Reflections on the motive power of heat and on machines fitted to develop that power

Carnot, Sadi; Thurston, R. H.; Carnot, Robert Henry; Kelvin, William Thomson

doi:10.5962/bhl.title.17778

Cited by 76 publications

(122 citation statements)

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“…It seems necessary to stress that conservation of heat for thermodynamic matter has been derived from conservation of mass and energy-momentum, and definitely differs from the old caloric theory of Carnot [20]. A relativistic version of the caloric theory would be to describe heat by an energy-momentum vector, the caloric current J H = εu + q, and conservation of heat by ∇ · J H = 0, as for conservation of mass.…”

Section: Discussionmentioning

confidence: 99%

Relativistic Thermodynamics

Hayward

2013

Black Holes

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Abstract. A generally relativistic theory of thermodynamics is developed, based on four main physical principles: heat is a local form of energy, therefore described by a thermal energy tensor; conservation of mass, equivalent to conservation of heat, or the local first law; entropy is a local current; and non-destruction of entropy, or the local second law. A fluid is defined by the thermostatic energy tensor being isotropic. The entropy current is related to the other fields by certain equations, including a generalised Gibbs equation for the thermostatic entropy, followed by linear and quadratic terms in the dissipative (thermal minus thermostatic) energy tensor. Then the second law suggests certain equations for the dissipative energy tensor, generalising the Israel-Stewart dissipative relations, which describe heat conduction and viscosity including relativistic effects and relaxation effects. In the thermostatic case, the perfect-fluid model is recovered. In the linear approximation for entropy, the Eckart theory is recovered. In the quadratic approximation for entropy, the theory is similar to that of Israel & Stewart, but involving neither state-space differentials, nor a non-equilibrium Gibbs equation, nor non-material frames. Also, unlike conventional thermodynamics, the thermal energy density is not assumed to be purely thermostatic, though this is derived in the linear approximation. Otherwise, the theory reduces in the non-relativistic limit to the extended thermodynamics of irreversible processes due to Müller. The dissipative energy density seems to be a new thermodynamical field, but also exists in relativistic kinetic theory of gases.

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Section: Discussionmentioning

confidence: 99%

Relativistic Thermodynamics

Hayward

2013

Black Holes

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“…We assume that the heat sink is at temperature Tc = 300 K, and model the sun as a blackbody emitter with a temperature of T h = 6000 K. The general expression for the engine efficiency is also shown in Figure 2b, which depends on the temperatures of individual elements and on the mechanisms of the energy delivery to and entropy rejection from the engine. In particular, if heat is delivered to an engine via blackbody radiation (I h ) and the engine rejects entropy to the environment via blackbody radiation (Sr) and heat conduction (Ss), the heat can be converted to work at a maximum efficiency that is less than the classical Carnot efficiency limit [53]. This efficiency is known as the Landsberg efficiency [3,44] (Figure 2c, blue dotted line), which is calculated under the assumptions that the heat source is the sun and there is no irreversible entropy generation in the engine (Sg = 0).…”

Section: Photon Entropy and Light Energy Conversion Limitsmentioning

confidence: 99%

Heat meets light on the nanoscale

et al. 2016

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Abstract:We discuss the state-of-the-art and remaining challenges in the fundamental understanding and technology development for controlling light-matter interactions in nanophotonic environments in and away from thermal equilibrium. The topics covered range from the basics of the thermodynamics of light emission and absorption to applications in solar thermal energy generation, thermophotovoltaics, optical refrigeration, personalized cooling technologies, development of coherent incandescent light sources, and spinoptics.Keywords: thermal emission; absorption; spectral selectivity; angular selectivity; optical refrigeration; solar thermal energy conversion; thermophotovoltaics; nearfield heat transfer; photon density of states; thermal upconversion; radiative cooling Thermodynamics of light and heatControl and optimization of energy conversion processes involving photon absorption and radiation require detailed understanding of thermodynamic properties of radiation as well as its interaction with matter [1-5]. Historically, thermodynamic treatment of electromagnetic radiation began over a century ago with Planck applying the thermodynamic principles established for a gas of material particles to an analogous "photon gas" [1]. In particular, he showed that thermodynamic parameters, such as the energy, volume, temperature, and pressure can be applied to electromagnetic radiation, reflecting the dual wave-particle nature of photons. In this section, we will review the general thermodynamic principles governing photon propagation and interaction with matter, as well

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“…Termín entropie zavedl Rudolf Clausius, přičemž pro entropii zvolil označení S na počest Sadi Carnota a jeho přelomové práce o teorii tepelných motorů z roku 1824 (Carnot, 2005), která upoutala pozornost tehdejších fyziků a inspirovala je k dalšímu výzkumu dané problematiky. Clausius formuloval dva "fundamentální teorémy mechanické teorie tepla" (Clausius, 1867, s. 365):…”

Section: Sonda Do Historie Pojmů a Terminologie Termodynamikyunclassified