Thermal efficiency characteristics of hydrogen internal combustion engine

To study the economic advantages of hydrogen internal combustion engine, an experimental study was carried out using a 2.0 L port fuel-injected (PFI) hydrogen internal combustion engine. Influences of fuel-air equivalence ratio Φ, speed, and ignition advance angle on heat efficiency were determined. Test results showed that indicated thermal efficiency (ITE) firstly increased with fuel-air equivalence ratio, achieved the maximum value of 40.4% (Φ=0.3), and then decreased when Φ was more than 0.3. ITE increased as speed rises. Mechanical efficiency increased as fuel-air equivalence ratio increased, whereas mechanical efficiency decreased as speed increased, with maximum mechanical efficiency reaching 90%. Brake thermal efficiency (BTE) was influenced by ITE and mechanical efficiency, at the maximum value of 35% (Φ=0.5, 2000 r/min). The optimal ignition advance angle of each condition resulting in the maximum BTE was also studied. With increasing fuel-air equivalence ratio, the optimal ignition angle became closer to the top dead center (TDC). The test results and the conclusions exhibited a guiding role on hydrogen internal combustion engine optimization.