Geometric Optimization of Scroll Compressors

Electric driven scroll compressors are widely used for the A/C systems in electric cars. Besides many other advantages scroll compressors offer comparable good efficiencies and can be used easily in both refrigeration and heat pump mode. Scroll compressors were first introduced in the early 20th century. Over the decades they have been further developed and optimized and became increasingly efficient. Among other things numerical simulations contributed to this process. However, most of the studies focus on the optimization of the scroll wraps and their design. Investigations concerning the discharge geometry of scroll wraps as well as the positioning and the design of pre-outlet and main outlet bores are rarely present. Therefore, this contribution focusses on the geometric optimization of the discharge geometry of scroll wraps by means of a geometrical and physical based numerical simulation. The first part outlines a brief literature study on the investigated topic. Subsequently, compressors with variable and constant wall thickness are compared. Afterwards, the study goes into detail, describing the outlet geometry (arc/arc and arc/line/arc) as well as the sizing and positioning of pre-outlet bores and the main outlet bore. The main focus lies on their influence on the compressor efficiencies, the outlet temperature as well as the torque fluctuations. The investigations are performed for different operating points using the above-mentioned simulation model. The contribution closes with a summary of all results and effects on the compressor efficiencies as well as some recommendations for future developments