Updated on 2022/05/21

写真a

 
GIANNETTI, Niccolo
 
Affiliation
Affiliated organization, Waseda Institute for Advanced Study
Job title
Associate Professor(non-tenure-track)

Concurrent Post

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

Education

  • 2013.09
    -
    2016.03

    Waseda University   Department of Applied Mechanics and Aerospace Engineering   Doctoral course  

  • 2012.10
    -
    2013.01

    Association of Professional Engineers of Florence (Italy)   Industrial Engineer (Professional Qualification)  

  • 2010.09
    -
    2012.10

    University of Florence (Italy)   Department of Industrial Engineering, Mechanical Engineering   Graduate school of Engineering (Master program)  

  • 2007.09
    -
    2010.12

    University of Florence (Italy)   Department of Industrial Engineering, Mechanical Engineering   Undergraduate school of Engineering (Bachelor program)  

  • 2002.02
    -
    2007.07

    Niccolo Rodolico high school, Florence (Italy)   Science oriented program  

Degree

  • Waseda University   Doctor of Engineering

Research Experience

  • 2021.04
    -
    Now

    Waseda University   Waseda Institute for Advanced Study   Associate Professor   Associate Professor (without tenure)

  • 2019.04
    -
    2021.03

    Waseda University   Institue for Advanced Study   Assistant Professor

  • 2017.04
    -
    2019.03

    Waseda University   Department of Applied Mechanics and Aerospace Engineering   Assistant Professor

  • 2014.04
    -
    2017.03

    Waseda University   Department of Applied Mechanics and Aerospace Engineering   Research Associate

  • 2013.03
    -
    2013.08

    University of Florence   Department of Industrial Engineering   Scholarship holder Researcher

Professional Memberships

  • 2019.09
    -
    Now

    The Japan Society of Mechanical Engineers

  • 2019.05
    -
    Now

    International Institute of Refrigeration (IIR)

  • 2014.01
    -
    Now

    JAPAN SOCIETY OF REFRIGERATING AND AIR CONDITIONING ENGINEERS

  • 2013.01
    -
    Now

    Association of Professional Engineers of Florence (Italy)

 

Research Areas

  • Thermal engineering   Turbomachinery

  • Thermal engineering   Energy Storage

  • Thermal engineering   Heat and Mass Transfer

  • Thermal engineering   Thermodynamic Optimization

  • Thermal engineering   Sorption

  • Thermal engineering   Refrigeration and Air-Conditioning

  • Fluid engineering   Fluid Dynamics

  • Control and system engineering

▼display all

Research Interests

  • Turbomachinery

  • Energy storage

  • Refrigeration and Air-Conditioning

  • Fluid Dynamics

  • Sorption

  • Thermodynamic Optimization

  • Heat and Mass Transfer

▼display all

Papers

  • Multiobjective geometry optimization of microchannel heat exchanger using real-coded genetic algorithm

    John Carlo S. Garcia, Hiroki Tanaka, Niccolo Giannetti, Yuichi Sei, Kiyoshi Saito, Mamoru Houfuku, Ryoichi Takafuji

    Applied Thermal Engineering   202   117821 - 117821  2022.02  [Refereed]

    DOI

  • Performance assessment of an R32 commercial heat pump water heater in different climates

    Muhamad Yulianto, Takaoki Suzuki, Zheng Ge, Takashi Tsuchino, Masakazu Urakawa, Shigeru Taira, Yoichi Miyaoka, Niccolo Giannetti, Liang Li, Kiyoshi Saito

    Sustainable Energy Technologies and Assessments   49   101679 - 101679  2022.02  [Refereed]

    DOI

  • Variational formulation of non-equilibrium void fraction

    Niccolo Giannetti, Moojoong Kim, Hiroaki Yoshimura, Kiyoshi Saito

    International Journal of Heat and Mass Transfer   183   122119 - 122119  2022.02  [Refereed]

    DOI

  • Thermodynamic investigation of asynchronous inverse air cycle integrated with compressed-air energy storage

    Niccolò Giannetti, Adriano Milazzo, Kiyoshi Saito

    Journal of Energy Storage   45   103750 - 103750  2022.01  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

  • Intelligent performance prediction of air conditioning systems based on refrigerant temperatures

    Sholahudin, Niccolo Giannetti, Yoichi Miyaoka, Kiyoshi Saito

    Thermal Science and Engineering Progress   27   101150 - 101150  2022.01  [Refereed]

    DOI

  • Design of a Numerical Simulator for Finned-Tube Heat Exchangers with Arbitrary Circuitry

    John Carlo S. Garcia, Niccolo Giannetti, Daryl Anne B. Varela, Richard Jayson Varela, Seiichi Yamaguchi, Kiyoshi Saito, Menandro S. Berana

    Heat Transfer Engineering     1 - 19  2021.11  [Refereed]

    DOI

  • 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  [Refereed]

    Authorship:Lead author, Corresponding author

    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  [Refereed]

    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   100856 - 100856  2020.12  [Refereed]

     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

  • 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  [Refereed]

    Authorship:Lead author, Corresponding author

     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

  • 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   115985 - 115985  2020.11  [Refereed]

     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  [Refereed]

    Authorship:Lead author, Corresponding author

     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  [Refereed]

    Authorship:Lead author, Corresponding author

    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  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

