Numerical investigation on the performance and vapor injection process of a scroll compressor with different injection features

Abstract

Using the vapor injection scroll compressor in heat pump systems for electric vehicles is one of the promising solutions for promoting the driving range in extremely cold climates. In this paper, a three-dimensional transient simulation model of the vapor injection scroll compressor with different injection features, including injection positions, shapes, and inclinations, is established and verified with a deviation within 8 %. And the influence of the injection flow on the internal flow field and the performance of the scroll compressor is the key problem to be studied. The results show that when the injection port gets closer to the discharge port, the increment of isentropic efficiency and the decrement of discharge temperature increase, and the maximum values can reach 6.7 % and 11.3 K, respectively. From the results of the flow field distribution, the heat aggregation is observed at the internal engaging point, and a shock pressure and two vortexes occur at the bottom of the orbiting scroll as the injection flow rushes into the working chamber, which may bring the operational stability of orbiting scroll and leakage troubles. The heat aggregation is weakened with a smaller injection inclination. Shock pressure gets smaller from single-circle injection port to waist and from the injection inclinations of 90° to 30°, with a reduction of 9.5 % and 26 % respectively. Overall, a vapor injection scroll compressor using a waist-shaped injection port with an injection inclination of 60° is recommended, which shows a better comprehensive effect.