Numerical Simulation And Experimental Research On The Temperature Field Of Cold Storage Cold Storage Directly Driven By Solar Energy

Storage of medical supplies is a difficult problem in areas where traditional refrigeration facilities are not available or where there is a severe shortage of electricity.In the solar energy directly driven cold storage,solar photovoltaic power generation drives the refrigeration system of the cold storage,and phase change cold storage device is used to maintain the stability and balance of temperature in the cold storage space.Compared with traditional cold storage,solar direct-driven cold storage does not rely on power grid operation and is very suitable for cold storage of vaccines,medicines and other medical supplies in remote areas and islands.At present,there are still many problems with solar energy directly driven cold storage.For example,solar photovoltaic power generation systems are greatly affected by the weather and are unstable.How to maintain uniform and stable storage temperature in the cold storage at night and in variable weather conditions The key issue of eligibility is that there are relatively few analyses and studies on solar direct drive cold storage cold storage.Since there are few analyses and researches on solar energy direct drive refrigeration storage,it is of great significance to analyze and study the problems of solar energy directly driven cold storage and propose solutions.The main research contents in this article are as follows:First of all,the system scheme of solar energy direct driving is proposed.The cold storage of 40m³ was taken as the research object.Through the design and calculation of cold storage,compressor and solar photovoltaic panel selection.The cold storage material was studied and analyzed,and H₂O was selected as the cold storage material.According to the actual situation of refrigeratorⅠ,Ⅱ,Ⅲput three cold box storage in a library.ANSYS-Fluent 16.0 software was used to simulate the cooling of cold storage in three different ways.The simulation results show that when the cooling time is 16h,the average temperature in the warehouse ofⅠis the lowest,3.08℃,the temperature is 16.92℃,the average temperature ofⅡis the highest,5.96℃,the temperature is 14.04℃,the average temperature ofⅢis 4.08℃,the temperature is 15.92℃.A comprehensive comparison is made between the average temperature of cargo storage area and the average temperature of the highest area and the average temperature in the warehouse.DemonstratedⅠstorage cold box put way of cooling effect is best,the most suitable for cold storage.Secondly,the solidification and melting of cold storage materials are analyzed theoretically.A type A cold storage box is taken as the research object,and the cold storage material is H₂O.ANSYS Fluent 16.0 software is used to conduct numerical simulation of the cold storage process and cooling release process of the cold storage box.The simulation results of the tank thermal storage process show that at 0-5h,the heat storage material is mainly sensible heat storage of H2O,and the temperature drops faster.After 5h,the phase change thermal storage process is the main,and the temperature decreases slowly.After that,the average temperature of H₂Odecreased from10.00℃to-2.69℃,and the liquid phase ratio decreased from 1 to 0.21.Nearly 80%of H₂O solidified into ice,which was regarded as the completion of cold storage.The simulation results of the cold storage tank cooling process show that in the first 6h,due to the supercooling degree of the cold storage material at 3℃,the cold storage material is mainly sensible heat release,the temperature increases rapidly,and the liquid phase rate growth rate in the first 20h is slightly Higher than the back.After 72 hours of cooling,the average temperature of H₂O is 5.30℃,the liquid phase ratio is 0.83,and more than 80%of the ice melts,which is regarded as the end of cooling of the cold storage box.Finally,set up the solar cold storage cold storage laboratory.The experiment was carried out on four aspects of cooling time,holding time,temperature uniformity and influence of opening and closing.The results of the cooling time experiment show that the temperature of the cold storage can be reduced to 2-8℃within 6 days（3 days of cloudy weather）when the initial temperature is about 20℃.During the experiment,it was found that different weather conditions,The intensity of solar radiation is different,and the output voltage of the solar photovoltaic system is different.It has a greater impact on the refrigeration system,which will directly affect the number of normal operation of the refrigeration unit and the speed of the compressor,thereby affecting the cooling performance of the cold storage.The result of the holding time experiment shows that the cold storage can maintain the temperature in the storage of 2-8℃for about 60 hours when the refrigeration unit is not working.Meet the design requirements of 48-72h insulation in cold storage.The result of temperature uniformity experiment proves that when the cold storage runs normally for 24h,the temperature in the cold storage at the same time is relatively uniform,and the maximum temperature difference of the cold storage at the same time is 1.1℃.The door opening and closing experiment results show that after four door openings and closings,the average temperature of each area in the cold storage has not exceeded 8℃,which meets the cold storage requirements.Infrared imager was used to detect and analyze the thermal insulation defects of the cold storage,and the Smartview software was used to process the thermal image.As a result,the thermal insulation defects of the cold storage were mainly concentrated in the door gap of the cold storage,the corner of the cold storage,the evaporation coil and the cold storage board The contact position,the splicing position of the storage board,the bottom of the cold storage,the hole of the insulation board of the cold storage and the unclosed place of the curtain.And the infrared imager was used to shoot the thermal image of the cold air in the cold room and the outdoor hot air when the cold room door was opened,and a theoretical analysis of the flow of cold and hot air was conducted.It was found that after the cold room door was opened,over time During the process,there is a clear dividing line between cold and hot air.The upper part of the dividing line is the hot air entering the cold storage,and the lower part is the cold air escaping from the cold storage,causing a large amount of cold loss.For the above-mentioned cold storage insulation defects,the performance of the insulation board,the joint of the storage board and the position of the storage door are improved in three aspects.In view of the low temperature of the cold storage,a constant temperature heat storage device is proposed and given The design scheme of the heat storage device is presented.