Theoretical And Experimental Research Of Independent Gas Engine-driven Heat Pump Based On New Environment-Friendly Refrigerants

As the international community pays more and more attention to the energy conservation and environmental protection, which is also becoming a research focus in the refrigeration and heat pump industry. The independent gas engine driven heat pump system (IGEHP) used natural gas or other clean energy as an independent energy input could provide the heating, cooling, hot water and autonomous power supply system. This article has mainly carried out the theoretical and experimental research on the independent gas engine driven heat pump system and new environment-friendly refrigerants.In the aspect of refrigerant, a series of new environment-friendly refrigerants with advantages of thermo-physical properties, market availability, lower global warming potential (GWP) and zero ozone depletion potential (ODP) were adopt. At the same time, the explosion limits of binary mixtures which include nonflammable refrigerants and flammable refrigerants DME, R32, R152a and R290s has been experimentally studied under the conditions of 290~295K and 101.325KPa (one atmosphere pressure, 760mm Hg). Furthermore, parameters of upper flammability limit (UFL), lower flammability limit (LFL) and minimum inert concentration (MIC) of nonflammable refrigerants were also obtained. On this basis, the inhibition coefficient of nonflammable refrigerants was analyzed and a novel equation of predicting the minimum inert concentration of nonflammable refrigerant has been proposed by analyzing the group contribution method and the theory of combustion in binary mixtures. Comparative analysis of the theoretical calculated values and experimental data, the result demonstrates that the theoretical data are in good agreement with experimental results under the condition of flammable refrigerants flame propagate velocity and the stoichiometric concentration exactly, and the novel equation is an excellent tool to analyze the minimum inerting concentration of nonflammable refrigerant. The theoretical results have significance on flammability experimental, theoretical research and the security application.The refrigerants cycle performance test-bed was built up, and performances of two mixture refrigerants (alternative for HCFC-22 and moderately-high temperature refrigerant) have been carried out in this water-to-water cycle performance heat pump system. The results show that the alternative mixture refrigerant can directly charge into the HCFC-22 heat pump system, and the performance of cooling capacity, pressure ratio, discharge temperature and coefficient of performance (COP) are better than that of HCFC-22, on the other hand, the compressor power between the alternative mixture refrigerant and HCFC-22 are close to each other. Therefore, this proposed environment- friendly refrigerant is an excellent alternative refrigerant for HCFC-22; The moderately-high temperature refrigerant charged into HFC-134a heat pump system could obtain above 80℃hot water, and the discharge temperature, condenser pressure and the pressure ratio was just 95.3℃, 19.3MPa and 6.0, respectively. The COP of this mixture refrigerant M2 was above 2.92 under the condition of evaporator water inlet temperature 44℃and condenser water outlet temperature 80℃.In the independent gas engine driven heat pump system scheme, the cooling and heating performance of independent gas engine driven heat pump using new environment-friendly mixture refrigerant (alternative for HFC-134a) has been experimentally studied. Furthermore, several effected factors (cooling model: evaporator water inlet flow rate, evaporator water inlet temperature and gas engine speeds; heating model: condenser water inlet flow rate, condenser water inlet temperature, gas engine speeds and evaporator temperature) on the independent gas engine driven heat pump system have been qualitatively and quantitatively analysed. The experimental results have laid out a foundation of demonstration and further popularization and application of IGEHP. Finally, the independent gas engine driven heat pump system could obtain better coefficient of performance (COP) and primary energy ratio (PER) using new environment-friendly mixture refrigerant.