“…Based on a careful analysis of the phenomenon, according to the research works [21,24,[30][31][32][33][42][43][44][45][46][47][48][49][50][51][52][53][54], the set of variables that describe the heat transfer in beams of tubular-rectangular cross-sectional area are: heat, heat rate, time, density (steel, air, paint/insulating material), constant-pressure specific heat of air, specific heat capacity (steel, air), thermal conductivity (steel, paint coat), thermal diffusivity of air, velocity normal to the plane where the shear stress is developed and its gradient, dynamic viscosity of air, kinematic viscosity of air, Prandtl number of air, Reynolds number of air, convection heat transfer coefficient, thickness of the paint volume of beam or paint coat, cross-sectional area of the beam, lateral area (x-z) of the beam, lateral area (x-y) of the beam, beam's dimensions, shape factor, cross-sectional perimeter, gravitational acceleration, temperature variation, coefficient of volume expansion (steel, air), Nusselt number, Grasshoff number along x direction, Péclet number, Biot number, Stanton number, Fourier number. All these variables and the measurement unities are presented in the section Nomenclature.…”