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  2. Thermal radiation - Wikipedia

    en.wikipedia.org/wiki/Thermal_radiation

    Radiation waves may travel in unusual patterns compared to conduction heat flow. Radiation allows waves to travel from a heated body through a cold non-absorbing or partially absorbing medium and reach a warmer body again. [14] An example is the case of the radiation waves that travel from the Sun to the Earth.

  3. Stefan–Boltzmann law - Wikipedia

    en.wikipedia.org/wiki/Stefan–Boltzmann_law

    Following Bartoli, Boltzmann considered an ideal heat engine using electromagnetic radiation instead of an ideal gas as working matter. The law was almost immediately experimentally verified. Heinrich Weber in 1888 pointed out deviations at higher temperatures, but perfect accuracy within measurement uncertainties was confirmed up to ...

  4. Heat equation - Wikipedia

    en.wikipedia.org/wiki/Heat_equation

    For heat flow, the heat equation follows from the physical laws of conduction of heat and conservation of energy (Cannon 1984). By Fourier's law for an isotropic medium, the rate of flow of heat energy per unit area through a surface is proportional to the negative temperature gradient across it:

  5. Heat transfer - Wikipedia

    en.wikipedia.org/wiki/Heat_transfer

    The heat equation is an important partial differential equation that describes the distribution of heat (or temperature variation) in a given region over time. In some cases, exact solutions of the equation are available; [ 26 ] in other cases the equation must be solved numerically using computational methods such as DEM-based models for ...

  6. Kirchhoff's law of thermal radiation - Wikipedia

    en.wikipedia.org/wiki/Kirchhoff's_law_of_thermal...

    Gustav Kirchhoff (1824–1887) . In heat transfer, Kirchhoff's law of thermal radiation refers to wavelength-specific radiative emission and absorption by a material body in thermodynamic equilibrium, including radiative exchange equilibrium.

  7. Heat - Wikipedia

    en.wikipedia.org/wiki/Heat

    In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by modes other than thermodynamic work and transfer of matter. Such modes are microscopic, mainly thermal conduction, radiation, and friction, as distinct from the macroscopic modes, thermodynamic work and transfer of matter. [1]

  8. Thermal energy - Wikipedia

    en.wikipedia.org/wiki/Thermal_energy

    Internal energy: The energy contained within a body of matter or radiation, excluding the potential energy of the whole system, and excluding the kinetic energy of the system moving as a whole. Heat: Energy in transfer between a system and its surroundings by mechanisms other than thermodynamic work and transfer of matter.

  9. Fundamental thermodynamic relation - Wikipedia

    en.wikipedia.org/wiki/Fundamental_thermodynamic...

    The above derivation uses the first and second laws of thermodynamics. The first law of thermodynamics is essentially a definition of heat, i.e. heat is the change in the internal energy of a system that is not caused by a change of the external parameters of the system.