Model Validation of Twin Screw Compressor with Optimized Injection Port for Unit Efficiency

A previously published paper examined the addition of an economizer to a twin-screw water chiller system with the intent of maximizing unit efficiency. The intent was to find the optimum economizer port within the twin-screw compressor. The port size and location were varied to understand how it affects the unit performance. The procedure developed to optimize the unit efficiency using internal modeling tools is reviewed within this paper. The selected port location was used to create a new screw compressor design predicted to achieve a 2–3% improvement in the unit coefficient of performance. The results of an experimental investigation of a twin screw compressor utilizing the optimized economizer port are also presented. From a compressor standpoint the inclusion of the economizer port increases compressor power, increases discharge mass flow, and reduces isentropic efficiency. However, the unit can achieve higher unit efficiency and capacity. The designed twin screw compressor has been tested on the gas cycle stand to validate economizer port optimization efforts. Tested compressor performance and system modeling was used to determine unit performance improvement of 3.6%.