Study On Indoor Thermal Performances Of Impinging Jet Ventilation Rooms Under Different Heights Of Outlet And Set Values Of Supply Air

With the rapid development of social productive forces and the improvement of people’s living standards, people are paying increasingly attention to the quality of indoor thermal environment. A healthy, comfortable, safe and energy-efficient indoor environment is the people’s ideals. Hence, ventilation has great impact on indoor air quality. The first generation of ventilation is mixing ventilation, considering that the indoor air is becoming more evenly, but the temperature’s stratification remain unobvious, and not to mention low efficiency of ventilation and energy, as well as strong feeling of draft. Followed by the rise of displacement ventilation so that air quality has improved, however, the ventilation is only suitable for cooling in summer, but not suitable for heating in winter, there are some limitations. Impingjing jet ventilation, as a new kind of ventilation, combined the advantage of mixing ventilation and displacement ventilation, and has no significant shortcomings. Since it’s still a brand new mode to our country, the research about collision jet ventilation, and alimentation of indoor thermal environment and human indoor thermal comfort, has greatly significance to China.Via combination of theoretical analysis and experimental methods, this paper focused on the indoor thermal performances of impinging jet ventilation rooms under different heights of outlet and set values of supply air, when it used as a supply of warm air. The experimental platform of collision jet system for heating was established to analyze the indoor thermal environment and human indoor thermal comfort under all kinds of condition, by setting different heights of outlet, different air’s speeds and different air’s temperature differences. By studying the number of outlet’s Archimedes, the distance of hot air diffusion, uniformity of temperature and uniformity of wind speed and the index of temperature efficiency η, this paper gained the understanding of the indoor thermal environment. At the same time, by studying the effective sense of air temperature AET and the air distribution performance index ADPI, the local thermal discomfort evaluation such as feeling of draft and discomfort caused by the vertical temperature difference, the human indoor thermal comfort is studied. Results are as follows:(1) With the gradually increase of outlet’s height, the temperature uniformity of the work area declined slightly after the first rise. Meanwhile, with the increase of outlet’s height, the diffusion distance of warm air on the ground declined. Hence, with the increase of outlet’s height, ADPI experienced an ascent and then reached a plain, and PD caused by vertical temperature difference reduced then remained and DR remained still then increased.(2) With the gradually increase of air velocity, the temperature uniformity is higher, while the uniformity of air velocity declined. At the same time, there were slower rise of the warm air, higher efficiency of the indoor temperature, and shorter diffusion distance of warm air on the ground. Hence, with the increase of air velocity, ADPI emerged unobvious ascension, and PD caused by vertical temperature difference diminished and DR caused by feeling of draft went strong.(3) The larger the temperature difference is, the longer time taken for indoor temperature to reach stable state from the start of the ventilation. Meanwhile, PD caused by vertical temperature difference and DR caused by feeling of draft diminished, and ADPI manifested an unobvious descend.