Calculation of the Mean Radiant Temperature Directly Using Radiant Intensities
J M. DeGreef, K S. Chapman
This paper develops and compares a new method for calculating the local mean radiant temperature to experimental data and the classical method described by American Society of Heating, Refrigerating, and Air-Conditioning Engineers (1997). The new method calculates the mean radiant temperature directly from the radiant intensity field at a particular point in the room. This approach, using the localized radiant intensity field, was theorized to be more accurate than using radiosities or surface temperatures and view factors currently described in the ASHRAE Handbook (1997). To benchmark the accuracy of the new method for calculating the mean radiant temperature, both methods of calculating the mean radiant temperature were compared to experimental measurements taken under carefully monitored conditions. The purpose of this process was to compare the classical and radiant intensity methods of mean radiant temperature calculation. From the four comparisons presented in this paper, using the radiant intensity field directly for the mean radiant temperature potion of the operative temperature calculations gave results 1-2 C(2-3 F) different from using view factors and surface temperatures and the experimental measurements. The radiant intensity method is a refinement to the mean radiant temperature calculation enabling a direct solution of the radiative transfer equation that can handle extreme boundary conditions.
building analysis algorithms, building technology, mean radiant temperature, radiative heat transfer, thermal