An Effective Calculation Method for Radiative Exchange in an Enclosure with Specular Surfaces

Abstract

A new calculation method is proposed to determine the radiative heat transfer in enclosures composed of specularly reflecting surfaces. This method is based on the concept of the transition reflection in the context of the ray-tracing method, by which only two reflections of ray tracing are necessary to consider in the evaluation of net radiative transfer rate. This method can also be used not only for diffuse and specular surfaces but also for directional surfaces such as non-Lambert surface. Because the radiative exchange rate can be obtained by considering only two reflections of ray tracing, the matrix inversion is not required, and thus computational time can be reduced substantially. In order to validate the present method, the radiative exchange between two parallel plates is calculated, and the results are compared with those of previous methods including analytic solutions and stochastic methods. The parameters tested are the wall emissivity and the ratio of the distance between two plates to the length of plates. For all cases considered, the present results are in excellent agreement with exact solutions within 0.5% error, and show better accuracy than other methods. The new calculation method is also tested for nondiffusely emitting and reflecting surfaces of platinum and glass.

Acknowledgments

The authors gratefully acknowledge that this work is partially supported by the NRL Program and the Micro Thermal System Research Center, Seoul National University.