Updated on 2024/02/27

写真a

 
SOK, Ratnak
 
Affiliation
Research Council (Research Organization), Research Organization for Next Generation Vehicles
Job title
Researcher(Associate Professor)
Degree
Dr. Eng. ( 2015 Waseda University )
MSME (cum laude) ( 2011 Institut Teknologi Bandung )
Diplôme d'Ingénieur, 1st class honor ( 2009 Institute de Technologie du Cambodge )
Diplôme Universitaire de Technologie, 1st class honor ( 2006 Institut de Technologie du Cambodge )
Mail Address
メールアドレス
Profile

- Editorial board members (AE) of SAE Int. J. of : Electrified Vehicles , Commercial Vehicles, STEEP, Non-Event Tech Papers

- Organizing Committees, 2024 IEEE Transporation, Electrification Conference & Expo, June 19-21, 2024, Rosemont, IL, USA.

- Session Organizer, ASME Automotive and Transportation System, MECC 2024, Oct 27-30, Chicago, IL, USA

- ASME ICE Division Ambassador 2024-2026. 

- Associate Chair: 15th Int ACM Automotive User Interfaces & Veh. Applications, Sep 18-21, 2023, Ingolstadt , Germany

- Program Committee, 2022 IEEE Int. Conference on AI in Engineering and Technology, Sep 13-15, 2022, Malaysia

- Guest Associate Editor / Review Editor: Frontiers in Future Transportation 

- Advisory Panel Member of multiple MDPI Journals: Vehicles, Future Transportation, Electrochemistry, Clean Technologies, Applied Sciences, Fire, Pollutants, Sustainability, Atmosphere ... 

- Event Committee, The 2nd Int. Electronic Conference on Processes: Process Engineering—Current State and Future Trends, May 17-31, 2023

- Reviewers: 20+ Journals & Conferences: Elsevier, SAE, IEEE, ASME, SAGE, MDPI, Springer, Taylor&Francis

Research Experience

  • 2020
    -
    Now

    Waseda University   Associate Professor (Research), Jin Kusaka Group

  • 2018
    -
    2020

    Waseda University   Assistant Professor (Research), Jin Kusaka Group

  • 2016
    -
    2017

    Suzuki Motor Corporation   Automobile Engineering Division   Engineer

  • 2015
    -
    2016

    Waseda University   Postdoctorate, Jin Kusaka Group

  • 2012
    -
    2015

    Waseda University   Research/Teaching Assistant, Jin Kusaka Group

  • 2012.08
     
     

    Kyoto University   Foreign Research Associate (w/ Prof. Masahiro Shioji)

  • 2012.07
     
     

    Hokkaido University   Visiting Researcher (w/ Prof. Takemi Chikahisa)

  • 2011
    -
    2012

    National Polytechnic Institute of Cambodia   Part-time lecturer

  • 2011
    -
    2012

    Institut de Technologie du Cambodge   Mechanical Engineering   Full-time Lecturer/Assistant Researcher

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Education Background

  • 2012
    -
    2015

    Waseda University   Mechanical Engineering   Doctor of Engineering  

    Supervisors: Jin Kusaka, Yasuhiro Daisho

  • 2009
    -
    2011

    Institut Teknologi Bandung   MSME (with Distinction)  

    Supervisors: Iman K Reksowardojo, Wiranto Arimunandar, Tirto Prakoso, Toshio Shudo

  • 2006
    -
    2009

    Institut de Technologie du Cambodge   Génie Mécanique   Diplôme d'Ingénieur (1st class honor degree)  

  • 2003
    -
    2006

    Institut de Technologie du Cambodge   Génie Mécanique   Diplôme Universitaire de Technologie (1st class honor degree)  

Committee Memberships

  • 2023.04
    -
    Now

    SAE International Journal of Sustainable Transportation, Energy, Environment, & Policy

  • 2023
    -
    Now

    SAE International  Non-Event Technical Papers

  • 2022
    -
    Now

    SAE International  SAE International Journal of Electrified Vehicles

  • 2022
    -
    Now

    SAE International  SAE International Journal of Commercial Vehicles

  • 2024
    -
    2026

    American Society of Mechanical Engineers  ICEF Ambassador https://event.asme.org/ICEF/About/ICE-Forward-Ambassadors

Professional Memberships

  • 2021
    -
    Now

    IEEE Intelligent Transportation Systems Society

  • 2021
    -
    Now

    IEEE Vehicular Technology Society

  • 2021
    -
    Now

    Institute of Electrical and Electronics Engineers (IEEE)

  • 2018
    -
    Now

    SOCIETY OF AUTOMOTIVE ENGINEERS OF JAPAN

  • 2014
    -
    Now

    The American Society of Mechanical Engineers

  • 2014
    -
    Now

    Society of Automotive Engineers, International

▼display all

Research Areas

  • Thermal engineering   Electrified Vehicles ; CFD; Internal Combustion Engines

Research Interests

  • xEVs thermal management

  • Electrified transportation

  • Thermoelectric waste heat recovery

  • Computational fluid dynamics

  • Internal combustion engine

Awards

  • Waseda Asia Special Fellowship for PhD Student (Full for 2012-2015)

    2012.09   Waseda University;  

  • JICA Fellowship for Guest Research Associate at Kyoto University

    2012.08  

  • JICA Fellowship for Visiting Researcher at Hokkaido University

    2012.07  

  • JICA Fellowship for Grad. Student (Full for 2009-2011)

    2009.09  

  • 1st class honor degree for Diplôme d'Ingénieur

    2009.07   Institut de Technologie du Cambodge;  

  • Youth Energy Representative to Asian Youth Energy Summit @NUS, Singapore

    2008.08   Ministry of Education, Youth and Sports  

  • Top 10 Finalists

    2008   HONDA YES (Honda Young Engineer and Scientist Award)  

  • 1st class honor degree for Diplôme Universitaire de Technologie

    2006.07   Institut de Technologie du Cambodge;  

  • University-Merit-Based Scholarship

    2004   Institut de Technologie du Cambodge;  

  • 1st Class Degree Student 2004-2009 (for 5 consecutive years)

    2004   SUMITOMO and ACATEL Fellowship  

▼display all

Media Coverage

  • ASME ICEF Ambassadors 2024-2024

    Promotional material

    American Society of Mechanical Engineers   https://event.asme.org/ICEF/About/ICE-Forward-Ambassadors  

    2024.02

  • Energy and Propulsion Expert Gives Insight Behind Research, Concepts, and Collaboration

    Newspaper, magazine

    SAE International   https://www.sae.org/blog/sok-energy-propulsion  

    2023.12

  • FTMD ITB Alumni Online Reunion for AUNSEED-Net/JICA Scholarship Awardee

    Internet

    Institut Teknologi Bandung   https://www.itb.ac.id/news/read/58144/home/ftmd-itb-alumni-online-reunion-for-aunseed-netjica-scholarship-awardee  

    Indonesia  

    2021.09

  • MAZDA: List of published papers outside the company

    Other

    Mazda Motor Corp.  

    https://www.mazda.com/globalassets/ja/assets/innovation/technology/gihou/2020/files/2020_no018.pdf  

    2019

  • JICA Report - ASEAN University Network

    Other

    Open JICA Report  

    https://openjicareport.jica.go.jp/pdf/12044335.pdf  

    2010.11

 

Papers

  • Experimental and numerical analysis of the effects of thermal degradation on carbon monoxide oxidation characteristics of a three-way catalyst

    Sota Aoyama, Yunosuke Kubo, Ratnak Sok, Jin Kusaka

    Heliyon     e26592 - e26592  2024.02  [Refereed]

    DOI

  • Development and Validation of a Battery Thermal Management Model for Electric Vehicles under Cold Driving

    Yunkui Ma, Ratnak Sok, Enbo Cui, Kentaro Kishida, Kamaleshwar Nandagopal, Yuto Ozawa, Jin Kusaka

    SAE Technical Paper Series    2023.10  [Refereed]

