In thermodynamics, a diathermal wall between two thermodynamic systems allows heat transfer but do not allow transfer of matter across it.

What is meant by diathermic wall?

A diathermic wall is a wall that allows heat exchange through it. Yes, heat is able to flow through it. On the opposite hand, adiabatic wall is a wall that does not allow any heat flow through it.

What is meant by adiabatic wall?

From Wikipedia, the free encyclopedia. In thermodynamics, an adiabatic wall between two thermodynamic systems does not allow heat or chemical substances to pass across it, in other words there is no heat transfer nor mass transfer.