Experimental Study On Capacity Control Of A Heat Pump System By Changing The Composition Of Refrigerant Mixtures

The capacity control by changing the composition of refrigerant mixtures can be defined as the modulation of cooling or heating capacity of a system through changing the composition of the mixture refrigerants in the system according to characteristics of the zeotropic mixtures. A good modulation effect could be obtained through this method in comparison with other capacity regulation methods .To be specific, additional energy consumption besides many problems such as compressor sympathetic vibration, refrigerant leakage,ect. can be avoided .So it has a promising application future. This thesis studies experimentally on the performance of a novel variable composition heat pump system. The main research contents are as follows:1. The development and recent status of capacity control by changing the composition of refrigerant mixtures at home and abroad are briefly reviewed .Based on the conventional systems, a novel capacity control heat pump system was researched, in which a variable composition device is used in the high pressure section of the cycle.2. An experiment apparatus for this novel capacity control heat pump is built up. The operation performance of the system is investigated using R32/R134a mixtures as refrigerant in the system.3. The PID automatic control principles and algorithms are discussed. Based on the theory ,the automatic control of the temperatures of inlet water to condenser andoutlet refrigerant from evaporator is achieved.