  • Optimization of HVAC system energy consumption in a building using artificial neural network and multi-objective genetic algorithm

    Nasruddin, Sholahudin, Pujo Satrio, Teuku Meurah, Indra Mahliad, Niccolo Giannetti, Kiyoshi Saito

    Sustainable Energy Technologies and Assessments   35   48 - 57  2019.10  [Refereed]

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

    Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito

    International Journal of Refrigeration   105   135 - 147  2019.09  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

  • Seasonal Performance Evaluation of CO2 Open Refrigerated Display Cabinets

    Mark Anthony Redo, Keisuke Ohno, Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito

    Applied Thermal Engineering   ( 114354 )  2019.09  [Refereed]

  • Characterization of two-phase flow distribution in microchannel heat exchanger header for air-conditioning system

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

    Experimental Thermal and Fluid Science   106   183 - 193  2019.09  [Refereed]

  • A practical heat and mass transfer model between air and ionic liquid solution in an internally cooled dehumidifier with partial wetting.

    Richard J. VARELA, Niccolo GIANNETTI, Hifni M. ARIYADI, Seiichi YAMAGUCHI, Kiyoshi SAITO, Xin-Ming WANG, Hiroshi NAKAYAMA

    Proceedings of the 25th IIR International Congress of Refrigeration: Montréal , Canada, August 24-30, 2019.    2019.08  [Refereed]

    DOI

  • Comparative analysis of ionic liquids as sorptive media for absorption cooling systems.

    Hifni M. ARIYADI, Niccolo GIANNETTI, Seiichi YAMAGUCHI, Kiyoshi SAITO

    Proceedings of the 25th IIR International Congress of Refrigeration: Montréal , Canada, August 24-30, 2019.    2019.08  [Refereed]

    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   113809  2019.07  [Refereed]

  • 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  [Refereed]

    Authorship:Lead author, Corresponding author

     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

  • 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  [Refereed]

    Authorship:Lead author, Corresponding author

     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  [Refereed]

    Authorship:Lead author, Corresponding author

    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]

    Authorship:Lead author, Corresponding author

    DOI

  • Operation performance enhancement of single-double-effect absorption chiller

    Arnas Lubis, Jongsoo Jeong, Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito, Hajime Yabase, Muhammad I. Alhamid, Nasruddin

    Applied Energy   219   299 - 311  2018.06  [Refereed]

     View Summary

    Absorption chillers constitute a valuable option for utilising solar energy. Specifically, when installed in tropical regions, this technology ideally matches the needs for refrigeration and air-conditioning because of the abundance of solar energy throughout the year. A single-double-effect absorption chiller combines the single and double-effect configurations to compensate for the unpredictable instantaneous availability of solar radiation and cooling load fluctuations. The operative performance of this system is strongly affected by internal parameters such as the absorber outlet solution flow rate and the solution distribution ratio, which connect the operability of the single and double-effect configurations. Therefore, these important parameters are currently used to maximise system performance while assuring its stability. This study discusses how the COP of a single-double-effect absorption chiller, for solar cooling applications in tropical areas, can be maximised (1.55 at full load, and up to 2.42 at 60% partial load) by manipulating those internal parameters. The simulation results were compared with the experimental data (field test data) and, by adopting the appropriate control method, showed an improvement of the system performance between 12 and 60% when compared to a corresponding double-effect configuration.

    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  [Refereed]

     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.

    DOI

  • Heat and mass transfer coefficients of falling-film absorption on a partially wetted horizontal tube

    Niccolò Giannetti, Andrea Rocchetti, Seiichi Yamaguchi, Kiyoshi Saito

    International Journal of Thermal Sciences   126   56 - 66  2018.04  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    Detailed, reliable, and time-saving methods to predict the transfer characteristics of horizontal-tube falling-film absorbers are critical to control system operability, such that it is closer to its technical limitations, and to optimise increasingly complex configurations. In this context, analytical approaches continue to hold their fundamental importance. This study presents an analytical solution of the governing transport equations of film absorption around a partially wetted tube. A film stability criterion and a wettability model extend the validity range of the resulting solution and increase its accuracy. Temperature and mass fraction fields are analytically expressed as functions of Prandtl, Schmidt, and Reynolds numbers as well as tube dimensionless diameter and wetting ratio of the exchange surface. Inlet conditions are arbitrary. The Lewis number and a dimensionless heat of absorption affect the characteristic equation and the corresponding eigenvalues. Consequently, local and average transfer coefficients are estimated and discussed with reference to the main geometrical and operative parameters. Finally, a first comparison with the numerical solution of the problem and experimental data from previous literature is presented to support the simplifying assumptions, which are introduced and as a first model validation.

    DOI

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

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

    International Journal of Refrigeration   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.

    DOI

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

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

    International Journal of Refrigeration   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.