    Authorship:Corresponding author

     View Summary

    <div class="section abstract"><div class="htmlview paragraph">Battery thermal management system (BTMS) significantly improves battery electric vehicle (BEV) performance, especially under cold weather. A tradeoff between battery power consumption and cabin heating performance must be considered in cold driving conditions. This preliminary study aims to develop an integrated battery pack and coolant channel model to predict the thermal behavior of a BEV thermal management system. In this study, we develop and calibrate the physical baseline model with testbench data using finite element and CFD software. First, an electrochemical battery cell 1D model (Pseudo-2D or P2D) is built and calibrated against the cell reference data. An integrated pack model consisting of four modules (each has 23 and 25 bricks and a total of 4416 cells) with coolant flow channels is developed using reference and benchmarked data. Then, the model is calibrated against experimental results from a mass-production, mid-size battery-electric SUV operated under cold driving conditions at a constant vehicle speed of 60 km/h for 5800 sec. The integrated model considers the heat transfer characteristics from cell-to-brick and brick-to-coolant channels. As a result, a thermodynamic model that can predict the average battery temperature rise, temperature changes, and pressure drops of the coolant of the battery pack is constructed. The result shows that the battery pack model can predict the coolant pressure drop of the pack with a mean absolute percentage error (MAPE) of 0.49 % and the coolant temperature rise with a 5.23% MAPE. The calibrated battery pack model can reasonably reproduce the terminal voltage with a MAPE of 0.30%. A 3D-CFD simulation result of the battery brick model is also reported on the cell-to-cell temperature distribution of 46 cells.</div></div>

    DOI

    Scopus

  • Impacts of Pre-Spark Heat Release on Unstretched Laminar Burning Velocity in Advanced Flex-Fuel Gasoline-Ethanol Engines

    Kohei Isobe, Kei Yoshimura, Takuma Kobayashi, Ratnak Sok, Jin Kusaka

       2023.09

    Authorship:Corresponding author

    DOI

  • Experimental and 3D-CFD Analysis of Synthetic Fuel Properties on Combustion and Exhaust Gas Emission Characteristics in Heavy-Duty Diesel Engines

    Kunihiro Shimizu, Tomoki Narushima, Ratnak Sok, Jin Kusaka

    SAE Technical Paper Series    2023.08  [Refereed]

    Authorship:Corresponding author

     View Summary

    <div class="section abstract"><div class="htmlview paragraph">Synthetic fuels can significantly improve the combustion and emission characteristics of heavy-duty diesel engines toward decarbonizing heavy-duty propulsion systems. This work analyzes the effects of engine operating conditions and synthetic fuel properties on spray, combustion, and emissions (soot, NOx) using a supercharging single-cylinder engine experiment and KIVA-4 code combined with CHEMKIN-II and in-house phenomenological soot model. The blended fuel ratio is fixed at 80% diesel and 20% n-paraffin by volume (hereafter DP). Diesel, DP1 (diesel with n-pentane C5H12), DP2 (diesel with n-hexane C6H14), and DP3 (diesel with n-heptane C7H16) are used in engine-like-condition constant volume chamber (CVC) and engine experiments.</div><div class="htmlview paragraph">Boosted engine experiments (1080 rpm, common-rail injection pressure 160 MPa, multi-pulse injection) are performed using the same DP fuel groups under various main injection timings, pulse-injection intervals, and EGR = 0-40%. Once the 3D-CFD model is validated with the CVC and experimental engine data, in-cylinder combustion and emissions are analyzed. The CVC experiments show that DP2 and DP3 liquid penetrations are shorter than diesel oil. In engine tests, NOx did not change much for all DP fuels for the same engine operating condition. However, shorter-penetrated DP2 and DP3 reduce soot emissions by more than 60% and CO without worsening brake-specific fuel consumption compared to diesel oil. The 3D-CFD results show that n-hexane shifts the penetration of the high-carbon number to the low-carbon fuel. Vapor penetrations are found to be shortened by blending low-volatility fuels with diesel oil. Visualizations of the in-cylinder confirmed a decrease in the amount of soot formation near the wall for DP2 and DP3 fuels. In addition, equivalence ratio – temperature (phi-T) maps of these fuels indicate that at 40% EGR, soot emissions are reduced at lower equivalence ratios than diesel oil.</div></div>

    DOI

    Scopus

  • Effects of Pre-Chamber Internal Shape on CH4-H2 Combustion Characteristics Using Rapid-Compression Expansion Machine Experiments and 3D-CFD Analysis

    Yixin Feng, Ryo Yamazaki, Ratnak Sok, Jin Kusaka

    SAE Technical Paper Series    2023.08  [Refereed]

    Authorship:Corresponding author

     View Summary

    <div class="section abstract"><div class="htmlview paragraph">Pre-chamber (PC) natural gas and hydrogen (CH<sub>4</sub>-H<sub>2</sub>) combustion can improve thermal efficiency and greenhouse gas emissions from decarbonized stationary engines. However, the engine efficiency is worsened by prolonged combustion duration due to PC jet velocity extinction. This work investigates the impact of cylindrical PC internal shapes to increase its jet velocity and shorten combustion duration. A rapid compression and expansion machine (RCEM) is used to investigate the combustion characteristics of premixed CH<sub>4</sub> gas. The combustion images are recorded using a high-speed camera of 10,000 fps. The experiments are conducted using two types of long PC shapes with diameters <i>φ=</i>4 mm (hereafter, long<i>φ</i>4) and 5 mm (hereafter, long <i>φ</i>5), and their combustions are compared against a short PC shape (<i>φ</i>=12 mm). For all designs of the PC shapes, the PC holes are 6 with 2 mm in diameter. Initial recorded results using only CH<sub>4</sub> show that jet extinction does not occur using the short and long 5mm types. The combustion duration of <i>φ</i>=4 mm PC is the shortest compared to the short-type and 5 mm PC. With CH<sub>4</sub>-H<sub>2</sub> blending (0%H<sub>2</sub>, 10%H<sub>2</sub>, 20%H<sub>2</sub>) and 4 mm shape, the combustion durations of 10%H<sub>2</sub> and 20%H<sub>2</sub> can be shortened compared to the CH<sub>4</sub>-only case (0%H<sub>2</sub>). However, the jet extinction probability is not zero.</div><div class="htmlview paragraph">3D-CFD combustion simulations are performed using CONVERGE software, and a 1/6 sector-mesh, GRI-Mech 3.0, G-equation combustion, and law-of-wall models are utilized in conjunction with RNG k-epsilon turbulence model. Simulated in-cylinder pressure and burning rate are validated against the recorded data. PC jet velocity, turbulent kinetic energy (TKE) of the main chamber, PC jet temperature, total heat loss in PC, and PC heat loss rate of 12 mm, 4 mm, and 5 mm are compared. Experimental combustion images and 3D-CFD temperature distribution with and without H<sub>2</sub> blending are also reported. The results show that long PC types can accelerate the jet velocity and shorten combustion duration. The jet extinction can be prevented by designing a small PC diameter area larger than the nozzle’s cross-sectional area. With H<sub>2</sub> blending, laminar burning velocity increases, and the jet ejection timing can be advanced. The result shows that the combustion duration can be shortened by 15 degrees using CH<sub>4</sub>-20%H<sub>2</sub> against CH<sub>4</sub> only.</div></div>

    DOI

    Scopus

  • Effects of Pre-spark Heat Release of Ethanol-Blended Gasoline Surrogate Fuels on Engine Combustion Behavior

    Kei Yoshimura, Kohei Isobe, Mitsutaka Kawashima, Kyohei Yamaguchi, Ratnak Sok, Satoshi Tokuhara, Jin Kusaka

    SAE International Journal of Fuels and Lubricants   17 ( 1 )  2023.05  [Refereed]

