exchanger is expected as the generator for the absorption refrigerator because of its capability to improve the speed of response and to drive the absorption refrigerator with lower temperature of the waste heat sources than the pool boiling type. In the latest research, we constructed the dynamic model of the pool boiling type generator and clarified the dynamic characteristics. This research aims to build the dynamic model of the falling film type generator for investigation of its dynamic characteristics in detail. First, dynamic model of the falling film type generator considering both heat and mass transfer is constructed. Then, the validity of this model is examined with the experiment of generator element installation. As a result, the validity was confirmed by the correspondence between the simulation results and experimental data.

    DOI

  • Dynamic Characteristics of the Generator for Absorption Refrigerator(1stReport : Pool Boiling Type Generator)

    Sung Gun Hyun, Kiyoshi Saito, Sunao Kawai

    Japan Society of Mechanical Engineers   65 ( 631 ) 256 - 263  1999

    DOI

  • Study on the characteristics of ammonia-water absorption refrigerator

    K Saito, S Kimijima, T Takei, S Kawai

    NATURAL WORKING FLUIDS'98: IIR - GUSTAV LORENTZEN CONFERENCE   1998 ( 4 ) 550 - 560  1998

     View Summary

    When an ammonia-water absorption refrigerator(called ammonia absorption refrigerator in this paper) is used for purposes such as freezing and ice accumulation requiring temperatures below 0 degrees C, it is usually operated throughout the year. In this case, operating conditions which greatly influence the characteristics of the absorption refrigerator, change very widely. According to these changes, the holdup volume of refrigerant (ammonia) or solution in the refrigerant and solution receiver, changes greatly, too. If the amount of ammonia charged in the ammonia absorption refrigerator is too small, the refrigerator cannot be operated normally and efficiently due to refrigerant vapor mixes with the refrigerant liquid flowing from the condenser to evaporator or interruption of the reflux pump. However, the ammonia charging quantity has to be as small as possible because of its toxicity.
    In this study, we made a static simulation model and clarified the detailed characteristics of the ammonia absorption refrigerator by simulation. The validity of this simulation model was confirmed with the experimental data using a commercial machine. The minimum ammonia charging quantity required to operate the ammonia absorption refrigerator normally and efficiently was obtained by simulation.

  • 蒸気式二重効用吸収冷凍機の起動特性解析

    齋藤潔, 西山教之, 河合素直

    日本機械学会論文集   63 ( 615B ) 201 - 209  1997.11

    DOI

  • 低温冷凍用アンモニア-水系吸収冷凍機の運転特性に関する実験・考察

    武居俊孝, 君島真仁, 齋藤潔, 河合素直

    日本冷凍空調学会論文集   14 ( 1 ) 27 - 38  1997.05

    DOI

  • 蒸気式二重効用吸収冷凍機の動特性解析

    齋藤潔, 西山教之, 河合素直

    日本機械学会論文集   63 ( 608B ) 269 - 276  1997.04

    DOI

  • Study on the Start-Up Characteristics of a Double-Effect Absorption Refrigerator Driven by Waste Steam

    Kiyoshi Saito, Noriyuki Nishiyama, Sunao Kawai

    Japan Society of Mechanical Engineers   63 ( 615 ) 201 - 209  1997

    DOI

  • Study on the Dynamic Characteristics of the Double-Effect Absorption Refrigerator Driven by Waste Steam

    Kiyoshi Saito, Sunao Kawai, Noriyuki Nishiyama

    Japan Society of Mechanical Engineers   63 ( 608 ) 269 - 276  1997

    DOI

  • Experimental Investigation on the Characteristics of the Ammonia-Water Absorption Refrigerator for Low Temperature Solution Cycle

    Toshitaka Takei, Sinji Kimijima, Kiyoshi Saito, Sunao Kawai

    Japan Society of Refrigeration and Air conditioning Engineers   14 ( 1 ) 27 - 38  1997

