Extreme Performance of Heat Engines as Macrosystems with Hierarchical Efficiency Criteria

The methods of finite-time thermodynamics allow to determine limits of performance for macrosystems. The efficiency criterion for macrosystems is their entropy production rate: for Heat Engines, there is a uniform dependence between the entropy production and the efficiency factor. In industrial applications, it is also important to consider other criteria, first of all, economic ones. For example, increasing heat transfer ratios at the contacts between a working fluid and high and low-heat sources requires additional costs, and therefore, it is important to know how efficient (cost-efficient from the economic point of view) such increase would be, and how much it would allow reducing the operating costs of a heat engine. The economic and thermodynamic criteria are hierarchically interconnected. This paper presents a study on the optimum distribution of temperatures and heat-transfer surfaces, which determines heat transfer ratios, with due consideration of thermodynamic and cost efficiency criteria.