How is fluid mechanics related to heat transfer?
History Background of Heat Transfer:Heat has always been perceived to be something that produces in us a sensational of warmth.In 1789 caloric theory proposed by the french chemist Antoine Lavoiser. The caloric theory asserts that heat is a fluid like substance called the caloric that is a massless, colorless, odorless, and tasteless substance that can be poured from one body to another. When caloric was added to a body, its temperature increased; and when caloric was removed from a body, its temperature decreased.This theory came under attack after its introduction. It maintained that heat is a substance that cannot be created or destroyed. But in 1798, the American Benjamin Thompson showed in his papers that heat can be generated continuously through friction. This put the caloric theory to rest. But this( Caloric theory) contributed greatly to the development of Thermodynamics and Heat transfer.In fluid mechanics, driving force is pressure difference, Similarly in heat transfer, driving force is temperature difference.In fluid mechanics, there is boundary layer for velocity, Similarly in heat transfer, there is the boundary layer for temperature.So we cannot say caloric theory meaningless; it is very significant for analysis of heat transfer and it describes the relation between Heat transfer and Fluid mechanics.Relation between Heat transfer and Fluid Mechanics:So heat transfer occurs in three modes,ConductionConvectionRadiationIn three of these conduction and convection, mainly convection is related to fluid mechanics. Convection is mode of heat transfer from a solid layer to adjacent liquid or gas layer. It involves the combined effect of Conduction and Fluid Motion. Greater the value of bulk motion of fluid, greater the rate of heat transfer(convection).So to analyze Convection, indepth knowledge of fluid mechanics is required.Source: Heat and Mass Transfer by Yunus A. Çengel and Afshin J. GhajarImage Source: Heat and Mass Transfer by Yunus A. Çengel and Afshin J. Ghajar
What is heat flux? And how it is related to heat transfer?
Heat flux is simply the amount of heat flowing per unit area. For a given body if heat is flowing in it through conduction then heat flux can be considerd as the ratio of the amount of heat flowing in the body to the Area normal to the direction of heat flow.
How are Heat Transfer and Density related to Earthquakes, Mountain Building, and Plate Tectonics?
Well, it is believed the heat convection is the driver of plate tectonics. From there it is plate tectonics that is responsible for the creation of mountains and earthquakes. When plates converge along with continental land masses, the result is a collision which is essentially mountain building. Also as plates move or grind past each other, earthquakes are created. Essentially, it is plate tectonics that cause mountain building and earthquakes, and plate tectonic are driven by heat - convection cells. Convenction cells occur by hot asthenosphere rising from the interior of the earth (less dense), as it moves closer to the surface, there is less heat so it cools and sinks again (more dense)...which then becomes hot and rises, cools and sinks (density variation from heating and cooling) Hope this helps.
How are heat and energy related?
In physics and thermodynamics, heat is the process of energy transfer from one body or system due to thermal contact, which in turn is defined as an energy transfer to a body in any other way than due to work performed on the body.[1] A related term is thermal energy, loosely defined as the energy of a body that increases with its temperature. Heat is also loosely referred to as thermal energy, although many definitions require this thermal energy to actually be in the process of movement between one body and another to be technically called heat (otherwise, many sources prefer to continue to refer to the static quantity as "thermal energy"). Heat is a form of Energy, but energy is not necessarily heat[citation needed]. Energy transfer by heat can occur between objects by radiation, conduction and convection. Temperature is used as a measure of the internal energy or enthalpy, that is the level of elementary motion giving rise to heat transfer. Energy can only be transferred by heat between objects - or areas within an object - with different temperatures (as given by the zeroth law of thermodynamics). This transfer happens spontaneously only in the direction of the colder body (as per the second law of thermodynamics). The transfer of energy by heat from one object to another object with an equal or higher temperature can happen only with the aid of a heat pump via mechanical work.
How hardness related to conduction heat transfer?
Generally I hope you Know the heat transfer takes place between solid, liquid and gas. The responsibility factor is K, h and Stefan constant for radiation. For solid the Kinetic collision takes place while applying heat, the structure will change (depends of material and properties) ….Now come to your question if more hardness material leads best heat transfer rate than low hardness material. Because the hardness is related to material composition and heat transfer ability of temperature travel through material.
What is the relation between heat transfer and turbulence?
There is a relation between heat transfer and turbulence but the exact inter dependent behavior differs from system to system. But I will try and explain this relation in terms of a very common system to make the idea a little concrete. The system that we can consider to illustrate the idea is a Shell and Tube Heat Exchanger which looks likes this :The Reynolds number for a flow in a circular pipe is given by:[math]Re=\frac{\rho V d}{\mu}[/math]Here [math]\rho[/math] is the density of the fluid, [math]V[/math] is the velocity , [math]\mu[/math] is the fluid viscosity while [math]d[/math] is the pipe diameter. Typically Re > 4000 are classified as turbulent flows. The relation between Heat Transfer and Reynolds number for this particular system can be written as:[math]Nu=0.023 Re^{0.8} Pr^n[/math]Here [math]Nu[/math] is the Nusselt Number and is given by[math]Nu=\frac{hd}{k}[/math]where [math]h[/math] is heat transfer coefficient. [math]Pr[/math] here refers to the Prandtl number. Also the value of [math]n[/math] and various other limitation to this above formulation can many a times be found in standard Chemical Engineering/ Heat Transfer related books. This particular relation of the Nusselt number, Reynolds number and Prandtl number is called the Dittus-Bolter equation. From this equation we can make a very qualitative inference that the heat transfer rate increases with turbulence for this particular system in consideration.
Explain radiation as it relates to heat transfer?
"Thermal radiation is emitted by matter as a result of changes in the electronic configuration s of the atoms or molecules within it. The energy is transported by electromagnetic waves (or photons). Unlike conduction, thermal radiation requires no intervening medium to propagate and can even take place in a vacuum. Solid surfaces, gases, and liquids all emit, absorb, and transmit thermal radiation to varying degrees." - straight from "Fundamentals of Engineering Thermodynamics" by Moran & Shapiro
Question related to heat transfer, Fourier's law of heat conduction?
A heat loss through a fire brick furnace wall, 0.2m thick(k=1.5 W/mK) insulated from outside by a brick wall(l=0.4 W/mK) is 400 W/m^2. The inside fire brick wall temperature is 1573 K and outside ambient air temperature is 293 K. Heat transfer coefficient at the exterior surface is given by h= (1/3) * ((∆T)^-0.25) where ∆T is the temperature difference between the surface and ambient air. Find thickness of insulating brick