Experimental Study On HCCI Combustion Characteristics Of Millimeter-scaled Reciprocating Piston ICE With Ether Fuel

The micro reciprocating piston internal combustion engine with high-energy density hydrocarbon fuel has potential application prospect in micro electromechanical systems?MEMS?,but the thermal efficiency of micro internal combustion engine drops sharply because the combustion deteriorates with the size reduction,it limits the size reduction and the improvement of thermal efficiency of micro internal combustion engine,improving the combustion efficiency of micro internal combustion engines has become a major problem in the development of micro internal combustion engines.Considering the characteristics of homogeneous charge compression ignition?HCCI?combustion mode such as simultaneous ignition,fast burning rate and low ignition temperature,a combustion test platform for micro internal combustion engine was built,and a HCCI micro combustion engine with 549mm³ displacement was taken as the research object,the combustion test was carried out to study the combustion adaptability of HCCI in millimeter scale micro internal combustion engine.The main contents of the thesis are as follows:Combustion test and evaluation of the HCCI micro engine at different speeds were carried out,the results show that:the p_mi of HCCI micro engine increases with the speed increase,the maximum average p_mi at 6000r/min was 0.19MPa;p_mi decreased with CA50 moving forward,It indicated that the combustion heat release in micro engine was advanced under test conditions.The combustion characteristics of same displacement level micro engine with different ignition modes were compared,it showed that:p_mi of micro engine with different ignition modes were small,the combustion heat release of HCCI micro engine was earlier than that of the glow ignition micro engine,and the combustion heat release duration was shorter than that of the glow ignite engine,the combustion stability was better than that of the glow ignite micro engine.Combustion test and evaluation of the HCCI micro engine at different compression ratios were carried out,the results showed that:when the compression ratio was 12.4,it could not ignite normally,when the compression ratio was increased from 14.1 to 19.9,p_mi decreased,combustion heat release advanced,main combustion duration shortened,when the compression ratio was increased to 25.2,combustion deteriorated in cylinder,p_mi was minimum;when compression ratio was 16.5,19.9 and 25.2,p_mi decreased with CA50 advance,it indicated the early of combustion heat release in the corresponding test conditions,when compression ratio was 14.1,p_mi changed parabolic with CA50,it indicated that the combustion heat release was more suitable under the current conditions.The combustion characteristics of HCCI micro engines at different cylinder block temperatures were compared,the results showed that:with the increase of cylinder block temperature,the combustion stability of micro engine was obviously enhanced,but p_mi decreased,the combustion heat release ahead,the combustion duration shortened,the intake flow rate decreased;by comparing the relationship between p_mi and CA50,it was pointed out that the reduction of air intake was the main reason leading to the decrease of p_mi with the increase of cylinder block temperature.The intake supercharging system of micro internal combustion engine was designed and built,combustion test and evaluation of HCCI micro engine under different intake pressure were carried out,the results showed that:increasing intake pressure could increase the intake flow rate,but the combustion characteristics of micro engine were not regular correspond to the increase of intake air flow,by comparing the relationship between p_mi and CA50 under different intake pressure,it was pointed out that increasing the intake pressure can increase the p_mi to a certain extent.