Theory and method for analysis of low temperature driven power cycles

A new method, using a combination of traditional first law and second law analysis, is developed to facilitate characterization and comparison of power cycles using low temperature heat sources. In trying to determine the best thermodynamic cycle and working media for a given application one must take the strongly non-linear effects of matching the pinch points of a particular cycle with a particular working media into account. The new method allows unbiased comparison of arbitrarily chosen power cycles, working fluids and component characteristics. The method also allows for operating conditions with finite capacity heat source and heat sink. The usefulness of the method is illustrated by the analysis of the effects of local temperature difference distribution for three different fully reversible power cycles using three different working media.The driver for developing this method is to simplify comparison and communication among users and industrial professionals and thus enable a better understanding of characteristics and design criteria for low temperature heat driven power cycles.

► We present a theory for analysis of performance of low temperature power cycles.
► We suggest a method on how to use the theory.
► We demonstrate a comparison of cycles, fluids and source/sink characteristics.
► Our purpose is to simplify communication of the thermodynamic performances.