Theoretical thermodynamic analysis of a closed-cycle process for the conversion of heat into electrical energy by means of a distiller and an electrochemical cell

摘要

We analyse a device aimed at the conversion of heat into electrical energy,based on a closed cycle in which a distiller generates two solutions atdifferent concentrations, and an electrochemical cell consumes theconcentration difference, converting it into electrical current. We first studyan ideal model of such a process. We show that, if the device works at a singlefixed pressure (i.e. with a ``single effect''), then the efficiency of theconversion of heat into electrical power can approach the efficiency of areversible Carnot engine operating between the boiling temperature of theconcentrated solution and that of the pure solvent. When two heat reservoirswith a higher temperature difference are available, the overall efficiency canbe incremented by employing an arrangement of multiple cells working atdifferent pressures (``multiple effects''). We find that a given efficiency canbe achieved with a reduced number of effects by using solutions with a highboiling point elevation.