What is Conduction heat: Definition and 12 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.

View More On Wikipedia.org
  1. U

    Heat conduction from an isotherm spherical cap

    On the surface of a semi-infinite solid, a point heat source releases a power ##q##; apart from this, the surface of the solid is adiabatic. The heat melts the solid so that a molten pool forms and grows. Let's hypothesize that the pool temperature is homogeneously equal to the melting...
  2. Nusselt

    Heat transfer problem for a long rectangular bar

    Summary:: Determine the temperature distribution in a bar (very long– 2D) with rectangular cross section, in steady state, with imposed flux at one face, convection at the opposing face (Tinf, h), and imposed temperature (T1) at the two remaining walls. I am trying to find the analytical...
  3. E

    Rate of conduction heat transfer with different hot-side and cold-side areas

    When we measure 'the rate of conduction heat transfer'=Q , we assume that the hot side and the cold side's area are same. But if the both side's area is different to each other, how can i know the rate of conduction heat transfer? like below figure. Would you like to help me?? Thanks.
  4. imselva

    Conduction heat transfer with varying cross section

    How to modify this Formula? and arrive at the solution. Q = -K(Th-Tc)A/thickness
  5. A

    What is the role of vibrational energy in heat conduction in solids?

    It is easy to understand heat conduction in a gas as the nucleus of atoms may collide with transfer of kinetic energy. But the space within a solid is vastly empty space and the nucleus of the atoms cannot collide. So if the surface of a solid is in contact with a hot gas, how is kinetic energy...
  6. R

    What is the final temperature of the air in a tube

    Homework Statement I have a copper tube with outer radius r2 and inner radius of r1. Half the tube is exposed to the surrounding air while the other half is embedded into the ground. The outside air temperature is T2 and the ground temperature is T3. What is the air temperature inside the tube...
  7. Ravi Singh choudhary

    Ice will melt faster which case -- over or below hot block?

    Natural convection always occurs opposite of gravity due to buoyancy; but I am confused as ice is solid so how could possibly convection even contribute to the heat transfer. I doubt about air movements nearby block that may contribute to greater heat transfer rate in case of hot block placed...
  8. H

    Is heat by conduction an electromagnetic wave?

    In my physiology (biological science) class it was explained that, upon eating some food source, some energy is converted into a useful form for the body, and some energy is lost in the form of heat. The lecturer didn't explain what form this heat is in. I thought that 'heat' must be an EM...
  9. M

    Conduction Heat Transfer Cross Check

    Hi, I was provided a http://eng-tips.com/viewthread.cfm?qid=372664# that I'm lost on. I was given an equation that we solved for earlier in the semester using the finite difference (dx method). (first image below). The http://eng-tips.com/viewthread.cfm?qid=372664# wasn't clear when...
  10. R

    Solving Conduction Heat Wave in Metal Bar

    Homework Statement A conduction heat wave is caused to pass through a metal bar of average temperature Tmean = 35.0 °C, altering its temperature sinusoidally with an amplitude of Ti = 2.0 °C. The equation which gives the temperature, T(x,t), of the metal bar at any place x (in meters) inside...
  11. J

    Conduction heat transfer mechanisms

    [b]1. Homework Statement [/b the ends of a 20cm long,2cm diameter rod are maintained at 0degrees and 100degrees by immersion in an ice-water bath and boiling water. heat is conducted through the rod at 4.5x10^4J/h. of what material is the rod made? Homework Equations Q/dt=k(A/L)dT The...