When heat passes through multiple layers (e.g., a wall with insulation), the total resistance is the sum of individual resistances in series:
Solutions explicitly state engineering assumptions to simplify the differential equations: Heat transfer is steady and one-dimensional. Thermal conductivities ( ) remain constant. When heat passes through multiple layers (e
The resistance to heat flow at the interface of two solid surfaces due to microscopic surface roughness and air gaps. a wall with insulation)
( R_total = 0.00833 + 0.00889 + 0.14815 + 0.00364 + 0.00303 = 0.17204 , K/W ) or fin). State assumptions clearly (e.g.
One of the most counter-intuitive concepts in this chapter is that
Draw the system (e.g., plane wall, pipe, or fin). State assumptions clearly (e.g., steady-state, 1D heat transfer, constant thermal conductivities, negligible radiation).