A basic equation for thermal radiation interaction of objects in a non-isothermal system and its application

This work proposes a basic equation of thermal radiation interaction between surface objects on the basis of the principle of heat balance in the interface. The solution of this equation takes account of the contribution of sensible heat flux and latent heat flux more completely, compared with traditional solution for surface cooling and heating processes. By the aid of the experimental data conducted in Xiaotangshan experimental site, Beijing, both the nonapplicability of Kirchoff´s law and the measurability of surface emissivity in a nonisothermal system have been highlighted. Two methods called ventilation and time-delay compensations have been proposed to reduce the error induced by change of surface temperatures of nonisothermal objects during the measurement of emissivity.