137. Overall heat transfer processes often involve two or more modes of heat transfer. Specifically, when heat is being transferred from one side of an air compressor cylinder wall to the opposite side, what mode of heat transfer is associated with that particular part of the overall process?

Heat transfer through a solid cylinder wall occurs via conduction, which involves molecular contact and temperature gradient. Convection requires fluid motion, and radiation involves electromagnetic waves, neither of which apply to heat transfer within the solid metal. The question focuses on the process within the wall itself, excluding heat transfer to or from surrounding fluids.