Application of infrared thermography to the evaluation of local convective heat transfer on arrays of cubical protrusions

This paper reports on the experimental technique and measurement method used for the investigation of the local convective heat transfer from cubical protrusions placed on a vertical wall of a rectangular-sectioned wind tunnel. This experimental configuration simulates a simplified air-cooled vertical electronic circuit board, resembling a situation in an electronic cabinet. A controlled heat flux was generated by internal heating of the elements. An advanced infrared system was used to measure the surface temperatures of the cubical elements, which is crucial for determining the local convective heat transfer. The difficulties and uncertainties encountered in the course of measurements are discussed together with possible solutions of the problems. A selection of results, validated by means of an uncertainty analysis, is presented, showing a strong variation of the local convective heat transfer around the individual elements. Qualitative interpretation of the local heat transfer coefficients was facilitated by smoke visualization of the mean flow pattern around the protrusions. (C) 1997 by Elsevier Science Inc.