Numerical investigation on indicated power and discharge process of three different discharge methods of swing compressor

Abstract

Pressure variation during the discharge process is important to the discharge flow loss and indicated power of swing compressor. Due to the small effective discharge area and the large discharge volume flow rate at the beginning of discharge process, pressure shoots up to a high value, which is 25%-35% higher than the nominal discharge pressure. Using a suitable discharge method is beneficial to reduce the maximum pressure and indicated power. This paper presents a numerical model to study the indicated power and pressure variation of three different discharge methods. The power consumption per revolution has been discussed to analyze the discharge flow loss. And the effects of over-compression, under-compression and operation speed have been analyzed. Simulation results show that the errors of indicated power are within 3% and the errors of mass flow rates are within 2%, which proves that the accuracy of the presented model is good enough. Furthermore, the major reason affecting the discharge flow loss is the effective discharge area rather than over-compression or under-compression. And compared with the discharge port with valve, the discharge port without valve has a larger effective discharge area. Adding discharge port without valve in swing compressor can reduce the indicated power.