Experimental investigation of natural convection heat transfer in horizontal and inclined annular fluid layers
Experimental investigation of natural convection heat transfer in horizontal and inclined annular fluid layers
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DOI：
10.1007/s00231-007-0337-5
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发表时间：
2008-06
影响因子：
2.2
通讯作者：
S. Nada
中科院分区：
文献类型：
--
作者：
S. Nada
在本研究中，对同心管界定的水平和倾斜环空中浮力驱动流的传热和流体流动特性进行了实验研究。通过向内管施加热通量，环空内表面保持在高温，而通过在外管周围以高质量流量循环冷却水，环空外表面保持在低温。实验在不同的环带间隙宽度（L/Do = 0.23、0.3 和 0.37）和不同的环带倾角（α = 0°、30° 和 60°）的瑞利数（5 × 104<Ra< 5 × 105）范围内进行。结果表明：（1）增加环空间隙宽度会显着增加传热率，（2）随着环空与水平面的倾斜度的增加，传热率略有下降，（3）增加Ra会增加任何L/Do和任何倾斜度下的传热率。由于环空中浮力驱动的流动而导致的传热增强的相关性已根据 Ra、L/Do 和 α 得到了发展。相关性的预测已与当前和以前的数据进行了比较，发现相当一致。
In the present study, an experimental investigation of heat transfer and fluid flow characteristics of buoyancy-driven flow in horizontal and inclined annuli bounded by concentric tubes has been carried out. The annulus inner surface is maintained at high temperature by applying heat flux to the inner tube while the annulus outer surface is maintained at low temperature by circulating cooling water at high mass flow rate around the outer tube. The experiments were carried out at a wide range of Rayleigh number (5 × 104<Ra< 5 × 105) for different annulus gap widths (L/Do= 0.23, 0.3, and 0.37) and different inclination of the annulus (α = 0°, 30° and 60°). The results showed that: (1) increasing the annulus gap width strongly increases the heat transfer rate, (2) the heat transfer rate slightly decreases with increasing the inclination of the annulus from the horizontal, and (3) increasingRaincreases the heat transfer rate for anyL/Doand at any inclination. Correlations of the heat transfer enhancement due to buoyancy driven flow in an annulus has been developed in terms ofRa,L/Doand α. The prediction of the correlation has been compared with the present and previous data and fair agreement was found.