Radiative transfer through arrays of discrete surfaces

Radiant transport involving arrays of discrete surfaces constitutes one of the major unresolved problems in the field of radiation heat transfer. This paper discusses the requirements for experimental validation of a general Monte Carlo solution to this class of problems. This work is a collaborative effort between Oregon State University, where the experimental portion is being accomplished, and the Pacific Northwest Laboratory, which is responsible for the Monte Carlo simulation. The design and calibration of a simple, compact, and flexible instrument for direct measurement of bidirectional reflectance are presented in some detail. The capability to measure full bidirectional reflectance, as provided by this instrument, is essential to an accurate portrayal of surface properties in a Monte Carlo simulation. Measured data for a common flat white paint are presented and clearly demonstrate the need for accurate and complete surface property information. Applications include volumetric air heating solar central receivers, ceramic fabrics, and fibrous insulation