Performance Study On Direct Contact Heat Transfer Ice Storage System Based On The Dehydrator

Air conditioners account for the largest proportion of the energy consumption in buildings,and the use of solar-powered refrigeration systems can effectively alleviate the building energy consumption problems and achieve the goal of energy conservation and emission reduction.In order to solve the instability problem of solar energy supply in solar refrigeration systems,energy storage is one of the most effective methods.For the photovoltaic-driven refrigeration systems,most of them use batteries as the energy storage units to achieve stable operation and continuous energy supply,however,there are some problems such as high initial investment,long payback period,and environmental protection of battery recycling.Therefore,the development of an ice storage mode replaces battery storage is one of the effective ways to solve the problem above.At the same time,to solve the problem of low heat exchange efficiency of the evaporator and inconvenient use of supercooled ice in the ice storage mode.The research on direct contact heat transfer ice storage system is also of great significance.In this work,in order to obtain the high efficiency energy storage refrigeration system characteristics,a dehydrator is designed to solve the problem of the influence of refrigerant moisture on the stability of refrigeration system after heat transfer,and the experimental study and performance analysis of the direct contact heat transfer ice storage system with dehydrator under different operating conditions were carried out.The research above provides some theoretical reference and technical support for the combination of solar energy and direct contact heat transfer ice storage refrigeration system.The main research work and important conclusions of this article are as follows:(1)A set of 0.735 kW direct contact heat transfer ice storage system was constructed,and the refrigerant and water were directly contacted for heat exchange.The research results show that the direct contact heat transfer ice storage system solved the problems which the reduction of heat transfer efficiencyheat of traditional submerged copper tube evaporator due to freezing and the energy waste caused by large degree of supercooling of the ice.(2)To solve the problems of system blockage and shutdown caused by the refrigerant moisture in the constructed direct contact refrigeration system,proposes and designs a dehydrator based on the difference freezing point between refrigerant and water by cooling,so as to remove moisture carried by refrigerant.The theoretical model in the process of dehydrator was derived,and the experimental results showed that the direct contact heat transfer ice storage refrigeration system can be continuously operated under the dehydrator device without shutdown,and the operation effect and stability are effectively improved.(3)Based on the refrigeration system with dehydrator device under different operating conditions,the experimental study was carried out and the system performance was analyzed.The uniformity of heat transfer was evaluated by volume heat transfer coefficient,it was found that the volume heat transfer coefficient of the system reached 35.67 kW/(m~3·℃)under different operating conditions.The COP of the constructed system reached 6.16 when the R-22 refrigerant was compressed by a compressor,and 4.8 kg of ice slurry could be prepared within 20 minutes.When R-134a refrigerant is used in the system,the COP is 4.96 and 2.3 kg of ice slurry can be prepared in the same time.The COP of the direct contact heat transfer ice storage refrigeration system is higher than those of the existing commercial refrigeration system.The research provided a good reference for the combination of solar energy and direct contact heat transfer ice storage refrigeration system.