On-Board Integrated Methylcyclohexane-Hydrogen System for Heavy-Duty Trucks: Thermodynamic Feasibility Assessment and Performance Benchmarking

The application of hydrogen in heavy-duty transportation is significantly hindered by onboard storage challenges. Methylcyclohexane (MCH), as a promising liquid organic hydrogen carrier (LOHC), presents a compelling alternative due to its high safety and compatibility with existing fueling infrastructure. This paper establishes a comprehensive, steady-state thermodynamic model of an onboard integrated MCH-hydrogen system, introducing a novel waste heat recovery strategy that simultaneously utilizes internal combustion engine (ICE) exhaust and cooling water jacket heat. Thermodynamic simulations demonstrate that under baseline operating equilibrium conditions, the MCH conversion rate reaches 99.80%. At this reference point, the ICE achieves a thermal efficiency of 42.2%, contributing to a net system efficiency of 31%. Comprehensive parametric analyses are conducted to investigate the coupled effects of reactor conditions, purification pressures, and the excess air ratio on the system performance. Furthermore, the vehicle’s driving range and potential payload penalties are evaluated across various fuel tank configurations. Finally, an economic assessment reveals that the proposed MCH-fueled truck achieves clear cost-competitiveness against traditional diesel heavy-duty trucks when the hydrogen infrastructure price drops below 2.0 USD/kg and diesel prices exceed 3.5 USD/gallon. This study establishes a robust thermodynamic benchmarking and offers critical design insights for the deployment of LOHC-powered heavy-duty transportation.