Thermo-mechanical systems with several heat reservoirs: maximum power processes

While endoreversible heat-to-power conversion systems operating between two heat reservoirs have been intensely studied, systems with several reservoirs have attracted little attention. Here we analyse the maximum power processes of such systems with stationary temperature reservoirs. We find that independent of the number of reservoirs the working fluid uses only two isotherms and two infinitely fast isentropes/ adiabats. One surprising result is that there may be reservoirs that are never used. This feature is explained for a simple system with three heat reservoirs.