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Heat transfer

About: Heat transfer is a research topic. Over the lifetime, 181795 publications have been published within this topic receiving 2923586 citations. The topic is also known as: heat exchange.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors derived formulas for the electron thermal conductivity in the collisional and collisionless limits for the case of destroyed magnetic surfaces and showed that these formulas can be used to derive a collision-free model of the electron conductivity.
Abstract: Formulas for the electron thermal conductivity have been derived in the collisional and collisionless limits for the case of destroyed magnetic surfaces.

1,128 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used radiometric dates to estimate the amount of heat lost by the earth during the last orogenic event, the distribution of heat-producing elements, and erosion.
Abstract: Simple thermal models based on the creation and cooling of the lithosphere can account for the observed subsidence of the ocean floor and the measured decreased in heat flow with age. In well-sedimented areas, where there is little loss of heat due to hydrothermal circulation, the surface heat flow decays uniformly from values in excess of 6 µcal/cm² s (250 mW/m²), for crust younger than 4 Ma (4 m.y. B.P.), to close to 1.1 µcal/cm² s (46 mW/m²) through crust between 120 and 140 Ma. After 200 Ma the heat flow is predicted to reach an equilibrium value of 0.9 µcal/cm² s (38 mW/m²). The surface heat flow on continents is controlled by many phenomena. On the time scale of geological periods the most important of these are the last orogenic event, the distribution of heat-producing elements, and erosion. To better understand the effects of age, each continent is separated into four provinces on the basis of radiometric dates. Reflecting the preponderance of Precambrian crust, two of these provinces cover the Archean to the middle Proterozoic, and the third covers the late Proterozoic to the Mesozoic. The mean heat flow decreases from a value of 1.84 µcal/cm² s (77 mW/m²) for the youngest province to a constant value of 1.1 µcal/cm² s (46 mW/m²) after 800 Ma. The nonradiogenic component of the surface heat flow decays to a constant value of between 0.65 and 0.5 µcal/cm² s (25 and 21 mW/m²) within 200–400 Ma. Using theoretical models, we compute the heat loss through the oceans to be 727 × 1010 cal/s (30.4 × 1012 W). The comparison between the theoretical and measured values allows an estimate of 241 × 1010 cal/s (10.1 × 1012 W) for the heat lost owing to hydrothermal circulation. We show that the heat flow through the marginal basins follows the same relation as that for crust created at a midocean spreading center. These basins have a corresponding heat loss of 71 × 1010 cal/s (3.0 × 1012 W). The heat loss through the continents is calculated from the observations and is 208 × 1010 cal/s (8.8 × 1012 W). Our estimate of the value for the shelves is 67 × 1010 cal/s (2.8 × 1012 W). The total heat loss of the earth is 1002 × 1010 cal/s (42.0 × 1012 W), of which 70% is through the deep oceans and marginal basins and 30% through the continents and continental shelves. The creation of lithosphere accounts for just under 90% of the heat lost through the oceans and hence about 60% of the worldwide heat loss. Convective processes, which include plate creation and orogeny on continents, dissipate two thirds of the heat lost by the earth. Conduction through the lithosphere is responsible for 20%, and the rest is lost by the radioactive decay of the continental and oceanic crust. We place bounds of between 0.6 and 0.9 µcal/cm² s (25 and 38 mW/m²) for the mantle heat flow beneath an ocean at equilibrium and between 0.40 and 0.75 µcal/cm² s (17 and 31 mW/m²) for the heat flow beneath an old stable continent. The computed range of geotherms for an equilibrium ocean overlaps the range of stable continental geotherms below a depth of 100 km. The mantle heat flow beneath a continent decays with a thermal time constant similar to that of the oceanic lithosphere. The continental basins subside with the same time constant. These observations are evidence that there is no detectable difference between the thermal structure of an equilibrium ocean and that of an old continent. Thus the concept of the lithosphere as a combination of a mechanical and a thermal boundary layer can be applied to both oceans and continents. We evaluate the constraints placed on models based on this concept by seismological observations. In the absence of compelling evidence to the contrary we favor these models because they provide a single explanation for the thermal structure of the lithosphere beneath an equilibrium ocean and a stable continent.

1,125 citations

Book
17 Nov 2014
TL;DR: In this paper, a dual-phase-leg model is proposed to describe the heat transfer in solids with micro-structures, and experimental evidence supports the lagging behaviour in heat transport under various circumstances, including the high-order effect of phase legs in the delayed response.
Abstract: This work introduces a new concept in heat transfer, developing a transient model describing the fast-transient process of heat transport in solids with micro-structures. In describing the microstructural interaction effect in the short-term response, it extends the "macroscopic" concept that practisings engineers are already familiar with. The dual-phase-leg model covers the existing macroscopic and microscopic models in the same framework, including the classical diffusion model employing the Fourier's law and the thermal wave model for dielectric films, insulators, and semi-conductors, and the photon-electron interaction model for metals (microscopic). Chapters cover the current status of microscale heat transfer, the lagging behaviour in the transient response, experimental evidence supporting the lagging behaviour in heat transport under various circumstances, the high-order effect of phase legs in the delayed response, and the possible effect of lagging responses in the related fields of elasticity and forced convention.

1,122 citations

Patent
02 Feb 1994
TL;DR: A thermal insulating element associated with the sensing element blocks the transfer of heat energy from between the temperature sensing element and the body as discussed by the authors, therefore measuring temperature without being affected by the surrounding thermal mass of the electrode.
Abstract: An ablation electrode carries a temperature sensing element for measuring the temperature of the tissue being ablated. A thermal insulating element associated with the sensing element blocks the transfer of heat energy from between the temperature sensing element and the body. The temperature sensing element therefore measures temperature without being affected by the surrounding thermal mass of the electrode.

1,098 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20235,737
202210,641
20217,860
20208,182
20198,826
20188,737