The Dynamics of Heat

Fuchs, Hans U.

doi:10.1007/978-1-4419-7604-8

Cited by 90 publications

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“…A complete dynamical theory of heat inspired by continuum thermodynamics has been worked out by Fuchs (1996Fuchs ( , 2010. It takes entropy (caloric) as one of two fundamental thermal quantities (the other is hotness as a foundation of temperature as the thermal potential).…”

Section: Entropy and Models Of Dynamical Thermal Processesmentioning

confidence: 99%

A Direct Entropic Approach to Uniform and Spatially Continuous Dynamical Models of Thermoelectric Devices

Fuchs

2014

Energy Harvesting and Systems

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If we accept temperature and entropy as primitive quantities, we can construct a direct approach to a dynamical thermal theory of spatially continuous and uniform processes. The theory of uniform models serves as a simple entry point for learners of modern thermodynamics. Such models can be applied fruitfully to an understanding of (the dynamics of) thermoelectric processes and devices. Entropy, temperature, charge, and voltage allow us to describe the role of energy concisely, and constitutive quantities can be given their natural entropic interpretation. In this paper, aggregate dynamical models of a Peltier device will be created and simulations will be compared to non-steady-state experimental data. Such overall models give us a simple image of the transport of charge and transport, production, and storage of entropy and can be easily extended to the spatially continuous case. Process diagrams for a uniform model can be used to visualize these processes and the role of energy. Device efficiency can be easily read from the model. Apart from external parameters such as load resistances or temperature differences, it depends upon three parameters of the device: internal electric resistance, entropy conductance, and Seebeck coefficient. The Second Law efficiency of a generator suggests how to define the figure of merit (zT) of the thermoelectric material. Distinction between ideal and dissipative processes and the rates at which energy is made available or used allows us to construct a simple argument for the equality of the Seebeck and Peltier coefficients.

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Section: Entropy and Models Of Dynamical Thermal Processesmentioning

confidence: 99%

A Direct Entropic Approach to Uniform and Spatially Continuous Dynamical Models of Thermoelectric Devices

Fuchs

2014

Energy Harvesting and Systems

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“…If we take entropy as the basic quantity of thermodynamics it's easier to write down the correct equations than if we take the energy as a conserved quantity [6]. However, for the equations themselves, it does not matter whether we start from the energy or from entropy as we have shown in the introduction.…”

Section: Thermodynamicsmentioning

confidence: 99%

Systems Physics Library

Maurer

Dumont

2014

Linköping Electronic Conference Proceedings

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In this poster the Modelica Systems Physics library is presented. The Systems Physics library is a free open-source library with models for different areas of physics [1]. The primary use of the library is for educational purpose in Physics courses at medium level.The library contains models from five different domains (hydraulics, translational and rotational mechanics, electrodynamics and thermodynamics). In the future, we plan to add chemistry as a sixth domain. Each domain contains connectors containing a substance-like quantity and the corresponding potential; basic models (capacitance and resistance); sensors and actuators as well as some domain specific elements, such as nonlinear accumulator, nonlinear resistors, valves, springs or inductances. In addition to the constitutive equations each model also comprises the energy balance. For example, dissipative elements calculate the loss energy and even the entropy production with the help of an additional thermodynamic connector.

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“…The notion of the chemical potential was introduced by Gibbs in 1875-1878 [8,9] and goes far beyond the scope of chemistry, affecting virtually every process in nature [18][19][20]. The chemical potential has a strong connection with the second law of thermodynamics in that every process in nature evolves from a state of higher chemical potential towards a state of lower chemical potential.…”

Section: Chemical Equilibria Entropy Production Chemical Potentialmentioning

confidence: 99%

A Unification between Dynamical System Theory and Thermodynamics Involving an Energy, Mass, and Entropy State Space Formalism

Haddad

2013

Entropy

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In this paper, we combine the two universalisms of thermodynamics and dynamical systems theory to develop a dynamical system formalism for classical thermodynamics. Specifically, using a compartmental dynamical system energy flow model involving heat flow, work energy, and chemical reactions, we develop a state-space dynamical system model that captures the key aspects of thermodynamics, including its fundamental laws. In addition, we show that our thermodynamically consistent dynamical system model is globally semistable with system states converging to a state of temperature equipartition. Furthermore, in the presence of chemical reactions, we use the law of mass-action and the notion of chemical potential to show that the dynamic system states converge to a state of temperature equipartition and zero affinity corresponding to a state of chemical equilibrium.

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The Dynamics of Heat

Cited by 90 publications

References 0 publications

A Direct Entropic Approach to Uniform and Spatially Continuous Dynamical Models of Thermoelectric Devices

A Direct Entropic Approach to Uniform and Spatially Continuous Dynamical Models of Thermoelectric Devices

Systems Physics Library

A Unification between Dynamical System Theory and Thermodynamics Involving an Energy, Mass, and Entropy State Space Formalism

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