The effects of cooled external exhaust gas recirculation （EGR） on the combustion and emission performance of diesel fuel homogeneous charge compression ignition （HCCI） are studied. Homogeneous mixture is formed by...The effects of cooled external exhaust gas recirculation （EGR） on the combustion and emission performance of diesel fuel homogeneous charge compression ignition （HCCI） are studied. Homogeneous mixture is formed by injecting fuel in-cylinder in the negative valve overlap （NVO） period. So, the HCCI combustion which has low NOx and smoke emission is achieved. Cooled external EGR can delay the start of combustion effectively, which is very useful for high cetane fuel （diesel） HCCI, because these fuels can easily self-ignition, which makes the start of combustion more early. External EGR can avoid the knock combustion of HCCI at high load which means that the EGR can expand the high load limit. HCCI maintains low smoke emission at various EGR rate and various load compared with conventional diesel engine because there is no fuel-rich area in cylinder.展开更多
Experimental study on homogeneous charge compression ignition （HCCI） combustion process was carried out on a single-cylinder direct injection diesel engine fueled with dimethyl ether（DME）. The influence of inert g...Experimental study on homogeneous charge compression ignition （HCCI） combustion process was carried out on a single-cylinder direct injection diesel engine fueled with dimethyl ether（DME）. The influence of inert gas CO2 on the ignition and combustion process was investigated. The research results indicate that because of the high cetane number of DME, the stable HCCI operating range is quite narrow while the engine has a high compression ratio. The HCCI operating range can be largely extended when the inert gas is inducted into the charging air. HCCI combustion of DME presents remarkable characteristic of two-stage combustion process. As the concentration of inert gas increases, the ignition timing of the first combustion stage delays, the peak heat release rate decreases, and the combustion duration extends. Inducting inert gas into charging air cannot make the combustion and heat release of DME occur at a perfect crank angle position. Therefore,to obtain HCCI operation for the fuel with high cetane number,other methods such as reducing engine compression ratio should be adopted. Emission results show that under HCCI operation, a nearly zero NOx emission can be obtained with no smoke emissions. But the HC and CO emissions are high, and both rise with the increase of the concentration of inert gases.展开更多
The experimental investigation of homogeneous charge compression ignition (HCCI) process is carried out on a 4-cylinder diesel engine. One of the cylinders is modified for HCCI combustion with mixed additives. The inf...The experimental investigation of homogeneous charge compression ignition (HCCI) process is carried out on a 4-cylinder diesel engine. One of the cylinders is modified for HCCI combustion with mixed additives. The influence of mixed additives on the HCCI combustion process is investigated. The experimental results indicate that the mixed additives are better than the single additives for HCCI fuel, causing ignition and heat release to be advanced and the peak of heat release rate to increase under the condition of different engine speeds and steady HCCI combustion. Moreover, with the increase in engine speed, the influence of mixed additives on HCCI combustion is more obvious. In addition, the mixed additives are beneficial to improve HCCI engine misfire at a high engine speed and make the engine operate stable.展开更多
The catalytic combustion of methane in a mierochannel whose surface was coated with platinum（Pt） catalyst was studied by numerical-simulation. The effects of gas-phase reactions on the whole catalytic combustion pro...The catalytic combustion of methane in a mierochannel whose surface was coated with platinum（Pt） catalyst was studied by numerical-simulation. The effects of gas-phase reactions on the whole catalytic combustion process were analyzed at a high inlet pressure. A sensitivity analysis of the detailed mechanisms of the surface reaction of methane on Pt revealed that the most sensitive reactions affecting the heterogeneous ignition are oxygen adsorption/desorption and methane adsorption, and the most sensitive reactions affecting the homogeneous ignition are OH and H2O adsorption/desorption. The combustion process of the homogeneous charge compression ignition（HCCI） engine whose piston face was coated with Pt catalyst was simulated. The effects of catalysis and the most sensitive reactions on the ignition timing and the concentration of the main intermediate species during the HCCI engine combustion are discussed. The results show that the ignition timing of the HCCI engine can be increased by catalysis, and the most sensitive reactions affecting the ignition timing of the HCCI engine are OH and H2O adsorption/desorption.展开更多
To meet the requirements of the homogeneous charge compression ignition gasoline engine’s rapid cylinder exhaust gas rate and accurate control of combustion phasing,a residual exhaust gas rate model was proposed.A he...To meet the requirements of the homogeneous charge compression ignition gasoline engine’s rapid cylinder exhaust gas rate and accurate control of combustion phasing,a residual exhaust gas rate model was proposed.A heat dissipation model for gas flow in the exhaust passage and exhaust pipe was established,and the exhaust gas was established.Flow through the exhaust valve was considered as an adiabatic expansion process,the exhaust temperature was used to estimate the temperature in the cylinder at the time that the valve was closed,and the cylinder exhaust gas rate was calculated.To meet the requirements of transient operating conditions,a first-order inertial link was used to correct the thermocouple temperature measurement.Addressing this delay problem and modification of the exhaust wall temperature according to different conditions effectively improved the accuracy of the model.The relative error between the calculated results of this model and the simulation results determined using GT-POWER software was within 3.5%.展开更多
基金This project is supported by National Basic Research Program of China (973Program, No. 2001CB209205)National Natural Science Foundation ofChina (No. 50406016)
文摘The effects of cooled external exhaust gas recirculation （EGR） on the combustion and emission performance of diesel fuel homogeneous charge compression ignition （HCCI） are studied. Homogeneous mixture is formed by injecting fuel in-cylinder in the negative valve overlap （NVO） period. So, the HCCI combustion which has low NOx and smoke emission is achieved. Cooled external EGR can delay the start of combustion effectively, which is very useful for high cetane fuel （diesel） HCCI, because these fuels can easily self-ignition, which makes the start of combustion more early. External EGR can avoid the knock combustion of HCCI at high load which means that the EGR can expand the high load limit. HCCI maintains low smoke emission at various EGR rate and various load compared with conventional diesel engine because there is no fuel-rich area in cylinder.
