Investigations on Thermal Performance of Oil Injected Twin Screw Compressor

Abstract

An oil injected twin screw compressor is a positive displacement machine which uses a pair of inter-meshing rotors with helical grooves (called as screws) separated by very small clearance, to compress the air. In order to achieve higher a pressure ratio, oil is inserted in an oil injected twin screw compressor which acts as a cooling, lubricating and sealing agent. At moderate pressure ratio condition, the screw compressor proves itself as the best option for compression among all other conventional compressors. Hence it becomes essential to optimize and enhance the performance of an oil injected twin screw compressor. Among various performance parameters, the volumetric efficiency of compressor is the main factor which decides the overall compressor efficiency. In the present study, attempts are made to analyze aspects related to volumetric efficiency. The clearance provided in between two rotors and between rotor and housing for smooth operation, form leakages due to continuous pressure growth in successive chambers. The mathematical modeling referred in the present work provides various equations for calculating different type of leakages generated in the working cavity of an oil injected twin screw compressor. In the present study, codes are made in Engineering Equation Solver (EES) and C++ which are utilized to determine the instantaneous values of all properties related to oil injected twin screw compressor. These properties are further used to determine leakage in oil injected twin screw compressor. All the four major leakages associated with the oil injected twin screw compressor are calculated individually by utilizing Engineering Equation Solver (EES) and C++. All results obtained by both codes are compared and percentage of individual leakage is determined. Present study encloses the influence of geometrical parameters like areas and clearances on total leakage rate. The volumetric efficiency of oil injected twin screw compressor is analyzed and the influences of different parameters on the volumetric efficiency are studied.