     View Summary

    <div>Regulations limiting greenhouse gas (GHG) emissions in the transport sector have become more restrictive in recent years, drawing interest to synthetic fuels such as e-fuels and biofuels that could “decarbonize” existing vehicles. This study focuses on the potential to increase the thermal efficiency of spark-ignition (SI) engines using ethanol as a renewable fuel, which requires a deep understanding of the effects of ethanol on combustion behavior with high compression ratios (CRs). An important phenomenon in this condition is pre-spark heat release (PSHR), which occurs in engines with high CRs in boosted conditions and changes the fuel reactivity, leading to changes in the burning velocity. Fuel blends containing ethanol display high octane sensitivity (OS) and limited low-temperature heat release (LTHR). Consequently, their burning velocities with PSHR may differ from that of gasoline. This study therefore aimed to clarify the effects of ethanol on SI combustion behavior under PSHR conditions. Combustion behavior was studied by performing single-cylinder engine experiments and chemical kinetics simulations. The experimental measurements were performed to characterize the relationship between the occurrence of PSHR and the main combustion duration. Analysis of this relationship showed that the ethanol-blended fuel has a lesser PSHR and a longer combustion duration than the non-ethanol fuel by approximately 5% in high engine load conditions. Simulations using input data from the experiments revealed that the ethanol-blended fuel has a lower laminar burning velocity due to the lower temperature in the unburned mixture caused by its PSHR. Additional simulations examining the chemical effect of partially oxidized reactants caused by PSHR on the laminar burning velocity showed that partially oxidized reactants increase the laminar burning velocity of the ethanol-blended fuel but decrease that of a reference fuel without ethanol. A large number of fuel radicals and oxides of the ethanol-blended fuel enhances chain-branching reactions in the pre-flame zone and possibly increases its laminar burning velocity. However, the thermodynamic effect of PSHR on laminar burning velocity exceeds the chemical effect, and thus the ethanol-blended fuel has a lower turbulent burning velocity in the PSHR conditions.</div>

    DOI

    Scopus

  • Development and validation of thermal performances in a novel thermoelectric generator model for automotive waste heat recovery systems

    Ratnak Sok, Jin Kusaka

    International Journal of Heat and Mass Transfer   202   123718 - 123718  2023.03  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • A novel laminar flame speed equation for quasi-dimensional combustion model refinement in advanced, ultra-lean gasoline spark-ignited engines

    Hidefumi Kataoka, Jin Kusaka, Akira Miyoshi, Rolf D. Reitz

    Fuel   333   126508 - 126508  2023.02  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Thermoelectric Generation from Exhaust Heat in Electrified Natural Gas Trucks: Modeling and Analysis of an Integrated Engine System Performance Improvement

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Hidetaka Minagata, Pavlos Dimitriou, Jinlong Liu

    Journal of Energy Resources Technology     1 - 19  2023.01  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    Abstract

    Using thermoelectric generators (TEG) to reduce exhaust heat loss from internal combustion engines can improve emissions and the fuel economy of conventional and electrified vehicles. However, TEG potentials have not been investigated in hybridized, compressed natural gas (CNG), twin-turbocharged, spark-ignited (SI) engines. This work demonstrates TEG's effectiveness in boosting a hybridized 3.0 L CNG engine using model-based development. TEG experiments are performed to measure thermal performances under different inlet gas conditions for model validations. Simplified user-defined functions of flow friction and heat transfer coefficients are used to calibrate the model. A fast-calibration model can reproduce measured heat transfer, pressure drop, and thermal performances. The engine performances are validated against measured 35 steady-state conditions from the production engine used in light-duty CNG trucks under the JE05 drive cycle. Next, the model is connected to the turbocharging system downstream of the well-calibrated 4-cylinder SI engine model. Under the peak performance condition (peak brake thermal efficiency BTE at 2400 RPM and 102 kW load), the results show that the engine BTE is improved by 0.56% using a 7×9 TEG module arrangement (3-sheet TEG with 1.5× A4 size). A 9×10 arrangement can enhance the BTE to 0.8%. Effective electrical power is generated up to 1.168 kW from the TEG, depending on the JE05 operating regions, without significant brake power loss.

    DOI

  • Experimental and modeling analysis on thermoelectric heat recovery to maximize the performance of next-generation diesel engines dedicated for future electrified powertrains

    Jin Kusaka

    Applied Thermal Engineering   219   119530 - 119530  2023.01  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Development and Comparison of Virtual Sensors Constructed using AI Techniques to Estimate the Performances of IC Engines

    Arravind Jeyamoorthy, Takuma Degawa, Toshikado Akimichi, Shigeaki Kurita, Masatoshi Ogawa, Takayuki Takei, Ikuta Hayashi, Jin Kusaka, Beini Zhou, Kyohei Yamaguchi, Iku Tanabe

    SAE Technical Paper Series    2022.11  [Refereed]

    Authorship:Corresponding author

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Modeling analysis on combined effects of VVT/VCR engine technology to reduce fuel consumption of light-duty parallel hybrid CNG trucks

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Hidetaka Minagata

    ASME Technical Paper    2022.11  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

  • Thermoelectric generation from exhaust heat in electrified natural gas trucks - part 1: modeling and baseline analysis on engine system efficiency improvement

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Hidetaka Minagata

    ASME Technical Paper    2022.11  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

  • Thermoelectric Exhaust Heat Recovery to Maximize Brake Thermal Efficiency of Advanced Diesel Engines: Modeling and Baseline Analysis

    Ratnak Sok, Jin Kusaka

    ASME 2022 ICE Forward Conference    2022.10  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    Abstract

    This work demonstrates the enhancement of brake thermal efficiency (BTE) of an advanced, turbocharged, production-intent 2.2 L diesel engine with a thermoelectric waste heat recovery system (TEG-WHR). The integrated engine model with the TEG is developed using 0D/1D software. Experimental data from the corrugated fin TEG under fin pitch = 1.0–2.0 mm, inlet gas temperatures (200–300 °C), and mass flow rates (5.0–15.0 g/s) are used for validating the model. The TEG model can reproduce measured pressure drop, heat transfer, and thermal performance characteristics. A 1-cylinder engine model parented from the advanced turbocharged diesel engine is developed. Under motoring and firing conditions, measured exhaust pressure, temperature, velocity, mass flow rate, and enthalpy are validated under various valve timings. Finally, the 3-layer TEG model is connected to the 4-cylinder engine to maximize its performance under a highly efficient (peak BTE) operating condition at 2250 RPM. Optimal size and thermoelectric module arrangement of the TEG system in the engine system considering a tradeoff between the TEG generated electrical power and engine pumping losses are suggested. The effective power of 1.1 kW and 1.1 % BTE improvement are obtained from the 3-sheet TEG system. As a result, a 49.9 % engine BTE is demonstrated without brake power loss.

    DOI

  • Waste Heat Recovery via Thermoelectric Generation in a Natural Gas Engine: Numerical Modeling and Baseline Analysis

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Hidetaka Minagata

    Proceeding of 7th Thermal and Fluids Engineering Conference (TFEC)    2022.05  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

  • Fuel-reforming effects on a gasoline direct injection engine under a low-temperature combustion mode: Experimental and kinetics analyses

    Ratnak Sok, Jin Kusaka

    Energy Conversion and Management   255   115304 - 115304  2022.03  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

    9
    Citation
    (Scopus)
  • Machine Learning Application to Predict Combustion Phase of a Direct Injection Spark Ignition Engine

    Rio Asakawa, Keisuke Yokota, Iku Tanabe, Kyohei Yamaguchi, Ratnak Sok, Hiroyuki Ishii, Jin Kusaka

    International Journal of Automotive Technology   23 ( 1 ) 265 - 272  2022.02  [Refereed]

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Predicting Unburned Hydrocarbons in the Thermal Boundary Layer Close to the Combustion-chamber Wall in a Gasoline Engine Using a 1-D Model

    Kei Yoshimura, Hajime Yahata, Shoya Tanamachi, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka, Satoshi Tokuhara

    International Journal of Automotive Technology   23 ( 1 ) 233 - 242  2022.02  [Refereed]

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Effects of Partial Oxidation and Octane Sensitivity on Flame Stretch Rate at Extinction under EGR Conditions

    Kei Yoshimura, Kohei Isobe, Satoshi Tokuhara, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka

    The Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines   2022.10   A5 - 3  2022

    DOI

  • Experimental Investigation on the Effects of Direct Fuel Injection Into Low-O2 Recompression Interval of an HCCI Engine

    Ratnak Sok, Jin Kusaka

    ASME Technical Paper    2021.11  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    <title>Abstract</title>
    Gasoline direct injection (GDI) and negative valve overlap (NVO) are standard strategies to control combustion characteristics and exhaust gas emissions in homogenous charge compression ignition (HCCI) engines. In this work, experimental data from a single-cylinder engine operated under the GDI-HCCI mode were analyzed. The experiments were performed at an equivalence ratio of 0.95 under a mid-load condition. A side-mounted injector delivered primary reference fuel with octane number 90 directly into the combustion chamber during the NVO. The measured results showed advanced combustion phase CA50 under the early start of injection (SOI) timings. Peak recompression pressures were lower than the motoring, emphasizing that the NVO reactions were net endothermic. Zero-dimensional kinetics calculations showed that classical reformate species increase almost linearly as a function of SOI timings.


