An exploratory study using computer simulations was undertaken to provide optimal design guidelines for an enlarged scroll compressor with the maximum possible overall efficiency. Computer simulations of the mechanical, volumetric and compression efficiencies are presented for a CO_2 scroll compressor with a suction volume of 18,000 cm~3, driven by a 4,000 kW (5,480 hp) motor under the rated conditions. For fixed values of 800 mm cylinder diameter and 20 mm scroll thickness, the optimal combination of involute base circle radius and scroll height, producing the maximum overall efficiency, was determined. The computer simulations were initially undertaken assuming radial and axial clearances of 0.1 mm, for which a 22 mm involute base circle radius and a 112 mm scroll height were found to yield a maximum overall efficiency of 88.8%. Subsequently, the radial and axial clearances were increased to 0.2 mm, and the simulations were repeated. The comparatively large increase in the radial and axial clearances from 0.1 mm to 0.2 mm resulted in a small decrease of 3.5% in overall efficiency for the same combination of involute base circle radius and scroll height.
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