Dissipation of Heat by Radiation

Heat dissipation is an ever-present factor affecting the design and operation of many kinds of electrical equipment. Usually, the problem is to get rid of heat due to losses. Sometimes the problem is how to conserve heat. Radiation, or convection, or conduction, or combinations of these, enter into all cases. Engineering literature as a rule presents conduction and convection in sound terms, but in many cases, the treatment of radiation is unsound, misleading, and sometimes in error. This paper is presented with the hope of putting heat radiation in engineering applications on a sounder basis. The usual laws given to cover total heat radiation are stated and discussed, and their limitations brought out. Net heat loss by radiation interchange for the cases of parallel and concentric surfaces are reviewed and stated. The problem of total radiation from a rectangular slot is attacked, the method of solution is indicated by example and discussion, and the results given.