Template:Wikipedia A heat engine typically uses energy provided in the form of heat to do work and then exhausts the heat which cannot be used to do work. They operate in a cyclic manner and are usually illustrated by a PV diagram.
[1] this site provides a concept map that explains heat engines.
A heat pump can be considered to be a "heat engine in reverse", in which energy is applied to transfer heat into or out of an area as desired.
Template:Stub User: kory_kusick 11:12, 5 October 2007 (PDT)