Radiation Heat Transfer in Three-Dimensional Closed Space Including Diffuse and Specular Surfaces : Numerical Calculation Method Using an Improved Ray-Tracing Method

A method of numerical calculation for radiation heat transfer in a three-dimensional closed space including diffuse and specular surfaces was developed. To enable an analysis of the radiation heat exchange on each surface considering multiple specular reflections and obstacles to rediation in the space, an improved heat ray-tracing method was presented to calculate view factors accurately. The method was determined to be applicable to complicated problems in test calculations using models with specular surfaces and obstacles. Continuing efforts are being applied to more realistic problems. The example examined in this paper is an infrared emitter with a parabolic specular reflector, which is a conventional electric heating apparatus. The measured result for radiant power distribution agrees well with the calculated one. The practical validity of our method was verified.