heat transfer coefficient wikipedia
R-value (insulation)
Installed faced fiberglass batt insulation with its R-value visible (R-21). In the context of construction, the R-value is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive flow of heat. R-value is the temperature difference per unit of heat flux needed to sustain one unit of heat …
Nucleate boiling
Nucleate boiling. In fluid thermodynamics, nucleate boiling is a type of boiling that takes place when the surface temperature is hotter than the saturated fluid temperature by a certain amount but where the heat flux is below the critical heat flux. For water, as shown in the graph below, nucleate boiling occurs when the surface temperature is ...
Heat transfer through fins
Heat transfer through fins. Fins are extensions on exterior surfaces of objects that increase the rate of heat transfer to or from the object by increasing convection. This is achieved by increasing the surface area of the body, which in turn increases the heat transfer rate by a sufficient degree. This is an efficient way of increasing the ...
Heat capacity
Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K).. Heat capacity is an extensive property.The corresponding intensive property is the specific heat capacity, found by dividing the heat …
Heat transfer
Heat transfer is the way the heat moves from one physical system (or body) to another. Heat transfer requires a difference in temperature. [1] Heat moves from the hotter body (higher temperature) to the colder one (lower temperature). [2] The bodies in question may be in a solid state, a liquid state or a gaseous state. [2]
Logarithmic mean temperature difference
Q is the exchanged heat duty, U is the heat transfer coefficient (watts per kelvin per square meter), A is the exchange area. Note that estimating the heat transfer coefficient may be quite complicated. This holds both for cocurrent flow, where the streams enter from the same end, and for countercurrent flow, where they enter from different ends.
Cooling load temperature difference calculation method
The equations for the use of the data retrieved from these tables are very simple. Q= heat gain, usually heat gain per unit time. A= surface area. U= Overall heat transfer coefficient. CLTD= cooling load temperature difference. SCL= solar cooling load factor. CLF= cooling load factor. SC= shading coefficient.
Specific heat capacity
Dimension. L 2 ⋅T −2 ⋅K −1. In thermodynamics, the specific heat capacity (symbol c) of a substance is the amount of heat that must be added to one unit of mass of the substance in order to cause an increase of one unit in temperature. It is also referred to as massic heat capacity or as the specific heat. More formally it is the heat ...
Heat transfer
SummaryOverviewMechanismsPhase transitionModeling approachesEngineeringApplicationsHistory
Heat transfer is the energy exchanged between materials (solid/liquid/gas) as a result of a temperature difference. The thermodynamic free energy is the amount of work that a thermodynamic system can perform. Enthalpy is a thermodynamic potential, designated by the letter "H", that is the sum of the internal energy of the system (U) plus the product of pressure (P) and volume (V). Joule is a unit to quantify energy, work, or the amount of heat.
Heat transfer enhancement
Heat transfer enhancement is the process of increasing the effectiveness of heat exchangers.This can be achieved when the heat transfer power of a given device is increased or when the pressure losses generated by the device are reduced. A variety of techniques can be applied to this effect, including generating strong secondary flows or …
Heat sink
A heat transfer theoretical model Sketch of a heat sink with equivalent thermal resistances Thermal resistance and heat transfer coefficient plotted against flow rate for the specific heat sink design used in. The data was generated using the equations provided in the article. The data shows that for an increasing air flow rate, the thermal ...
Thermal conduction
Conduction is the process by which heat is transferred from the hotter end to the colder end of an object. The ability of the object to conduct heat is known as its thermal conductivity, and is denoted k.. Heat spontaneously flows along a temperature gradient (i.e. from a hotter body to a colder body). For example, heat is conducted from the hotplate of an electric …
Condenser (heat transfer)
A condenser is designed to transfer heat from a working fluid (e.g. water in a steam power plant) to a secondary fluid or the surrounding air. The condenser relies on the efficient heat transfer that occurs during phase changes, in this case during the condensation of a vapor into a liquid. The vapor typically enters the condenser at a ...
Thermal insulation
Mineral wool insulation, 1600 dpi scan. Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object …
List of thermal conductivities
In heat transfer, the thermal conductivity of a substance, k, is an intensive property that indicates its ability to conduct heat. For most materials, the amount of heat conducted varies (usually non-linearly) with temperature. Thermal conductivity is often measured with laser flash analysis. Alternative measurements are also established.
