A universal Carnot theorem for the efficient use of energy by any kind of thermodynamical device

M. A. Martínez Negrete


Sadi Carnot, in his seminal work of 1824 Reflections on the Motive Power of Fire (Dover, 1988) developed the theory of the thermal motors, showing that the most efficient use of heat energy is achieved by a motor functioning reversibly between a hot furnace at temperature $T_1 $ and a condenser at temperature $T_2 $ with efficiency $\eta _{\max } = 1 -( T_{2} / T_{1})$. In his book Carnot sets the basis for the second law of thermodynamics, but also opens the way to study the maximum efficiency of other thermal devices like heat pumps, refrigerators, etc. Based on a previous work [4] here it is shown that Carnot's results for thermal devices can be extended to all other sorts of thermodynamical apparatuses like air pumps and wind generators, as well as to any other functioning device between a ``furnace'' at high $Y_1 $ and a ``condenser'' at low $T_2 $, where $Y$ is any intensive thermodynamical variable. Then $\eta _{\max } = 1 - Y_{2}/Y_{1}$ sets the norm for the achievement of an efficient use of energy by these generalized means.


Thermal motors, thermodynamic efficiency, Carnot theorem

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Revista Mexicana de Física S

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