Numerical Study Of Air Distribution And Negative Pressure Monitor In Infectious Isolation Room

The patient with infectious respiratory disease in hospital produces droplet-nucleiwith pathogens, if not under control, results in nosocomial infection by airbornetransmission. The infectious isolation room is necessary for controlling source andpreventing airborne transmission. This paper investigates the ventilation strategy andthe monitoring of room pressure with CFD. The ward model of continuous or unsteady contamination sources wasestablished with specifying the contamination expelling characteristics. The removingpress of particles once released was simulated to compare the influence of differentventilation rate and air distribution. The steady distribution of particles was simulated,and optimizing analyses of the air distribution were carried by investigating the influ-ence of ventilation strategy, supply air temperature and heating mode. The differencebetween the concentration distribution of aseous or granular contamination wassimulated and the reasons to make this difference were analyzed. The ventilationsystems were evaluated with the ventilation efficiency. The local pollutantconcentration was decided by the air distribution and the location of contaminationsource, so the index of contamination source was defined to evaluate the localpollutant degree by the contaminant source. The relationships between air infiltration flux through cracks under door andpressure difference and those between flux coefficient and geometry property wasobtained based on CFD. The velocity through the doorframe was obtained, and thebest way of adjusting flux of ventilation opening to obtain directional flow wasinvestigated. The field of velocity and pressure caused by different door swing (intoroom, out of room or along a wall) was simulated by dynamic mesh method. Theindoor contaminant diffusion in the press of people moving into room was simulatedand the influence of the direction of door swing on the airborne transfer ofcontamination was investigated. Serious experiments was done in an isolation room was done to teat thevalidity of the model and related coefficient used in numerical simulation. Thesimulation results of velocity and pressure field under closed door or without door arein well agreement with measured values of velocity and pressure. The concentrationunder steady state when tracer gas CO2 releasing and the decaying press after itstopped releasing are simulated, the value got by simulating and the measured valueof measuring points are close. The gas diffusion simulations with 3D model withoutdoor and with 2D simplified model with door swing are done respectively. Thecombined simulation results are closed to the change of concentration at themeasuring points in anteroom.The study results would administer to the design and assessment of the effectof air distribution and ventilation strategy in health care facility.