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Homogeneous charge compression combustion mode fuel economy and lower emissions of NOx and soot . As a new combustion , HCCI engines are widely popular, and it can improve the thermal efficiency of the spark ignition engine , can also reduce emissions of compression ignition engines . However , the application before the actual HCCI engine , there are many technical problems to be solved , such as HCCI engine fire control is one of the most critical technical issues . HCCI combustion , the combustion process is mainly affected by the chemical reaction kinetics control . In order to ensure efficient operation of the HCCI engine , it is necessary so that the ignition point of the fuel occurs in the near TDC . To this end, based on the single-zone model , application CHEMKIN 4.1 ignition point of impact of different parameters on HCCI engine , including compression ratio , initial temperature , initial pressure , speed , equivalence ratio and EGR . Which focus on the EGR in NO impact and low load HCCI combustion emissions . The results show that : With the increase in the compression ratio , the ignition timing is closer to the upper dead point . Is relatively large when the ratio relative to the same time , the compression cylinder smaller volume before the ignition , resulting in - cylinder gas concentration is very high , so that the ignition advance ; With the intake air temperature increases , the ignition advance , and the maximum cylinder temperature also will increase ; with increasing initial pressure , the ignition advance; as the speed increases, the ignition point delayed , which is caused by the chemical reaction rate is much lower than the engine speed . If the cylinder gas is not sufficient to fire, as the equivalence ratio continues to increase , the increase in the heat capacity of the gas mixture and the cylinder temperature is further reduced ; cylinder gas fire, as the equivalence ratio increases , the ignition point postponed . When the other parameters of the compression ratio is constant , the EGR rate is higher , the ignition point of the more forward . EGR and NO at a concentration of less than 30ppm , the inhibiting effect of n - heptane / toluene mixed combustion of the fuel ; play a catalytic role , then the combustion process of the fuel when the concentration of NO in EGR exceed 30ppm .
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