Irreversibility parameter of a combined cycle model for power generation

In this paper we study the energetic performance of a series arrangement of totally irreversible heat engine models (combined cycle (CC) type). The origin of the irreversibilities is both of the external and internal types. The external irreversibilities are associated with the heat flows towards and from the temperature reservoirs, while the internal irreversibilities are associated to all those dissipative processes that occur within the working fluids. On the other hand, our model includes information provided by different optimization criteria that are commonly used in studies of irreversible heat engine models. This model, allow us to analyze two commercial CC-power plants which use fossil fuel and compare them with two commercial nuclear power plants, from the energetic point of view. Under this first approach to the comparison, we found that, despite of the high efficiency reported by CC manufacturers, the large temperature gradients required by these plants result in irreversibility parameters bigger than those for nuclear plants currently in operation.This so-called irreversibility parameter is defined as the quotient between the entropy produced by internal irreversibilities and the thermal conductances involved in the heat fluxes. By means of this energetic approach we find that CC plants have some economical disadvantages with respect to the nuclear power plants.