NET RADIATION METHOD FOR ENCLOSURE SYSTEMS INVOLVING PARTIALLY TRANSPARENT WALLS

摘要

The net radiation method is developed for analyzing radiation heat transfer in enclosure systems involving partially transparent walls. One such system is an enclosure with windows in it. The conventional net radiation method was developed by Hottel, Poljak, and others for enclosures having opaque walls. If a partially transparent wall is present, it will permit radiation to enter and leave the enclosure. The net radiation equations are developed here for gray and semigray enclosures with one or more windows. Another system of interest, such as in a flat plate solar collector, consists of a series of parallel partially transparent layers. The transmission char¬acteristics of such window systems are obtained by the net radiation method, and the technique appears to be more convenient than the ray tracing method which has been used in the past. Relations are developed for windows consisting of any number of parallel layers having differing absorption coefficients and differing surface reflectivities, and for systems composed of parallel transmitting layers and opaque plates.