    This work also presents the effects of intake boosting pressure and single versus double pulses injections on CA50, burn duration CA10-90, peak cylinder pressure, combustion noise metrics, thermal efficiency, and emissions. The combustion noise metrics were over the engine constraint limit under advanced SOI timings, but a double-pulse injection could reduce the combustion noise metrics and NOx emission. Late fuel injection in the intake stroke could reduce NOx to a single digit.

    DOI

  • Experimental Investigation of Direct Fuel Injection Into Low-Oxygen Recompression Interval in a Homogenous Charge Compression Ignition Engine

    Ratnak Sok, Jin Kusaka

    Journal of Energy Resources Technology   144 ( 1 ) 1 - 8  2021.10  [Refereed]  [International journal]

    Authorship:Lead author, Corresponding author

     View Summary

    <title>Abstract</title>
    This work analyzed measured data from a single-cylinder engine operated under gasoline direction injection homogenous charge compression ignition (GDI-HCCI) mode. The experiments were conducted at a 0.95 equivalence ratio (φ) under 0.5 MPa indicated mean effective pressure and 1500RPM. A side-mounted injector delivered primary reference fuel (octane number 90) into the combustion chamber during negative valve overlap (NVO). Advanced combustion phase CA50 were observed as a function of the start of injection (SOI) timings. Under φ=0.95, peak NVO in-cylinder pressures were lower than motoring for single and split injections, emphasizing that NVO reactions were endothermic. Zero-dimensional kinetics calculations showed classical reformate species (C3H6, C2H4, CH4) from the NVO rich mixture increased almost linearly due to SOI timings, while H2 and CO were typically low. These kinetically reformed species shortened predicted ignition delays. This work also analyzed the effects of intake pressure and single versus double pulses injections on CA50, burn duration, peak cylinder pressure, combustion noise, thermal efficiency, and emissions. Advanced SOI (single-injection) generated excessive combustion noise metrics over constraint limits, but the double-pulse injection could significantly reduce the metrics (Ringing Intensity ≤ 5 MW/m2, Maximum Pressure Rise Rate = 0.6 MPa/CA) and NOx emission. The engine's net indicated thermal efficiency reached 41% under GDI-HCCI mode against 36% under SI mode for the same operating conditions. Under GDI-HCCI mode and without spark-ignition, late fuel injection in the intake stroke could reduce NOx to a single digit.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Effects of Partial Oxidation in an Unburned Mixture on a Flame Stretch under EGR Conditions

    Kei Yoshimura, Kohei Ozawa, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka, Masaaki Togawa, Satoshi Tokuhara

    SAE Technical Paper Series    2021.09  [Refereed]

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • A Model for Predicting Turbulent Burning Velocity by using Karlovitz Number and Markstein Number under EGR Conditions

    Kei Yoshimura, Kohei Ozawa, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka, Masaaki Togawa, Satoshi Tokuhara

    SAE Technical Paper Series   ( 2021 )  2021.09  [Refereed]

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • A Novel Integrated Series Hybrid Electric Vehicle Model Reveals Possibilities for Reducing Fuel Consumption and Improving Exhaust Gas Purification Performance

    Takehiro Yamagishi, Hajime Shingyouchi, Kyohei Yamaguchi, Norifumi Mizushima, Takahiro Noyori, Jin Kusaka, Toshinori Okajima, Ratnak Sok, Makoto Nagata

    SAE Technical Paper Series    2021.09  [Refereed]

    Authorship:Corresponding author

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Avoidance Algorithm Development to Control Unrealistic Operating Conditions of Diesel Engine Systems under Transient Conditions

    Rio Asakawa, Iku Tanabe, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka, Masatoshi Ogawa, Takuma Degawa, Shigeaki Kurita, Arravind Jeyamoorthy, Zhou Beini

    SAE Technical Paper Series    2021.09  [Refereed]

    Authorship:Corresponding author

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Reaction Analysis and Modeling of Fast SCR in a Cu-Chabazite SCR Catalyst Considering Generation and Decomposition of Ammonium Nitrate

    Keiichiro Seki, Rikuto Ueyama, Yoshihisa Tsukamoto, Kenya Ogawa, Kohei Oka, Ratnak Sok, Jin Kusaka

    SAE Technical Paper Series    2021.09  [Refereed]

    Authorship:Corresponding author

    DOI

    Scopus

  • Numerical Study on the Adaptation of Diesel Wave Breakup Model for Large-Eddy Simulation of Non-Reactive Gasoline Spray

    Ratnak Sok, Beini Zhou, Jin Kusaka

    ASME Technical Paper    2021.07  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    <title>Abstract</title>
    Gasoline direct injection (GDI) is a promising solution to increase engine thermal efficiency and reduce exhaust gas emissions. The GDI operation requires an understanding of fuel penetration and droplet size, which can be investigated numerically. In the numerical simulation, primary and secondary breakup phenomena are studied by the Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) wave breakup models. The models were initially developed for diesel fuel injection, and in the present work, the models are extended to the GDI application combined using large-eddy simulation (LES). The simulation is conducted using the KIVA4 code.


    Measured data of experimental spray penetration and Mie-scattering image comparisons are carried out under non-reactive conditions at an ambient temperature of 613K and a density of 4.84 kg/m3. The spray penetration and structures using LES are compared with traditional Reynolds-Averaged Navier-Stokes (RANS). Grid size effects in the simulation using LES and RANS models are also investigated to find a reasonable cell size for future reactive gasoline spray/combustion studies. The fuel spray penetration and droplet size are dependent on specific parameters. Parametric studies on the effects of adjustable constants of the KH-RT models, such as time constants, size constants, and breakup length constant, are discussed. Liquid penetrations from the RANS turbulence model are similar to that of the LES turbulence model’s prediction. However, the RANS model is not able to capture the spray structure well.

    DOI

  • Experimental and numerical analysis on the influences of direct fuel injection into oxygen-depleted environment of a homogeneous charge compression ignition engine

    Sok, R., Yoshimura, K., Nakama, K., Kusaka, J.

    Journal of Energy Resources Technology, Transactions of the ASME   143 ( 12 )  2021.03  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    <title>Abstract</title>
    The oxygen-depleted environment in the recompression stroke can convert gasoline fuel into light hydrocarbons due to thermal cracking, partial oxidation, and water-gas shift reactions. These reformate species can influence the combustion characteristics of gasoline direct injection homogeneous charge compression ignition (GDI-HCCI) engines. In this work, the combustion phenomena are investigated using a single-cylinder research engine under a medium load. The main combustion phases are experimentally advanced by direct fuel injection into the negative valve overlap (NVO) compared with that of intake stroke under single/double-pulse injections. NVO peak in-cylinder pressures are lower than that of motoring due to the limited O2 concentration, emphasizing that endothermic reactions occur during the overlap. This phenomenon limits the oxidation reactions, and the thermal effect is not pronounced. The zero-dimensional chemical kinetics results present the same increasing tendencies of classical reformed species of rich mixture such as C3H6, C2H4, CH4, CO, and H2 as functions of injection timings. Predicted ignition delays are shortened due to the additions of these reformed species. The influences of the reformates on the main combustion are confirmed by three-dimensional computational fluid dynamics (CFD) calculations, and the results show that OH radicals are advanced under NVO injections relative to intake stroke injections. Consequently, earlier heat release and cylinder pressure are noticeable. Parametric studies on the effects of injection pressure, double-pulse injection, and equivalence ratio on the combustion and emissions are also discussed experimentally.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • A MODELING STUDY ON FUEL CONSUMPTION IMPROVEMENT OF A LIGHT-DUTY CNG TRUCK EQUIPPED WITH A HYBRID POWERTRAIN

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Makoto Akaike

    ASTFE Technical Paper    2021  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

  • Prediction of Ultra-Lean Spark Ignition Engine Performances by Quasi-Dimensional Combustion Model with a Refined Laminar Flame Speed Correlation

    Sok, R., Yamaguchi, K., Kusaka, J.

