Experimental Study On Two-stage Compression Heat Pump System Coupled With Dual-cylinder Rolling Piston Compressor

In order to substitute for R22and improve the energy efficiency grades of home airconditioner, a new system named two-stage compression heat pump system coupledwith dual-cylinder rolling piston compressor was provided. Based on theenvironmental friendly working fluid of R410A and general two-stage compression,the dual-cylinder rolling piston compressor had been used. The working fluid aftercondensation flowed into the flash-tank and separated the two phases. The isolatedsaturated vapor mixed with the vapor came from low compression before entering theadvanced compression, so as to reduce the exhaust gas temperature and the pressuredifference. The system was researched in detail by using the methods combinedtheoretical analysis and experimental verification.The two-stage compression heat pump system coupled with dual-cylinder rollingpiston compressor is different from the common two-stage compression system,because introduction of flash-tank and dual-cylinder rolling piston compressor. It hasits own unique operating characteristics. A mathematical model of the whole systemwas set according to the theory of thermodynamics, in order to find out how theoperating parameters and geometric parameters influenced the system. And manyfactors were taken into account, such as the volume ratio of high-pressure stage tolow-pressure stage, the structure of flash-tank, and the design of compensatingpipeline, for the optimum performance. By optimizing the components and system,the energy efficiency ratio, refrigerating (heating) capacity and the heating capacityunder the ultra-low temperature operating condition was improved. Experimentalverification was developed on the basis of establishing the prototype.Through theoretical analysis and experimental data, the principle of circulationprocesses and different types of two-stage compression were discussed. As results, itwas provided the optimum household heat pump type air-conditioner. The bestenergy efficiency ratio corresponding to volume ratio of high-pressure stage tolow-pressure stage was showed in specific working conditions. The optimumintermediate temperature for different working conditions and specific volume ratiowas displayed. The indicated efficiency calculation formula of the dual-cylinderrolling piston compressor was simulated according to experimental data. Thestructure of flash-tank was redesigned. The compensating pipeline was pointed outthat was influenced by internal diameter of pipe. For a specific volume ratio ofhigh-pressure stage to low-pressure stage, it was discussed that evaporating temperature, condensing temperature and middle pressure effected on the cycleperformance under working conditions of cooling, heating and ultra-low temperatureheating. Results showed that the two-stage compression heat pump system coupledwith dual-cylinder rolling piston compressor could improve energy efficiency ratio,refrigerating (heating) capacity and reduce exhaust gas temperature...