    DOI

  • Thermodynamic analysis of irreversible desiccant systems

    Giannetti N, Yamaguchi S, Rocchetti A, Saito K

    Entropy   20 ( 8 )  2018  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

  • Performance evaluation method of heat pump driven refrigerated display cabinets

    Keisuke Ohno, Mark Anthony Redo, Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito

    Refrigeration Science and Technology   2018-   294 - 301  2018  [Refereed]

     View Summary

    Annual heat load, energy consumption and COP of open refrigerated display cabinets (ORDC) driven by heat pump in supermarkets are assessed by means of a dedicated performance evaluation method. The system modelling approach is firstly presented, and subsequently fitted to experimental data measured within actual equipment working in a comprehensive range of operative conditions. The obtained characteristic equations for estimating the heat load of the ORDC and energy consumption of the condensing unit are employed for a first screening of the results with reference to the effect of the display cabinet set temperature, refrigerant evaporating temperature and supermarket room temperature. Seasonal temperature distributions of three representative locations are applied for the performance calculation of a selected arrangement of 5 different models of ORDCs in a store. This methodology is integrated in a dedicated software, with a user friendly interface, which is generally capable of predicting the annual performance of various combinations of different ORDCs and can therefore be used for benchmarking and identifying energy conservation opportunities.

    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]

    Authorship:Lead author, Corresponding author

     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

  • Cascade refrigeration system with inverse Brayton cycle on the cold side

    Niccolo Giannetti, Adriano Milazzo, Andrea Rocchetti, Kiyoshi Saito

    APPLIED THERMAL ENGINEERING   127   986 - 995  2017.12  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    temperature refrigeration of cold stores poses some specific issues: single stage, vapour compression cycles have modest COP at low evaporation temperature; cold evaporator surfaces require de-frosting and a fan for air circulation; a part of the refrigeration load may be delivered at intermediate temperature levels, e.g. for the cold store loading dock. Cascade system may improve the COP and add flexibility on the temperature levels and working fluids, but the problems related to the cold evaporator surface remain unsolved.
    The refrigeration system presented herein features a cascade configuration combining a vapour compression cycle and an inverse Brayton cycle. Both cycles use "natural" fluids, complying with strictest regulations. The top cycle uses Ammonia in order to increase efficiency, while the bottom cycle uses air, which directly circulates in the cold space and hence eliminates the cold heat exchanger. A detailed thermodynamic analysis allows a complete screening of the relevant design parameters for an overall system optimization.
    The results show that, notwithstanding the intrinsic gap of efficiency suffered by the Brayton cycle, the proposed system features an acceptable global performance and widens the implementation field of this technology. This system configuration shows a COP 50% higher than the corresponding simple Brayton cycle at temperatures of the refrigerated storage of -50 degrees C. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

  • 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]

    Authorship:Lead author, Corresponding author

     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

  • Solar-assisted single-double-effect absorption chiller for use in Asian tropical climates

    Arnas Lubis, Jongsoo Jeong, Kiyoshi Saito, Niccolo Giannetti, Hajime Yabase, Muhammad Idrus Alhamid, Nasruddin

    RENEWABLE ENERGY   99   825 - 835  2016.12  [Refereed]

     View Summary

    Solar energy is accessible throughout the year in tropical regions. The latest development of absorption chillers has demonstrated that these systems are suitable for effective use of solar energy. The utilisation of solar energy for heat-driven cooling systems has significant advantages. Without a doubt, solar energy represents a clean energy source that is available without any additional fuel cost, and that can be proportionally accessible when the cooling load increases during the middle hours of the day. This study focuses on a single-double-effect absorption chiller machine that was installed in Indonesia. The system is driven by a dual-heat source that combines gas and solar energy. This system is characterised by simulating its performance in various conditions in terms of the cooling water (28-34 degrees C) and the hot water (75-90 degrees C) inlet temperatures. The reference operating condition of this system is 239 kW of cooling capacity. The mathematical model is validated and shows a good agreement with experimental data. In the operative range considered, simulation results yield a coefficient of performance between 1.4 and 3.3, and a gas reduction ratio from 7 to 58% when compared to a double-effect absorption chiller driven by gas. Based on the simulation results, this system is expected to have a good potential for widespread use in tropical Asia regions. (C) 2016 Elsevier Ltd. All rights reserved.

    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]

    Authorship:Lead author, Corresponding author

     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

  • Optimization of a cascade refrigeration system using refrigerant C3H8 in high temperature circuits (HTC) and a mixture of C2H6/CO2 in low temperature circuits (LTC)

    Nasruddin, S. Sholahudin, N. Giannetti, Arnas

    APPLIED THERMAL ENGINEERING   104   96 - 103  2016.07  [Refereed]

     View Summary

    This paper discusses the multi-objectives optimization of a cascade refrigeration system using refrigerant C3H8 in high temperature circuits (HTC) and a mixture of C2H6/CO2 in low temperature circuits (LTC). The evaporator temperature, condenser temperature, C2H6/CO2 mixture condensation temperature, cascade temperature differences, and the CO2 mass fraction are chosen as the decision variables. Whereas cooling capacity, cold space temperature, and ambient temperature are taken as the constraints. The purpose of this research is to design a cascade refrigeration system whose optimum performance are defined in terms of economics and thermodynamics. Accordingly, there are two objective functions that should be simultaneously optimized including the total annual cost which consists of the capital and operational cost and the total exergy destruction of the system. To this aim, the optimum operating temperature of the system and CO2 fraction should be determined so that the system has minimum exergy destruction and annual cost. Results show that, the optimum value of the decision variables for this system can be determined by trade-off between annual cost and exergy destruction. (C) 2016 Elsevier Ltd. All rights reserved.

