| Air source heat pump system can be used as cold and heat source design scheme of hot summer and cold winter region.However,the conventional air source heat pump system uses outdoor finned tube heat exchanger to heat exchange with air,which results in the cooling performance of summer is lower than that of water-cooled heat pump system and the outdoor heat exchanger is easy to frosting during winter heating.These disadvantages restrict the promotion of air source heat pump.In view of the above shortcomings,this paper proposes a new solution dehumidifying air source heat pump system.The system is based on the traditional air source heat pump,which added the solution tower in the air inlet side of the outdoor finned tube heat exchanger.During the summer,the operation medium of the solution tower is replaced with water.In winter,the solution tower operating medium is replaced with a dehumidifying solution to prevent the frosting of outdoor heat exchanger.In this paper,theoretical and experimental research is carried out on the proposed frost-free air source heat pump system.The main research contents are as follows:Firstly,the system is analyzed theoretically.Based on the conservation of mass and energy,the thermodynamic calculation model of the heat pump system is established.The performance of cooling,heating,regeneration and comprehensive performance of heating under the theoretical conditions is studied.The results show that system cooling COP can reach 3.77 under the operation condition of outdoor air temperature 35 ?,relative humidity60% and the comprehensive performance of heating reach 2.92 under the operation condition of outdoor air temperature 5.5 ?,relative humidity 60%,solution mass fraction 0.35.The system is an efficient air source heat pump system during summer and winter.Secondly,the experimental platform of the proposed frost-free air source heat pump system is constructed for experimental study.Because of the presence of the solution tower device,the heat and mass transfer characteristics of the system are studied under the winter operation condition.Results show that the system efficiency of dehumidification and regeneration is about 0.6,which are approximately equal to theoretical value.The dehumidification and regeneration efficiency are not affected by air temperature,humidity,solution temperature and solution mass fraction,which further proves the rationality of theoretical model hypothesis.At the same time,the experimental results can be used to guide the design and operation of air source heat pump system.Finally,the performance of the system is studied through the experiment platform of frost-free air source heat pump.The results show that outdoor air dry bulb temperature,relative humidity,chilled water and cooling water flow have a great influence on the cooling COP,while the outdoor air flow has less influence on the cooling COP.At the same time,cooling COP can reach up to 3.3 under the experimental condition.Heating water temperature,outdoor air temperature,heating water flow and air flow have a great influence on the heating COP of the system,while the outdoor air humidity,solution flow rate and solution mass fraction have a less influence on heating COP of the system.The solution temperature of solution inlet,solution flow rate and air flow rate have a great influence on the regenerative COP of the system.the comprehensive performance of heating is calculated.The results show that as the outdoor temperature increased from-6? to 5.5?,COP increased from 2.1 to 2.47.By comparing the comprehensive performance of heating to experimental data of traditional reverse circulation defrost air source heat pump system in the literature,It is known that system is more suitable for the promotion than the traditional reverse circulation defrost air source heat pump system in low temperature and high humidity area.The study of frost-free air source heat pump system has enriched the theory of frost-free air source heat pump system,which also provide the basis for optimal design of frost-free air source heat pump system and provide references for future research. |
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