    DOI

  • 単効用吸収冷凍機の起動特性解析

    菅野直紀, 齋藤潔, 河合素直, 西山教之, 本間立

    日本機械学会論文集   62 ( 596 ) 304 - 310  1996.04

    DOI

  • 二重効用吸収冷凍機の吸収サイクルの構成法がその特性に与える影響の検討

    齋藤潔, 五十嵐洋晃, 河合素直

    日本機械学会論文集   62 ( 595B ) 361 - 367  1996.03

    DOI

  • 低温熱源駆動アンモニア-水系二段発生式吸収冷凍機のシミュレーション解析

    武居俊孝, 君島真仁, 齋藤潔, 河合素直

    日本冷凍空調学会論文集   13 ( 1 ) 77 - 88  1996.03

    DOI

  • アンモニア-水系吸収冷凍機において冷却水温度がその特性(COP等)および冷媒充填量に与える影響の検討

    武居俊孝, 齋藤潔, 河合素直

    日本冷凍空調学会論文集   13 ( 1 ) 57 - 65  1996.03

    DOI

  • Study on the effect of the difference of Absorption Cycles on the Characteristics of Double-Effect Absorption Refrigerator

    Kiyoshi Saito, Hiroteru Igarashi, Sunao Kawai

    Japan Society of Mechanical Engineers   62 ( 595 ) 361 - 367  1996

    DOI

  • Simulation and Experimental Research of Start-Up Characteristics of Single-Effect Absorption Refrigerators Driven by Waste Hot Water.

    SUGANO Naoki, SAITO Kiyoshi, KAWAI Sunao, NISHIYAMA Noriyuki, HOMMA Ritu

    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B   62 ( 596 ) 1584 - 1590  1996

     View Summary

    Recently, the absorption refrigerator has attracted much attention because it does not use freon as the coolant and it can be driven by waste heat. The absorption refrigerator contains much solution and coolant in it. Therefore, it requires a long start-up time because of the large heat capacities of the solution and the coolant. Moreover, it is known that much more heat is necessary at start-up than in steady-state operation. If it is driven by waste hot water of e. g. a combustion gas engine, the hot water return temperature becomes low at the start-up which adversely affects the engine. The purpose of this study is to construct an analytical model of the start-up characteristics of the single-effect absorption refrigerator driven by waste hot water, which can be used as a tool for investigating the problem of the start-up. Moreover, the validity of this model is confirmed by comparing the simulation results with the experimental results.

    DOI CiNii

  • Simulation Analysis of the NH3-H2O Two-Stage Desorption Type Absorption Refrigerator Driven by Low Grade Waste Heat

    Toshitaka Takei, Sinji Kimijima, Kiyoshi Saito, Sunao Kawai

    Japan Society of Refrigeration and Air conditioning Engineers   13 ( 1 ) 77 - 88  1996

    DOI

  • Investigation of the influence of cooling water inlet temperature on characteristics and ammonia charging quantity of ammonia water absorption refrigerator

    Toshitaka Takei, Kiyoshi Saito, Sunao Kawai

    Japan Society of Refrigeration and Air conditioning Engineers   13 ( 1 ) 57 - 65  1996

    DOI

  • Evaluation of Enthalpy Diagrams for NH_3-H_2O Absorption Refrigerator(Analysis and Comparison Between Ziegler's Equations and Merkel's Enthalpy Diagrams. )

    TAKEI Toshitaka, SAITO Kiyoshi, KAWAI Sunao

    Transactions of the Japan Society of Refrigerating and Air Conditioning Engineers   12 ( 1 ) 95 - 105  1995.03

     View Summary

    The protection of environment is becoming a grave problem nowadays and an absorption refrigerator, which does not use fleon as a refrigerant, is acquiring a close attention. Among the absorption refrigerators, a number of ammonia-water absorption refrigerators are being used in realm such as refrigeration and ice accumulation, since this type of refrigerator can produce below zero degree products.<br>It is essential to conduct an investigation on the characteristics of ammonia-water absorption refrigerator in detail by means of computer simulation in order to realize low cost, highly efficient operation. Unfortunately, there have been number of problems in order to conduct computer simulations. Firstly, Merkel's achievements of enthalpy diagram does not give the relational equations. And secondly, although relational equation are being proposed by Ziegler, simpler equations that can be applied to computer simulation are yet to be proposed.<br>In this research, simper equations based on Ziegler's equations have been derived to make computer simulation concerning the performance of ammonia-water absorption refrigerator possible-Both results of computer simulations using simple equations and Merkel's enthalpy diagram respectively, have been compared with the actual experimental data of one staged ammonia-water absorption refrigerator. Consequently, it is clarified that the results from Ziegler's equations agree with experimental data better than those from Merkel's enthalpy diagram.

