The Analysis Of Heating Effect And Energy Saving Of Impinging Jet Ventilation System

Now a days, people spend more and more time on work and study in the room, therefore, the requirements of work environment in the room are gradually improving. Ventilation is a technology, which can make the outdoor air replace the indoor air by natural or mechanical method to improve air quality.There are many traditional ventilation modes, such as mixing ventilation, displacement ventilation, and other modes. Mixing ventilation is the most common modes since the introduction of air-condition, it means that the jet of roof send the fresh air which has been treated into the room in greater speed, the indoor air is well mixed with them, and then through the breathing zone, it is clear that the air quality of this ventilation is not very good. Displacement ventilation was introduced in 70s of the twentieth century, one of its unique features is the use of layered to avoid the supply air mixing with indoor air, compared with mixing ventilation, the indoor air quality has improved. However, displacement ventilation has a big drawback is that this mode only for the indoor cooling system, not for heating systems, and the use of this mode is limited when the room has a large span, so impinging jet ventilation had been proposed under this situation. It can be applied to the buildings which have a relatively large span, and it can overcome the disadvantage that the displacement ventilation is not suitable for heating, it can be used to send hot air, the indoor air distribution is similar to mixing ventilation.Based on the previous research, in the present study the commerical FLUENT software was used to simulate the distribution of flow field and temperature field by numerical simulation, when impinging jet ventilation system is applied to heat in large space in different air supply conditions. The influence of diffusion distance and the indoor thermal comfort in different air supply conditions were discussed.The results show that, in the heating room by impinging jet ventilation system, the bigger the air velocity, the more well-mixed the air flow inside room, the longer the diffusion distance of hot air. In the same air velocity, the lower the height of air supply, the longer the diffusion distance of hot air. The height and velocity of air supply have bigger influence on indoor flow field and distribution of temperature field, but the air supply temperature difference has little influence on that. When making the heating design, the air supply velocity should be set up more than 1.0m/s to ensure indoor thermal comfort.When making the impinging jet ventilation design, we can determine the diffusion distance of hot air according to the area which the air supply outlet is in charge of,to choose the best height of air supply outlet and the air velocity, temperature difference of outlet to meet the requirements of indoor thermal comfort.