辐射对流耦合换热过程性能优化准则分析

An Analysis of Performance Optimization Criteria for a Coupled Radiative-Convective Heat Transfer Process

(火积)耗散极值原理和基于(火积)理论的热阻最小原理在传热过程优化中有着广泛应用,但在多种传热方式耦合传热过程中的应用尚未见报道。本文针对一典型的辐射对流耦合传热问题,定义了耦合传热过程的总(火积)耗散率和总热阻,并用数值方法验证了在给定总发射率、辐射热端温度、冷却流体温度和对流换热系数的前提下,当(火积)耗散率取极大值和热阻取极小值时,对应着用最小的辐射换热温差获得最大的换热热流,从而说明了(火积)耗散极值原理和热阻最小原理在该耦合传热过程分析与优化中的适用性,而此时熵产最小原理并不适用。

The principles of extremum entransy dissipation and minimum entransy-theory-based thermal resistance have been widely used in heat transfer optimization, but their applications to the coupled problems of different heat transfer ways were not previously reported. In this paper, for a typical coupled radiative-convective heat transfer process, the total entransy dissipation rate and entransy-theory-based thermal resistance are defined. It is numerically verified that the maximum total entransy dissipation rate and the minimum total thermal resistance correspond to obtaining the maximum heat flow at the cost of the minimum temperature difference of radiative heat transfer when the total emissivity, the hot end temperature of the radiative heat transfer, the temperature of the cooling fluid and the convection heat transfer coefficient are given. These results show the applicability of the principles of extrenmm entransy dissipation and minimum thermal resistance to the coupled radiative-convective heat transfer process. In addition, it is demonstrated that the principle of minimum entropy generation is not appropriate to optimize this process.