Optimization of hydrogen production and system efficiency enhancement through exhaust heat utilization in hydrogen-enriched internal combustion engine

Muhammad Ihsan Shahid, Muhammad Farhan, Anas Rao, Hamza Ahmad Salam, Tianhao Chen, Qiuhong Xiao, Xin Li and Fanhua Ma

Energy, 2025, vol. 319, issue C

Abstract: The increasing fuel prices driven by the depletion of fossil fuel reserves have sparked renewed interest in methods to enhance the thermal efficiency of engines. One promising approach to improving system efficiency is converting engine waste heat into a more useful form of energy. This study uses exhaust heat to investigate hydrogen production and improve overall system efficiency in hydrogen-enriched compressed natural gas (HCNG) engines. The experiment analyzes the exhaust heat at hydrogen ratios of 20 %, EGR (Exhaust gas recirculation) ratios of 20 %, engine load at 75 %, and speed at 1200 rpm under stoichiometric conditions. The objective is to produce hydrogen via the steam methane reforming (SMR) method using ASPEN Plus software. The heat duties of the heat exchangers and reformer components in the SMR process were also evaluated. At the specified operating conditions, the engine's exhaust reached a maximum temperature of 974 K, with an exhaust mass flow rate of 0.1640 kg/s and an available exhaust heat of 134 kW. The hydrogen production rate increased by 23.31 % by rising reformer temperature from 973K to 1273K. Hydrogen was produced at a rate of 5.62 kg/h, with a steam temperature of 873 K and a reformer temperature of 1273 K, utilizing an additional heat duty of 72 kW for the reformer. The engine efficiency under these conditions was 36.44 %, while the overall system efficiency reached 62.23 % after hydrogen production.

Keywords: Hydrogen-enriched compressed natural gas (HCNG); Exhaust heat rate; Steam methane reformer; ASPEN plus; Hydrogen production (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:319:y:2025:i:c:s0360544225006930

DOI: 10.1016/j.energy.2025.135051

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