Comparative analysis study on the variable-wall-thickness and constant-wall-thickness scroll profiles for scroll compressors

Abstract

Scroll compressors are widely utilized in various applications as a type of efficient positive displacement compressor. The improvement of scroll compressor profiles can further improve the performance and efficiency of scroll compressors. In this article, the geometric model of the variable-wall-thickness scroll (VWTS) based on profiles generated by the involute of variable-diameter base circle is derived, with refined calculation methods for average leakage line length and wall thickness of the VWTS. A comprehensive thermodynamic model considering leakage, valve motion, and intermediate discharge port are established for the scroll compressor with the VWTS. Additionally, a dynamic model is developed to calculate the gas forces on the VWTS. The above models are solved using CO₂ as the refrigerant. Comparative analysis with the constant-wall-thickness scroll (CWTS) compressor under the same suction volume reveals that the VWTS can be optimized to a certain extent in terms of size, length of leakage line, and gas force. In addition, owing to its variable wall thickness characteristics, the leakage in the initial compression stage increases slightly, leading to a marginal reduction in volumetric efficiency. But the leakage in the later stage is reduced, resulting in a slight improvement in isentropic efficiency. Furthermore, compared with CWTS, VWTS has a 2–3% optimization in indicated power.