    Journal of Energy Resources Technology, Transactions of the ASME   143 ( 3 )  2021  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    <title>Abstract</title>
    The turbulent combustion in gasoline engines is highly dependent on laminar flame speed SL. A major issue of the quasi-dimensional (QD) combustion model is an accurate prediction of the SL, which is unstable under low engine speeds and ultra-lean mixture. This work investigates the applicability of the combustion model with a refined SL correlation for evaluating the combustion characteristics of a high-tumble port gasoline engine operated under ultra-lean mixtures. The SL correlation is modified and validated for a five-component gasoline surrogate. Predicted SL values from the conventional and refined functions are compared with measurements taken from a constant-volume chamber under micro-gravity conditions. The SL data are measured at reference and elevated conditions. The results show that the conventional SL overpredicts the flame speeds under all conditions. Moreover, the conventional model predicts negative SL at equivalence ratio ϕ ≤ 0.3 and ϕ ≥ 1.9, while the revised SL is well validated against the measurements. The improved SL correlation is incorporated into the QD combustion model by a user-defined function. The engine data are measured at 1000–2000 rpm under engine load net indicated mean effective pressure (IMEPn) = 0.4–0.8 MPa and ϕ = 0.5. The predicted engine performances and combustions are well validated with the measured data, and the model sensitivity analysis also shows a good agreement with the engine experiments under cycle-by-cycle variations.

    DOI

    Scopus

    18
    Citation
    (Scopus)
  • Experimental and Numerical Analysis on the Influence of Direct Fuel Injection Into O2-Depleted Environment of a GDI-HCCI Engine

    Ratnak Sok, Jin Kusaka

    ASME Technical Paper    2020.11  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    <title>Abstract</title>
    Injected gasoline into the O2-depleted environment in the recompression stroke can be converted into light hydrocarbons due to thermal cracking, partial oxidation, and water-gas shift reaction. These reformate species influence the combustion phenomena of gasoline direct injection homogeneous charge compression ignition (GDI-HCCI) engines. In this work, a production-based single-cylinder research engine was boosted to reach IMEPn = 0.55 MPa in which its indicated efficiency peaks at 40–41%. Experimentally, the main combustion phases are advanced under single-pulse direct fuel injection into the negative valve overlap (NVO) compared with that of the intake stroke. NVO peak in-cylinder pressures are lower than that of motoring, which emphasizes that endothermic reaction occurs during the interval. Low O2 concentration could play a role in this evaporative charge cooling effect. This phenomenon limits the oxidation reaction, and the thermal effect is not pronounced. For understanding the recompression reaction phenomena, 0D simulation with three different chemical reaction mechanisms is studied to clarify that influences of direct injection timing in NVO on combustion advancements are kinetically limited by reforming. The 0D results show the same increasing tendencies of classical reformed species of rich-mixture such as C3H6, C2H4, CH4, CO, and H2 as functions of injection timings. By combining these reformed species into the main fuel-air mixture, predicted ignition delays are shortened.


    The effects of the reformed species on the main combustion are confirmed by 3D-CFD calculation, and the results show that OH radical generation is advanced under NVO fuel injection compared with that of intake stroke conditions thus earlier heat release and cylinder pressure are noticeable. Also, parametric studies on injection pressure and double-pulse injections on engine combustion are performed experimentally.

    DOI

  • Numerical Methods on VVA and VCR Concepts for Fuel Economy Improvement of a Commercial CNG Truck

    Sok, R., Takeuchi, K., Yamaguchi, K., Kusaka, J.

    SAE Technical Papers   ( 2020 )  2020.09  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Prediction of Ultra-Lean SI Engine Performance by QD-Combustion Model With an Improved Laminar Flame Speed

    Ratnak Sok, Jin Kusaka, Kyohei Yamaguchi

    ASME Technical Paper    2020.08  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    <title>Abstract</title>
    A quasi-dimensional (QD) simulation model is a preferred method to predict combustion in the gasoline engines with reliable results and shorter calculation time compared with multi-dimensional simulation. The combustion phenomena in spark ignition (SI) engines are highly turbulent, and at initial stage of the combustion process, turbulent flame speed highly depends on laminar burning velocity SL. A major parameter of the QD combustion model is an accurate prediction of the SL, which is unstable under low engine speed and ultra-lean mixture.


    This work investigates the applicability of the combustion model for evaluating the combustion characteristics of a high-tumble port gasoline engine operated under ultra-lean mixture (equivalence ratio up to ϕ = 0.5) which is out of the range of currently available SL functions initially developed for a single component fuel. In this study, the SL correlation is improved for a gasoline surrogate fuel (5 components). Predicted SL data from the conventional and improved functions are compared with experimental SL data taken from a constant-volume chamber under micro-gravity condition. The SL measurements are done at reference conditions at temperature of 300K, pressure of 0.1MPaa, and at elevated conditions whose temperature = 360K, pressure = 0.1, 0.3, and 0.5 MPaa. Results show that the conventional SL model over-predicts flame speeds under all conditions. Moreover, the model predicts negative SL at very lean (ϕ ≤ 0.3) and rich (ϕ ≥ 1.9) mixture while the revised SL is well validated with the measured data. The improved SL formula is then incorporated into the QD combustion model by a user-defined function in GT-Power simulation. The engine experimental data are taken at 1000 RPM and 2000 RPM under engine load IMEPn = 0.4–0.8 MPa (with 0.1 increment) and ϕ ranges are up to 0.5. The results shows that the simulated engine performances and combustion characteristics are well validated with the experiments within 6% accuracy by using the QD combustion model coupled with the improved SL. A sensitivity analysis of the model is also in good agreement with the experiments under cyclic variation (averaged cycle, high IMEP or stable cycle, and low IMEP or unstable cycle).

    DOI

  • A Fundamental Study on Combustion Characteristics in a Pre-Chamber Type Lean Burn Natural Gas Engine

    Tanamura, M., Nakai, S., Nakatsuka, M., Taki, S., Ozawa, K., Zhou, B., Sok, R., Daisho, Y., Kusaka, J.

    SAE Technical Papers   2019-September ( September )  2019.09  [Refereed]

    Authorship:Corresponding author

    DOI

    Scopus

    13
    Citation
    (Scopus)
  • A Study on Combustion Characteristics of a High Compression Ratio SI Engine with High Pressure Gasoline Injection

    Kaminaga, T., Yamaguchi, K., Ratnak, S., Kusaka, J., Youso, T., Fujikawa, T., Yamakawa, M.

    SAE Technical Papers   2019-September ( September )  2019.09  [Refereed]

    DOI

    Scopus

    23
    Citation
    (Scopus)
  • 0D/1D turbulent combustion model assessment from an ultra-lean spark ignition engine

    Sok, R., Yamaguchi, K., Kusaka, J.

    SAE Technical Papers   2019-March ( March )  2019.03  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

    14
    Citation
    (Scopus)
  • Effect of Fuel Injection Timing During Negative Valve Overlap Period on a GDI-HCCI Engine

    Sok Ratnak, Jin Kusaka, Yasuhiro Daisho, Kei Yoshimura, Kenjiro Nakama

    Volume 1: Large Bore Engines; Fuels; Advanced Combustion   1  2018.11  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    Gasoline Direct Injection Homogeneous Charge Compression (GDI-HCCI) combustion is achieved by closing early the exhaust valves for trapping hot residual gases combined with direct fuel injection. The combustion is chemically controlled by multi-point auto-ignition which its main combustion phase can be controlled by direct injection timing of fuel. This work investigates the effect of single pulse injection timing on a supercharged GDI-HCCI combustion engine by using a four-stroke single cylinder engine with a side-mounted direct fuel injector.