    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  [Refereed]

    Authorship:Lead author, Corresponding author

     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

  • 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  [Refereed]

    Authorship:Lead author, Corresponding author

     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

  • Analytical description of falling film absorption

    Giannetti N, Rocchetti A, Saito K, Yamaguchi S

    ACRA 2016 - 8th Asian Conference on Refrigeration and Air-Conditioning    2016  [Refereed]

    Authorship:Lead author, Corresponding author

  • 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  [Refereed]

    Authorship:Lead author, Corresponding author

     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  [Refereed]

    Authorship:Lead author, Corresponding author

     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

  • Local entropy generation analysis of water vapour absorption in a LiBr-H2O solution film, over a horizontal cooled tube

    Niccolò Giannetti, Andrea Rocchetti, Kiyoshi Saito, Seiichi Yamaguchi

    Refrigeration Science and Technology     786 - 793  2015  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    This study is based on a numerical analysis of water vapour absorption in a laminar, gravity driven, viscous, incompressible liquid film of LiBr-H2O solution, flowing over a horizontal cooled tube. The hydrodynamic description is based on Nusselt boundary layer assumptions. A local entropy generation calculation can be performed referring to velocity, temperature and concentration fields. From a general form of volumetric entropy generation, a suitable expression for the absorption process has been obtained and different irreversibility sources have been highlighted. The impact of each term (fluid friction, heat transfer, mass transfer and their coupling effects) has been locally examined. Results have been explored for different tube radii, wall temperatures and operative conditions (representing both chiller and heat transformer configurations), in order to characterise the process from a second law point of view and establish a criterion for the optimisation of the absorber.

    DOI

  • Cascade refrigeration system with inverse Brayton cycle on the cold side

    Niccolò Giannetti, Adriano Milazzo, Andrea Rocchetti

    Refrigeration Science and Technology     2846 - 2853  2015  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    The cold store refrigeration system proposed herein features a cascade configuration which has a vapour compression cycle as the top cycle and an inverse Brayton as the bottom cycle. The cold store air is used as working fluid in the Brayton cycle. Therefore, the cold side heat exchanger (that would be the evaporator in a vapour compression cycle) is replaced by a cold air inlet. Frost formation inside the cold store, as well as the heat load due to the air circulation fan, are hence eliminated. On the other hand, the Brayton cycle has lower efficiency when compared to vapour compression cycles. This gap may be reduced once the temperature range is lowered by the cascade configuration. The top vapour compression cycle may also refrigerate the loading dock. This paper describes a first screening of the relevant design parameters for an overall system optimization.

    DOI

  • Entropy parameters for desiccant wheel design

    Niccolo Giannetti, Andrea Rocchetti, Kiyoshi Saito, Seiichi Yamaguchi

    APPLIED THERMAL ENGINEERING   75   826 - 838  2015.01  [Refereed]

    Authorship:Lead author, Corresponding author

     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

  • Thermodynamic analysis of regenerated air-cycle refrigeration in high and low pressure configuration

    N. Giannetti, A. Milazzo

    INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID   40   97 - 110  2014.04  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    A thermodynamic analysis is performed on open, regenerated, inverse air-cycles, focussing on low temperature refrigeration, in order to provide general optimization criteria, support for a rational configuration choice and potential performance improvement for this specific application. The effect of high regenerator effectiveness (0.95) is explored, showing that it may double the air cycle COP in the case at hand. Low and high pressure configurations (i.e. featuring only one heat exchanger on the cold or hot cycle side) are compared. High pressure configuration, normally preferred in the field of low temperature refrigeration, has a lower efficiency, but the gap reduces as regenerator effectiveness increases. Avoidance of a cold heat exchanger eliminates frosting problems and power input for the circulation fan, so that the small COP decrease suffered by the high pressure cycle can easily be compensated for and eventually yield higher average plant efficiency. The feasibility of such a highly effective regenerator, already reported in the literature, is demonstrated using classic Kays and London (1964) data. (C) 2013 Elsevier Ltd and IIR. All rights reserved.

    DOI

▼display all

Awards

  • Outstanding Lecture Award

    2021.09   Japan Society of Refrigerating and Air Conditioning Engineers (JSRAE)   Assessment of Marangoni convection and partial wetting in falling film absorbers

    Winner: Niccolo Giannetti

  • Outstanding contribution in Reviewing

    2018.06   Elsevier, Applied Energy  

    Winner: Niccolo Giannetti

  • Outstanding contribution in Reviewing

    2018.02   Elsevier, International Journal of Refrigeration  

    Winner: Niccolo Giannetti

  • ISHPC2017, Young Researcher Award

    2017.08   2017 International Sorption Heat Pump Conference Organizing Committee   Simplified expressions of the transfer coefficients on a partially wet absorber tube

    Winner: Niccolo Giannetti

  • Japan Refrigeration and Air Conditioning Association Award

    2016.09   Japan Refrigeration and Air Conditioning Association   Thermo-fluid dynamics of falling film type vapour absorption process

    Winner: Niccolo Giannetti

Research Projects

  • Lagrange-Dirac Systems and Applications

    Japan Science and Technology Agency (JST) 

    Project Year :

    2019.04
    -
    2024.03
     

  • Development of Assessment Techniques for Next-Generation Refrigerants with Low GWP Values

    New Energy and Industrial Technology Development Organization (NEDO) 

    Project Year :

    2018.04
    -
    2023.03
     

  • Study on Unsteady Analysis of Two-Stage Turbo Chiller

    Mitsubishi Heavy Industries Thermal Systems 

    Project Year :

