Energy and exergy analysis for a turbocharged direct-injection hydrogen engine to achieve efficient and high-economy performances

Hydrogen is a potential alternative fuel for combustion engines with its higher renewability, near zero emission, and excellent combustion performance. The direct-injection (DI) engine provides favorable brake thermal efficiency (BTE), less dependence on the hydrogen purity but sacrificing the production cost. This study explores both effects of turbocharging and DI on the energy and exergy balances, as well as the cost-effective analysis on a spark ignition engine. Results reveal the exergy efficiencies are related to the engine speeds and loads, while its maximum is 58.8% with 3500 rpm and 1.4 MPa of brake mean effective pressure. The DI system increases 2.6% maximum BTE from the port fuel injection. However, the exhaust energy proportions exceed 32.8% and 18.9% at the maximum power and BTE. An organic Rankine cycle is utilized to improve the exergy to the maximum of 58.9%. The valuable experience can be widely applied for hydrogen engine design.