Performance Analysis And System Improvement Study On Commercial Air Source Heat Pump Under Extreme Environment Temperature

Air source heat pump unit (heat pump for short) is selected to be researched, then research work have finished with theoretical analysis and esperimental methods to improve the problems of unit under extreme environment temperature. The influence of the environment temperature have been discussed to unit’s reliability and integrated performance, then proposed the project of combine wet heat exchange technology and gas injection increased enthalpy technology in one unit.Main work includes theoretical analysis of the unit in order to adapt extreme environment temperature, the summary and establish of optimal technical solutions; The development of experimental prototype and form a complete set of equipment including conventional air source heat pump units and low temperature air source heat pump units and spray water based on the technology of wet heat exchange device; Complete comprehensive performance testing of the prototype unit, data acquisition, result analysis and the argumentation of the optimization of technical solutions based on unit reliability and operational characteristics. Through the above research, the main conclusions are:(1) The problems of the conventional air source heat pump in extreme temperature environment could be resolved to a certain extent by component optimization and system matching optimization design. And the combined application of wet heat exchange technology and gas injection increased enthalpy technology is feasible;(2) In high temperature conditions, compared with the conventional air source heat pump units, the prototype based on the technology of wet heat exchange technology has better operating characteristics, exhaust pressure getting lower, reduce the compressor power input, increases the refrigerating capacity and coefficient of performance of the system improved. Application of wet heat exchange technology of the prototype is better-adapted to the cold quantity demand of users in hot summer. While the environment temperature higher, the unit performance improvement effect is more obvious. As the environment temperature between35-43degrees, the refrigerating capacity increase by15%～15%, coefficient of performance increased by22%～63%, the exhaust pressure reduced by13%～20%, and the input power reduced by5%～19%;(3) In low temperature conditions, low temperature heat pump based on the technology of gas injection increased enthalpy technology compared with the conventional heat pump, the input power, vacuum/exhaust pressure are basic quite, but gap of heating capacity is obvious, the application of gas injection increased enthalpy technology can effectively improve heating capacityof the prototype, and the lower the environment temperature is, the lower range can be improved. As environment temperature between-10～2degrees, the heat capacity increased by28.9%, and averagly increased by16.7%, the coefficient of performance increased by29.5%, averagely increased by15.7%.