    2021.04
    -
    2022.03
     

    Niccolo Giannetti

  • Research on Capacity Estimation Method of Multi-Air Conditioners for Buildings by Machine Learning

    Tokyo Electric Power Company Holdings 

    Project Year :

    2020.04
    -
    2022.03
     

  • Research and development of technology for innovative use of unused heat energy / Research and development of technology for innovative use of unused heat energy

    New Energy and Industrial Technology Development Organization (NEDO) 

    Project Year :

    2015.04
    -
    2021.03
     

  • Analysis of inverse air cycle refrigeration systems for low temperature applications with particular regard to the problem of frost formation

    Research grant service, biomedical and technological center of the University of Florence  Post-graduate research grant, Call for proposal no. 185 of December 17th, 2012

    Project Year :

    2013.03
    -
    2013.08
     

    Niccolo Giannetti

  • Study on Marangoni convection within high temperature absorbers for heat transformer applications

    Waseda University  2017 B - 122 Specific assignment B, Specific subject research grant

    Niccolo Giannetti

▼display all

Presentations

  • Variational Framework for the Theoretical Modelling of Thermal Systems

     [Invited]

    WOI(Waseda Open Innovation Forum) 

    Presentation date: 2022.03

    Event date:
    2022.03
     
     
  • Characterization and Freezing Prediction of Supercooled Water Droplets Formed on Solid Surface

    Yuta SAKAI, Niccolo GIANNETTI, Jongsoo JEONG, Kiyoshi SAITO

    JSRAE Annual Conference 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Development of Assessment Techniques for Next-Generation Refrigerant with Low GWP Values 6th report: Efforts and outcomes on simulator development in FY2020

    Jongsoo Jeong, Giannetti Niccolo, Yoichi Miyaoka, Kiyoshi Saito

    JSRAE Annual Conference 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Efficiency Improvement of Liquid Desiccant Air Conditioning System

    Tatsuki HOSHO, Richard Jayson VARELA, Niccolo GIANNETTI, Jongsoo JEONG, Kiyoshi SAITO

    JSRAE Annual Conference 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Assessment of Marangoni convection and partial wetting in falling film absorbers

    Niccolo Giannetti

    JSRAE Annual Conference 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Development of Assessment Techniques for Next-Generation Refrigerant with Low GWP Values Fifth report: Efforts and outcomes on development of dynamic performance evaluation equipment

    Yoichi MIYAOKA, Niccolo GIANNETTI, Jongsoo JEONG, Kiyoshi SAITO

    JSRAE Annual Conference 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Development of Assessment Techniques for Next-Generation Refrigerants with Low GWP Values Fourth report: Efforts and outcomes on heat exchanger optimization in FY 2020

    Niccolo GIANNETTI, John Carlo, GARCIA, Richard, Jayson VARELA, Yuichi SEI, Koji ENOKI, Jongsoo JEONG, Kiyoshi SAITO

    JSRAE Annual Conference 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Numerically Trained Artificial Neural Network for Experimental Performance Prediction of Air Conditioning Systems

    Sholahudin, Giannetti N, Miyaoka Y, Jeong J, Saito K

    2021 60th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Digital Cloning of Air-Conditioners: Scalable and generalizable system identification method using Artificial Neural Network

    Niccolo Giannetti  [Invited]

    Environmental Engineering Division, Japan Society of Mechanical Engineers 'Thermoinformatics Research Group', 2nd meeting. 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Non-Equilibrium Formulation of Void Fraction in Two-Phase Flows

    Niccolo GIANNETTI, Moojoong KIM, Hiroaki YOSHIMURA, Kiyoshi SAITO

    Thermophysical properties and Transfer Processes of Refrigerants Conference 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • CFD investigation of the wetting characteristics of aqueous ionic liquid solution on an aluminum fin-tube substrate

    Richard Jayson VARELA, Hifni ARIYADI, Niccolo GIANNETTI, Kiyoshi SAITO

    Thermophysical properties and Transfer Processes of Refrigerants Conference 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Modeling of Flow Distribution in Multi-Branch Channels using the Second Law of Thermodynamics

    Mark Anthony REDO, Niccolo GIANNETTI, Hiroaki YOSHIMURA, Kiyoshi SAITO

    Thermophysical properties and Transfer Processes of Refrigerants Conference 2021 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Design optimization of three-fluid desiccant contactor using genetic algorithm

    Hosho Tatsuki, Varela Richard Jayson, Giannetti Niccolo, Jeong Jongsoo, Miyaoka Yoichi, Saito Kiyoshi

    ISHPC2021 

    Presentation date: 2021.08

    Event date:
    2021.08
     
     
  • The Influence of Temperature on Marangoni Convection during Vapor Absorption

    Giannetti Niccolo, Fukui Ryota, Fleßner Christian, Meyer Thomas, Saito Kiyoshi

    ISHPC2021 

    Presentation date: 2021.08

    Event date:
    2021.08
     
     
  • Scalability and generalization in HVAC performance prediction using Artificial Neural Network

    Damiano DONDINI, SHOLAHUDIN, Niccolo GIANNETTI, Yoichi MIYAOKA, Kiyoshi SAITO

    第31回 環境工学総合シンポジウム2021 

    Presentation date: 2021.07

    Event date:
    2021.07
     
     
  • Assessment of surfactant-induced Marangoni convection within high-temperature aqueous Lithium-Bromide solution

