Study On Pressure Difference Control For An Infectious Disease Hospital Based On Multizone Model

Pressure differences should be maintained between rooms with different pollution levels to direct the airflow in infectious disease hospitals to avoid airborne pathogen spread in the whole hospital.However,pressure differences cannot be maintained easily in dynamic scenarios,such as doors opening.Although the guidelines have specified the values of pressure differences should be maintained in the static scenario,none of them suggest a measure for coping with this situation.Variable air volume（VAV）dampers are set in the exhaust ducts of negative pressure isolation wards attempt to achieve active control by VAV in dynamic scenarios,but they are often set to deliver constant air volume（CAV）,perhaps due to a lack of awareness of adjustment effect of the VAV.Therefore,in order to fill the gap of guidelines and promote the application of VAVs for active pressure difference control in infectious disease hospitals,it is needed to obtain the appropriate control strategy for the active pressure difference control,its adjustment effect,and its operating influence in infectious disease hospitals.According to the research demands,Multizone model is chosen as the simulation method in this study.By classifying,summarizing and comparing the simulation tools of multizone model used in previous studies,the multi-domain integration simulation tool with obvious advantages is chosen for the subsequent simulation.In order to ensure the reliability of the simulation results,the key parameters of the multi-zone model are determined by the building pressurization measurement,literatures and guidelines.Based on a real infectious disease hospital,a single isolation room model built and verified is used to explore an appropriate active pressure difference control strategy for VAVs in the negative pressure isolation ward.It is determined by selecting typical cases and comparing the adjustment effects.The control strategy isΔp_{BR to NPIW} andΔp_{EC to NPIW} should be fed back to VAV and the VAV should not operate when the door between the NPIW and the EC is opened.With this control strategy,the pressure difference deviations can be reduced by 9.98%to 25.73%and after the door is closed,stable pressure differences can be achieved during 24.45s to 50.87 s for different leakage paths of the isolation room.Then,this control strategy is applied to a validated single-floor infectious disease hospital model to analyze the influence of the VAV operation on multiple rooms pressure differences in the hospital.The results show the stability of the pressure differences during VAV operation in the face of the usual dynamic scenario.The pressure difference redundancies are obtained with reference to the pressure difference deviation in the worst scenario.In addition,the leakage paths airtightness of the door at the junction of the three zones and the external window should be reduced to strengthen the anti-interference ability of pressure difference facing the leakage airflow rate change.