Endoreversible thermal cycle with a nonlinear heat transfer law

Abstract

We calculate the efficiency of an endoreversible Carnot-type cycle in the maximum power regime by using a nonlinear heat transfer law (the so-called Dulong and Petit’s law of cooling). The results obtained from this model compare well (around 99% in some cases) with observed efficiencies for several power plants. The considered law of cooling includes conductive- convective and radiative contributions to the heat exchange between the working fluid and its surroundings. Our calculations improve considerably those obtained by means of a linear heat transfer law for the same power sources. We also analyze a nuclear power plant using an ecological optimization criterion for finite-time heat engines.

Local Stability of Curzon-Ahlborn Cycle with Non-Linear Heat Transfer for Maximum Power Output Regime

“…Nevertheless a more real model has to consider all possibilities of heat transfer. Thus, some authors have used particularly the Dulong and Petit heat transfer law because it allows a better model than the Newton heat transfer model is [15][16][17][18]. In [15][16][17] numerical results appear near to the experimental values reported in the literature for power plants working at maximum power output, and in [17,18] for nuclear plants working at maximum ecological function [14].…”

“…Table 1 shows a comparison between efficiencies in (15), for the case of some conventional power plants working in a maximum power output regime, reported in [16,17]. Even more, the difference between the eficiencies (13a) and (14a) is shown in Figure 2.…”

“…On other hand, the Curzon and Ahlborn engine gives more realistic values of efficiency with this heat transfer than it gives with the Newton heat transfer, in case of maximum power output regime [15]. Results in [14,15] are compared with different reported values of power plants.…”

“…On other hand, the Curzon and Ahlborn engine gives more realistic values of efficiency with this heat transfer than it gives with the Newton heat transfer, in case of maximum power output regime [15]. Results in [14,15] are compared with different reported values of power plants. More recently, at maximum power output regime and at maximum ecological function regime, assuming 5 4 k  , analytical approximated expressions for the efficiency were found as [16,18] …”

Linear Approximation of Efficiency for Similar Non- Endoreversible Cycles to the Carnot Cycle

“…The ecological efficiency has been calculated using Dulong and Petit's heat transfer law in [30], maximizing ecological function for instantaneous adiabats. When the time for all the processes of the Curzon and Ahlborn cycle is taken into account, efficiencies in both regimens, maximum power output and maximum ecological function, can be obtained, following the procedure employed.…”