Exergy Analysis in Highly Hydrogen-Enriched Methane Fueled Spark-Ignition Engine at Diverse Equivalence Ratios via Two-Zone Quasi-Dimensional Modeling

Dimitrios C. Rakopoulos, Constantine D. Rakopoulos (), George M. Kosmadakis, Evangelos G. Giakoumis and Dimitrios C. Kyritsis
Additional contact information
Dimitrios C. Rakopoulos: Chemical Process and Energy Resources Institute, Center for Research and Technology Hellas, GR-57001 Thermi, Thessaloniki, Greece
Constantine D. Rakopoulos: Department of Thermal Engineering, School of Mechanical Engineering, National Technical University of Athens, Zografou Campus, 9 Heroon Polytechniou Street, 15780 Athens, Greece
George M. Kosmadakis: Department of Thermal Engineering, School of Mechanical Engineering, National Technical University of Athens, Zografou Campus, 9 Heroon Polytechniou Street, 15780 Athens, Greece
Evangelos G. Giakoumis: Department of Thermal Engineering, School of Mechanical Engineering, National Technical University of Athens, Zografou Campus, 9 Heroon Polytechniou Street, 15780 Athens, Greece
Dimitrios C. Kyritsis: NEOM Education, Research and Innovation Foundation and NEOM University, Al Khuraybah, Tabuk 49643-9136, Saudi Arabia

Energies, 2024, vol. 17, issue 16, 1-44

Abstract: In the endeavor to accomplish a fully de-carbonized globe, sparkling interest is growing towards using natural gas (NG) having as vastly major component methane (CH 4 ). This has the lowest carbon/hydrogen atom ratio compared to other conventional fossil fuels used in engines and power-plants hence mitigating carbon dioxide (CO 2 ) emissions. Given that using neat hydrogen (H 2 ) containing nil carbon still possesses several issues, blending CH 4 with H 2 constitutes a stepping-stone towards the ultimate goal of zero producing CO 2 . In this context, the current work investigates the exergy terms development in high-speed spark-ignition engine (SI) fueled with various hydrogen/methane blends from neat CH 4 to 50% vol. fraction H 2 , at equivalence ratios (EQR) from stoichiometric into the lean region. Experimental data available for that engine were used for validation from the first-law (energy) perspective plus emissions and cycle-by-cycle variations (CCV), using in-house, comprehensive, two-zone (unburned and burned), quasi-dimensional turbulent combustion model tracking tightly the flame-front pathway, developed and reported recently by authors. The latter is expanded to comprise exergy terms accompanying the energy outcomes, affording extra valuable information on judicious energy usage. The development in each zone, over the engine cycle, of various exergy terms accounting too for the reactive and diffusion components making up the chemical exergy is calculated and assessed. The correct calculation of species and temperature histories inside the burned zone subsequent to entrainment of fresh mixture from the unburned zone contributes to more exact computation, especially considering the H 2 percentage in the fuel blend modifying temperature-levels, which is key factor when the irreversibility is calculated from a balance comprising all rest exergy terms. Illustrative diagrams of the exergy terms in every zone and whole charge reveal the influence of H 2 and EQR values on exergy terms, furnishing thorough information. Concerning the joint content of both zones normalized exergy values over the engine cycle, the heat loss transfer exergy curves acquire higher values the higher the H 2 or EQR, the work transfer exergy curves acquire slightly higher values the higher the H 2 and slightly higher values the lower the EQR, and the irreversibility curves acquire lower values the higher the H 2 or EQR. This exergy approach can offer new reflection for the prospective research to advancing engines performance along judicious use of fully friendly ecological fuel as H 2 . This extended and in-depth exergy analysis on the use of hydrogen in engines has not appeared in the literature. It can lead to undertaking corrective actions for the irreversibility, exergy losses, and chemical exergy, eventually increasing the knowledge of the SI engines science and technology for building smarter control devices when fueling the IC engines with H 2 fuel, which can prove to be game changer to attaining a clean energy environment transition.

Keywords: hydrogen; methane; spark-ignition engine; irreversibility; exergy losses; chemical exergy; two-zone; quasi-dimensional combustion modeling; fuel blend; equivalence ratio (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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