Modelling and experimental analysis of automotive reciprocating air compressor

Abstract

The modern automotive vehicles with air or air assisted brake system use a reciprocating air compressor with disc, reed or ring valves. Automotive compressors are driven by the engine itself through a proper belt driven arrangement. Mathematical model will be an effective tool in compressor design and for analysing the effect of various physical and operating parameters on compressor performance parameters like volumetric efficiency and power required. Most of the researchers have focused their attention on refrigerating compressors and have not dealt with the effect of varying index of compression and expansion which have a significant effect on the prediction of power required to run the compressor. A few researchers have developed mathematical model using simple equations for hermetic compressors. The aim of the present work is to construct a mathematical model which is easy to understand, easy to detect errors in the process of building a model and easy to compute numerical solution. The work presents a simplified and effective mathematical model for the estimation of reciprocating compressor performance using personal computers that can be easily handled. A software code has been developed for model analysis. The model has been developed with minimum number of assumptions in the ideal compressor. Experimental results are obtained from four different compressors to validate the developed model performance. The effect of various physical parameters like, clearance volume, cylinder diameter, connecting rod length, crank radius and valve lift and operating parameters like, discharge pressure and compressor speed on the thermodynamic behaviour of compressor in working condition has been analysed. The predicted performance parameters are in good agreement with the experimental results and thus ensure the effectiveness of the developed mathematical model. The model developed can predict the performance parameters of any type of reciprocating air compressor with a deviation of ± 6 %. newline newline newline