The Theoretical and Experimental Investigation of the Effect of Variation of Thermodynamical Parameters of Egr fluid on No Emissions in S I Engines

Exhaust Gas Recirculation (EGR) concept is the most simple and Abstract more economical method for NO pollutant reduction in spark ignition engines. However, when the higher amount of the EGR gas enters into the engine, the power, torque and fuel economy of the engine decrease. One effective solution for reduction of undesirable effect of this method is to use cooled EGR, that results in more reduction of NO pollutant, in the meantime imposing lesser reduction on engine performance. For this purpose a mathematical model has been developed for simulation this method by using two zone combustion model. Results indicate that, when the cooled EGR is use d, be ca use o f the higher he a ting specific values of two principle species existed in exhaust gases, namely CO2 and H2O, reduction of combust ion chamber temperature is higher, hence, the amount of NO emission decreases further. In turn, because of higher specific mass of cooled EGR gas in comparison with hot EGR, the mass of the mixture in cylinder will increase, thus increasing the peak pressure of the combust ion chamber accordingly, and so the power output of the engine will not decrease notably in comparison with non EGR case . The comparison shows that there exist good agreement between the experimental and predicted results.