Optimal Design of Vaneless Diffuser for MVR Centrifugal Compressor

Mechanical vapor recompression (MVR) is a system designed to recycle low-temperature, low-pressure waste heat generated during production processes by heating and pressurizing steam using a compressor. A key component of the MVR system is the turbocompressor, a type of compressible turbomachines. Centrifugal compressors are notable for their vertical inlet and outlet passages. This configuration can introduce several potential sources of loss, one of which is backflow in vaneless diffusers. Such backflow can adversely affect both the pressure loss coefficient and the static pressure recovery coefficient, which serve as important performance indicators for the diffuser. This study aims to enhance the efficiency of an MVR system that utilizes a centrifugal compressor by optimizing the design of the vaneless diffuser. Two design factors related to the pinch width and pinch radius of a vaneless diffuser have been introduced. An optimized design was implemented to enhance the performance coefficients of the diffuser. As a result, the total pressure loss coefficient and static pressure recovery coefficient were im proved. The optimal design of a vaneless diffuser provides the effective suppression of the flow separation and friction loss. Therefore, the compressor’s isentropic efficiency and total-total pressure ratio showed improvement at overall flow rates.