低温送风散流器结构优化与送风特性数值分析

Structural optimization of low-temperature air supply diffuser and numerical analysis of air supply characteristics

针对低温送风空调系统散流器表面结露问题,提出一种在普通散流器导流叶片上开设环形条孔引射低温气流的新型散流器设计。采用数值模拟方法分析了环形条孔参数与送风风速对新型散流器送风特性的影响,评估了其应用于低温送风系统的防结露能力。结果表明:当环形条孔宽度≥12. 5 mm,由于条孔引射的低温气流作用,在散流器下方附近区域形成了"温度隔层",有效阻隔了房间工作区域的湿热空气与散流器表面接触,起到了明显防结露效果;而房间工作区域流场与温度场几乎不受环形条孔引射的低温气流影响,可满足室内热舒适性要求;在环形条孔宽度一定时,散流器送风速度对散流器下方"温度隔层"温度梯度几乎不产生影响。

In view of the problem of surface condensation of multi-cone diffusers with good air distribution characteristics in cold air distribution system,an innovative design of cold air multi-cone diffuser by opening an annular strip hole on cone of the diffuser to eject low temperature air was proposed,its viability for preventing surface condensation was assessed based on the flow and temperature fields of air-conditioning rooms applied with this innovative diffuser in an upper supply and bottom exhaust air distribution. The effects of the annular strip hole parameters and the supply air velocities on the supply air characteristics were further analyzed numerically. The results show that when the width of the annular strip hole is larger than 12. 5 mm,a"temperature layer"can be formed in the vicinity below the diffuser due to the low temperature air flow ejected from the strip hole,which effectively prevents the entrained humid and hot room air from contacting the cone surfaces,and thus preventing surface condensation;whereas the flow and temperature field in the working area of air-conditioning room are little influenced by the low temperature air flow ejected from the annular strip hole,still the requirements of indoor thermal comfort are met. Furthermore,for a certain width of the annular strip hole,the supply air velocities are found to have little effect on the temperature gradient of the"temperature layer"below the diffuser.