Optimization of two-cold one-hot reservoir low-dissipation heat engines

Abstract We propose a new low-dissipation model for heat engines with two cold reservoirs and one hot reservoir. This model is useful for studying systems with two energy rejection channels toward two cold sources of very different temperatures, where the energy fluxes per channel are of very different magnitudes. We show that it is necessary to add a new parameter to the model: the reversible entropy partitioning ratio, which ensures the model’s correctness in the reversible limit. We study the properties of some heat engines when operating at maximum power, demonstrating that the new model allows the system’s working properties to be optimized almost as easily as other thermal engine models in the low-dissipation approximation. In the final part of the work, we numerically study some properties of the machines when operating at maximum power.