关键词:
Air Film;Numerical Simulation;Coanda Effect;Cooling
摘要:
Large-span air-conditioning plant rooms have a large roof area and suffer from serious solar radiation in summer. The outside roof surface temperature is very high, so cooling load of roof occupies a large proportion in the envelope structure cooling load of large-span air-conditioning plant rooms. Based on the Coanda airfoil air induction unit, the author combined with exhaust air in large-span air-conditioning plant rooms to design the roof air film cooling system of large-span air-conditioning plant rooms. The adherence air film formed on the outside surface takes away heat on the outside surface of the roof, so as to reduce outside roof surface temperature of the roof, decrease heat transfer temperature difference between inside and outside roof surfaces of, and reduce roof cooling cold. Furthermore, the mathematical model and numerical simulation method of considering fluid-structure interaction for heat transfer and influences of solar radiation on air film formation of outside surface and cooling were constructed. Moreover, the numerical simulation method was conducted the validation of effectiveness. Also, the author discussed the air film formation mechanism and air film cooling ability of outside surface in large-span air-conditioning plant rooms without natural wind, developed a new air film cooling technology for the roof of large-span air-conditioning plant rooms, and supplemented the existing roof cooling technology.
期刊:
Heat Transfer Engineering,2018年39(20):1731-1752 ISSN:0145-7632
通讯作者:
Zhao, Fu-Yun
作者机构:
[Wang, Han-Qing; Li, Lin; Zhao, Fu-Yun] Hunan Univ Technol, Sch Civil Engn, Zhuzhou, Hunan, Peoples R China.;[Hu, Jiang-Tao; Zhao, Fu-Yun] Wuhan Univ, Sch Power & Mech Engn, Dong Hu Southern Rd, Wuhan 430072, Hubei, Peoples R China.;[Liu, Di] China Univ Petr, Coll Pipeline & Civil Engn, Qingdao, Shandong, Peoples R China.;[Wang, Han-Qing] Univ South China, Sch Civil Engn, Hengyang, Hunan, Peoples R China.
通讯机构:
[Zhao, Fu-Yun] W;Wuhan Univ, Sch Power & Mech Engn, Dong Hu Southern Rd, Wuhan 430072, Hubei, Peoples R China.
摘要:
Combined heat and moisture transportation in an enclosure has been numerically investigated, which could benefit the sustainable building energy conservations and electronic cooling designs. An adiabatic and impermeable partition of finite thickness is considered, placed in the enclosure following an ordered arrangement. Effects of length and location of the partition, buoyancy ratio and thermal Rayleigh number on convective heat and moisture transfer rates in the enclosure are discussed. Firstly, this situation of the partition placed in the horizontal wall is studied, where inhibition effect of partition is observed. It is seen that the location of partition put relatively weaker influences on the heat and mass transfer in the regime of thermal-driven flow, when its length exceeds the critical value. Additionally, inhibition effect is more pronounced as the partition is fixed in center of vertical wall. Furthermore, local heat and mass transfer rates could be suppressed when the buoyancy ratio becomes negative. Finally, thermal Rayleigh number greatly affects the transport structures of fluid, heat and moisture, whatever aiding flow or opposing flow situations. Heat and mass transfer potentials could be promoted with increasing thermal Rayleigh numbers. Present work could be adopted to optimize the enclosure flows simultaneously with heat and moisture transport.
摘要:
Combined thermal and moisture convections in an enclosure partially filled with porous medium are numerically and analytically investigated, aiming to enhance moisture transport in the thermal energy storage unit. Two representative configurations of porous layers were taken into considerations, being placed centrally in the space or attached to the vertical walls. Moist air motions are simultaneously driven by the internal heat generation and external concentration difference imposed across the enclosure. Effects of Darcy number, mass diffusion coefficient, thermal Rayleigh number and buoyancy ratio on the heat and moisture transfer across the enclosure are discussed. Heat and mass transfer of the fluid/porous interface is analyzed as a function of the permeability of the porous layer. In the extreme case of high permeability and solutal-driven flow, a scale analysis is applied to predict the order of magnitudes involved in the boundary layer regime. Also, correlations for the average Nusselt and Sherwood numbers based on discrete numerical results are proposed. There is an agreement between the analytical and numerical results of moisture transfer rate, while a slight difference of heat transfer rate is observed due to different configurations of porous layers were imposed. Present research could benefit future development of sustainable building energy storage.
作者机构:
[郭韵恬] School of Urban and Environmental, Hunan University of Technology, Zhuzhou;412007, China;[王汉青] School of Civil Engineering, University of South China, Hengyang;421000, China;[郭韵恬] 412007, China
通讯机构:
[Wang, H.] S;School of Civil Engineering, University of South China, Hengyang, China