Numerical Simulation Of Indoor Air Quality In The Condition Of Impinging Jet Vetilation

With the improvement of the living standard, there is a greater demand for a betterlifequality and a growing concern and awareness over indoor air quality. Since theenergy crisis broke out in1970’s, energy-saving is advocated and strictly implementedworldwidely. In Heating, Ventilation and Air Conditioning(HVAC), its energyconsumption maybe is30~40percent of the total energy consumption, so it is critical totake proper actions in HVAC system. Therefore, how to solve the thermal comfort andIndoor Air Quality (IAQ) problems without consuming too much energy is a verychallenging topic. As a new ventilation style, impinging jet ventilation can improve theindoor air quality and has relatively small energy consumption, so its applicationbecomes more and more extensive.In this dissertation, the characteristics of the indoor impinging jet ventilationsystem are studied. This research mainly adopts the theory analysis and numericalsimulation method, establishes the indoor impinging jet ventilation fluid dynamic model,numerical simulates the indoor air distribution forms, thermal comfort and indoor airquality. Main research contents are as follows:(1) The κ-ε two-equation turbulence model and method of SIMPLE are adopted tosimulate the three-dimensional air distribution of the office, effect of buoyant force onκ-ε model and the wall function are used for the boundary condition. Governingequation discrete, solving of the conjugated algebraic equation set and SIMPLE methodare also discussed in this paper.(2) The paper simulates the the velocity field, temperature field, PMV-PPD andmean age of air in different air-supply temperatures, air-supply velocities and air-supplyoutlet sizes at the condition of impinging jet ventilation in summer. The results showthat the temperature at the same point is increasing and the temperature gradient invertical direction is decreasing while the air-supply temperature is increasing; thevelocity at the same point is increasing and the indoor velocity field is almost the samewhile the air-supply velocity is increasing, but jet flow range is decreasing; the indoorairflow distribution is not changed under various air-supply outlet sizes, but Variety ofair-supply outlet sizes lead to different air-supply volumes, this could have greatinfluence on the indoor air quality and thermal comfort.(3) In winter, with heat supply of impinging jet ventilation, the velocity field, temperature field, PMV-PPD and mean age of air are simulated in different air-supplytemperature and air-supply velocity respectively. The results show that the velocity fieldthat fresh air directly feed into and near the floor is divided into two layers obviously,and in a horizontal direction it would have a temperature gradient; when the air-supplytemperature is increasing, it would reduce the fresh air that can reach the farthestdistance, but the horizontal temperature gradient is increasing; the temperature at thesame point and the jet flow range are both increasing while the air-supply velocity isincreasing.