Research On The Flow And Heat Transfer Process In Positive Pressure Respirator

Since the outbreak of the COVID-19,the field of respiratory protection has received increasing attention.The positive pressure respirator is widely used in the field of respiratory protection.The device uses a face shield to separate human breathing from the external environment.Keep the internal breathing environment in a positive pressure state at all times,and provide clean and safe respiratory airflow for the human body through the powered air supply filtration system.However,in the actual use process,uneven temperature distribution and local temperature accumulation in the breathing cavity will lead to poor thermal comfort,and due to high ambient temperature,face heat dissipation and other effects,the heat cannot be discharged in a timely manner resulting in a higher temperature inside the respirator,which seriously affects the working efficiency and physiological health of the wearer.Based on the above problems,this paper studies the influencing factors and distribution characteristics of the heat flow field in the positive pressure respirator.At the same time,carries out experimental comparison and verification,and designs a thermoelectric cooling device for hot weather.Firstly,analysis of the main influencing factors of the heat flow field inside the positive pressure respirator.By analyzing the regulation of human heat production and heat dissipation,the heat exchange model between the human face and the breathing cavity was established.At the same time,the relevant parameters of the breathing cavity are studied to provide a theoretical basis for the subsequent simulation.Secondly,ANSYS Fluent was used to study the heat flow field in the breathing chamber of the positive pressure respirator.Exploring the variation pattern of temperature field in the breathing chamber.The effects of different labor intensity,intake air flow temperature and flow rate on the temperature in the face shield were summarized.Investigating the effects of different face shield side distances and air intake methods on the temperature inside the positive pressure respirator.Provide the design basis for the positive pressure respirator structure,and improve the thermal comfort of the positive pressure respirator.Then,based on the above simulation results,a thermoelectric cooling device is designed for hot environment conditions,and the shape and size of the fin heat exchanger are determined by numerical simulation analysis of different plate fin coolers at the cooling end of the thermoelectric cooling device.Provide a thermoelectric cooling device with good cooling effect.Finally,the positive pressure respirator prototype and temperature experiment were carried out.Making an experimental prototype,building a temperature experimented platform and carry out human wearing experiments of the positive pressure respirator.Collect the temperature values of the three monitoring points in the respirator under the medium labor level.At the same time,use the questionnaire to obtain the thermal subjective feeling score of the subjects,and obtain the temperature change rule in the positive pressure respirator.Test the comfort of the improved fan-shaped air intake respirator.Verify the correctness of the simulation method and results.