低温送风散流器结构优化与送风特性数值分析
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摘要
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.
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.
引文
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[2]李莉,朱彩霞,张建一.与冰蓄冷相结合的低温送风系统[J].低温工程,2004(5):59-62.
[3]李莉,张建一.低温送风空调系统的风管得热与温升[J].低温工程,2005(6):60-63.
[4]石俊龙,刘洋.冰蓄冷低温送风空调系统气流组织模拟研究[J].低温与超导,2014,42(9):49-54.
[5]栾茹,王佳.送风速度对室内气流分布影响的数值模拟[J].制冷学报,2007,28(5):31-35.
[6]Chuah Y K,Hu S C,Shieh M F.A study on the control of surface condensation on a multi-cone diffuser in cold air distribution applications[J].Indoor&Built Environment,2004,13(3):223-231.
[7]苏飞.低温送风诱导式缩放风管优化研究[D].北京:华北电力大学,2016.
[8]Youssef A A,Mina E M,Elbaz A R,et al.Studying comfort in a room with cold air system using computational fluid dynamics[J].Ain Shams Engineering Journal,2018,9(4):1753-1762.
[9]虞婷婷,刘恩海.基于低温送风空调系统的室内气流组织分析[J].低温与超导,2014,42(4):83-88.
[10]苏飞.低温送风诱导式缩放风管优化研究[D].北京:华北电力大学,2016.
[11]张智力,张旭,张恩泽.低温送风条件下风口结露实验研究[J].暖通空调,2005,35(5):120-122.
[12]Knebel D E,John D A.Cold air distribution application and field evaluation of a nozzle-type diffuser[J].ASHRAE Trans.,1993,17(2):1337-1348.
[13]曾燕琳,蔡德源,刘应清.冰蓄冷空调系统低温送风末端装置的研究[J].重庆大学学报,1997,19(5):73-77.
[14]蔡德源,关彦征,曾燕琳.低温送风系统散流器的性能评价[J].西南交通大学学报,2002,37(1):85-89.
[15]周东一,石楚平,肖飚,等.一种新型低温送风口的设计与实验研究[J].制冷学报,2008,29(5):33-38.
[16]Zhou D,Shi C,Yuan W.Design and experimental research on a novel cold air diffuser[C]//International Conference on Intelligent System Design and Engineering Application.IEEE,2011:494-497.
[17]牛利敏,赵建成,宋业辉.国产旋流风口用于低温送风系统的试验研究[J].暖通空调,2007,37(12):111-115.
[18]Sun Y,Smith T F.Air flow characteristics of a room with square cone diffusers[J].Building&Environment,2005,40(5):589-600.
[19]Aziz M A,Gad I A M,Mohammed E S F A,et al.Experimental and numerical study of influence of air ceiling diffusers on room air flow characteristics[J].Energy&Buildings,2012,55(10):738-746.
[20]韩占忠.Fluent流体工程仿真计算实例与分析[M].北京:北京理工大学出版社,2009.
[21]王福军.计算流体动力学分析[M].北京:清华大学出版社,2004.