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Comparison of ventilating effect of indoor displacement and mixing ventilation |
YUAN Jian-Ping, WANG Long-Yan, HE Zhi-Xia, LIU Xiao-Fan |
(Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang, Jiangsu 212013, China) |
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Abstract The main objective of the article is to investigate the difference in indoor thermal comfort and air quality by means of numerical simulation based on a wellvalidated CFD(computational fluid dynamics) model when a commercial kitchen is subject to mixing and displacement ventilation. It was shown that using thermal displacement ventilation in the kitchen can reduce indoor temperature without increasing the airconditioning system capacity. Under the same indoor environmental conditions, the flow velocity of mixing ventilation (MV) is almost twice that of displacement ventilation (DV) in average, and the crossdrafts exists which leads to an uneven flow pattern. The temperature stratification is evident for DV, the temperature gradually gets higher upwards, and it has an appropriate value in the human breathing zone. Also, the air quality in the human breathing zone of DV is better than that of MV system which operates in the same air velocity. Moreover, the average air age of the former is less than 100 s in the kitchen. A properly designed displacement ventilation can maintain a thermally comfortable environment where the air velocity is lower than 0.3 m/s, the difference in temperature is below 2 °C between the head and ankle level, and the percentage dissatisfied people in breathing zone is smaller than 15%, and eventually can provide a better IAQ(indoor air quality) in the occupied zone.
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Received: 01 December 2011
Published: 30 September 2012
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[1]Elisabeth M. Convection flows above common heat sources in rooms with displacement ventilation system[J]. Room Vent Norway, 1990 (3): 17-20.[2]马仁民.置换通风的通风效率及其微热环境评价[J]. 暖通空调, 1997, 27(4):1-6,65.Ma Renmin. Displacement ventilation effectiveness and evaluation of the micro thermal environment[J]. HV & AC, 1997, 27(4):1-6,65.(in Chinese)[3]赵彬, 李先庭, 彦启森. 置换通风的数值模拟[J]. 应用力学学报, 2002, 19(4):75-79.Zhao Bin, Li Xianting, Yan Qisen. Numerical simulation for displacement ventilation[J]. Chinese Journal of Applied Mechanics, 2002, 19(4): 75-79.(in Chinese)[4]Wan Xiongfeng, Yu Likui, Hou Huabo. Comparison of two ventilation systems in a Chinese Commercial Kitchen[C]//Proceedings of the Sixth International Conference for Enhanced Building Operations. Shenzhen, China:[s.n.],2006.[5]李强民. 置换通风原理、设计及应用[J]. 暖通空调, 2000, 30(5): 41-46.Li Qiangmin. Displacement ventilation: Principles, design and applications[J]. HV & AC, 2000, 30(5): 41-46.(in Chinese)[6]胡建军, 王汉青. 厨房排风系统现状分析[J]. 制冷空调与电力机械, 2005,26(6): 53-56.Hu Jianjun, Wang Hanqing. Research on the kitchen ventilation system[J]. Construction Machinery For Hydraulic Engineering & Power Station, 2005,26(6): 53-56.(in Chinese)[7]Fanger P O. Thermal environment—Human requirements[J]. The Environmentalist, 1986,6(4):275-278.[8]Zhao Bin, Li Xianting, Yan Qisen. A simplified system for indoor airflow simulation[J]. Building and Environment, 2003,38(4):543-552.[9]Deng Shiming. Ventilation for Chinese kitchens in hotels in Hong Kong[C]//Proceedings of the International Conference on Energy and the Environment. Shanghai, China: Energy and the Environment, 2003,2:1482-1485.[10]Park HeeJin, Holland Dale. The effect of location of a convective heat source on displacement ventilation: CFD study[J]. Building and Environment, 2001,36(7):883-889. |
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