Effect of supply velocity and heat generation density on cooling and ventilation effectiveness in room with impinging jet ventilation system
Effect of supply velocity and heat generation density on cooling and ventilation effectiveness in room with impinging jet ventilation system
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DOI：
10.1016/j.buildenv.2021.108299
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发表时间：
2021-11
影响因子：
7.4
通讯作者：
Haruna Yamasawa;Tomohiro Kobayashi;Toshio Yamanaka;N. Choi;M. Cehlin;A. Ameen
中科院分区：
文献类型：
--
作者：
Haruna Yamasawa;Tomohiro Kobayashi;Toshio Yamanaka;N. Choi;M. Cehlin;A. Ameen
本研究旨在了解送风动量与生热密度对具有冲击射流通风系统的房间的冷却与通风效果的影响。通过CFD分析进行了参数研究，并将供应终端和居住者的数量作为参数进行了变化。在参数研究之前，通过比较实验和分析结果进行CFD验证。RNG k-ε模型和SST k-ω模型的模拟精度相近，选择SST k-ω模型进行参数研究。结果表明，航站楼和/或人员的数量越多，气流组织越趋于置换流，而航站楼和/或人员的数量越少，气流组织越趋于混合流。将送风终端设置在墙壁中央比设置在房间角落可以保持房间内更高的通风效率和冷却效率。当送风速度小于0.833 m/s时，中心断面脚踝处的送风率（DR）在距离终端水平距离0.5 m以内的区域可保持在20%以下，在距离终端水平距离1.0 m以内的区域可保持在15%以下。最后，在具体的研究案例中，冷却和通风效率表示为阿基米德数（供应动量和浮力之间的平衡）的函数。大，小阿基米德数的渐近值得到每个指标表示冷却和通风的有效性。
This study aims to understand the effect of supply momentum and heat generation density on the cooling and ventilation effectiveness in a room with an impinging jet ventilation system (IJV). A parametric study was conducted by CFD analysis, and the number of supply terminals and occupants were varied as parameters. CFD validation was conducted before the parametric study by comparing the experimental and analytical results. RNG k-ε and SST k-ω model showed almost the same accuracy for simulating, and SST k-ω model was chosen to be used for the parametric study. It is shown that the larger number of terminals and/or occupants leads to the air distribution to be displacement flow, whereas the smaller number leads to that of mixed condition. The ventilation effectiveness and cooling effectiveness within the room could be kept higher by locating the supply terminal at the centre of the walls than at the corner of the room. When the supply velocity was smaller than 0.833 m/s, the draught rate (DR) at ankle level in the central cross-section could keep lower than: 20% in the region farther than 0.5 m horizontally away from the terminals, and 15% in the region farther than 1.0 m away from the terminals. Finally, the cooling and ventilation effectiveness is expressed as the function of Archimedes number (the balance between supply momentum and buoyancy) in the specific studied cases. The asymptotic values for both large and small Archimedes numbers are obtained for each index expressing cooling and ventilation effectiveness.