Study On Thermal Performance Of Vaccine Cold Storage At 2?8?

During the Covid-19 pandemic,the supply security of EPI vaccine and non EPI vaccine has experienced the most severe test in history.After the issue,Chinese government and enterprises are aware of the importance and necessity of the construction of vaccine cold chain transportation system.In terms of capacity-building of vaccine cold chain,relative governmental office has clearly put forward the requirements for capital budget and the number of facilities and equipment.And the construction of vaccine cold chain transportation system will usher in a turning point.Vaccines have been proved to be one of the most effective weapons against infectious diseases in modern times.Their proper use can reduce millions of deaths and cases every year.Because of its high heat sensitivity,most vaccines should be kept at a constant temperature of 2 ? 8? during transportation and storage.Therefore,it is very important to ensure the stability of vaccine storage environment in order to successfully carry out the global immunization program.At present,although most of the vaccine cold storage units have almost reached the designed temperature,the temperature distribution in the cold storage is not uniform,which still poses a threat to the safety of the cold storage.Therefore,the construction and management of vaccine cold storage is of great importance.Good air distribution in cold storage is the key to achieve uniform temperature distribution.Among all the factors that affect the thermal performance of vaccine cold storage,air distribution is an important factor that does not increase the initial investment,and has great potential in reducing operating costs and improving the performance of cold storage.The air distribution in the cold storage is affected by many factors,such as the arrangement of the air cooler,the arrangement of the goods in the cold storage and the length-width ratio of the cold storage.To optimize the air distribution in the cold storage and improve the temperature uniformity are our fundamental goal.In this paper,the representative 2 ? 8? vaccine cold storage in northern,central and southern Jiangsu province are selected as the research object.Based on the two key factors of the internal geometry and working conditions of vaccine cold storage,the internal temperature field and air distribution of the vaccine cold storage are comprehensively analyzed,and the existing thermal performance problems are summarized.Firstly,the effects of different layout of cooling fans(number of cooling fans,layout position of cooling fans),different vaccine loads(0/80%),door opening and closing conditions and door opening angle(?9030??(28),)on the internal thermal performance of the vaccine cold storage are analyzed and optimized experimentally.And based on the evaluation index system of the thermal performance of the vaccine cold storage during the stable operation period and the measurement period,the qualitative and quantitative analysis and discussion are carried out,and the geometric structure of the storage can be gradually improved.Then,based on the theoretical model,the CFD simulation method is used to further optimize the installation height((28)6.15.14.1mmm H,,)and length-width ratio of the cooling fan in the cold storage.Finally,the ideal structure model based on the theoretical model is obtained,and the deviation of the actual model is calculated.The research results of this paper can provide support for the design and optimization of vaccine cold storage as the reference for the interior design and improvement of vaccine refrigerated vehicle with similar structure.