Research On The Operating Characteristics And Engineering Experiment Of Cold Water Phase Change Heat Pump System

Using heat pump technology to extract the potential of phase change in cold water can solve the problem of limited heat source of heat pump system,which can alleviate the energy consumption and environmental pollution caused by HVAC.But there are still two key problems to be solved in the cold water phase variable energy heat pump system,one is the heat transfer characteristics in the continuous ice-draining process of phase-transforming heat transfer heater,and the other is the operation efficiency of the heat transfer in the actual application of the heat pump system.Energy conservation and economics have been studied to provide data reference for engineering application design.Firstly,in order to study the factors that affect heat transfer performance in the process of non-steady heat transfer of phase-transforming heaters,the rationality of quasi-steady state hypothesis under continuous ice-freezing conditions of phase-transformed heaters is analyzed,and the phase interface energy conservation equation under the dominant premise of cold water and intermediate water-side convection is established.The standard formula and the ice growth law of the ice thickness of the heat exchanger are obtained without cause secondary analysis,the coefficient of solidification and heat transfer of phase-transforming heater is defined,and the instantaneous and time-changing heat exchange calculation correlation of phase-transformation heat is derived by using the non-caused sub-ice thickness.The heat transfer performance of phase-transformed heat transfer is not only related to the heat transfer temperature and flow of the fluid on both sides,but also to the thickness of the ice and the texture of the ice.Then,in view of the heat transfer performance of the heat pump system under different operating conditions,combined with the actual engineering to build the experimental station,the macro-growth process of the ice is observed and analyzed,the instantaneous heat transfer coefficient and heat exchange heat exchange ritrated under the conditions of each operating condition are calculated,and the influence of the operating conditions on the heat transfer performance of the heat exchanger is further analyzed.To,cold water flow,intermediate water flow,ice thickness by affecting the ice texture,heat exchange rheumator,heat transfer heat resistance and thus affect the heat transfer performance of the heat exchanger;K)left and right;in the ice formation stage,the heat transfer coefficient increases and then decreases,and the maximum heat transfer coefficient is 0.64kW/(m ~2.K)around,the average heat transfer coefficient is 0.57kW/(m 2.K)around.Secondly,in order to clarify the system efficiency and operating energy consumption of the heat pump system,the calculation and analysis of the unit and system efficiency in the most adverse conditions of the heating and cooling season,and compared with the energy saving and environmental protection benefits of the traditional heating and cooling system.The results show that the cold water phase variable energy pump system is stable in the heating and cooling season,the heating season system performance coefficient cop _s is around 2.76,the cooling season performance factor factor is compared with the traditional heating system The primary energy utilization rate is 1.06,the energy saving efficiency can reach 38%,and it has high energy saving and environmental protection.After that,the system economy evaluation standard is established for the cold water phase variable energy pump system,and the cold water phase variable energy pump system is compared with the direct combustion unit system,air source heat pump system,municipal central heating and chiller system initial investment cost and system operation cost.Finally,taking the Jiqing high speed red island clean energy station as the engineering foundation,the cold source phase change heat pump(LED)+valley electricity energy storage+air source heat pump multi-source coupling heating and cooling system is designed.The system operation efficiency,energy saving,environmental protection and economy are evaluated and analyzed.The results show that the average COP s of the system is about 3when heating in winter,and the average EER _s of the system is about 3.7 when cooling.The system has a higher operating efficiency.The initial investment cost of the system is about74 yuan/m ~2,and the annual average operating cost is 33 yuan/m ~2,which can reduce the initial investment of about 25%compared with the traditional heating and cooling system,reduce the annual running cost by 40%,and save 2801.85 tons per year of standard coal.The energy saving rate reaches 41.2%..The popularization and application of the system is of great practical significance to solve the heating and cooling problems in the water scarcity areas of northern China.