Topic

# Heat capacity

About: Heat capacity is a research topic. Over the lifetime, 19258 publications have been published within this topic receiving 366966 citations. The topic is also known as: thermal capacity.

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TL;DR: In this article, the authors used Darcey's law to derive the equation K∇2ψ+∇K·∇ψ +g∂K/∂z=−ρsA∆ψ/∆t for the capillary conduction of liquids in porous mediums.

Abstract: The flow of liquids in unsaturated porous mediums follows the ordinary laws of hydrodynamics, the motion being produced by gravity and the pressure gradient force acting in the liquid. By making use of Darcey's law, that flow is proportional to the forces producing flow, the equation K∇2ψ+∇K·∇ψ+g∂K/∂z=−ρsA∂ψ/∂t may be derived for the capillary conduction of liquids in porous mediums. It is possible experimentally to determine the capillary potential ψ=∫dp/ρ, the capillary conductivity K, which is defined by the flow equation q=K(g−▿ψ), and the capillary capacity A, which is the rate of change of the liquid content of the medium with respect to ψ. These variables are analogous, respectively, to the temperature, thermal conductivity, and thermal capacity in the case of heat flow. Data are presented and application of the equations is made for the capillary conduction of water through soil and clay but the mathematical formulations and the experimental methods developed may be used to express capillary flow ...

5,340 citations

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TL;DR: In this article, the authors present a new equation of state in the form of a fundamental equation explicit in the Helmholtz free energy, which is able to represent even the most accurate data to within their experimental uncertainty.

Abstract: This work reviews the available data on thermodynamic properties of carbon dioxide and presents a new equation of state in the form of a fundamental equation explicit in the Helmholtz free energy. The function for the residual part of the Helmholtz free energy was fitted to selected data of the following properties: (a) thermal properties of the single‐phase region (pρT) and (b) of the liquid‐vapor saturation curve (p s, ρ′, ρ″) including the Maxwell criterion, (c) speed of soundw and (d) specific isobaric heat capacityc p of the single phase region and of the saturation curve, (e) specific isochoric heat capacityc v , (f) specific enthalpyh, (g) specific internal energyu, and (h) Joule–Thomson coefficient μ. By applying modern strategies for the optimization of the mathematical form of the equation of state and for the simultaneous nonlinear fit to the data of all these properties, the resulting formulation is able to represent even the most accurate data to within their experimental uncertainty. In the technically most important region up to pressures of 30 MPa and up to temperatures of 523 K, the estimated uncertainty of the equation ranges from ±0.03% to ±0.05% in the density, ±0.03% to ±1% in the speed of sound, and ±0.15% to ±1.5% in the isobaric heat capacity. Special interest has been focused on the description of the critical region and the extrapolation behavior of the formulation. Without a complex coupling to a scaled equation of state, the new formulation yields a reasonable description even of the caloric properties in the immediate vicinity of the critical point. At least for the basic properties such as pressure, fugacity, and enthalpy, the equation can be extrapolated up to the limits of the chemical stability of carbon dioxide. Independent equations for the vapor pressure and for the pressure on the sublimation and melting curve, for the saturated liquid and vapor densities, and for the isobaric ideal gas heat capacity are also included. Property tables calculated from the equation of state are given in the appendix.

3,942 citations

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TL;DR: A relatively new class of materials has been found in which exhibit unusual temperature dependences in their low-temperature properties, including several examples in which the specific heat divided by temperature shows a singular $\mathrm{log}T$ temperature dependence over more than two orders of magnitude as mentioned in this paper.

Abstract: A relatively new class of materials has been found in which the basic assumption of Landau Fermi-liquid theory---that at low energies the electrons in a metal should behave essentially as a collection of weakly interacting particles---is violated. These ``non-Fermi-liquid'' systems exhibit unusual temperature dependences in their low-temperature properties, including several examples in which the specific heat divided by temperature shows a singular $\mathrm{log}T$ temperature dependence over more than two orders of magnitude, from the lowest measured temperatures in the milliKelvin regime to temperatures over 10 K. These anomalous properties, with their often pure power-law or logarithmic temperature dependences over broad temperature ranges and inherent low characteristic energies, have attracted active theoretical interest from the first experimental report in 1991. This article first describes the various theoretical approaches to trying to understand the source of strong temperature- and frequency-dependent electron-electron interactions in non-Fermi-liquid systems. It then discusses the current experimental body of knowledge, including a compilation of data on non-Fermi-liquid behavior in over 50 systems. The disparate data reveal some interesting correlations and trends and serve to point up a number of areas where further theoretical and experimental work is needed.

1,289 citations

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01 Jan 2006TL;DR: In this paper, the basic principles of glass formation and composition are discussed, including linear elasticity, phase separation and liquid immiscibility, and dielectric properties of glass.

Abstract: Introduction. Fundamentals of the Glassy State. Glass Formation Principles. Glass Microstructure: Phase Separation and Liquid Immiscibility. Glass Compositions and Structures. Composition-Structure-Property Relationship Principles. Density and Molar Volume. Elastic Properties and Microhardness of Glass. The Viscosity of Glass. Thermal Expansion of Glass. Heat Capacity of Glass. Thermal Conductivity and Heat Transfer in Glass. Glass Transition Range Behavior. Permeation, Diffusion and Ionic Conduction in Glass. Dielectric Properties. Electronic Conduction. Chemical Durability. Strength and Toughness. Optical Properties. Fundamentals of Inorganic Glassmaking. Appendix I: Elements of Linear Elasticity. Appendix II: Units and General Data Conversions. Subject Index.

1,169 citations

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TL;DR: In this article, the dependence of the strength of the electron-phonon coupling and the electron heat capacity on the electron temperature was investigated for eight representative metals, Al, Cu, Ag, Au, Ni, Pt, W, and Ti.

Abstract: The dependence of the strength of the electron-phonon coupling and the electron heat capacity on the electron temperature is investigated for eight representative metals, Al, Cu, Ag, Au, Ni, Pt, W, and Ti, for the conditions of strong electron-phonon nonequilibrium. These conditions are characteristic of metal targets subjected to energetic ion bombardment or short-pulse laser irradiation. Computational analysis based on first-principles electronic structure calculations of the electron density of states predicts large deviations (up to an order of magnitude) from the commonly used approximations of linear temperature dependence of the electron heat capacity and a constant electron-phonon coupling. These thermophysical properties are found to be very sensitive to details of the electronic structure of the material. The strength of the electron-phonon coupling can either increase (Al, Au, Ag, Cu, and W), decrease (Ni and Pt), or exhibit nonmonotonic changes (Ti) with increasing electron temperature. The electron heat capacity can exhibit either positive (Au, Ag, Cu, and W) or negative (Ni and Pt) deviations from the linear temperature dependence. The large variations of the thermophysical properties, revealed in this work for the range of electron temperatures typically realized in femtosecond laser material processing applications, have important implications for quantitative computational analysis of ultrafast processes associated with laser interaction with metals.

1,165 citations