Study On The Performance Of Exhaust Heat Recovery Of Refrigeration Compressor

In the indirect refrigeration cycle system,it is an important means to recover the heat from the exhaust of the refrigeration compressor and to heat the refrigerant for defrosting.Its effect is equivalent to that of the hot gas defrosting and the hot fluorine defrosting in the direct refrigeration cycle system.In order to grasp the best time of defrosting operation,the time needed for the refrigerant to be heated was studied.It has been widely used in industry and household appliances.Therefore,it is of great practical significance to study the characteristics of heat recovery equipment.The indirect refrigeration system is better than the direct refrigeration cycle system,specifically as follows: 1)the charge capacity of the refrigerant is less;2)only the refrigerant enters into the cold storage workshop for atmospheric circulation,to a certain extent,to ensure the safety of food and production;3)It stores the cold in the low peak period of power consumption,which is effective In order to save the operation cost of the system,the peak shifting and valley filling type cold storage was carried out.In addition,the refrigerant can directly recover the exhaust heat of the refrigeration compressor to defrost.The condensation heat recovery is that a heat exchange equipment is added to recover the condensation heat to meet the needs of production and domestic water,such as the process hot water for defrosting,the refrigerant steam heat plus hot water;the hot water is directly sprayed on the coil of the cooling fan during defrosting,this kind of operation needs a lot of water resources,but it is not suitable in the area where water resources are extremely scarce,and this operation has certain harm,and the temperature in the reservoir fluctuates greatly.In this paper,a heat recovery device for defrosting in indirect refrigeration system is proposed on the basis of relevant analysis,calculation,simulation and experimental research of heat recovery technology.The constructed heat recovery water tank can realize the heat consumption of defrosting in a single cold storage.The main work and conclusions are as follows:In this paper,an indirect refrigeration unit with a customized cooling capacity of68 kW is used for simulation and experimental research.Firstly,a heat recovery water tank is designed and manufactured to heat refrigerant and defrost.According to the nature and the heat load of the cold storage,the heat transfer area required for heat exchange is calculated.Combined with the characteristics of various heat exchangers,the heat exchange structure with six serpentine tubes and distributed refrigerant is determined,and a heat recovery water tank with the size of 1.5m×0.75m×0.75 m is equipped.Secondly,the physical and mathematical models are established,the correspondingmodel parameters are called,the temperature field in the fluid is solved,coupled to the laminar flow interface,and the complex problems of three-dimensional flow in the inflow and outflow manifold are solved.The temperature field of the cooling water tank during static and dynamic heating is simulated,and the heat transfer analysis of the serpentine tube is carried out.The temperature required for heating 800 L refrigerant from 20°C to 23°C for defrost is 10 minutes for static heating simulation;When the cooling load of the imported refrigerant is lower than that of the hot refrigerant in the tank and the heat load provided by the refrigerant,the heat transfer efficiency of the water tank increases with the increase of the mass flow of the refrigerant,the heat transfer effect of the refrigerant and the heat exchange tube decreases with the increase of the inlet temperature,and the temperature is higher in the heat exchange balance.When the refrigerant is in equilibrium with the inlet temperature,and the inlet low temperature refrigerant only exchanges heat with the refrigerant,the temperature of the refrigerant decreases with the increase of the mass flow rate.When the inlet temperature is 10?,the mass flow rate of the refrigerant is 2kg/s ~4kg/s,it is better for the defrosting.Again,based on the simulation performance of the coolant tank,the distribution of the heat recovery coolant tank is analyzed,and then the experimental research is carried out.It is found that the temperature change curve of the simulation results is basically the same as that of the experimental data.The temperature in the serpentine tube decreases gradually along the direction of refrigerant flow.The phenomenon of the temperature stratification appears.It is shown that the upper temperature is higher than the lower temperature of the water tank,which verifies the reliability of the mathematical model.It has a certain guiding significance for the design of subsequent heat exchange tubes.Finally,the existing heat recovery water tank is optimized,and the built-in heat exchange tube is moved to the lower part of the water tank under the same other conditions.The simulation results show that the refrigerant in the new heat recovery water tank is evenly heated.