Design of a High Efficiency Scroll Wrap Profile for Alternative Refrigerant R410A

The scroll compressor, using R41 OA that has higher density and works at higher pressure than R22, is required to redesign its geometry such as wrap profile. The design parameters of wrap profile such as base circle radius, wrap height, involute end angle and discharge port have to be well determined to obtain high compressor efficiency. At first, a simulation program has been developed to predict scroll compressor performance. Using the program the optimized wrap profiles were designed by parametric study. Later, deformation of the wrap profile was examined by FEM analysis. NOMENCLATURE a : Base circle radius h : Wrap height t : Wrap thickness v. : Stroke volume N : Scroll turns cjl, : Outer involute start angle cjl. : Involute end angle Eld : Discharge start angle P, : Suction pressure pd : Discharge pressure INTRODUCTION R41 OA works at higher pressure and performs cooling capacity as much as R22 with smaller stroke volume. Compressor performance decreases when the R41 OA is used in the conventional R22 compressor without geometry change, because increased gas force causes higher mechanical loss, and optimum geometry must be changed. The most important design parameters are base circle radius a, wrap height h, wrap thickness t, involute end angle c)l., and discharge start angle Eld. In the many past studies such as Ishii et al. had dealt with parameters a and h. However it is difficult to find studies dealt cjl., which we found affecting compressor efficiency noticeably. In this study, we calculated performances with various design parameter of scroll compressor using R4I OA and designed optimized scroll wrap profile. Then, we examined its defonnation characteristics with thennal and pressure load using FEM analysis.