Heat Transfer


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Heat transfer

Heat, a form of kinetic energy, is transferred in three ways: conduction, convection, and radiation. Heat transfer (also called thermal transfer) can occur only if a temperature difference exists, and then only in the direction of decreasing temperature. Beyond this, the mechanisms and laws governing each of these ways are quite different. See Conduction (heat), Convection (heat), Heat radiation

By utilizing a knowledge of the principles governing the three methods of heat transfer and by a proper selection and fabrication of materials, the designer attempts to obtain the required heat flow. This may involve the flow of large amounts of heat to some point in a process or the reduction in flow in others. All three methods operate in processes that are commonplace.

In industry, for example, it is generally desired to extract heat from one fluid stream and add it to another. Devices used for this purpose have passages for each of the two streams separated by a heat-exchange surface in the form of plates or tubes and are known as heat exchangers. The automobile radiator, the hot-water heater, the steam or hot-water radiator in a house, the steam boiler, the condenser and evaporator on the household refrigerator or air conditioner, and even the ordinary cooking utensils in everyday use are all heat exchangers. See Heat

Heat transfer

A generic term for thermal conduction, convection, and radiation.

Heat Transfer

 

the spontaneous irreversible movement of heat in space owing to a nonuniform temperature field. In the general case, heat transfer may also result from the nonuniformity of the fields of other physical quantities; an example is a difference in concentrations. Heat is transferred in three ways: conduction, convection, and radiation. In practice, heat transfer usually occurs through all three mechanisms at the same time.

Heat transfer determines or accompanies many processes in daily life, in technology, and in nature—for example, meteorological processes at the earth’s surface and the evolution of stars and planets. In many cases, such as in the study of dehydration, evaporative cooling, and diffusion, heat transfer is considered together with mass transfer. A special case of heat transfer is the flow of heat from one heat-transfer fluid to another through a solid wall separating the fluids or through an interface between the fluids.

heat transfer

[′hēt ¦tranz·fər]
(thermodynamics)
The movement of heat from one body to another (gas, liquid, solid, or combinations thereof) by means of radiation, convection, or conduction.

Heat transfer

Heat, a form of kinetic energy, is transferred in three ways: conduction, convection, and radiation. Heat transfer (also called thermal transfer) can occur only if a temperature difference exists, and then only in the direction of decreasing temperature. Beyond this, the mechanisms and laws governing each of these ways are quite different. See Conduction (heat), Convection (heat)

By utilizing a knowledge of the principles governing the three methods of heat transfer and by a proper selection and fabrication of materials, the designer attempts to obtain the required heat flow. This may involve the flow of large amounts of heat to some point in a process or the reduction in flow in others. All three methods operate in processes that are commonplace.

In industry, for example, it is generally desired to extract heat from one fluid stream and add it to another. Devices used for this purpose have passages for each of the two streams separated by a heat-exchange surface in the form of plates or tubes and are known as heat exchangers. The automobile radiator, the hot-water heater, the steam or hot-water radiator in a house, the steam boiler, the condenser and evaporator on the household refrigerator or air conditioner, and even the ordinary cooking utensils in everyday use are all heat exchangers. See Heat exchanger

heat transfer

The flow of heat from one body at higher temperature to another body at a lower temperature, until the two temperatures are equal.
References in periodicals archive ?
Nucleate pool boiling heat transfer characteristics of refrigerant/oil mixtures on metal foam covers were experimentally investigated at a wide range of oil concentrations.
By achieving such a thin coating, the additional layer of alumina did not appreciably increase thermal resistance, but it did increase the overall heat transfer.
An increase of the device current-carrying capacity can be achieved by increasing the heat transfer coefficient [alpha], which in turn causes a decrease of resistance [R.
Nowadays, the study and intensification of heat transfer in thermal processes of various technical and technological equipments represent up-to-date discussion topics not only in terms of maximum energy utilisation and consequently also time and finance savings, but also in terms of environmental protection.
Several studies compared heat transfer and pressure drop of three to ten refrigerants, thereby comparing low GWP alternatives to more conventional refrigerants, while others studied refrigerant performance in systems (Bolaji, 2010; Bella et al.
5], Gao [6] and Donovan [7], concluded that the local heat transfer coefficients for confined jets are more sensitive to Reynolds number and nozzle-to-plate spacing.
Analysis of Heat Transfer Equation of Thermal Probe in Single-Phase Flow
To characterize the heating behavior of canned particulates in this retort, the researchers filled the cans with a single nylon particle, in an unlimited heat transfer condition, in glycerin, and processed it under different operating temperatures: 110 C and 130 C; at from 0 to 240 reciprocations per minute; and at different amplitudes ranging from 0 cm to 25 cm.
A heat flux sensor (greenTEG gSkin) was used to measure the heat transfer coefficient beneath the impingement dryer.
The nano-additive increases the heat transfer efficiency of the heat transfer fluid, and reduces the moisture content.
compared between using Heat Transfer Fluid (HTF) and Direct Steam Generation (DSG).
This gives you the overall heat-transfer coefficient, which is the heat transfer between the polymer and the cooling medium.