Study On Effect Of Brown Gas On Performance Of Butanol/Gasoline Engine

With the progress of science and technology and the development of society,the energy crisis and environmental pollution problems have become increasingly prominent.In order to alleviate the dependence of internal combustion engines on fossil fuels and reduce pollutant emissions,the application of clean and efficient alternative fuels has become one of the main development directions of the internal combustion engine.Alcohol fuels have been a hot research topic for alternative fuels due to their excellent physicochemical properties and regenerative properties.Butanol fuel is considered to be a cleaner fuel with a higher potential to replace gasoline because it has higher calorific value and lower latent heat of vaporization than other alcohol fuels,and its physicochemical properties are closest to those of gasoline,and it does not require much change to the engine structure when used in engines.Brown gas（HHO）,as an emerging hydrogen fuel,has been attracting more attention in recent years because of the excellent physical and chemical properties similar to those of hydrogen and its portability in application.In view of this,this thesis applies butanol in combination with HHO to the engine and investigates the effect of blending Brown gas on the combustion and emission characteristics of the butanol/gasoline engine through engine test bench experiments to clarify the synergistic effect of butanol,gasoline and Brown gas.The main conclusions are as follows:First,based on the established engine test bench,this thesis explores the influence of different butanol direct injection time and direct injection ratio conditions on engine performance under the condition of theoretical mixture（λ=1.0）.The results show that,with the increase of HHO flux,the engine Pmax,IMEP and NO_xemissions increase while APmax,CA 0-10,CA 10-90,CO emissions and HC emissions decrease.Blending 16L/min HHO not only further enhances butanol/gasoline engine dynamics and reduces emissions,but also weakens the negative impact of latent heat of butanol vaporization on combustion,shortens the performance gap between different butanol direct injection time,and increases the optimal butanol direct injection ratio from 40%to 60%.In addition,the cooling effect of direct injection of butanol on cylinder temperature can reduce the high NO_xemissions caused by blending Brown gas.Therefore,there is a good synergistic working relationship between HHO and butanol,and the engine has the best overall performance under the conditions of butanol direct injection time 300°CA BTDC,butanol direct injection ratio 40%～60%and HHO flux 16L/min.On the basis of the excellent synergistic effect between butanol and HHO,in order to further investigate the potential of HHO to enhance engine performance and improve the high NO_x emissions after blending HHO,this thesis investigates the effect of blending different HHO flux on the lean-burn characteristics of butanol/gasoline engines through engine test bench.The results show that due to the lower ignition energy and faster flame propagation speed of Brown gas,it can promote the stable formation of flame core and accelerate the propagation of flame under lean-burn conditions.Blending 16L/min HHO can make CA 0-10 and CA10-90 at a low level under the condition ofλ=1.1～1.4,which can suppress the occurrence of in-cylinder misfire and ensure the normal process of combustion.Therefore,blending HHO can make the butanol/gasoline engine gain better power performance and lower emissions under lean-burn conditions.In addition,lean-burn reduces the in-cylinder temperature and effectively controls the increase of NO_xemissions after blending HHO.Under the condition of blending 16L/min HHO,the NO_x emissions ofλ=1.3 and 1.4 are reduced by 33.51%and 57.28%compared to the value ofλ=1.0.Whenλ≤1.3,blending 16L/min HHO can shorten the performance gap between 40%and 80%butanol direct injection ratio.And the combination of16L/min HHO and 80%butanol direct injection ratio can make the engine have excellent lean-burn characteristics while obtaining lower NO_x emissions and reducing the engine’s consumption of gasoline.Blending Brown gas significantly improves the combustion stability of butanol/gasoline engine.The Co V_IMEP of butanol/gasoline engine can be maintained below 2.5%whenλ≤1.4 by blending 8L/min HHO.In addition,the lean-burn limit of the butanol/gasoline engine is extended after blending Brown gas.On the basis of butanol direct injection ratio 40%,the lean-burn limit of the engine can be increased from 1.41 to 1.83 by blending 16L/min HHO.In summary,blending Brown gas can improve the combustion characteristics of butanol/gasoline engine,especially at lean-burn conditions,inhibit the negative impact of latent heat of butanol vaporization,improve the tolerance of engine to butanol,and make the engine have better power and emissions characteristics.In addition,both direct injecting butanol and lean-burn can reduce the temperature in the cylinder of the engine,thus reducing the NO_x emissions of the engine after blending Brown gas.