非均匀竖直平板自然对流耦合边界的数值研究

The Numerical Research on the Natural Convection of Vertical Plate with Uneven Temperature Distribution

以板管式换热器为应用背景,采用SIMPLEC算法求解了竖直薄平板温度不均匀时边界导热与自然对流的耦合传热。数值计算结果表明,对自然对流而言,在≤108,采用铝平板已经可以获得足够好的传热性能,再增加平板的导热性能对传热几乎没有影响;而在≤104的情况下,采用钢平板可以获得跟铝平板几乎一致的传热效果;平板温度不均匀,明显增加了自然对流边界层厚度,但在顶端和底端加热盘管之间的平板区域其局部数与等壁温情况相差不大;对在104～107的范围内提出一个非均匀平板自然对流平均数计算公式,其误差约为5%。

With the applied background of wrapped type heat exchanger, the conjugated heat transfer problem of vertical thin plate with uneven temperature distribution was solved by SIMPLEC arithmetic. The numerical results show that for natural convection, the aluminum plate has enough good heat transfer performance and it has little effect on heat transfer performance by improving the heat conductivity of plate when Ra 〈 10^8. The iron plate has the same heat transfer performance as the aluminum plate when Ra 〈 10^4. The thinness of natural convection boundary layer is increased because of the unevenly distribution of plate temperature. The local Nusselt numbers between the bottom heating pipe and the top heating pipe are found to agree well with the ones of plate with even temperature distribution. For Ra ranging from 10^4 to 10^7, an average Nusselt number correlation of plate with uneven temperature distribution is proposed with the error 5%.