Abstract :
The present work discusses the existing formulae for calculation of the thermal radiation exergy. Some clarifications of
terms used are given with interpretative comments. Discussed are the author’s derivation procedures for three categories of
radiation; enclosed system, black flux, and any arbitrary radiation flux. The formulae for radiation conversion to work or heat
are established. The following peculiarities of thermal radiation are next discussed: irreversibility of emission and absorption
of radiation, significance of thermal radiation exergy for a zero environment temperature, exergy of ‘‘lacking radiation’’,
exergy at a varying environment temperature, and the analogy between exergy of substance and radiation. Utilization of solar
radiation, by an absorbing surface, is evaluated and the optimum temperature of this surface is determined. The above
considerations were the basis for discussing the exergy radiation formulae by Spanner and Jeter, as well as for discussing the
viewpoints of Bejan and some other researchers.
2003 Elsevier Ltd. All rights reserved.
