General heat radiation exchange between two surfaces.
partial function HeatRadiationTwoSurfaces input Modelica.Units.SI.Temperature T1 "Temperature of surface 1"; input Modelica.Units.SI.Temperature T2 "Temperature of surface 2"; output Modelica.Units.SI.HeatFlux q_flow "Specific net long-wave radiation flow between surface 1 and 2"; end HeatRadiationTwoSurfaces;