... glass sheet 3- 14C Convection heat transfer through the wall is expressed as Q& = hAs (Ts − T∞ ) In steady heat transfer, heat transfer rate to the wall and from the wall are equal Therefore at... multidimensional problems are (1) to assume any plane wall normal to the x-axis to be isothermal and (2) to assume any plane parallel to the x-axis to be adiabatic 3- 53 A typical section of a building wall... at an interface is by conduction and radiation Evacuating the interface eliminates heat transfer by conduction, and thus increases the thermal contact resistance 3- 45C Thermal contact resistance