NO_x emission characteristics of hydrogen internal combustion engine

To study the economic advantages of hydrogen internal combustion engine, an experimen- tal 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 was more than 0. 3. ITE increased as speed rises. Mechanical efficiency increased as fuel-air equiva- lence ratio increased, whereas mechanical efficiency decreased as speed increased, with maximum mechanical efficiency reaching 90%. Brake thermal efficiency （BTE） was influenced by ITE and me- chanical efficiency, at the maximum value of 35% （φ =0.5, 2 000 r/min）. The optimal ignition ad- vance 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 opti- mization.

Experimental and Numerical Studies of a Microscale Internal Combustion Swing Engine(MICSE)

In this paper,the operation characteristics of a microscale internal combustion swing engine(MICSE)were investigated experimentally and numerically.The energy flow path of MICSE was comprehensively analyzed based on the first law of thermodynamics.The accuracy of zero-dimensional model was verified by experiments.The indicative thermal efficiency of the engine increases first and then decreases with the increase of equivalent ratio or ignition advance angle.The results show that there exists an optimum equivalent ratio and ignition advance angle during operation.The maximum efficiency of the engine reaches 12.5%when the equivalent ratio and ignition advance angle are 0.8 and−0.553,respectively.MICSE can operate normally when the equivalent ratio is greater than 0.6.The peak value of net heat release rate lags behind that of pressure change,which is different from the conventional crank engine.Experimental and simulation results show that the leakage of MICSE is serious,and it is the main loss of MICSE.The order of energy terms is as follows:leakage loss>exhaust loss>heat loss>indicative work.