On thermoelectric power conversion from heat re-circulating combustion systems

The thermodynamic theory governing the absolute maximum efficiency of energy conversion by thermoelectric devices that operate as part of the heat recycle in regenerative burners, is examined. Comparison with series of elementary Carnot cycles helps to address the question of whether higher system efficiencies are realisable by rejecting the unconverted heat to the cold surroundings or to the incoming reactants as part of the recycle. Whilst for the Second Law heat engine cycles the maximum power that can be extracted is independent of layout, a particular combination of both is shown to be most advantageous in the case of a novel configuration of the irreversible thermoelectric assemblies. The heat exchanger/thermoelectric converter is made up of a coaxial assembly of many annular elements in series and a section in which heat is rejected to the incoming reactants is followed by a second section which discards unconverted heat to cold surroundings. It is shown that the efficiencies of such devices substantially exceed the maximum efficiencies of the best present day thermoelectric conversion systems and the theory suggests practical designs for small, combustion driven, power supplies. 1