Convective Heat Transfer

Warning: mkdir() [function.mkdir]: Permission denied in /home/webs/affiliatelib2/CacheManager.php on line 12

Warning: mkdir() [function.mkdir]: No such file or directory in /home/webs/affiliatelib2/CacheManager.php on line 12

Warning: fopen(/home/templatecore2cache//*cluesnet.com/10/10a77dd9c57d4825383a07d59acb23c7c2b8634a.tc2cache) [function.fopen]: failed to open stream: No such file or directory in /home/webs/affiliatelib2/CacheManager.php on line 130

Warning: fwrite(): supplied argument is not a valid stream resource in /home/webs/affiliatelib2/CacheManager.php on line 131

Warning: fclose(): supplied argument is not a valid stream resource in /home/webs/affiliatelib2/CacheManager.php on line 132

Convective heat transfer is a mechanism of heat transfer occurring because of bulk motion (observable movement) of fluids. This can be contrasted with Heat conduction heat transfer, which is the transfer of energy molecule by molecule through a solid or fluid, and radiation heat transfer, the transfer of energy through electromagnetic waves.

convection heat transfer is split into two categories: natural (or free) convection and forced (or advective) convection, also known as heat advection.

Natural convective heat transfer Natural convection is a mechanism, or type of heat transport in which the fluid motion is not generated by any external source (like a pump, fan, suction device, etc.) but only by density differences in the fluid occurring due to temperature :wikt:gradients. In natural convection, fluid surrounding a heat source receives heat, becomes less dense and rises. The surrounding, cooler fluid then moves to replace it. This cooler fluid is then heated and the process continues, forming a convection current. The driving force for natural convection is buoyancy, a result of differences in fluid density. Because of this, the presence of gravity or an equivalent force (arising from the equivalence principle, such as acceleration, centrifugal force or Coriolis force) is essential for natural convection. Natural convection does not operate as it does on Earth in the micro gravity environment of the orbiting International Space Station, where other heat transfer mechanisms are required to prevent electronic components from overheating.

Natural convection has attracted a great deal of attention by researchers because of its presence both in nature, seen in the rising plume of hot air from fire, oceanic currents, and sea-wind formation, and in engineering applications like formation of microstructures during the cooling of molten metals and in shrouded fins and solar ponds. Mathematically, the tendency of a particular system towards natural convection relies on the Grashof number (Gr), which is a ratio of buoyancy force and viscosity force.

Gr= \frac{g \beta \Delta T L^3}{\nu^2}

The parameter \beta is the rate of change of density with respect to the change in temperature (T), and ν is the viscosity. Thus, the Grashof number can be thought of as the ratio of the upwards buoyancy of the heated fluid to the internal friction slowing it down. In very sticky, viscous fluids, fluid movement is restricted, along with natural convection. In the extreme case of infinite viscosity, the fluid could not move and all heat transfer would be through conductive heat transfer.

A similar equation can be written for natural convection occurring due to a concentration gradient, sometimes termed thermo-solutal convection. In this case, a concentration of hot fluid diffuses into a cold fluid, in much the same way that ink poured into a container of water diffuses to dye the entire space.

Gr= \frac{g \beta \Delta C L^3}{\nu^2}

Forced convective heat transfer (advective heat transfer) Forced convection is a mechanism, or type of heat transport in which fluid motion is generated by an external source (like a pump, fan, suction device, etc.). Forced convection is often encountered by engineers designing or analyzing heat exchangers, pipe flow, and flow over a plate at a different temperature than the stream (the case of a shuttle wing during re-entry, for example). However, in any forced convection situation, some amount of natural convection is always present. When the natural convection is not negligible, such flows are typically referred to as mixed convection.

When analysing potentially mixed convection, a parameter called the Archimedes number (Ar) parametizes the relative strength of free and forced convection. The Archimedes number is the ratio of Grashof number and the square of Reynolds number, which represents the ratio of buoyancy force and inertia force, and which stands in for the contribution of natural convection. When Ar >> 1, natural convection dominates and when Ar

Convective heat transfer - Wikipedia, the free encyclopedia
Convective heat transfer is a mechanism of heat transfer occurring because of bulk motion (observable movement) of fluids. This can be contrasted with conductive heat transfer ...

Convection - Wikipedia, the free encyclopedia
Convection in the most general terms refers to the movement of molecules within fluids (i.e. liquids, gases and rheids). Convection is one of the major modes of heat transfer and ...

Free Convective Heat Transfer ina Partially Open Cavity
Free Convective Heat Transfer ina Partially Open Cavity Francesco Devia, Mario Misale, Giovanni Tanda. Dipartimentodi Termoenergeticae Condizionamento Ambientale (DITEC) ...

FREE CONVECTIVE HEAT TRANSFER WITHIN ROTATING ANNULI
3456789 1011121314151617 10 0 10 1 10 2 10 3 10 4 10 5 Hollands et al(1975) Niemela et al(2000) Grossmann & Lohse(2000) Cavity A(Bohn et al, 1995) Cavity B(Bohn et al, 1995) Cavity ...

Convective Heat Transfer
Heat transfer between a solid and a moving fluid is called convection. This is a short tutorial about convective heat transfer

McGraw-Hill Education Europe
... edition of CHMT continues the trend, initiated with the 3rd ed., of encouraging the use of a numerically based, computational approach to solving convective heat and mass transfer ...

Unsteady laminar flow and convective heat transfer in a sharp 180 ...
Unsteady laminar flow and convective heat transfer in a sharp 180° bend. Chung, Y.M. and Tucker, P.G. and Roychowdhury, D. (2003) Unsteady laminar flow and convective heat ...

Strathprints - An adaptive conflation between computational fluid ...
An adaptive conflation between computational fluid dynamics and thermal simulation for modelling indoor air flow and convective heat transfer at internal building surfaces

Correlations for Convective Heat Transfer
Recommended equations for calculation of heat transfer coefficients ... More on Shell and Tube Exchangers from Cheresources.com: FREE Resources

The Solutionof Convective Heat Transfer Problems Using Adaptive Moving ...
The Solutionof Convective Heat Transfer Problems Using Adaptive Moving Meshes Grant GR/R26023/01-Review Report Principal Investigator: DrJ.A. Mackenzie Co-investigator 1: