Development of a turbocharged direct-injection hydrogen engine to achieve clean, efficient, and high-power performance

Hydrogen, as clean and renewable energy, is an ideal fuel for internal combustion engines. The direct-injection (DI) hydrogen engine can offer large power with low cost and rely less on hydrogen purity. In this study, a 2.0L DI turbocharged hydrogen engine is implemented to achieve clean, efficient, and high-power performance. Peak power of 120 kW @ 4400 rpm and a maximum torque of 340 N·m @ 2000 rpm can be achieved with the matched turbocharger. Appropriate retarded injection can suppress abnormal combustion and broaden the dynamic boundaries. A maximum brake thermal efficiency (BTE) of 42.6% is obtained with the slightly lean excess air coefficient (λ) of 1.91 @ 2000 rpm and 40.4% BTE with the λ of 2.47 @ 3000 rpm. The high conversion efficiency of NOx emissions of over 99.5% is reached at low speeds (below 2000 rpm) and drops to 90% at 4400 rpm with the use of the NH₃-SCR after-treatment system. The NOx emissions of approximately two-thirds of the whole working conditions can be reduced below 20 ppm. The optimized DI hydrogen engine can achieve large power (Brake mean effective pressure = 17 bar), high efficiency (Brake thermal efficiency = 42.1%), and near-zero emissions (NOx < 20 ppm) simultaneously.