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 ?
To this aim, experimental work will be done in order to improve the understanding of heat transfer mechanisms and the loss of strength of composite high-pressure vessels in fire conditions.
In the Automotive industry, CFD software is used to analyze the feasibility of the heat transfer mechanisms such as ventilation, cooling, underhood thermal management, and aerodynamics of an automobile.
There are various heat transfer mechanisms in porous material, including conduction through both gas and solid, convection through gas, and radiation between the gas and solid interfaces (7).
The truth is that radiation heat transfer is always present but is not always significant in magnitude relative to the other heat transfer mechanisms operative in a given situation.
The latter is calculated as the heat transfer load, that is, the thermal load due to convective, radiative, and conductive heat transfer mechanisms plus the infiltration load.
Accurate measurement of the flow boiling heat transfer coefficients and a better understanding of the heat transfer mechanisms are essential for developing compact heat exchangers and novel refrigeration systems over a wide range of operating conditions.
6 clo can be achieved without any additional body heat transfer mechanisms (like shivering, vasoconstriction, vasodilatation or sweating), within 22.
A comprehensive review of the study of convective heat transfer mechanisms through porous media in relation to the applications to the above areas has been made by Nield and Bejan [7].
At the end the governing heat transfer mechanisms in the bubble influence area are treated briefly.
The process of vapor state penetration combines the interaction of metallic vapor diffusion with heat transfer mechanisms.
Evaporative Heat Transfer Mechanisms within a Heat Melt Compactor Experiment," Eric Golliher, NASA's Glenn Research Center, Cleveland
The prototype is capable of reversing the direction of working fluid (R-134a) flow and simulation of the dominant heat transfer mechanisms found in smart thermosiphons in contact with various media.