Effect Of Ventilation On Indoor Polutant Concentration Distribution

With the development of social economy, more and more buildings are massively decorated, plus the need of energy conservation, the room airtight is strengthened, which cause massive low density volatile organic compounds exist in the room, they will be harm to the human body. Studying on the interior contaminant distribution characteristic and appraising discharging pollutant ability of different ventilation pattern are one of important job on building environment studies, which is very important to perfect valuation system of indoor air quality, to design building ventilation system, and consider interior air quality in engineering design.Indoor air quality,ventilation efficiency and ventilation pattern was introduced in this paper. Summed up the present situation and existed problems of indoor air quality and CFD research, combined numerical simulation and experiment method, made use of computational fluid dynamics software PHOENICS, by means of many times simulation, selected the mathematic model describing the pollutant distribution and set pollution source reasonably. Tested the formaldehyde concentration of air-conditioning room, verified the correctness of simulation procedure. Aimed at energy conservation demonstrated building, discussed the effect of natural ventilation and mechanical ventilation on indoor pollutant distribution, discussed the effect of inlet position and inlet area of natural ventilation on indoor pollutant distribution, and discussed the effect of air exchange rate and velocity of mechanical ventilation on indoor pollutant distribution.The experiment results show that, the natural ventilation of demonstrated building could discharge indoor pollutant effetely; the tested results of natural ventilation show that, the HCHO and TVOC concentration of decorated building can satisfy the indoor air quality standard after one year; the tested results of mechanical ventilation show that, the effect of ventilation quantity on indoor pollutant distribution is not obvious, the velocity of discharging indoor pollutant with the maximum is lower than natural ventilation.The numerical simulation results of natural ventilation show that, inlet position,inlet area and inlet temperature can influence the indoor pollutant distribution, when half area of east and west window open, indoor pollutant can be discharged effetely; Enlarge area of inlet, the ability of discharging indoor pollutant is strengthened; in autumn, natural ventilation under wind and hot pressure can discharge indoor pollutant quickly, the ventilation efficiency is very high, natural ventilation can improve indoor air quality obviously. The pollutant distribution under natural ventilation is homogeneous on height direction.The numerical simulation results of mechanical ventilation show that, the air exchange rate, exhaust velocity and inlet position can influence indoor pollutant distribution. When air exchange rate increase, the ability of discharging indoor pollutant is strengthened; when exhaust velocity increases, ventilation efficiency also increases; the outlet position keeps invariant, change the inlet position, the ventilation efficiency also increases. The pollutant concentration of mechanical ventilation is high at the bottom of room and low at the upper part of room.