Skin friction drag
The skin friction coefficient is a strong function of the Reynolds number, as increases decreases. ... (Nu), which indicates the magnitude of convectional heat transfer. Turbine blades, for example, require the analysis of heat transfer in their design process since they are imposed in high temperature gas, which can damage them with the heat. ...
Thermal diffusivity
In heat transfer analysis, thermal diffusivity is the thermal conductivity divided by density and specific heat capacity at constant pressure. It is a measure of the rate of heat transfer inside a material. It has units of m 2 /s. Thermal diffusivity is usually denoted by lowercase alpha (α), but a, h, κ (), K, and D are also used.. The formula is:
HEAT TRANSFER COEFFICIENT
533889. Heat transfer coefficient is a quantitative characteristic of convective heat transfer between a fluid medium (a fluid) and the surface (wall) flowed over by the fluid. This characteristic appears as a proportionality factor a in the Newton-Richmann relation. where is the heat flux density on the wall, T w the wall temperature, T t the ...
Mass transfer coefficient
Mass transfer coefficient. In engineering, the mass transfer coefficient is a diffusion rate constant that relates the mass transfer rate, mass transfer area, and concentration change as driving force: [1] Where: k c {displaystyle k_ {c}} is the mass transfer coefficient [mol/ (s·m 2 )/ (mol/m 3 )], or m/s.
Nusselt number
In thermal fluid dynamics, the Nusselt number (Nu, after Wilhelm Nusselt: 336 ) is the ratio of total heat transfer to conductive heat transfer at a boundary in a fluid.Total heat transfer combines conduction and convection nvection includes both advection (fluid motion) and diffusion (conduction). The conductive component is measured under the same …
General equation of heat transfer
In fluid dynamics, the general equation of heat transfer is a nonlinear partial differential equation describing specific entropy production in a Newtonian fluid subject to thermal conduction and viscous forces: [1] [2] where is the specific entropy, is the fluid''s density, is the fluid''s temperature, is the material derivative, is the thermal ...
Plate heat exchanger
The total rate of heat transfer between the hot and cold fluids passing through a plate heat exchanger may be expressed as: Q = UA∆Tm where U is the Overall heat transfer coefficient, A is the total plate area, and ∆Tm is the Log mean temperature difference. U is dependent upon the heat transfer coefficients in the hot and cold streams.
Talk:Heat transfer coefficient
The heat transfer coefficient in this page is only on component of the overall heat transfer coefficient. Sturgman 00:50, 7 May 2015 (UTC) That said, I think we should make the heat transfer coefficient page a redirect to Newton''s law of cooling section in the convective heat transfer page.
Heat transfer physics
Heat transfer physics describes the kinetics of energy storage, transport, and energy transformation by principal energy carriers: phonons (lattice vibration waves), electrons, fluid particles, and photons. Heat is thermal energy stored in temperature-dependent motion of particles including electrons, atomic nuclei, individual atoms, and molecules. Heat is …
Thermal transmittance
Thermal transmittance. Thermal transmittance is the rate of transfer of heat through matter. The thermal transmittance of a material (such as insulation or concrete) or an assembly (such as a wall or window) is expressed as a U-value. The thermal insulance of a structure is the reciprocal of its thermal transmittance.
Window insulation
Window insulation reduces heat transfer from one side of a window to the other. The U-value is used to refer to the amount of heat that can pass through a window, called thermal transmittance, with a lower score being better. The U-factor of a window can often be found on the rating label of the window. Although the concept of U-value (or U-factor) is …
Fin (extended surface)
Fin (extended surface) In the study of heat transfer, fins are surfaces that extend from an object to increase the rate of heat transfer to or from the environment by increasing convection. The amount of conduction, convection, or radiation of an object determines the amount of heat it transfers. Increasing the temperature gradient between the ...
Schwarzschild''s equation for radiative transfer
In the study of heat transfer, Schwarzschild''s equation [1] [2] [3] is used to calculate radiative transfer ( energy transfer via electromagnetic radiation) through a medium in local thermodynamic equilibrium that both absorbs and emits radiation. The incremental change in spectral intensity, [4] ( dIλ, [W/sr/m 2 /μm]) at a given wavelength ...
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