Thermodynamic analysis of the rotary tooth compressor

Abstract

The Roots blower has no built-in compression and therefore is not efficient when it discharges gases at pressures substantially higher than at suction. The rotary tooth compressor, which includes built-in compression, has been proposed as a more efficient alternative. This paper describes an analytical study of the rotary tooth compressor. A mathematical model has been constructed to simulate the thermodynamic processes within it and hence predict its performance. The model allows for gas leakage as well as the main gas flow into and out of the working chamber. The estimated performance has been compared with experimental test results. The mathematical model was thereby validated. Further analyses were then carried out, using the validated mathematical model, to determine the magnitude of power and capacity losses in the machine. It is shown that the rotary tooth compressor is more efficient than the Roots blower at pressure ratios greater than about 1.4. Loss in capacity is most affected by gas leakage, and the main cause of loss in adiabatic efficiency is the power loss associated with high gas velocities during discharge.