Effect of brown gas (HHO) addition on combustion and emission in gasoline engine with exhaust gas recirculation (EGR) and gasoline direct injection

Abstract

As a hydrogen-based fuel that can be used immediately after generation without storage, brown gas (HHO) has important research significance and practical development prospect. In this paper, the exhaust gas recirculation (EGR) and lean-burn of gasoline direct injection (GDI) engine blended with HHO are studied. The effects of different HHO flux, λ and EGR rate on engine performance were studied experimentally. The results show that peak in-cylinder pressure (Pmax), Torque and its best EGR rate increases with the increase of HHO flux. When λ is 1, EGR is 18%, HHO flux is 16L/min, Torque reaches the maximum 53.47N·m. coefficient of indicated mean effective pressure variation (CoVIMEP), crank angle corresponding to Pmax (APmax), ignition delay period (CA 0–10) and rapid combustion period (CA 10–90) decreases with the increase of HHO flux. When λ is 1.2, EGR is 18%, HHO flux increases from 0 to 16L/min, the maximum reduction of CA 0–10 and CA 10–90 is 27.36% and 34.41%. Under lean-burn conditions, IMEP increases first and then decreases with the increase of HHO flux and EGR rate; when λ is 1.1, EGR is 12%，HHO flux is 16L/min, IMEP reaches the maximum value of 4.23 bar; when HHO flux is 16L/min, EGR is greater than or equal to 6% and less than or equal to less than or equal to 12%, both Pmax and APmax are at the best level. Carbon monoxide (CO) and hydrocarbon (HC) on the whole decreases with the increase of HHO flux. And when HHO is 16L/min, EGR less than 6%, CO and HC always at a low level. nitric oxide (NO) increases with the increase of HHO flux. under three λ conditions, when HHO flux is 16L/min and EGR rate increases from 0% to 18%, NO can still be reduced by 79.36%, 87.98% and 87.56%%, respectively. In general, GDI add HHO add EGR mode can effectively improve the combustion and emission characteristics of the gasoline engine, especially in the lean-burn condition. And 16L/min HHO and 6% ≤ EGR ≤ 12% is the optimal combination.