Conjugate Natural Convection Heat Transfer

关于自然对流换热的研究已有很多，大多数情况下，固体表面的热条件被假定为等温或恒流。然而，这种情况在现实中不可能发生，除非满足一组特定的热和流体动力学条件。在对流换热问题中，固体表面的热状态不能先验地确定，而必须作为温度解的一部分来求得。其中最基本的问题之一是评估从加热的垂直板在静止流体中的传热。考虑到共轭问题，我们假设板的一个表面以恒定温度加热，另一个表面暴露于流体。对于未知的表面温度，发展了一维理论。然后<th>推导出未知表面温度的5阶代数方程。平均传热速率，即努塞尔数，然后作为表观瑞利数a的乘积获得 ...更多信息 平均表面温度。一维理论的实验验证也进行了使用水容器与加热壁安装在一个垂直的墙壁。测量了从壁面到水的传热速率和平均表面温度。实验结果与理论预测进行了比较。我们研究的另一个问题是两个对流水库的情况下，由一个垂直分区有限的传导率的平均传热速率和分区表面的平均温度的理论上使用类似的一维方法获得上述。还进行了实验，以测试所提出的理论一个显着的性质，目前的一维理论在于它的简单性和它的权力，将所有的条件（参数）中涉及的问题。这个问题被扩展到水甘油和水多孔系统。实验证明，该理论同样适用于这些扩展的情况下。水平平板上的强迫对流和各种几何形状的共轭自然对流问题已经以类似的方式进行了研究。还研究了从地热墙钻孔到周围岩层的热损失。少

There have been many works about natural convection heat transfer The thermal conditions on the solid surface are assumed to be isothermal or constant flux in most cases. However, this situation can not occur in reality unless a set of certain thermal and hydrodynamic conditions is fulfilled. In convective heat transfer problems the thermal condition at the solid surface can not be determined apriori, but it must be obtained as a part of the temperature solution. One of the most fundamental problems is to evaluate heat transfer from a heated vertical plate in a still fluid. In view of conjugate problem, we assume that one surface of the plate is heated with a constant temperature and the other is exposed to the fluid. One-dimensional theory is developed for the unknown surface temperature. A 5^<th> order algebraic equation for the unknown surface temperature is then derived. The mean heat transfer rate, the Nusselt number, is then obtained as a product of the apparent Rayleigh number a … More nd the average surface temperature. An experimental verification of the one-dimensional theory is also conducted using a water vessel with a heated wall installed on one of the vertical walls. The heat transfer rates from the wall to the water and the average surface temperature are measured. The experimental results are well compared with the theoretical prediction. Another problem that we studied is a case where two convecting reservoirs are separated by a vertical partition of finite conductivity An average heat transfer rate and the mean temperatures of the partition surfaces are obtained theoretically using a similar one-dimensional approach described above. An experiment is also carried out in order to test the proposed theory A marked nature of the present one-dimensional theory lies in its simplicity and its power to incorporate all the conditions (parameters) involved in the problem. The problem was extended to water-glycerin and water-porous systems. It is experimentally proved that the theory works equally well for these extended cases. Forced convection over a horizontal plate and conjugate natural convection problems for various geometries have been investigated in a similar manner. Heat loss from a geothermal wall bore to surrounding rock formation is also studied. Less