Theoretical And Experimental Study On A Variable Capacity Air-source Heat Pump System With Ternary Mixture Refrigerants

Air-source heat pump has a wide range of applications in the south areas of China because of its safety, energy conversation and environmental protection. But there are some limitations in the application:the heat capacity can not match the heat load of the building because of the heat attenuation with the low outside temperature during winter which directly impacts thermal comfort. However, the advantages of mixed refrigerants working as the substitute for R22 provides a feasibility for solving the limitation above, together with the application of non-azeotropic mixed refrigerants in the capacity controllable technology. Based on this, this thesis carried out experimental and theoretical studies on a variable capacity heat pump system. The main contents are as follows:To begin with, the development direction of this subject is summarized, and is mainly reflected in two terms:the selection of mixtures and system design.Secondly, ternary refrigerant is determined to work as the working fluid through theoretical calculations. And experimental studies are carried out with them. Considering that the system performance has a close relationship with the evaporation temperature, suction pressure and the mass fraction of the mixtures, the experimental studies include performance-evaporation temperature experiments and performance-suction pressure experiments. Then the comparison is done between the results from R23/R32/R134a and those of R32/R134a. Experimental results show that, the new mixture refrigerant shows a good application value in the separation characteristic, variable capacity and adjustable temperature range, together with system performance.Then, a simulation and analysis are carried out based on the analysis of experimental results. The variable capacity of the system is studied from the theoretical analysis. And the comparison of experimental results and the simulation results are made. In addition, the source of the deviation is analyzed during the simulation process.Finally, an improvement for the system design is given after analyzing all kinds of systems in this field at home and abroad, taking the questions during experiments into account. This new system design enables the system from laboratory to the product one step further.