Study On Ventilation And Air Conditioning System That Combine Normal Time With Emergency In Infectious Disease Hospital

In response to frequent outbreaks,the normalization of epidemic prevention is the inevitable trend of future medical system construction.As one of the most critical links,the research on the strategy of epidemic prevention in the ventilation and air conditioning system is very important.Through literature research,theoretical analysis and other methods,this paper sorted out the zoning principles and design parameters of ventilation and air conditioning system in peacetime and epidemic time,summarized the zoning points and main parameter of infection ward that combine normal time with emergency.Three combination methods are recommended: non-respiratory infectious ward-circulating wind isolation ward,respiratory infectious ward-circulating wind isolation ward,and respiratory infectious ward-fresh wind isolation ward.The air distribution of infectious ward in peacetime and epidemic period is analyzed respectively by using the method of numerical simulation.By comparing the pressure distribution and pollution levels in the ward,the optimization scheme of negative pressure construction and tuyere layout in the ward was put forward.The following conclusions are drawn.The layout principle of ’ three districts and two channels ’ should be adopted in the building both in peacetime and during the outbreak.Ventilation and air conditioning systems should be set up in clean area,semi-polluted area and polluted area in the combined disease area separately.In the epidemic,it is usually necessary to subdivide the ventilation and air conditioning system to avoid excessive system volume.Ventilation and air conditioning systems are recommended for every 5 ～ 6 fresh air isolation wards.The core of the transition from normal to epidemic is the transformation of ward functions,and the difference of design parameters is mainly reflected in the large demand for ventilation and high demand for pressure control during epidemic.In normal times,indoor thermal environment is good,and the pressure distribution is uniform.The absolute value of negative pressure in the non-respiratory infectious ward and the respiratory infectious room is small,so that the isolation effect is limited.Nonrespiratory infectious ward pollution control ability is poor,indoor pollution is serious.The control ability of pollutants in the respiratory infectious ward is relatively good,but the concentration level of pollutants is also high.During epidemic,the negative pressure value in the ward decreased by about 50%compared with normal times,and the isolation effect was improved.However,the effect was limited,further optimization was needed.Compared with the normal times,the pollution situation in the unit of each epidemic combined ward has been effectively improved,but it still needs to be further optimized.The net exhaust volume and building air tightness affect the indoor pressure condition at the same time,it is difficult to control the pressure by increase either of them blindly.3ACH is the recommended net exhaust volume to control the differential pressure of 5Pa,supplemented by building air tightness optimization measures.To improve the indoor environment,the non-respiratory infectious ward should adopt the form of air distribution of upper and lower discharge.When the return air inlet of the circulating air isolation ward is set near the pollution source in the lower part of the room,the indoor pollution level can be effectively reduced and the purification efficiency of the circulating air equipment can be improved.When the return air inlet is set on the upper part,it should be set in an area with relatively low air quality requirements.When the tuyere are shared during peacetime and epidemics,usual usage needs should be considered first when select the air supply port,and exhaust outlet will determine by the exhaust volume during the epidemic.If the air outlet should be added in the epidemic time,the lower air outlet should be added near the pollution source,and the air supply grille should be added near the head of the bed.