Rate of heat flow

The heat flow or heat flux (symbol according to DIN 1304, or) is a physical quantity for the quantitative description of heat transfer processes. It is defined as the time in the amount of heat transferred DELTA.t Dq:

The spelling with symbolizes that heat is not a state variable, but a process variable.

The heat flow is a heat output and is measured by calorimeters in watts.

The flow direction of the heat flow can be automatically only from a region of higher temperature to a region of lower temperature, depend ( Second Law of Thermodynamics ).