Effect of pressure balance between multi-stages on part-load performance of centrifugal compressor for turbo chiller

摘要

Effects of pressure balance between multi-stages on part-load performance of centrifugal compressor for turbo chiller were analyzed by using CFD (Computational Fluid Dynamics). The analysis domains were two stages including the first and second variable inlet guide vanes (IGVs) arranged upstream of each compressor stage. The numerical simulation involved three-dimensional, steady, and compressible flow analysis with ANSYS-CFX~(?). The flash gas injected from the intermediate inlet of the economizer passage was taken into account. The part-load efficiency was measured while changing the opening ratios for the first and second variable IGVs. The predicted part-load efficiency corresponded to the measured one. We confirmed that the pressure balance between the first and second stages improved by adjusting the opening ratios of the first and second IGVs according to the flow ratio. The predicted flow pattern indicated that higher efficiency could be obtained by adjusting the opening ratio of the first and second variable IGVs to suppress excessive prewhirl from the first impeller and stall in the second impeller.