The Study Of The Influence On Temperature Field Of Cold Storage Reduced Defrost Heat By Above Cooling Plate

After cold storage runs a period of time,evaporator appears phenomenon of frost in the refrigeration system,and serious frost causes evaporator evaporation capacity reduction,a substantial increase of energy consumption and other bad effects,so it is necessary to defrost.At present,commonly used methods of defrosting have electric heating defrosting and hot gas defrosting.No matter what kind of defrosting method,there always will be most of the heat scared to the surrounding environment,which not only makes the energy loss,but also damages the surrounding temperature field.In order to ensure the quality of the food storage,this paper focuses on the study of cold storage equipment which can reduce the temperature fluctuation of cold storage.In this paper,the influence of frost structure,physical parameters and the performance parameters of evaporator is analyzed theoretically,and then focus on theoretical analysis and calculation of cold storage,and calculates the maximum possible needed cold storage quantity in the process of continuous double evaporator defrosting.Using Fluent software simulates the air flow field in the cold storage with cold-storage device which is in process of continuous defrost,then analyse the simulation results,and verify the reliability of the simulation values with experimental values.Finally began to cool experiment in cold storage,cold storage temperature is maintained at-18±0.5℃ for about half an hour,and cold storage temperature is reached steady state.When the cool storage reaches to defrost requirements and starts defrost,the paper studies the cold storage section temperature at 0m,0.7m,1.4m,2m and whole temperature in cool storage,the bottom of the hold-over plate temperature at 1and 2 fan axis location,the defrosting energy consumption and so on whether the presence of hold-over plate and whether the presence of the frost layer.The results show that the temperature of installing the hold-over plate is lower than temperature of empty cool storage during the defrosting process.The temperature fluctuation of installing the hold-over plate decreases 2.48℃ than temperature fluctuation of empty cool storage.The defrost energy consumption of installing the hold-over plate increases by 1.36% than defrost energy consumption of empty cool storage,and hold-over plate installation affect on the defrosting energy consumption can be neglected during cooling fan with frost.The temperature fluctuation of installing the hold-over plate decreases 2.92℃ than temperature fluctuations of empty cool storage.The defrost energy consumption of installing the hold-over plate increases by 1.81% than defrost energy consumption of empty cool storage,and hold-over plate installation affect on the defrosting energy consumption also can be neglected during cooling fan with no frost.The temperature at the bottom of the hold-over plate which is away from the location of the fan is higher at cooling fan axis location,and the temperature at the bottom of the hold-over plate which is away from the location of the fan is lower at defrost the fan axis location.By comparison,that the cold storage top installs hold-over plate can effectively reduce the cool storage temperature fluctuations in the process of continuous defrost.The cold storage device which is on top of cool storage not only reduces the cold storage temperature fluctuations,but also ensures the constant humidity in the cool storage during the double evaporator defrosting process.