    N. Giannetti

    The 14th IIR Gustav Lorentzen Conference on Natural refrigerants 

    Presentation date: 2020.12

    Event date:
    2020.12
     
     
  • Numerical Investigation of CO2 Heat Pump Water Heater Performance

    M. Yulianto, N. Giannetti, co-auth

    The 14th IIR Gustav Lorentzen Conference on Natural refrigerants 

    Event date:
    2020.12
     
     
  • Experimental performance analysis and simulation of an internally cooled liquid desiccant air conditioning system using a novel ionic liquid

    R.J. Varela, N. Giannetti (co-author)

    The 14th IIR Gustav Lorentzen Conference on Natural refrigerants 

    Event date:
    2020.12
     
     
  • Thermodynamic investigation of asynchronous open inverse air cycle integrated with compressed air energy storage

    A. Milazzo, N. Giannetti, K. Saito

    The 14th IIR Gustav Lorentzen Conference on Natural refrigerants 

    Event date:
    2020.12
     
     
  • Semi-Theoretical Formulation of Annular Flow Void-Fraction

    Niccolo Giannetti

    The 11th International Meeting on Advances in Thermofluids 

    Presentation date: 2019.11

    Event date:
    2019.11
     
     
  • Numerical investigation of mixed refrigerants flow in the expansion valve

    INOUE Yohei, MINATO Akihiko, SEI Yuichi, SEKIGUCHI Michie, SAITO Kiyoshi, YAMAGUCHI Seiichi, GIANNETTI Niccolo, MIYAOKA Yoichi

    JSRAE Annual Conference 

    Presentation date: 2019.09

  • Development of Assessment Techniques for Next Generation Refrigerant with Low GWP Values

    MIYAOKA Yoichi, GIANNETTI Niccolo, YAMAGUCHI Seiichi, SAITO Kiyoshi, ENOKI Koji, INOUE Yohei, SEI Yuichi, MINATO Akihiko, SEKIGUCHI Michie

    JSRAE Annual Conference 

    Presentation date: 2019.09

  • Semi-theoretical model of ionic liquid wetting characteristics on a gas-liquid finned-tube contactor

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

    25th IIR International Congress of Refrigeration 

    Presentation date: 2019.08

  • A practical heat and mass transfer model between air and ionic liquid solution in an internally cooled dehumidifier with partial wetting

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

    25th IIR International Congress of Refrigeration 

    Presentation date: 2019.08

  • Comparative analysis of ionic liquids as sorptive media for absorption cooling systems

    Hifni Ariyadi, Niccolo Giannetti, Seiichi Yamaguchi, Kiyoshi Saito

    25th IIIR International Congress of Refrigeration 

    Presentation date: 2019.08

  • Development of Finned-Tube Heat Exchanger Simulator for Heat Pumps

    S. Yamaguchi, J.C. Garcia, N. Giannetti, K. Saito

    International Workshop on Environmental Engineering 

    Presentation date: 2019.06

  • Theoretical Formulation of Two-phase Flow Distribution in Microchannel Heat Exchangers using Electric Circuit Analogy

    Niccolo Giannetti, M.A. Redo, J. Jeong, S. Yamaguchi, K. Saito, H. Kim

    International Workshop on Environmental Engineering 

    Presentation date: 2019.06

  • Numerical Simulation of Falling-Film Absorbers at High Temperature

    Y. Ohashi, R. Moriwaki, N. Giannetti, S. Yamaguchi, K. Saito

    International Workshop on Environmental Engineering 

    Presentation date: 2019.06

  • Numerical simulations of finned-tube heat exchangers with arbitrary connectivity and flexible set of input conditions

    The 5th International Symposium on Innovative Materials and Processes in Energy Systems 

    Event date:
    2018.10
     
     
  • Theoretical prediction of the wetting characteristics of aqueous ionic liquid on a finned-tube desiccant contactor

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2018.09

  • Annual performance evaluation of CO2 refrigerated display cabinets relative to geographical location

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2018.09

  • Influence of the Fluid Distribution Width on the Wettability of Rivulet Flow over Vertical Flat Surfaces

    Niccolo Giannetti

    17th International Refrigeration and Air Conditioning Conference at Purdue 

    Presentation date: 2018.07

  • Film Rupture and Partial Wetting over Flat Surfaces

    Niccolo Giannetti

    17th International Refrigeration and Air Conditioning Conference at Purdue 

    Presentation date: 2018.07

  • Modelling of water vapor absorption by aqueous ionic liquid fluids in a vertical-tube falling film absorber

    Niccolo Giannetti

    Grand Renewable Energy 2018 

    Presentation date: 2018.06

  • MULTISTAGE TYPE-II ABSORPTION HEAT PUMP FOR STEAM GENERATION UP TO 180°C; Development and Performance Demonstration

    Niccolo Giannetti  [Invited]

    9th Asian Conference on Refrigeration and Air Conditioning 

    Presentation date: 2018.06

  • Thermodynamic analysis of irreversible desiccant systems

    Niccolo Giannetti

    Entropy 2018: From Physics to Information Sciences and Geometry 

    Presentation date: 2018.05

  • Performance evaluation method of heat pump driven refrigerated display cabinets

