Theoretical study of two-stage water vapor compression systems
Shen, J and Feng, G and Xing, Z and Wang, Xiaolin, Theoretical study of two-stage water vapor compression systems, Applied Thermal Engineering, 147 pp. 972-982. ISSN 1359-4311 (2019) [Refereed Article]
Water vapor compression is a key technology that greatly affects system performance in heat pump and mechanical vapor compression/recompression applications. In this paper, two-stage water vapor compression methods (cascaded centrifugal compressors and combined centrifugal and twin-screw compressors) were proposed and studied to deal with the water compression process with large suction volume flow rates and high compression pressure ratios. A mathematical model was developed, and the thermal characteristics, achievable volume flow rate and saturation temperature rise of the two water compression systems were presented. The two-stage compression process using cascaded centrifugal compressors was found to be better for applications with total saturation temperature rise lower than 40 °C. The two-stage compression process using combined centrifugal and twin-screw compressors was found to satisfy applications with a saturation temperature rise as high as 80 °C. Further investigation showed that the second method could deliver a suction volume flow rate of 1418 m3/min with a suction vapor temperature of 50 °C using a current market-available twin-screw compressor with a capacity of 600 m3/min. The performance of the combined systems was largely affected by the pressure ratio and the compressor efficiency, system suction vapor temperature, and total vapor saturation temperature rise. The analyses showed that the combined system had high energy efficiency above 3.4 under all studied working conditions.
vapor compression, centrifugal compressor, twin-screw compressor, energy efficient, compressor efficiency