What is Heat conduction: Definition and 109 Discussions
Thermal conduction is the transfer of internal energy by microscopic collisions of particles and movement of electrons within a body. The colliding particles, which include molecules, atoms and electrons, transfer disorganized microscopic kinetic and potential energy, jointly known as internal energy. Conduction takes place in all phases: solid, liquid, and gas.
Heat spontaneously flows from a hotter to a colder body. For example, heat is conducted from the hotplate of an electric stove to the bottom of a saucepan in contact with it. In the absence of an opposing external driving energy source, within a body or between bodies, temperature differences decay over time, and thermal equilibrium is approached, temperature becoming more uniform.
In conduction, the heat flow is within and through the body itself. In contrast, in heat transfer by thermal radiation, the transfer is often between bodies, which may be separated spatially. Also possible is the transfer of heat by a combination of conduction and thermal radiation. In convection, the internal energy is carried between bodies by a moving material carrier. In solids, conduction is mediated by the combination of vibrations and collisions of molecules, of propagation and collisions of phonons, and of diffusion and collisions of free electrons. In gases and liquids, conduction is due to the collisions and diffusion of molecules during their random motion. Photons in this context do not collide with one another, and so heat transport by electromagnetic radiation is conceptually distinct from heat conduction by microscopic diffusion and collisions of material particles and phonons. But the distinction is often not easily observed unless the material is semi-transparent.
In the engineering sciences, heat transfer includes the processes of thermal radiation, convection, and sometimes mass transfer. Usually, more than one of these processes occurs in a given situation.
The conventional symbol for thermal conductivity is k.
Homework Statement
The elements of a boiling water nuclear reactor consist of long cylindrical rods of uranium dioxide (U02) of diameter 8mm surrounded by a thin layer of aluminium cladding. In the reactor core the elements are cooled by boiling water at 285°C with a heat transfer...
A solid sphere of radius a is immersed in a vat of fluid at a temperature T_0. Heat is conducted into the sphere according to
dT/dt = D(d^2T/dr^2) (d-> partial derivative btw)
If the temperature at the boundary is fixed at T_0 and the initial temperature of the sphere is T_1, find the...
Sir,
1) Two spheres of different materials, one with double the radius and 1/4th wall thickness of the other are filled with ice. If the time taken for complete melting of ice in the large sphere is 25 minutes and that in smaller sphere is 16 minutes, what is the ratio of the thermal...
Help with Heat Conduction Question
My question is:
These days they reinforce concrete walls with steel bars. Would the steel bars enhance or degrade the insulating value of the concrete wall? Explain?
Metal is a good conductor and concrete is a good insulator. My answer so far is that it...
Given the 3-D rectangular solid with sides of length a, b and c in the x, y and z direction respectively.
Find T(x,y,z) in the interior of the solid when laplace T = 0
Boundary condition are following conditions:
1) x=0, T=0
2) x=a, dT/dx=0
3) y=0, dT/dy=0
4) y=b, dT/dy=0
5) z=0, T=0
6)...
A styrofoam cooler (K = .030 W/mo C) has an average surface area of 0.465 m2 and an average thickness of 2.0 cm. About how long, in seconds will it take for 4.10 kg of ice at 0oC to melt in the cooler if the outside temperature is 28.0oC?
delta Q/delta t = (k*A*deltaT)/d
delta Q = 333 J/g...
I'm doing a projekt on heat conduction i a box.
The point is to simulate a house very simple. We have time varying temperature conditions on the outside, and want to model the temperature inside the box over time as outside temperature changes. The box will consist og an outer wall, insulation...
Hello friends
I have a problem and also know its answer but I have some trouble figuring it out. Here goes
Two vessels filled with different liquids are at temperatures T_{1} and T_{2} respectively. They are joined by a metal rod of length l; area of cross-section A and thermal...