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Combining the Pieces
Published in S. Can Gülen, Gas Turbine Combined Cycle Power Plants, 2019
The maximum possible efficiency of a heat engine operating on a power cycle is given by the efficiency of a Carnot cycle operating between two thermal reservoirs, one at the mean-effective heat addition temperature and the other at the mean-effective heat rejection temperature of the said engine.
Availability Equations
Published in W. Li Kam, Applied Thermodynamics: Availability Method And Energy Conversion, 2018
Before the conclusion of this section, it is of interest to apply the availability equation to a thermal reservoir. A thermal reservoir is a body of infinite capacity and therefore would not experience any change in temperature and pressure in an interaction with its surroundings. When the thermal reservoir is treated as a closed system, the availability equation would become () A2−A1=Aq+Aw−I
Engineering Thermodynamics
Published in Raj P. Chhabra, CRC Handbook of Thermal Engineering Second Edition, 2017
Michael J. Moran, George Tsatsaronis
The Kelvin–Planck statement of the second law of thermodynamics refers to a thermal reservoir. A thermal reservoir is a system that remains at a constant temperature even though energy is added or removed by heat transfer. A reservoir is an idealization, of course, but such a system can be approximated in a number of ways—by the Earth’s atmosphere, large bodies of water (lakes, oceans), and so on. Extensive properties of thermal reservoirs, such as internal energy, can change in interactions with other systems even though the reservoir temperature remains constant, however.
Exergetic port-Hamiltonian systems: modelling basics
Published in Mathematical and Computer Modelling of Dynamical Systems, 2021
Markus Lohmayer, Paul Kotyczka, Sigrid Leyendecker
In contrast, exergetic port-Hamiltonian systems are coherent with both the first and the second law of thermodynamics and link passivity to degradation of energy. We consider the oscillator from Example 4.1 as an exergetic port-Hamiltonian system: Example 4.2 (Exergetic model of the damped harmonic oscillator). Let us explicitly assume that the system is isothermal because it is in thermal equilibrium with its environment having constant temperature . We consider the environment as an (infinitely large) thermal reservoir. We need not consider for instance its volume, mass or chemical composition because at this point only thermal interaction with the environment is relevant. From the isothermal condition it follows that is a fundamental equation for the environment. Its exergy content with respect to itself is , see Equation (10). Thus, the Hamiltonian already is (or at least can be interpreted as) an exergetic storage function.