    DOI CiNii

  • Study on the dynamic characteristics of double effect absorption refrigerator driven by waste steam

    Kiyoshi Saito, Sunao Kawai, Noriyuki Nishiyama, Ritu Homma

    19th international congress of refrigeration, Hague, Netherlands     983 - 990  1995

  • Evaluation of Enthalpy for NH3-H20 Absorption Refrigerator

    Toshitaka Takei, Kiyoshi Saito, Sunao Kawai

    Japan Society of Refrigerating and Air Conditioning Engineers   12 ( 1 ) 95 - 105  1995

    DOI

  • 温水だき単効用吸収冷凍機の動特性解析

    菅野直紀, 齋藤潔, 河合素直, 西山教之, 本間立, 脇水広記

    日本機械学会論文集   60 ( 576B ) 290 - 296  1994.08

    DOI

  • 二熱源駆動吸収冷凍機の特性解析(第2報)

    齋藤潔, 菅野直紀, 河合素直, 西山教之, 本間立, 脇水広記

    日本機械学会論文集   60 ( 573B ) 258 - 264  1994.05

  • 二熱源駆動吸収冷凍機の特性解析(第1報)

    齋藤潔, 菅野直紀, 河合素直, 西山教之, 本間立, 脇水広記

    日本機械学会論文集   60 ( 573B ) 250 - 257  1994.05

  • Studies on the Characteristics of Absorption Refrigerator Driven by Two Different Heat Sources. 2nd Report, Hot Water and Combustion Gas.

    Nishiyama Noriyuki, Homma Ritsu, Wakimizu Hiroki, Kawai Sunao, Sugano Naoki, Saito Kiyoshi

    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B   60 ( 573 ) 1778 - 1784  1994

     View Summary

    There are some types of absorption refrigerators which are driven by two different heat sources. In the last paper, the refrigerator driven by hot water and steam which were the waste heat of fuel cell was simulated. In this paper, another type of refrigerator driven by hot water and combustion gas which makes up for the shortage of hot water as the waste heat is simulated and its characteristics are clarified. Furthermore, the optimum control of this machine to use hot water effectively is suggested.

    DOI CiNii

  • Studies on the Characteristics of Absorption Refrigerator Driven by Two Different Heat Sources. 1st Report, Hot Water and Steam.

    Saito Kiyoshi, Sugano Naoki, Kawai Sunao, Nishiyama Noriyuki, Homma Ritsu, Wakimizu Hiroki

    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B   60 ( 573 ) 1770 - 1777  1994

     View Summary

    In this report, we investigate the characteristics of an absorption refrigerator driven by two different heat sources, hot water and steam, to make use of waste heat from fuel cell. This type of refrigerator consists of the cyclic combination of the single-effect absorption refrigerator and the double-effect one. For absorption refrigerators, there are many types of cycles which depend on solution circulation and generator combinations. First, the optimum cycle from the viewpoint of recovering waste heat is clarified. Then the simulation model is constructed and the static characteristics are investigated. Furthermore, the effects of low-level heat source on the total COP is clarified. There is a lower limit of temperature of the low-level heat source because the temperature becomes lower than solution temperature. Furthermore, we discuss the temperature control when low-level heat source conditions vary and the flow rate of steam is varied.

    DOI CiNii

  • Simulation and Experimental Research of Dynamic Characteristics of Single-Effect Absorption Refrigerator Driven by Waste Hot Water

    Naoki Sugano, Kiyoshi Saito, Sunao Kawai, Noriyuki Nishiyama, Ritu Homma, Hiroki Wakimizu

    Japan Society of Mechanical Engineers   60 ( 576 ) 290 - 296  1994

    DOI

  • Next generation gas driven air conditioning system under the condition of the higher setting temperature of the room in the cooling mode and higher ventilation

    Katsuyuki Inagaki, Yasuaki Nakagawa, Kiyoshi Saito, Sunao Kawai

    International refrigeration and air conditioning conference at Purdue  

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Books and Other Publications

  • デシカント空調システムの基礎理論と最新技術

    齋藤, 潔(機械工学)

