Stanislaw Sieniutycz

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Abstract A novel trend in the theory of thermodynamic limits for energy convertors and traditional heat & mass exchangers is analysed where certain special controls called the Carnot control variables play a common role. In terms of these controls an expression for the lost work has the same form in irreversible energy convertors and in traditional(More)
We discuss description of macroscopic representations of thermal fields with finite signal speed by composite variational principles involving suitably constructed potentials along with original physical variables. A variational formulation for a given vector field treats all field equations as constraints that are linked by Lagrange multipliers to the(More)
We consider typical problems of the field called the finite time thermodynamics (also called the optimization thermodynamics). We also outline selected formal methods applied to solve these problems and discuss some results obtained. It is shown that by introducing constraints imposed on the intensity of fluxes and on the magnitude of coefficients in(More)
This paper unifies power optimization approaches in various energy converters, such as: thermal, solar, chemical, and electrochemical engines, in particular fuel cells. Thermodynamics leads to converter’s efficiency and limiting power. Efficiency equations serve to solve problems of upgrading and downgrading of resources. While optimization of steady(More)
This research presents a unified approach to power limits in power producing and power consuming systems, in particular those using renewable resources. As a benchmark system which generates or consumes power, a well-known standardized arrangement is considered, in which two different reservoirs are separated by an engine or a heat pump. Either of these(More)
Bellman's method of dynamic programming is used to synthesize diverse optimization approaches to active (work producing) and inactive (entropy generating) multiphase flow systems. Thermal machines, optimally controlled unit operations, nonlinear heat conduction, spontaneous relaxation processes, and self-propagating wave fronts are all shown to satisfy a(More)