Analytical and experimental analysis on scroll compressor for automobile air conditioning system

Abstract

The project involved the development of an automobile scroll compressor using basic circle involute. The studies covered both analytical, and experimental works. The aim of the project was intended to assist in the manufacturing of the involute of the scroll. The analytical work focused on the evaluations of the geometrical parameters, thermodynamic properties inside the scroll and the compressor performance. The study was conducted taking into account of the flank leakage, the tip leakage and suction loss due to the gas heating at suction. The simulation studies were carried out under different leakage clearances. The heat transfer analyses include the thermal contact loss between the fixed and the orbit scrolls, the conduction heat transfer through the bases of the orbit and the fixed scroll, and the convection heat transfer between the refrigerant and the scroll walls in the suction port. The computer model predicted the pressure and temperature inside the suction compression and discharge process, the mass flow rate, the average wall temperature for the suction and discharge, the power, the adiabatic efficiency and volumetric efficiency of the scroll compressor. The geometrical analysis of hexagonal and square involutes was also included as a comparison. The experimental rig was developed to verify the analytical results. The pressure inside the scroll pockets was measured using four piezoelectric pressure sensors mounted in the fixed scroll at different locations with the aid of the data acquisition system to cover most part of the compressor cycle. The compressor capacity was determined by evaluating the mass flow rate. It was measured by two methods-the flow meter and heat balance inside the calorimeter. The experimental and computed pressure, instantaneous torque, mass flow rate, coefficient of performance, adiabatic efficiency and the discharge temperature were compared at different working conditions and found that the data were in a good agreement. From the geometrical point of view it seems that manufacturing of hexagonal involute is easier as it can be done without the use of any software.