Evaluation of air inlet angle effects in swirling diffuser of UFAD systems on micron particles pattern distribution

Particle pollutants in indoor environment are a serious threat for human health. Therefore, it seems necessary to recognize and control the distribution of these particles. In the present study, the effect of air inlet angle of swirling diffusers in UFAD systems has been investigated on micron particles pattern distribution by considering the thermal comfort condition. For evaluating the flow and particle distribution, OpenFoam developed solver by the Eulerian-Lagrangian method and for two node model are used for predicting the flow and thermal conditions. Inlet angles are set in three cases: 30, 45 and 60. Based on the results, in all three cases, the TSENS index is in the comfort zone. But, by changing the inlet angle from 30 to 60, the vertical temperature difference can be reduced about 1 . The results showed that at inlet angle 30 and 60, the percentage of particles exited with 2.5 micrometers diameter were 32% and 55% of the total particles. In other words, increasing the inlet angle can leads to exit more amount of any size of particles from the room. In addition, by increasing particles size, larger particles removed faster from the breathing zone, and smaller particles will remain longer time in the air. In other words, smaller particles have a greater impact on the indoor air quality.