    S&T出版  2015.09 ISBN: 9784907002435

  • 未利用工場排熱の有効活用技術と実用展開 : 要素技術の開発・高性能化と導入事例・システム

    齋藤, 潔

    サイエンス&テクノロジー  2014.03 ISBN: 9784864280969

  • 高効率冷凍・空調・給湯機器の最新技術

    鹿園直毅, 齋藤潔 他

    シーエムシー出版  2011.11 ISBN: 9784781304328

  • エネルギーの辞典

    齋藤潔 他

    朝倉書店  2009.10

Misc

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Awards

  • 文部科学大臣表彰 (科学技術賞 研究部門)

    2022.04   文部科学省  

  • 早稲田リサーチアワード

    2022.02   早稲田大学  

  • 早稲田リサーチアワード

    2021.02   早稲田大学  

  • 早稲田リサーチアワード

    2020.04   早稲田大学  

  • 日本機械学会賞

    2013  

  • 日本冷凍空調学会学術賞

    2012  

  • ERDT Best paper award

    2010  

  • SAREK Best paper award

    2010  

  • 日本冷凍空調学会学術賞

    2010  

  • 日本機械学会奨励賞

    2001  

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Research Projects

  • エゼクター式吸収器によるハイブリッド吸収ヒートポンプの高効率化に関する研究

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(奨励研究(A))

  • ハイブリッド空調システムの動特性の究明と高効率運転に関する研究

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(若手研究(B))

  • 太陽熱駆動エジェクター式ヒートポンプの数理モデル構築と最適設計・制御に関する研究

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(基盤研究(C))

  • Optimum design of latent heat recovery heat exchangers

  • Study on the advanced tubes of absorber for absorption refrigerator

  • デシカント空調システムの性能評価

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Specific Research

  • 第二種吸収式ヒートポンプ用高温吸収器の流動, 伝熱特性評価

    2014  

     View Summary

    本研究は,第二種吸収式ヒートポンプの吸収器の伝熱性能を実験と解析により明らかにしようとするものである.従来の吸収器は,冷凍サイクルとして用いられたため,吸収溶液は40~50℃程度で伝熱管外表面を流動していた.これに対して第二種吸収ヒートポンプでは,150℃程度の吸収溶液が伝熱管外表面を流動するため,伝熱特性が大きく変わり,機器の過剰設計や性能不足といった問題を引き起こす. そこで,吸収器の要素試験により,溶液流量を1~6kg/min,溶液温度を60℃から160℃まで,広範囲に変化させて熱伝達率を測定した.また,この実験結果から,Nu数が0.03~1.0程度までの広範囲に吸収器の伝熱性能を予測可能な伝熱評価式を構築することができた.&nbsp;

  • エネルギーシステムの統一的解析理論の確立とヒートポンプサイクルの大域的非定常解析

    2010  

     View Summary

    ヒートポンプをはじめとしたエネルギーシステムにおいては,規格で評価された性能と実運転状況下で評価された性能に大きな乖離があることが指摘されている.このため,機器の真の性能向上を実現するためには,常に制御により非定常な状態で運転される機器の非定常実運転性能を詳細に把握し,高効率化を実現することが必要である.このような検討には,非定常シミュレーションが必要不可欠である.そこで,エネルギーシステムの中でも二相流の分岐・混合,チョークが発生するだけでなく,断続運転のような大振幅非線形非定常現象が発生するため解析が困難となるヒートポンプシステムを対象としてその非定常解析を実施する.同時にこのような最難関の非定常解析を通じて,申請者が15年にわたり,研究を実施してきたエネルギーシステムの統一的解析理論を非定常現象への拡張することを目的とする.これまでに,定常解析については,すでに本解析理論の構築をほぼ終え,多様なエネルギーシステムの解析を可能とし,単に論文発表だけでなく,受託研究を通じて実際にその成果を上げている.しかし,エネルギーシステムの非定常解析についてもすでに複数の研究を受託し,様々な成果を残してきたが,これらはすべて簡易な非定常解析モデルを採用した結果である.このため,ヒートポンプシステム,発電システム等のエネルギーシステムの中でしばしば見られる二相流の分岐・混合現象,高速二相流のチョーク等の現象に対してどのように一般性のある解析を実現するか,また非線形解析の収束性を改善し,どのように計算の安定性を改善するか等クリアーすべき課題が複数残されているのが現状である.そこで,本研究では,エネルギーシステムの非定常解析を実現する上で十分に検討がなされていない二相流の分岐・混合現象,高速2相流現象が含まれるとともに,断続運転,起動,停止運転等の大振幅非線形非定常現象を含むヒートポンプを対象とし,その大域的非定常解析を可能とする.また,ヒートポンプの高度な非定常解析を通じてエネルギーシステムの統一的理論を非定常解析にまで拡張することが目的となる.本研究の結果,大振幅非線形非定常問題となるヒートポンプの断続運転,起動・停止運転の合理的解析手法を明確とすることができた.また,システムの制御特性に大きな影響を及ぼす断続運転の周期,振幅等がシステムの性能にどのような影響を与えるかも詳細に明らかにすることができた.また,上記ヒートポンプの解析を実現しながら,ヒートポンプだけでなく,多様なエネルギーシステムの合理的解析を実現するための手法をさらに強化することができた.

