Comparative analysis of two ecological type modes of performance for a simple energy converter

In this article a comparative analysis of two optimisation criteria for finite time heat engine models is presented. The compared criteria are: the so called efficient power defined as the product of power output by efficiency, and the so called ecological criterion consisting of the maximisation of a function of merit defined as the power output minus the dissipation function. Both optimisation methods pertain to those named ecological type criteria accomplishing a good compromise between high power output and low dissipation. Among this kind of criteria of merit, there is also the so called Ω criterion and the saving functions method. In previous works, the equivalence between the last two methods and the ecological criterion was shown. In the present work, some characteristic functions are used, such as the power output, thermal efficiency and dissipation, and additionally, the so called compromise functions for the thermodynamic comparison. Under this approach it is shown that the ecological method leads to a better economical performance than the efficient power one, since it allows the highest possible power output at the lowest cost and highest efficiency.