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THERMAL SCIENCE
International Scientific Journal
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NUMERICAL STUDY ON THE CHARACTERISTICS OF ENERGY CONVERSION FOR CHEMICAL REACTIONS IN AN AMMONIA/HYDROGEN-AIR MICRO-COMBUSTOR
ABSTRACT
Micro-combustors have attracted significant attention due to their high efficiency and energy density. The thermal, physical, and chemical processes that occur in these combustors involve complex energy conversion, the mechanism and characteristics of which are not well understood. In this work, a thermodynamic model of the combustion process is proposed based on the energy conversion process, and a method for evaluating exergy efficiency is provided. The model is applied to the exergy analysis of an ammonia/hydrogen micro-combustor. The changes in thermal, chemical, and thermomechanical exergies, as well as the exergy loss rate during single-step chemical reactions, are calculated. The effects of key parameters, including the hydrogen blending ratio (ε = 0.4-0.5), the equivalence ratio (φ = 0.8-1.0), and the inlet velocity (vin = 0.2-0.4 m/s), on energy conversion are investigated. Then, the exergy efficiency of various chemical reactions and the local exergy efficiency at the flame front are calculated. The crucial chemical reactions for energy conversion are identified, and the performance of the micro-combustor is evaluated. The results indicate that fuel pyrolysis (NH3 + OH = NH2 + H2O, H2 + OH = H + H2O) plays an important role in energy conversion. The exergy efficiency of important reactions is 0.2-0.8. Reducing the hydrogen blending ratio from 0.5 to 0.4 and increasing the inlet velocity from 0.2 to 0.4 can enhance energy conversion.
KEYWORDS
PAPER SUBMITTED: 2026-01-21
PAPER REVISED: 2026-05-18
PAPER ACCEPTED: 2026-05-27
PUBLISHED ONLINE: 2026-07-11
DOI REFERENCE: https://doi.org/10.2298/TSCI260121097W
[1] Ioan, G., et al., The green dilemma: energy efficiency, renewables and economic challenges in Eastern Europe, Energy Policy, 206 (2025), 114791
[2] Wang, Y., et al., Intensified coupling of regional water and energy efficiencies by wastewater treatment-coal power infrastructure symbiosis, Environmental Impact Assessment Review, 116 (2026), 108096
[3] Rakopoulos, C. D., Giakoumis, E. G., Second-law Analyses Applied to Internal Combustion Engines Operation, Progress in Energy and Combustion Science, 32 (2006), 1, pp. 2-47
[4] Costa, V. A. F., On the exergy balance equation and the exergy destruction, Energy, 116 (2016), 1, pp. 824-835
[5] Trinh, V. T., et al., Experimental and numerical investigation of co-firing lighting coal with upgraded coal and bituminous coal in a drop tube furnace, Thermal Science, 29 (2025), 5B, pp. 3955-3966
[6] Cai, L., et al., Effect analysis on thermal performance enhancement and entropy generation reduction in micro-combustors with different geometric structures fueled with the hydrogen/air and hydrogen/ammonia/air, Fuel, 374 (2024), 132535
[7] Jiaqiang, E., et al., A review of enhancing micro combustion to improve energy conversion performance in micro power system, International Journal of Hydrogen Energy, 47 (2022), 53, pp. 22574-22601
[8] Grazia, D. G. M., et al., The influence of radiation modeling on flame characteristics and emissions prediction in micro-combustors with ammonia/hydrogen blends, Fuel, 377 (2024), 132759
[9] You, J., et al., A novel two-stage thermophotovoltaic-thermoelectric system based on micro combustion, Applied Thermal Engineering, 232 (2023), 121018
[10] Ding, J., et al., Effect analysis on energy conversion enhancement of porous medium micro-combustor and thermoelectric system and its optimization, Energy Conversion and Management, 292 (2023), 117441
[11] Abdulrahman, Y., et al., AI and blockchain synergy in aerospace engineering: an impact survey on operational efficiency and technological challenges, IEEE Access, 11 (2023), pp. 87790-87804
[12] Zhang, Z., et al., Numerical analysis of radiative and energy conversion for ammonia/ hydrogen-air premixed flame in a planar micro-combustor, Fuel, 400 (2025), 135734
[13] Zhang, Z., et al., Experimental and numerical analysis of the thermodynamic characteristics of a hydrocarbon flame with an improved second-law thermodynamic model, Energy, 325 (2025), 136055
[14] Xue, S., et al., Effects of strain and pressure on entropy generation in laminar flames, Combustion and Flame, 269 (2024), 113688
[15] Zhang, X., et al., The thermodynamic relationship between reducing exergy destruction and improving thermal efficiency in internal combustion engines, Applied Thermal Engineering, 268 (2025), 125875
[16] Sinha, I., et al., Effect of different quaternary blends of diesel-ethanol-methanol-butanol on combustion and spray characteristics of diesel engine, Thermal Science, 29 (2025), 1B, pp. 411-
[17] Jin, M., et al., Numerical simulation on NOx reduction in the float glass furnace with gradient oxygen-enhanced combustion, Thermal Science, 29 (2025), 4A, pp. 2627-2640
[18] Li, W., et al., Numerical identifications of T-shaped rod effect on thermal performance and exergy efficiency in methane/air combustion, Applied Thermal Engineering, 239 (2024), 122143
[19] Lv, E., et al., Analysis of entropy generation and exergy efficiency of a micro-combustor with a passive exhaust gas recirculation channel, International Journal of Hydrogen Energy, 86 (2024), 1337-1347
[20] Zhang, Y., et al., Study on the non-premixed combustion characteristics and exergy analysis of H2/Air in vase-shaped micro combustor, Applied Thermal Engineering, 233 (2023), 121104
[21] Xue, Z., et al., Exergy analysis and energy output improvement of the micro-thermophotovoltaic system via investigating the fractal angles of secondary Y-shaped fins in the micro combustor, Fuel, 334 (2023), 126504
[22] Rong, H., et al., Enhancing thermal and exergy performances in a CO2-Free micro-combustor with reverse flow double-channel outlet structure, Applied Thermal Engineering, 233 (2023), 121180
[23] He, Z., et al., Heat transfer enhancement and exergy efficiency improvement of a micro combustor with internal spiral fins for thermophotovoltaic systems, Applied Thermal Engineering, 189 (2021), 116723
[24] Cai, L., et al., Effect analysis on thermal performance enhancement and entropy generation reduction in micro-combustors with different geometric structures fueled with the hydrogen/air and hydrogen/ammonia/air, Fuel, 374 (2024), 132535
[25] Liu, S., et al., Assessing of potential of chemiluminescence to characterize NO formation in NH 3-CH4 premixed flat flames, Thermal Science, 30 (2026), 2B, pp. 1375-1388
[26] Zhang, Q., et al., Analysis of entropy generation and exergy efficiency of the methane/dimethyl ether/air premixed combustion in a micro-channel, International Journal of Heat and Mass Transfer, 218 (2024), 124801
[27] Wang, Y., et al., Investigation of swirler effect on combustion and exergy efficiency of hydrogen/ chlorine combustor based on entropy generation analysis, Energy, 300 (2024), 131593
[28] Zhua, Y., et al., The combustion chemistry of ammonia and ammonia/hydrogen mixtures: A comprehensive chemical kinetic modeling study, Combust and Flame, 260 (2024), 113239
[29] Cai, T., et al., Experimental and kinetic analyses on the flame dynamics and stabilization of ammonia/hydrogen-air mixtures in a micro-planar combustor. Chemical Engineering Journal, 477 (2023), 147038
© 2026 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International licence