  • 汎用熱システム解析手法による湿式除湿機の動特性の究明と最適設計・制御手法の確立

    2007  

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     近年,次世代の除湿装置としてリキッドデシカントシステムが注目されている.リキッドデシカントシステムは,低温排熱による駆動が可能なこと,結露を伴わず衛生的であること,吸収液による空気の除菌や消臭が可能なことなどの特徴がある. これまでに,実機による性能評価試験や,シミュレーションにより,リキッドデシカントシステムの有用性を示してきた.しかし,本システムの設計・制御手法などについては,いまだ確立されていないのが現状である.特に,システムの主要要素である吸収・再生器充填層における熱・物質移動特性は,不明な点が多く,その設計指針が得られているとは言えない. そこで,この吸収・再生器用充填層の要素試験を行い,その圧力損失や熱・物質移動特性について明らかにする.具体的には,乾燥時の圧力損失を実験とCFDによるシミュレーションの双方から評価する.さらに,熱・物質移動特性として,空気面速や溶液質量流束などが熱・物質通過率に与える影響について調査する.  その結果,今回対象とする充填層の乾燥時の圧力損失を測定したところ,レイノルズ数が200付近で層流から乱流に遷移することが分かった.また,このときのレイノルズ数と損失係数の関係を整理式としてまとめることができた. また,溶液質量流束および空気面速度が充填層出口の空気お温度・湿度に与える影響を実験的に明らかにできた.また,溶液質量流束が小さい領域で,空気が吸収熱により加熱されて排出されうることを確認した.さらに,物質通過率・熱通過率で整理したところ,溶液質量流束の増加に対しては物質通過率・熱通過率ともに上昇していくが,空気面風速の影響については明確な依存関係は見いだせなかった.

  • 三重効用吸収冷凍機のモデル化と最適設計に関する研究

    2004  

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     近年,地球環境保全や省エネルギー化の観点から吸収冷凍機の大幅な高効率化を実現する三重効用吸収サイクルの研究が進められている.しかし,三重効用吸収冷凍機の開発には,様々な技術的課題が残されている.特に高温の臭化リチウム溶液による高温再生器缶胴の腐食,高温再生器内の高圧化が大きな問題とされており,未だ実用化にはいたっていない. そこで,本研究ではシミュレーションにより,三重効用吸収冷凍機の特性を評価することにより,高温再生器内の低温,低圧化を可能とする設計指針を得ることを目的とする.具体的には,三重効用吸収サイクルの3つの代表的なサイクルであるシリーズ,リバース,パラレルを対象に,(1)蒸発器・吸収器をそれぞれ2基とした2段吸収の効果(2)冷却水経路を通常の実機とは逆に凝縮器→吸収器とした効果(3)パラレルフローにおける吸収溶液分配比を含むサイクルの最適化の効果について検討を行う. 三重効用吸収サイクルの最適化計算には,試行錯誤法と外点ペナルティ法を採用する.外点ペナルティ法は,制約条件付き最小化問題を無制約最小化問題に変換し,最適点を導出する手法である. 解析の結果,次のことが明らかとなった.(1)蒸発器・吸収器を2段とし,冷却水経路を従来とは逆に凝縮器から吸収器へと流動させることにより,COPを0.2以上向上させ,高温再生器溶液出口温度を約30℃低下させ,高温再生器内圧力をシリーズ,リバースフローでは約200kPa,パラレルフローでは約100kPa低減させることができる.(2)高温再生器出口温度に限界温度を設定し,その範囲で,パラレルフローの溶液分配比を含めたそれぞれのフローの最適点での性能比較を行った結果,パラレルフローは,COPが最も高く,高温再生器圧力も最も低くできる.