    Injection of primary reference fuel PRF90 under the near-stoichiometric-boosted condition is studied. The fuel is injected during negative valve overlap (NVO) or recompression period for fuel reformation under low oxygen concentration and the injection is retarded to intake stroke for the homogeneous mixture. It is found that the early fuel injection in NVO period advances the combustion phasing compared with the retarded injection in the intake stroke. Noticeable slower combustion rate from intake stroke fuel injection is obtained compared with the NVO injection due to charge cooling effect. Zero-dimensional combustion simulations with multiple chemical reaction mechanisms are simulated to provide chemical understanding from the effect of fuel injection timing on intermediate species generations. The species such as C2H4, C3H6, CH4, and H2 are found to be formed during the NVO injection period from the calculations. The effects of single pulse injection timings on combustion characteristics such pressure rise rate, combustion stability, and emissions are also discussed in this study.

    DOI

  • Experiments and Simulations of a Lean-Boost Spark Ignition Engine for Thermal Efficiency Improvement

    Ratnak Sok, Jin Kusaka, Yasuhiro Daisho, Kei Yoshimura, Kenjiro Nakama

    SAE International Journal of Engines   9 ( 1 ) 379 - 396  2015.11  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    &lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Primary work is to investigate premixed laminar flame propagation in a constant volume chamber of iso-octane/air combustion. Experimental and numerical results are investigated by comparing flame front displacements under lean to rich conditions. As the laminar flame depends on equivalence ratio, temperature, and pressure conditions, it is a main property for chemical reaction mechanism validation. Firstly, one-dimensional laminar flame burning velocities are predicted in order to validate a reduced chemical reaction mechanism. A set of laminar burning velocities with pressure, temperature, and mixture equivalence ratio dependences are combined into a 3D-CFD calculation to compare the predicted flame front displacements with that of experiments. It is found that the reaction mechanism is well validated under the coupled 1D-3D combustion calculations. Next, lean experiments are operated in a SI engine by boosting intake pressure to maintain high efficiency without output power penalty. The peak indicated thermal efficiency are finally achieved under λ=1.3 with intake manifold absolute pressure 150 kPa in experiment. Data of in-cylinder pressure and rate of heat release from the 3D-CFD simulations combined with the validated chemical reaction mechanism are reproduced. NOx emissions from experiment and simulation are also in good agreements under the lean-boost combustion. Further thermal efficiency improvements of the lean-boost SI engine are investigated numerically by using dilution rate, high induced in-cylinder flow, and high knock resistant fuel. The peak indicated thermal efficiency and load of the SI engine is achieved. In addition, methods to prevent knock for high efficiency spark ignition engine are also discussed.&lt;/div&gt;&lt;/div&gt;

    DOI

  • Thermal Efficiency Improvement of a Lean-Boosted Spark Ignition Engine by Multidimensional Simulation with Detailed Chemical Kinetics

    Ratnak Sok, Jin Kusaka, Yasuhiro Daisho, Kei Yoshimura, Kenjiro Nakama

    International Journal of Automotive Engineering   6 ( 4 ) 97 - 104  2015.06  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    This paper aims to improve thermal efficiency of spark ignition engine by numerical calculation with detailed chemistry. Experimental results from a four-stroke-single-cylinder engine are compared with that of simulations. It is experimentally found that peak efficiency is achieved at lean-limit combustion under excess air ratio λ=1.6. Due to engine output power loss, further investigations are conducted under lean-boost operations. The best condition of the lean-boost mode is at λ=1.3 and 150 kPa boosted pressure (abs). To further improve the efficiency without power loss, simulations are conducted under lean-boost combustion with dilution rate, high engine swirl, and high knock resistant fuel.

    DOI CiNii

    Scopus

    21
    Citation
    (Scopus)
  • 3D Simulations on Premixed Laminar Flame Propagation of iso-Octane/Air Mixture at Elevated Pressure and Temperature

    Ratnak, S., Kusaka, J., Daisho, Y.

    SAE Technical Papers   2015-March ( March )  2015.03  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Computational Study to Improve Thermal Efficiency of Spark Ignition Engine

    Ratnak, S., Katori, K., Kusaka, J., Daisho, Y., Yoshimura, K., Kenjiro, N.

    SAE Technical Papers   2015-March ( March )  2015.03  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

    Scopus

    12
    Citation
    (Scopus)
  • The Effect of Biodiesel Fuel from Rubber (Hevea Brasilliensis) Seed Oil on a Direct Injection (DI) Diesel Engine

    Ratnak Sok

    ASEAN Engineering Journal   1 ( 1 ) 65 - 81  2011.03  [Refereed]  [International journal]

    Authorship:Corresponding author

▼display all

Presentations

  • On the Potential of Thermoelectric Generators in Improving the Thermal Efficiency of Heavy-Duty Natural Gas Engines

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Hidetaka Minagata

    ASME 2023 International Mechanical Engineering Congress and Exposition 

    Presentation date: 2023.11

    Event date:
    2023.10
    -
    2023.11
  • Modeling analysis on combined effects of VVT/VCR engine technology to reduce fuel consumption of light-duty parallel hybrid CNG trucks

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Hidetaka Minagata

    ASME International Mechanical Engineering Congress and Exposition @ Columbus, OH 

    Presentation date: 2022.11

    Event date:
    2022.10
    -
    2022.11
  • Thermoelectric generation from exhaust heat in electrified natural gas trucks - part 1: modeling and baseline analysis on engine system efficiency improvement

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Hidetaka Minagata

    ASME International Mechanical Engineering Congress and Exposition @ Columbus, OH 

    Presentation date: 2022.11

    Event date:
    2022.10
    -
    2022.11
  • Thermoelectric exhaust heat recovery to maximize brake thermal efficiency of advanced diesel engines: modeling and baseline analysis

    Ratnak Sok, Jin Kusaka

    ASME Internal Combustion Engine Division Fall Technical Conference @ Indianapolis 

    Presentation date: 2022.10

    Event date:
    2022.10
     
     
  • Development and Comparison of Virtual Sensors Constructed using AI Techniques to Estimate the Performances of IC engines

    Arravind Jeyamoorthy, Takuma Degawa, Ratnak Sok, Toshikado Akimichi, Shigeaki Kurita, Masatoshi Ogawa, Takayuki Takei, Ikuta Hayashi, Jin Kusaka, Beini Zhou, Kyohei Yamaguchi, Iku Tanabe

    SAE Powertrains, Fuels & Lubricants Conference & Exhibition @ Krakow, Poland 

    Presentation date: 2022.09

    Event date:
    2022.09
     
     
  • Effects of Partial Oxidation in an Unburned Mixture on Turbulent Combustion with Ethanol-Blended Gasoline Surrogate Fuels toward Higher Thermal Efficiency of Spark-Ignition Engines with Renewable Fuels

    Kei Yoshimura, Kohei Isobe, Mitsutaka Kawashima, Satoshi Tokuhara, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka

    SAE Powertrains, Fuels & Lubricants Conference & Exhibition @ Krakow, Poland 

    Presentation date: 2022.09

    Event date:
    2022.09
     
     
  • A Model for Predicting Turbulent Burning Velocity with Low-Temperature Oxidation Reactions in Unburned Mixtures

    Kohei Isobe, Kei Yoshimura, Satoshi Tokuhara, Mitsutaka Kawashima, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka

    SAE Powertrains, Fuels & Lubricants Conference & Exhibition @ Krakow, Poland 

    Presentation date: 2022.09

    Event date:
    2022.09
     
     
  • Effects of Partial Oxidation and Octane Sensitivity on Flame Stretch Rate at Extinction under EGR Conditions Potential of Renewable Fuels toward Higher Thermal Efficiency of Spark-ignition Engines

