Building thermal environment solution model and radiation heat transfer calculation model based on Gebhart absorption coefficient

Abstract

The building walls temperatures are different, and there are radiation heat transfers between the walls, which have the characteristics of multiple reflections and multiple absorptions. The Gebhart absorption coefficient considers the radiation energy both directly absorbed by the wall and indirectly absorbed by other walls multiple times reflections. The absorption coefficient Gij is used to represent the proportion of radiation energy absorbed by surface j from the radiation energy of surface i. Through employing Gebhart absorption coefficient, the Gebhart absorption coefficient matrix is constructed based on the wall angle factors and the wall radiation emissivity. The building thermal environment solution model is established, which can calculate the indoor air temperature and wall temperature. The wall radiation heat transfer calculation model is built to calculate the net radiation heat transfer of the walls. An experimental bench was carried out to verify the above theoretical calculation results. The research results showed that the theoretical calculated values of the air temperatures of the building thermal environment solution model were basically consistent with the measured values, and the deviation was within 0.25°C. The deviation between the calculated values of the wall temperatures and the measured values was basically within 1.0°C. The error between the calculated values of the wall radiation heat transfer calculation model and the measured values varied within a small range. The Gebhart absorption coefficient is more appropriate in characterizing radiation heat transfer mechanism of the walls, and it provides a new way and thought for the analysis of radiation heat transfer on building wall.