基于CFD双P型辐射管扁形度的影响特性

Influence characteristics of the degree of flattening on the performance of double-P type radiant tubes studied by CFD simulation

为改善辐射管热效率,本文设计了一个扁双P型辐射管,选取辐射管中心管截面长半轴A与短半轴B的比例为1.0、1.1、1.2、1.3和1.4五种扁形度,借助于FLUENT软件就扁形度对辐射管传热性能的影响进行研究.结果表明:在保持双P型辐射管换热表面积不变的情况下,随着双P型辐射管扁形度的增加,辐射管对带钢的辐射角系数增大,辐射管对炉内辐射换热量增加,辐射管热效率升高;但是,随着双P型辐射管扁形度的增加,辐射管表面温差逐渐增大,扁形度达到1.3后,表面温度不均匀系数显著增加.综合考虑辐射管的表面温差和辐射热效率,扁形度为1.2的扁双P型辐射管性能较优,与扁形度为1.0时(即辐射管未被压扁的时候)相比,表面温度均匀性几乎不变,而辐射管热效率提高约1%.

In order to improve the thermal efficiency of radiant tubes, a flat double-P type radiant tube was designed, and five major axis-to-minor axis ratios of 1.0, 1.1, 1.2, 1.3 and 1.4 on the cross section of the center pipe were taken for numerical simula- tion to investigate the influence characteristics of the degree of flattening on the performance of the radiant tube by using the commer- cial software FLUENT. It is found that in the case of keeping the heat transfer surface area of the radiant tube invariable, when the degree of flattening increases, the radiant angle factor for the radiant tube and strip steel gradually grows, the radiant heat flow improves, and then thermal efficiency of the radiant tube rises. However, with an increase in the degree of flattening, the surface temperature difference of the radiant tube gradually increases, and the surface temperature uniformity significantly deteriorates after the degree of flattening reaches 1.3. In consideration of the thermal efficiency and surface temperature uniformity of the radiant tube, the better degree of flattening is 1.2. At this degree of flattening the radiation heat efficiency of the radiant tube increases by about 1% compared with that at the degree of flattening of 1.0, while the surface temperature uniformity is almost the same.