Numerical And Experimental Investigation On Indoor Air Stability

Indoor air quality becomes a research hotspot in both domestic and overseas nowadays. But scholars have not yet studied the similarities between indoor air and outdoor air as well as the characteristics of the spreading of indoor air pollutants under certain airflow organization condition (especially temperature profile). So taking this as the research background, the connection of the indoor temperature profile, indoor air stability and the migration of indoor air pollutants is deeply studied in this paper.Indoor environment assessment methods in recent years and forefathers research results are summarized in this paper first, and then the indoor air stability is defined as a kind of character or capability of indoor air to inhibit transverse motion of air parcel or particle. Some new concepts were also presented, including temperature lapse rate and indoor dry adiabatic lapse rate, etc. And the indoor air stability is categorized into three patterns, including unstable, neutral and stable patterns.The method of numerical simulation combined with experimental investigation is adopted in this paper. The software of FLUENT is used to simulate pollution transport property of ammonia in three different indoor air stabilities. The result shows that there are some Internal Relations between indoor air stability and the pollution transport property. The correctness of the indoor air stability theory is further verified by the experimental research. Radiant floor cooling or heating is used to achieve the indoor air temperature vertical gradient, that is, to achieve three different stability conditions, and then release the flue-gas as the pollutant under the three different stability conditions respectively. The spreading of flue-gas was observed and shot. The research shows that turbulence flow is intensified when indoor air is unstable type, so the capability of transverse motion is greater, but the speed along the outflow direction is slower compared with stable type. And if indoor air is of the stable type, the pollution diffuse is restrained, but it arrives outlet faster.The result will provide a scientific foundation for the research of the indoor air organization, the assessment, optimization, and the control of the indoor environment.