    Kei Yoshimura, Kohei Isobe, Satoshi Tokuhara, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka

    COMODIA 2022 -The 10th International Conference on Modeling and Diagnostics for Advanced Engine Systems 

    Presentation date: 2022.07

    Event date:
    2022.07
     
     
  • Waste Heat Recovery via Thermoelectric Generation in Light-Duty Natural Gas Electrified Trucks: -Part1: Integrated Engine System Modeling and Baseline Analysis-

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Hidetaka Minagata

    ASTFE Thermal and Fluids Engineering Conference (TFEC) @ University of Nevada, LV 

    Presentation date: 2022.05

    Event date:
    2022.05
     
     
  • On the Laminar Flame Speed Correlations to Improve Prediction Accuracy of a Phenomenological Combustion Submodel in an Ultra-Lean SI Engine

    Ratnak Sok, Kyohei Yamaguchi, Jin Kusaka, Hidefumi Kataoka

    2021 JSAE 32nd Internal Combustion Engine Symposium 

    Event date:
    2021.12
     
     
  • Prediction of Potential Fuel Economy Improvements of an Electrified Natural Gas Truck Equipped With a VVT/VCR Engine

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Makoto Akaike, Hidetaka Minagata

    ASME 2021 International Mechanical Engineering Congress and Exposition 

    Presentation date: 2021.11

    Event date:
    2021.11
     
     
  • Experimental Investigation on the Effects of Direct Fuel Injection Into Low-O2 Recompression Interval of an HCCI Engine

    Ratnak Sok, Jin Kusaka

    ASME 2021 International Mechanical Engineering Congress and Exposition 

    Presentation date: 2021.11

    Event date:
    2021.11
     
     
  • A Model for Predicting Turbulent Burning Velocity by using Karlovitz Number and Markstein Number under EGR Conditions

    Kei Yoshimura, Kohei Ozawa, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka, Masaaki Togawa, Satoshi Tokuhara

    SAE Powertrains, Fuels & Lubricants Digital Summit 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Effects of Partial Oxidation in an Unburned Mixture on a Flame Stretch under EGR Conditions

    Kei Yoshimura, Kohei Ozawa, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka, Masaaki Togawa, Satoshi Tokuhara

    SAE Powertrains, Fuels & Lubricants Digital Summit 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Fast Nonlinear Model Predictive Control Using Machine Learning for Air Path Control of a Diesel Engine

    Kyohei Yamaguchi, Keisuke Yokota, Rio Asakawa, Iku Tanabe, Ratnak Sok, Beini Zhou, Jin Kusaka, Masatoshi Ogawa, Takuma Degawa, Shigeaki Kurita

    SAE Powertrains, Fuels & Lubricants Digital Summit 

    Event date:
    2021.09
     
     
  • A Novel Integrated Series Hybrid Electric Vehicle Model Reveals Possibilities for Reducing Fuel Consumption and Improving Exhaust Gas Purification Performance

    Takehiro Yamagishi, Hajime Shingyouchi, Kyohei Yamaguchi, Norifumi Mizushima, Takahiro Noyori, Jin Kusaka, Toshinori Okajima, Ratnak Sok, Makoto Nagata

    SAE Powertrains, Fuels & Lubricants Digital Summit 

    Presentation date: 2021.09

  • Avoidance Algorithm Development to Control Unrealistic Operating Conditions of Diesel Engine Systems under Transient Conditions

    Rio Asakawa, Iku Tanabe, Kyohei Yamaguchi, Ratnak Sok, Jin Kusaka, Masatoshi Ogawa, Takuma Degawa, Shigeaki Kurita, Arravind Jeyamoorthy, Zhou Beini

    SAE 15th International Conference on Engines & Vehicles @ Capri, Italy 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Reaction Analysis and Modeling of Fast SCR in a Cu-Chabazite SCR Catalyst Considering Generation and Decomposition of Ammonium Nitrate

    Keiichiro Seki, Rikuto Ueyama, Yoshihisa Tsukamoto, Kenya Ogawa, Kohei Oka, Ratnak Sok, Jin Kusaka

    SAE 15th International Conference on Engines & Vehicles @ Capri, Italy 

    Presentation date: 2021.09

    Event date:
    2021.09
     
     
  • Numerical Study on the Adaptation of Diesel Wave Breakup Model for Large-Eddy Simulation of Non-Reactive Gasoline Spray

    Ratnak Sok, Beini Zhou, Jin Kusaka

    ASME 2021 Power Conference 

    Presentation date: 2021.07

  • A MODELING STUDY ON FUEL CONSUMPTION IMPROVEMENT OF A LIGHT-DUTY CNG TRUCK EQUIPPED WITH A HYBRID POWERTRAIN

    Ratnak Sok, Jin Kusaka, Hisaharu Nakashima, Makoto Akaike

    ASTFE 5-6th Thermal and Fluids Engineering Conference (TFEC) 

    Presentation date: 2021.05

  • Experimental and Numerical Analysis on the Influence of Direct Fuel Injection into O2-Depleted Environment of a GDI-HCCI Engine

    Ratnak Sok, Jin Kusaka

    ASME 2020 Internal Combustion Engine Division Fall Technical Conference, USA 

    Presentation date: 2020

  • Prediction of Ultra-Lean SI Engine Performance by QD-Combustion Model With an Improved Laminar Flame Speed

    Ratnak Sok, Kyohei Yamaguchi, Jin Kusaka

    ASME 2020 Power Conference collocated with the 2020 International Conference on Nuclear Engineering, USA 

    Presentation date: 2020

  • Numerical Methods on VVA and VCR Concepts for Fuel Economy Improvement of a Commercial CNG Truck

    Ratnak Sok, Kazuki Takeuchi, Kyohei Yamaguchi, Jin Kusaka

    SAE Powertrains, Fuels & Lubricants Meeting, Poland 

    Presentation date: 2020

  • Roles of Computer-Aided-Engineering on Vehicle Powertrain Research & Development

    Ratnak Sok  [Invited]

    National Polytechnic Institute of Cambodia (Ministry of Labor and Vocational Training) 

    Presentation date: 2019.08

  • Roles of Computer-Aided Engineering on Vehicle Powertrain Research & Development

    Ratnak Sok  [Invited]

    Institut de Technologie du Cambodge 

    Presentation date: 2019.08

  • A Fundamental Study on Combustion Characteristics in a Pre-Chamber Type Lean Burn Natural Gas Engine

    Masashi Tanamura, Shintaro Nakai, Mahoko Nakatsuka, Shota Taki, Kohei Ozawa, Beini Zhou, Ratnak Sok, Yasuhiro Daisho, Jin Kusaka

    14th International Conference on Engines & Vehicles, Italy 

    Presentation date: 2019

  • 0D/1D Turbulent Combustion Model Assessment from an Ultra-Lean Spark Ignition Engine

    Ratnak Sok, Kyohei Yamaguchi, Jin Kusaka

    Asia-Pacific Automotive Engineering Conference, Thailand 

    Presentation date: 2019

  • A Study on Combustion Characteristics of a High Compression Ratio SI Engine with High Pressure Gasoline Injection

    Takashi Kaminaga, Kyohei Yamaguchi, Sok Ratnak, Jin Kusaka, Takashi Youso, Tatsuya Fujikawa, Masahisa Yamakawa

    14th International Conference on Engines & Vehicles, Italy 

    Presentation date: 2019

  • Effect of Fuel Injection Timing During Negative Valve Overlap Period on a GDI-HCCI Engine

    Ratnak Sok, Jin Kusaka, Yasuhiro Daisho, Kei Yoshimura, Kenjiro Nakama

    ASME 2018 Internal Combustion Engine Division Fall Technical Conference, USA 

    Presentation date: 2018

  • 3D Simulations on Premixed Laminar Flame Propagation of iso-Octane/Air Mixture at Elevated Pressure and Temperature