  • エゼクター式吸収器によるハイブリッド吸収ヒートポンプの高効率化に関する研究

    2002  

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     エゼクターは,動作流体の膨張過程において不可逆損失として熱エネルギーに変換されてしまう力学的エネルギーを回収することができる.このため,吸収式冷凍機に用いられているいくつかの膨張弁のかわりにエゼクターを採用し,この力学的エネルギーを吸収器内圧力の上昇に用いることで冷凍機の大幅な効率向上が可能である. そこで,本研究では,シミュレーションによりエゼクターの特性解析ならびにエゼクターを吸収冷凍機に組み入れた場合の性能を評価することを目的とする. まず,エゼクターならびに吸収式冷凍機のシミュレーションモデルを構築した.ここでは,エゼクターを駆動流ノズル,吸引流ノズル,混合部,ディフューザーからなるシステムと見なし,それぞれの要素を連続方程式,エネルギー方程式,断熱効率からなる数式モデルで表す.そして,それぞれのモデルを接続することによりエゼクター全体のモデルを構築した.同様の手法で,吸収式冷凍機全体のモデルも構築した. その結果,まず,エゼクターの特性として排出流の排圧が最大となる最適な混合部入口圧力が存在することが明らかとなった.この点では,エゼクター内でのエントロピー生成が最小となる. また,水-アンモニアを作動媒体とする吸収式冷凍機において冷凍機の蒸発温度が-10℃の場合には約15%もの性能向上が見込めることがわかった.

  • WMVRハイブリッド吸収冷凍機の最適設計・制御に関する研究

    2000  

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     吸収冷凍機はコージェネレーションにおける排熱を駆動熱源として利用することが可能なことから、省エネルギーを実現できる有効な冷凍、空調機器である。排熱駆動吸収冷凍機により排熱の利用が進めば、一次エネルギーの消費に伴うCO2の排出量を削減することが可能となり、地球環境保護に対して極めて有効ということができる。ところが吸収冷凍機の駆動源として排熱だけを使用すると、冷房負荷が減少した場合には余剰な排熱が生じたり、排熱量が不足した場合には所定の冷房負荷を満足することができなくなる。このような場合には、全冷房負荷を排熱駆動の冷凍機だけで担うことなく、安定した駆動源で駆動される冷凍機でバックアップしていくことが有効となる。 そこで、本研究では、圧縮式サイクル(MVRサイクル)と排熱駆動の単効用吸収サイクルを複合することにより一台の冷凍機で排熱と動力を同時に用いて駆動可能なハイブリッド吸収冷凍機を新たに提案する。本冷凍機により排熱の変動に対して動力あるいは電力という安定した駆動源でのバックアップ運転が可能となる。このハイブリッド吸収冷凍機を採用すれば、ガスエンジンヒートポンプの大幅な効率向上、太陽エネルギーあるいはプロセス工場などで発生する排熱の有効利用による省エネルギーを実現することが可能となる。 本冷凍機を対象に、詳細な特性解析を行い、設計に関する指針を得ることを目的として検討を進めた結果、次のような結論を得た。 (1)一般的な吸収冷凍機の入力条件で、本冷凍機を設計した結果、排熱側サイクルのCOPはおよそ0.75、MVR側サイクルのCOPはおよそ4.92と極めて高い効率が得られることがわかった。 (2)MVR再生器内の圧力について検討を行った結果、MVR再生器内の圧力は、圧縮機の容積と吸収溶液の腐食性を考慮すると最適な圧力が存在することがわかった。 (3)濃度幅の増加により、動作点におけるMVR側、排熱側サイクルそれぞれのCOPは向上するが、MVR再生器出口の吸収溶液の温度が上昇するため腐食の問題を考慮することが必要となることがわかった。

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Overseas Activities

  • 熱システムにおける汎用的解析手法ならびに新要素技術の確立

    2005.06
    -
    2006.05

    アメリカ   Univ. of Illinois

 

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