Carnot's theorem states that all heat engines between two heat reservoirs are less efficient than a
Carnot heat engine operating between the same reservoirs. Every Carnot heat engine between a pair of heat reservoirs is equally efficient, regardless of the working substance employed or the operation details.
The maximum efficiency is the ratio of the temperature difference between the reservoirs and the temperature of the hot reservoir, expressed in the equation
where
TC and
TH are the
absolute temperatures of the cold and hot reservoirs, respectively, and the efficiency
is the ratio of the work done by the engine to the heat drawn out of the hot reservoir.