A single zone thermodynamic simulation model for predicting the combustion and performance characteristics of a CI engine and its validation using statistical analysis

Abstract

In this investigation, a single zone thermodynamic model was developed to predict the combustion characteristics such as in-cylinder pressure, rate of pressure rise (ROPR)), ignition delay and combustion duration and performance characteristics such as brake power (BP), brake specific fuel consumption (BSFC), and brake thermal efficiency (BTE) using fundamental thermodynamic equations and various models. The test was performed on a four-stroke 1- cylinder diesel engine fueled with MnP15 and neat diesel fuel at different loading conditions. The success of the thermodynamic model was evaluated by statistical metrics (R2, standard error (S), Pearson’s correlation (r), P-value, and Z-test). The model accurately predicted the numerical results of cylinder pressure and ROPR for diesel fuel and MnP15 blend at all tested loading conditions. The statistical analysis of the predicted data by regression method and Z-test showed strong evidence of significant data by this model. The maximum standard error (S) found for in-cylinder pressure data by regression analysis was 2.47 for the MnP15 blend at 100% load, and the minimum error was 1.336 for the MnP15 blend at 25% load. The mean values of the numerical data lay within 95% confidence interval in Z test analysis, and also calculated value of Z fell less than the tabulated value of Z (=1.96) of 95% confidence interval level, for diesel and MP15 blend at all tested loading conditions. The engine performance output such as BP, BSFC, and BTE computed accurately. The coefficient of determination (R2) for the performance parameters (BSFC and BTE) was above 98%, and Pearson’s correlation (r) was also above 0.9 for both blends, whereas the maximum relative error was 7.58% for the MnP15 blend in BSFC output at 75% load and 6.07 % in BP output in the case of diesel fuel, implying an accurate simulation model for a diesel engine. In conclusion, the model could be used to accurately predict the performance and combustion characteristics of the C.I. engine.