Numerical Simulation Of Air Distribution In An Artificial Laboratory Animal Environment Designed To Minimize Energy Costs

The outbreak of COVID-19 has brought great harm to the world.Vaccine development and laboratory animal clinical trials are imminent.Comfortable,healthy and safe environment for laboratory animals is particularly important.Traditional laboratory animal facilities have some problems,such as high energy consumption and unreasonable airflow organization,which affect the development and economy of laboratory animal models.In order to solve the problems of laboratory animal facilities,this paper uses computational fluid dynamics numerical simulation and experiment to analyze a barrier environment laboratory animal facility,optimize the airflow organization of artificial environment,and study the key technology of cleanliness,thermal and humid environment and energy saving of laboratory animal facilities,as well as the effect of individually ventilated cage system.The main contents of this paper are as follows.(1)The test of a typical cleanliness class 7 barrier environment laboratory animal facility is carried out by using automatic control system and experimental equipment,including temperature and humidity,fresh air volume,air change rate,pressure difference,air cleanliness and ammonia concentration.The uniformity of parameters on each side is analyzed and compared.(2)Based on the test data,the computational fluid dynamics numerical simulation model of cleanliness class 7 barrier environment laboratory animal facility is established to find the best combination of exhaust outlet position,exhaust outlet size,cage position,cage type and air change rate.The accuracy of simulation is verified through experiment,and the air distribution of laboratory animal artificial environment is optimized.(3)The theoretical analysis of the IVC system is carried out.The fresh air cooling load index of the IVC and open cage system is calculated,and the energy saving effect and feasibility of applying air directional flow technology in the laboratory animal facility of the barrier environment are explored.The results show that the position and size of the exhaust outlet have little effect on the overall average parameters and the root mean square deviation of the environment.Increasing the number and size of the exhaust outlet appropriately can reduce the local airflow velocity and make the airflow distribution more even.Different cage position and type have great influence on the airflow organization in the artificial environment of laboratory animal.The arrangement of cages along the width direction is more reasonable than that along the length direction of the cage.The average air age of the former is 25 seconds lower than that of the latter,and the fluctuation range is small.The optimal cage distance can make the airflow reach the laboratory animal as quickly as possible,with the freshest air and the best air quality.The air conditioning system of cleanliness class 7 barrier environment laboratory animal facility has the problem of high energy consumption.When the air change rate is 28 times per hour,the cooling load index of fresh air in summer is 987 watt per square meter,accounting for 95.7% of the total cooling load.On the basis of ensuring the cleanliness,thermal and humid environment parameters,the IVC system can effectively isolate the environment inside the cage from the environment outside the cage,avoiding the pollution of the laboratory animal compared with the open cage system.When the air change rate inside the cage is 15 times per hour and the air change rate outside the cage is 5 times per hour,the theoretical energy saving rate is 62.6%.