Study on the Inter-Stage Release Characteristics of Two-Stage Compression Heat Pump System
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The intermediate injection combined with two-stage compression technology can improve the low-temperature adaptability of air source heat pump, but the problem of “frosting” is still to be improved. Considered the two characteristics of variable capacity and inter-stage release, the technology of inter-stage hot gas bypass defrosting for two-stage compression is presented. In addition, a two-stage compression dynamic coupling model with inter-stage release characteristics is established. Based on the simulation model, the influences of matching relations between inter-stage release parameters and compressor capacity, the dynamic characteristics of inter-stage parameters on system performance were analyzed in the absence of injection. It aims to provide a reliable guiding significance for solving the frosting problems encountered in the promotion of two-stage compression heat pump heating technology. Based on the simulation results, there is an optimum COP when the release ratio mrat = 0.1–0.3. When the release ratio mrat = 0–0.6, the inter-stage release process can reduce the system heating capacity Qhot by 7–37%, which can increase the system heating performance coefficient COPhot by 7–11%.
KeywordsHeat pump Two-stage compression Inter-stage release Inter-stage injection Dynamic coupling
The project is supported by the Science and Technology Project of Educational Commission of Jilin Province, China (No. JJKH20180097KJ), the Development and Innovation Project of Science and Technology Commission of Jilin City, China (No. 201750214), and the Key Technology Research Project of Science and Technology Commission of Jilin Province, China (No. 20180201006SF).
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