Influence Of Air Supply Angle Of Air Conditioning In Container Isolation Ward On Indoor Thermal Environment And Air Environment In Winter

In the spring of 2020,COVID-19 broke out in the world.Among them,the number of countries diagnosed by Italy increased rapidly,the medical system collapsed and a large number of patients could not receive effective treatment.In the struggle against the epidemic situation,a mobile isolation ward with high flexibility has been used abroad.Inspired by the wartime field hospital,this ward is transformed into a mobile isolation ward by using the common containers.Container isolation ward is a new type of isolation ward rising in recent years.It is a mobile isolation ward based on the traditional negative pressure isolation ward and reconstructed from a container to adapt to the new situation.Generally,the transfer is carried out by truck.The ward has good negative pressure isolation measures,which can effectively prevent cross infection and prevent the spread of virus while receiving patients.At present,container isolation ward is mainly used to temporarily transfer or urgently isolate infectious patients,and realize the centralized treatment of infectious patients when there is no infectious ward or the capacity of infectious ward is insufficient.Therefore,this ward needs to have the characteristics of small floor area,strong flexibility and easy disassembly,These advantages also make this kind of ward have great limitations in enclosure structure and air conditioning conditions.Specifically,the enclosure structure of the ward has poor thermal insulation effect,large energy loss and low heating level in winter,resulting in patients being in an obviously uncomfortable thermal environment for a long time.Due to the characteristics of container isolation ward,its indoor air temperature distribution and virus concentration distribution characteristics exhaled by patients are sensitive to the change of air supply angle in winter.Therefore,taking the container reconstructed isolation ward as the research object,this paper studies and analyzes the impact of air supply angle on thermal environment and pollutant environment under different outdoor temperatures,The pollutant concentration and removal effect at different exhaust outlet positions are discussed.Using FLUENT software as the simulation tool,the best air supply angle under limited conditions is found,and the thermal advantages of air supply angle after outdoor temperature rise are simulated and analyzed.The results show that,different from the traditional ward,the characteristics of the container reconstructed isolation ward make it sensitive to the change of air supply angle,so it can not achieve the unity of the best air supply angle in meeting the two requirements of thermal comfort and maintaining low virus concentration.When the outdoor temperature is low,the air flow with an air supply angle of 0 ° is seriously affected by the wall,resulting in high wall temperature,10%increase in wall heat loss compared with 30 ° air supply,and excessive head foot temperature difference in the room;When the air supply angle is 30 °,it is difficult for the hot air to reach the ground in winter,and the thermal comfort of the lower space is poor;The optimal air supply angle is about 15 °,the energy consumption is only 3.7% higher than that of 30 °,and the thermal environment is also better than that of 0 °;When the outdoor air temperature rises,although the thermal environment is still the best under the air supply angle of 15 °,the heat loss on the wall is 6.7% higher than the air supply angle of 30 °,and the difference in operating temperature between the air supply angle and 30 ° is reduced from 2 ℃ to 0.5 ℃.When the outdoor temperature is low,the indoor average virus concentration is the lowest at0 ° air supply angle and the highest at 30 ° air supply angle;When the air supply angle is 0 °,the room sewage level is significantly higher,so that the concentration at most observation points in the ward remains at a low level,and the position where the high concentration occurs is far lower than the human respiratory height;When the outdoor temperature is high,the blowdown capacity of 0 ° air supply angle becomes more and more prominent.At low air temperature,the blowdown efficiency of 0° air supply angle is 7% higher than that of 30 ° air supply angle,and the blowdown efficiency is 18% higher after the temperature increases.With the increase of temperature,the gap between 0 ° air supply angle and the other two air supply angles in removing pollutants will become larger and larger.In view of the fact that the container converted ward can not achieve unity in meeting thermal comfort and eliminating virus gas,it is recommended to adjust the air supply angle of the air conditioner according to the actual situation to meet the highest priority demand.When the outdoor temperature is high,it is recommended to give priority to ensuring the low virus concentration level in the room and adjust the air supply angle to 0 °;When the outdoor temperature is low,it is recommended to give priority to meeting the thermal comfort requirements of personnel and adjust the air supply angle by 15°.