    Niccolo Giannetti

    5th IIR Conference on Sustainability and the Cold Chain 

    Presentation date: 2018.04

  • Thermodynamic modelling of Two-Phase Flow within Heat Pump systems

    Niccolo Giannetti  [Invited]

    International Workshop on The Multi-phase Flow 

    Presentation date: 2017.12

  • Two-phase Flow Distribution at Wider Flow Range within the Vertical Header of Microchannel Heat Exchanger

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2017.09

  • Annual Performance Evaluation of Refrigerated Display Cabinets

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2017.09

  • Simple expressions of the heat and mass transfer coefficients for horizontal-tube falling film absorbers

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2017.09

  • Wetting Characteristics of falling films on a fin-tube contactor

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2017.09

  • Numerical simulation of Marangoni convection within horizontal tube falling film absorbers

    Niccolo Giannetti

    28th International Symposium on Transport Phenomena 

    Presentation date: 2017.09

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

    Niccolo Giannetti

    International Sorption Heat Pump Conference 

    Presentation date: 2017.08

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

    Niccolo Giannetti

    International Sorption Heat Pump Conference 

    Presentation date: 2017.08

  • Correlations for the Heat and Mass Transfer Coefficients in a Structured Packed Bed Regenerator

    Niccolo Giannetti

    International Sorption Heat Pump Conference 

    Presentation date: 2017.08

  • Two-phase flow distribution of R410A within the vertical header of a microchannel heat exchanger

    Niccolo Giannetti

    27th Symposium on Environmental Engineering 

    Presentation date: 2017.07

  • Thermodynamic modelling of humid-air expansion within an R717/R729 cascade refrigeration system for cold store applications

    Niccolo Giannetti

    5th IIR International Conference on Thermophysical Properties and Transfer Processes of Refrigerants 

    Presentation date: 2017.04

  • Experiment and Visualization of R410A Flow Distribution within the Vertical Header of Microchannel Heat Exchanger

    Niccolo Giannetti

    5th IIR Int. Conference on Thermodynamics and Transport Processes 

    Presentation date: 2017.04

  • Derivation and Validation of Dimensionless Models for the Heat and Mass Transfer Coefficients of a Structured Packed Bed Dehumidifier

    Niccolo Giannetti

    2nd International Conference on Energy and Indoor Environment for Hot Climates 

    Presentation date: 2017.02

  • Effect of internal and external wetting on the global transfer coefficients inside high temperature absorbers

    Niccolo Giannetti

    27th International Symposium on Transport Phenomena 

    Presentation date: 2016.09

  • Marangoni convection within absorptive falling films over an inclined wall, Modelling and numerical simulations

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2016.09

  • Experimental study on absorption phenomenon of a falling film absorber

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2016.09

  • Analytical description of falling film absorption

    Niccolo Giannetti

    8th Asian Conference on Refrigeration and Air Conditioning 

    Presentation date: 2016.05

  • Energy-based criterion for annular two-phase flow stability in mini- and micro-channels

    Niccolo Giannetti

    50th Joint Meeting on Air-Conditioning and Refrigeration 

    Presentation date: 2016.04

  • Energy-based model for the prediction of mini-channels dry-out condition

    Niccolo Giannetti

    9th International Conference on Multiphase Flow 

    Presentation date: 2016.04

  • Analytical expression of heat and mass transfer coefficients on a partially wetted horizontal tube of falling film absorber

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2015.10

  • Analytical study of falling film absorption on a partially wetted horizontal tube

    Niccolo Giannetti

    26th International Symposium on Transport Phenomena 

    Presentation date: 2015.10

  • Local entropy generation analysis of water vapour absorption in a LiBr-H2O solution film, over a horizontal cooled tube

    Niccolo Giannetti

    24th IIR International Congress of Refrigeration 

    Presentation date: 2015.08

  • Cascade refrigeration system with inverse Bryton cycle on the cold side

    Niccolo Giannetti

    24th IIR International Congress of Refrigeration 

    Presentation date: 2015.08

  • Thermodynamic optimization of three-thermal irreversible systems

    Niccolo Giannetti

    Constructal Law & Second Law Conference 

    Presentation date: 2015.05

  • A new model for partial wetting of inclined surfaces

    Niccolo Giannetti

    49th Joint Meeting on Air-Conditioning and Refrigeration 

    Presentation date: 2015.04

  • Heat and mass transfer characteristics of falling film on a partially-wetted horizontal tube

    Niccolo Giannetti

    JSRAE Annual Conference 

    Presentation date: 2014.09

  • Semi-theoretical wettability model for falling film heat exchangers

    Niccolo Giannetti

    48th Joint Meeting on Air-Conditioning and Refrigeration 

    Presentation date: 2014.04

  • Hysteresis phenomena of annular flow dryout within small-size channels, Development of a thermodynamic model

    Niccolo Giannetti

    JSRAE Annual Conference 

▼display all

Specific Research

  • The Influence of Temperature on Marangoni Convection during Vapor Absorption

    2021   Kiyoshi Saito, Thomas Meyer

     View Summary

    A dedicated experimental facility was designedfor reproducing and visualizing Marangoni convection in a wide range ofsolution temperatures representative of the operative conditions of differentabsorption systems. Experimental measurements of the absorbed vapour mass were conducted with and without surfactant additives, which trigger Marangoni convection. A methodology was devised for ensuringcoherence in the mass fraction condition of the solution while generating differentsolution temperatures. Parallel visualization of the phenomenon withfluorescent uranine and UV lights enabled the observation of the intensity ofthe interfacial turbulence and thickness variations due to Marangoni convection.The study has newly demonstrated and quantified the research hypothesis thatthe intensity of Marangoni convection weakens at higher operative temperatureand suggest the existence of a temperature limitation where the interfacialturbulence does not occur. Correspondingly, a 2-dimensional numerical modelable to reproduce the characteristics of the phenomenon in the same range wasconstructed and validated. These finding are critical for the scientificclarification of Marangoni convection phenomenon and for its technicalapplication within absorption thermal systems. The developed model may accordingly guide the design of these systems for taking maximum advantage from this phenomenon.