    Ratnak Sok, Jin Kusaka, Yasuhiro Daisho

    18th Asia Pacific Automotive Engineering Conference, Australia 

    Presentation date: 2015

  • Computational Study to Improve Thermal Efficiency of Spark Ignition Engine

    Ratnak Sok, Kohei Katori, Jin Kusaka, Yasuhiro Daisho, Kei Yoshimura, Nakama Kenjiro

    18th Asia Pacific Automotive Engineering Conference, Australia 

    Presentation date: 2015

  • Experiments and Simulations of a Lean-Boost Spark Ignition Engine for Thermal Efficiency Improvement

    Ratnak Sok, Jin Kusaka, Yasuhiro Daisho, Kei Yoshimura, Kenjiro Nakama

    SAE/JSAE Small Engines Technology Conference, Japan 

    Presentation date: 2015

  • Numerical and Experimental Studies on Flame Propagation of Iso-octane in a Constant Volume Chamber

    Ratnak Sok, Jin Kusaka

    The Proceedings of the National Symposium on Power and Energy Systems, Japan 

    Presentation date: 2014

  • Studies of Hydroxy (HHO) gas Addition on Performance and Exhaust gas Emissions of a Compression Ignition Engine fuelled with Rubber Seed Methyl Ester

    Ratnak Sok, IK REKSOWARDOJO, T PRAKOSO, Toshio Shudo, Wiranto Arismunandar

    JICA AUN/SEED-Net 5th Regional Conference on New and Renewable Energy, Vietnam 

    Presentation date: 2011

  • The Effect of Biodiesel Fuel from Rubber (Hevea brasiliensis) Seed Oil on a Direct Injection Diesel Engine

    Iman Reksowardojo, Hung Ngoc Bui, Ratnak Sok, Athol Kilgour, Tirto Brodjonegoro, Tatang Soerawidjaja, Mai Xuan Pham, Toshio Shudo, Wiranto Arismunandar

    3rd AUN/SEED-Net Regionale Conférence, New and Renewable Energy @ Penang, Malaysia 

    Presentation date: 2010.10

  • The Study of Biodiesel from Rubber (Hevea Brasiliensis) Seed Oil with HHO Gas Additive on a DI Engine

    Ratnak Sok, Iman REKSOWARDOJO, Tirto PRAKOSO, Toshio Shudo, Wiranto Arismunandar

    The 2nd Conference on Engineering and Technology, Cambodia 

    Presentation date: 2010

  • Experimental Study on the Performances of Yanmar NS70 Diesel Engine using Jatropha Curcas Oil

    Ratnak Sok, Sovanna Pan, Sopheak Rey  [Invited]

    Asian Youth Energy Summit, Singapore 

    Presentation date: 2008

▼display all

Research Projects

  • LD truck's battery pack performance active control by cooling its boundary condition

    Truck OEM 

    Project Year :

    2023.04
    -
    2024.04
     

    Jin Kusaka, Ratnak Sok

  • MBD on battery thermal management of BEVs

    Automotive supplier 

    Project Year :

    2022
    -
    2024
     

    Jin Kusaka, Ratnak Sok

  • Thermal management MBD of PHEV

    Automotive OEM 

    Project Year :

    2022
    -
    2024
     

    Jin Kusaka, Ratnak Sok

  • Compact passenger car engine designs via MBD

    Automotive Industry 

    Project Year :

    2018
    -
    2024
     

    Jin Kusaka, Ratnak Sok, Kyohei Yamaguchi

  • Development of high-efficiency gas engine for power generation by controlling flow of decarbonized fuels

    NEDO 

    Project Year :

    2021
    -
    2022
     

    Beini Zou, Kyohei Yamaguchi, Ratnak Sok

  • Reducing CO2 emissions by optimizing the combustion method and diesel surrogate blending of future engines

    Petroleum and Automotive Associations 

    Project Year :

    2021
    -
    2022
     

    Jin Kusaka, Beini Zhou, Ratnak Sok

  • MBD Approach to improve fuel economy of natural gas hybrid trucks

    Energy supplier 

    Project Year :

    2018
    -
    2021
     

    Jin Kusaka, Ratnak Sok

  • ML-based MPC controller development for engine control

    Automotive Supplier 

    Project Year :

    2018
    -
    2021
     

    Jin Kusaka, Kyohei Yamaguchi, Ratnak Sok, Beini Zhou

  • Gasoline Engine Control

    European automotive supplier 

    Project Year :

    2019
    -
    2020
     

    Hiroyuki Ishii, Jin Kusaka, Ratnak Sok, Kyohei Yamaguchi

  • SIP Innovative Combustion Technology

    JST 

    Project Year :

    2014
    -
    2019
     

  • LBE Program: Education Capacity Building by Lab-Based Education Improvement

    Japan International Cooperation Agency 

    Project Year :

    2017
    -
    2018
     

    Ratnak Sok, Sovanna Pan (within a whole research unit)

  • High-efficiency engine development for subcompact cars

    Automotive Industry 

    Project Year :

    2012
    -
    2015
     

  • Utilisation of Biogas from Animal Waste and Biomass from Agricultural Waste in Internal Combustion Engine

    Japan International Cooperation Agency 

    Project Year :

    2011
    -
    2012
     

    (ITC: Sopheak Rey, Ratnak Sok), (Kyoto Univ: Masahiro Shioji)

  • Design of threshing machine for agricultural use

    Japan International Cooperation Agency 

    Project Year :

    2011
    -
    2012
     

    Dara To, Ratnak Sok

  • Development of a Small Scale Biomass Gas Generator

    Japan International Cooperation Agency 

    Project Year :

    2011
    -
    2012
     

    Ratnak Sok, Dara To

  • Performance and Durability Test of Mixed Combustion of Jatropha Curcas L. Oil and Biogas for Power Generation

    NEDO 

    Project Year :

    2011
    -
    2012
     

    (ITC: Rey Sopheak, Sovanna Pan, Ratnak Sok, Thavarith Chunhieng, Romny Om) (Chugoku EPCO: Yukimasa Yamamura, Ichiro Uchiyama, Toshiki Yamasaki, Akifumi Nakamura, Yoshihisa Shimizu)

  • LBE Program: Education Capacity Building by Lab-Based Education Improvement

    Japan International Cooperation Agency 

    Project Year :

    2011
    -
    2012
     

    Ratnak Sok, Sopheak Rey, Sovanna Pan (within a whole research unit)

▼display all

 

Teaching Experience

  • TA on Thermal energy reaction engineering

    Waseda University  

    2018
    -
    Now
     

  • TA on Thermal energy reaction engineering

    Waseda University  

    2012
    -
    2015
     

  • ICEs, GD&T Fundamentals, Material Sciences

    National Polytechnics Institute of Cambodia  

    2011
    -
    2012
     

  • ICEs, Machine elements, mechanical constructions

    Institut de Technologie du Cambodge  

    2011
    -
    2012
     

 

Academic Activities

  • Editorial board members in SAE International

    Academic research

    2022
    -
    Now
  • Guest Associate/Review Editor in Frontiers in Future Transportation

    Scientific advice/Review

    https://www.frontiersin.org/journals/future-transportation/sections/transportation-emissions#editorial-board  

    2022
    -
    Now
  • Topic Advisory Panel Member (10+ MDPI Journals)

    Peer review

    2022
    -
    Now
  • Reviewer for 20+ Journals and Conferences (ASME, Elsevier, IEEE, SAE, SAGE, MDPI, Springer, Taylor&Francis)

    Peer review

    2020
    -
    Now
  • Organizing Committees (Track Chair)

    Academic society, research group, etc.

    2024.06
     
     
  • Associate Chair (15th International ACM Conference on Automotive User Interfaces and Interactive Vehicular Applications)

    Academic society, research group, etc.

    2023.09
     
     
  • Event Committee (The 2nd International Electronic Conference on Processes: Process Engineering—Current State and Future Trends)

    Competition, symposium, etc.

    2023.05
     
     
  • Program Committee (2022 IEEE International Conference on Artificial Intelligence in Engineering and Technology)

    Competition, symposium, etc.

    2022.09
     
     

▼display all

Research Institute

  • 2022
    -
    2024

    Waseda Center for a Carbon Neutral Society   Concurrent Researcher