Occult parasitic energy loss in heat engines

Abstract

When a reversible process, such as the compression of a working gas, is treated as a feedback mechanism coupling adjacent heat engine cycles, analysis reveals a parasitic energy loss unaccounted for by traditional theory. Including this feedback-induced energy loss in the derivation of an efficiency relation yields predictions that reproduce experimental observations with sufficient accuracy as to propose this effect as being the primary source of disparity between practice and existing theory. Further, it is shown that both the Carnot and Curzon–Ahlborn efficiency relations are derivable special cases of this more general result. Finally, it is postulated that substantial gains in thermodynamic efficiency may be affected in practical heat engines, including increases on the order of 30% in internal combustion engines, by frustrating these feedback mechanisms through simple mechanical modifications. Copyright © 2007 John Wiley & Sons, Ltd.