Simulation And Optimization Of Medical Waste Microwave Sterilization Equipment Based On Multi-Physical Field Coupling

With the improvement of medical and health level,the generation of medical waste is increasing year by year.Since the outbreak of COVID-19,the amount of medical waste produced has increased dramatically everywhere.As medical waste is very hazardous,it needs to be disposed of in time.Among all kinds of disposal methods,the microwave sterilization equipment of medical waste using microwave disinfection technology can realize the daily sales of medical waste and very quick and timely opening and closing.In this paper,multi-physical field simulation modeling was carried out on the microwave sterilization experimental platform of medical waste to explore the influence of different factors on the uniformity of microwave heating,and Python script was written to automatically screen and calculate the simulation data.According to the simulation results,the experiment platform was optimized and the sterilization experiment was carried out to explore the optimal sterilization condition of the sterilization experiment platform.The simulation results show that when the fluid with screw conveyor is heated by microwave,the heating uniformity of laminar flow becomes better with the increase of rotational speed,and the heating uniformity of turbulent flow decreases with the increase of rotational speed.When the screw speed is 0.05 r /s,the heating effect is the best,too fast speed will lead to the fluid not enough heat exchange to flow out;The screw pitch has little effect on the average temperature and temperature uniformity of fluid.The spiral conveyor adopts microwave reflective material than microwave transmission material to improve the uniformity of temperature.The influence of changing the position of microwave waveguide on the temperature in the outlet region was investigated.Under the same condition,the waveguide layout had little influence on the average temperature in the outlet region,but the dispersion of waveguide layout had better heating uniformity in the outlet region.Under the same condition,the average temperature and temperature uniformity of the outlet region can be significantly improved by using external heat source preheating,and the temperature uniformity of the outlet region can be improved by 38.23% at 120 s.According to the simulation results,the microwave sterilization experimental bench was modified,and the spores of Bacillus subtilis var.niger（ATCC 9372）were used as the indicator strains,and the microwave sterilization effect was tested by qualitative and quantitative experiments.The results show that the sterilization effect of steam preheating is better than that of electric heating preheating.Sterilization rate will increase with the increase of microwave power,moisture content and time.The optimal conditions were determined by designing orthogonal experiment: microwave power of25 k W,moisture content of 60%,equipment residence time of 14 min.Among them,the time factor has the greatest influence on the sterilization effect,followed by the moisture content,and the power has less influence.