  • Modelling thermal engineering processes with variational principle of non equilibrium thermodynamics

    2020  

     View Summary

    A generalizable understanding of the fundamental transportphenomena occurring within thermal systems is necessary to keep up with theirfast-paced technological progress, which is evolving towards advancedconfigurations and new working substances. Accordingly, this research targetsthe generalized modeling of interfacial multiphase processes for thermalsystems optimization and control through an interdisciplinary effort clusteringengineering experiments, artificial intelligence AI, and physical modeling. Research outcomes resulted into general formulations ofinterfacial multiphase processes (surface wetting, flow pattern transition,void fraction arrangement of two-phase flows, and two-phase flow separation) atsteady-state within the theory of nonequilibrium thermodynamics while providingcorresponding experimental validations. The above-mentioned formulation is thenused as the basis for a variational representation which extends the classicalLagrangian formulation in mechanics to nonequilibrium thermodynamic systemsincluding irreversible processes.The theoretical framework consequently obtained is combinedto corrective coefficients from computational fluid dynamics and experimentaldata to achieve phenomenon representations with higher accuracy. The use of machine learning tools is then guided by thegained theoretical understanding of the process to select the essentialtraining parameters for generalizing the applicability of such tool, whiletaking advantage of the powerful ability of AI to reconstruct complexintercorrelations between input and output quantities.

  • Interdisciplinary Theory of Interfacial Multiphase Processes for Advanced Modelling and Control of Engineering Thermal Systems

    2019  

     View Summary

    The first outcomes of this research project cover the application of variational principle for the mathematical formulations ofengineering phenomena recurrent in thermal systems, development of semi-theoretical phenomena combining the above-said mathematical formulations with collected experimental data, in parallel to the investigation of Artificial Intelligence approach for device optimisation procedures . Specifically, the Principleof minimum energy and Prigogine’s Theorem of minimum entropy generation have been applied tofalling-film wetting and two-phase refrigerant distribution in microchannelheat exchangers, respectively, along with the construction of a Lagrangian formulation able to include time evolution and unify different variational approaches.  A simplified formulation through Taylor series approximation was implemented as the mathematical framework for modelling open refrigerated display cabinets in combination with the representation given by collected experimental data. Other semi-theoretical models were obtained for desiccant wetting and two-phase flow void fraction. Genetic Algorithm has beenimplemented for circuitry optimisation in finned-tube heat exchangers andsystem-scale optimal operation. 

  • Study on Marangoni convection within high temperature absorbers for heat transformer applications

    2017  

     View Summary

    Absorption heat pumps and low exergy heat recovery have been named as keytechnologies for contributing to the solution of energy provision problems andrelated environmental issues. In order to achieve a better understanding and predictive models for thephenomena occurring in high temperature absorption heat transformers thisproject focus on Marangoni convection and high temperature absorption phenomenaas critical aspects yet to be clarified.To achieve this goal, experimental investigations at high temperatureoperability and direct visualization of falling film absorbers have beencarried out as terms of comparison for refining and validate the developednumerical models. Preliminary results have been summarized into papers,presented to domestic and international conferences and submitted tointernational journals.Finally, the equipment for the fundamental characterization and PIVmeasurement of Marangoni convection in a nearly-bi-dimensional space wasdesigned, constructed and instrumented for investigating the driving force ofthis phenomenon, the most suitable surfactant characteristics and theabsorption performance enhancement with respect to pure aqueous Lithium-Bromidemixtures.

 

Syllabus

▼display all

Teaching Experience

  • Dynamics B

    Waseda University  

    2020.04
    -
    Now
     

  • Dynamics A

    Waseda University  

    2020.04
    -
    Now
     

  • Thermodynamics B

    Waseda University  

    2019.09
    -
    Now
     

  • Thermodynamics A

    Waseda University  

    2019.09
    -
    Now
     

  • Heat Transfer (伝熱工学)

    School of Fundamental Science and Engineering  

  • Control Engineering (制御工学)

    School of Fundamental Science and Engineering  

  • Dynamics of Engineering Systems 1 (工学系の解析設計演習)

    School of Fundamental Science and Engineering  

  • IPSE Science and Engineering Laboratory 2A (Applied physics)

    School of Fundamental Science and Engineering  

  • IPSE Science and Engineering Laboratory 1B (Applied physics)

    School of Fundamental Science and Engineering  

▼display all

 

Committee Memberships

  • 2019.07
    -
    Now

    14th IIR-Gustav Lorentzen Conference on Natural Refrigerants - GL2020  Organizing Committee, Secretary General

  • 2014.08
    -
    Now

    Waseda University, International Institute of Refrigeration  ISHPC Organizing Committee