A Predictive Tool for Engine Performance and NOx Emission 982462

An engine cycle simulation program has been developed to predict both engine performance and NO_x emission with reasonable accuracy. The program is a product that combines two programs, VIPRE™ and ALAMO_ENGINE, both developed at Southwest Research Institute (SwRI). VIPRE™ is a comprehensive tool for engine systems with intake and exhaust dynamics, emphasizing engine performance ^[1], while ALAMO_ENGINE is a program focusing on NO_x prediction ^[2].

Demonstrations in this paper were based on a six-cylinder, turbocharged diesel engine with a high-pressure exhaust gas recirculation (EGR) loop. The EGR system is connected upstream of the intake manifold from the exhaust manifold located in the turbine entrance. A two-way butterfly valve is used to control the EGR rate. The major challenge in this modeling work is the prediction of engine performance and NO_x emission in an acceptable and systematical fashion. There are many programs used for either engine performance or NO_x prediction in literature. ^{[3, 4 and 5]} However, very few programs are capable of predicting both engine performance and NO_x emission over wide operating conditions with acceptable accuracy. This paper will demonstrate that the program developed by SwRI is one of only a few programs that can carry out this task.

Comparisons of engine performance and NO_x emission between simulations and measurements were carried out over a wide range of operating conditions. It was shown that the integrated program could predict both engine performance and relative NO_x with reasonable accuracy.