文摘Experimental study on homogeneous charge compression ignition （HCCI） combustion process was carried out on a single-cylinder direct injection diesel engine fueled with dimethyl ether（DME）. The influence of inert gas CO2 on the ignition and combustion process was investigated. The research results indicate that because of the high cetane number of DME, the stable HCCI operating range is quite narrow while the engine has a high compression ratio. The HCCI operating range can be largely extended when the inert gas is inducted into the charging air. HCCI combustion of DME presents remarkable characteristic of two-stage combustion process. As the concentration of inert gas increases, the ignition timing of the first combustion stage delays, the peak heat release rate decreases, and the combustion duration extends. Inducting inert gas into charging air cannot make the combustion and heat release of DME occur at a perfect crank angle position. Therefore,to obtain HCCI operation for the fuel with high cetane number,other methods such as reducing engine compression ratio should be adopted. Emission results show that under HCCI operation, a nearly zero NOx emission can be obtained with no smoke emissions. But the HC and CO emissions are high, and both rise with the increase of the concentration of inert gases.
基金National Natural Science Foundation of China (50522202)National Key Basic Research Programof China (2001CB209201)
文摘The experimental investigation of homogeneous charge compression ignition (HCCI) process is carried out on a 4-cylinder diesel engine. One of the cylinders is modified for HCCI combustion with mixed additives. The influence of mixed additives on the HCCI combustion process is investigated. The experimental results indicate that the mixed additives are better than the single additives for HCCI fuel, causing ignition and heat release to be advanced and the peak of heat release rate to increase under the condition of different engine speeds and steady HCCI combustion. Moreover, with the increase in engine speed, the influence of mixed additives on HCCI combustion is more obvious. In addition, the mixed additives are beneficial to improve HCCI engine misfire at a high engine speed and make the engine operate stable.
基金Supported by the National Key Basic Research Development Project of China(No.2001CB209201).
文摘The catalytic combustion of methane in a mierochannel whose surface was coated with platinum（Pt） catalyst was studied by numerical-simulation. The effects of gas-phase reactions on the whole catalytic combustion process were analyzed at a high inlet pressure. A sensitivity analysis of the detailed mechanisms of the surface reaction of methane on Pt revealed that the most sensitive reactions affecting the heterogeneous ignition are oxygen adsorption/desorption and methane adsorption, and the most sensitive reactions affecting the homogeneous ignition are OH and H2O adsorption/desorption. The combustion process of the homogeneous charge compression ignition（HCCI） engine whose piston face was coated with Pt catalyst was simulated. The effects of catalysis and the most sensitive reactions on the ignition timing and the concentration of the main intermediate species during the HCCI engine combustion are discussed. The results show that the ignition timing of the HCCI engine can be increased by catalysis, and the most sensitive reactions affecting the ignition timing of the HCCI engine are OH and H2O adsorption/desorption.
基金Hebei Provincial Science and Technology Research Project(Grant No.Z2015092)Langfang Science and Technology Bureau High-Tech Support Project(Grant No.2016011018)Yanjing Institute of Technology Research Project(Grant No.2017YITSRF105)are thanked for joint funding.
文摘To meet the requirements of the homogeneous charge compression ignition gasoline engine’s rapid cylinder exhaust gas rate and accurate control of combustion phasing,a residual exhaust gas rate model was proposed.A heat dissipation model for gas flow in the exhaust passage and exhaust pipe was established,and the exhaust gas was established.Flow through the exhaust valve was considered as an adiabatic expansion process,the exhaust temperature was used to estimate the temperature in the cylinder at the time that the valve was closed,and the cylinder exhaust gas rate was calculated.To meet the requirements of transient operating conditions,a first-order inertial link was used to correct the thermocouple temperature measurement.Addressing this delay problem and modification of the exhaust wall temperature according to different conditions effectively improved the accuracy of the model.The relative error between the calculated results of this model and the simulation results determined using GT-POWER software was within 3.5%.
