Numerical Simulation Of Fumigation Process In Animal Laboratory

Before carrying out the animal experiment,or when a large epidemic situation causes serious pollution by bacteria and viruses,the animal laboratory needs fumigation to inactivate all indoor bacteria to prevent the infection of bacteria on the animal experiment,so as to make the experimental surgical process sterile and clean.Fumigation is divided into closed and ventilated.Airtight fumigation is to close doors and windows and air conditioning system,artificial potassium permanganate and formalin solution into the indoor,heating volatile formaldehyde gas,airtight for a period of time to cover the whole space after disinfection ventilation exhaust clean.Ventilation fumigation uses the fumigation gas generation equipment added between the air supply pipe and the exhaust pipe,close the air supply valve and the exhaust air valve,open the fumigation gas generation equipment and fan,circulate the indoor air to promote gas diffusion,so as to shorten the fumigation time and quickly sterilize.After a period of rest,close the fumigation gas generating equipment,open the air supply valve and exhaust valve,and completely discharge the fumigation gas,so that the lowest concentration reaches the national standard before the human and animal enter the laboratory for experiments.In this paper,the ventilation and fumigation gas diffusion process and gas elimination process of CFD numerical simulation,the calculation of interior space fumigation gas concentration field and humidity field,,using transient calculation method,change of wind speed and ventilation rate first,find the fumigation gas concentration and humidity meet the requirements of the sterilization of different time points corresponding to the minimum air changes;The influence of air distribution on the concentration distribution of fumigation gas diffusion and removal under different air supply forms was calculated by changing the position and form of air supply outlet.Finally,the room floor and ceiling temperatures were changed to simulate the influence of different indoor temperature distribution on the fumigation gas diffusion and removal.It is concluded that increasing the air exchange rate is conducive to the rapid diffusion of sterilizing gases,and the air exchange rate with a minimum concentration of more than 8mg/L is 7 times per hour at 800 seconds of diffusion.The indoor minimum gas concentration and Humidity are the largest when an air supply outlet is arranged.The neutral stability fumigation effect is the best when the indoor temperature is Homeostasis.The time to reduce the maximum indoor gas concentration to below 0.08mg/m3 will be shortened with the increase of ventilation rate.When the air exchange rate is 30 times /h,the shortest time to completely eliminate indoor harmful gases is 800 seconds.The maximum concentration of indoor gas and Humidity can be reduced by increasing the air supply outlets and dispersing them when removing harmful gas.Narrowing indoor temperature difference and unstable working conditions are conducive to the rapid removal of harmful gases.This study is of great significance to the biosafety issues in animal laboratories and is helpful for the reasonable setting of fumigation conditions.In the fumigation process of the ventilation system,personnel are prevented from directly contacting the disinfectant,thus ensuring the safety of operators.The prediction of indoor gas concentration field has a guiding effect on the uniform distribution of gas and the sterilization of the whole space without dead corners.