. . . . . "\\(\\Phi\\)"^^ . "http://en.wikipedia.org/wiki/Rate_of_heat_flow"^^ . . . . . "Heat Flow Rate"@en . "\\(heat-flow-rate\\)"^^ . . . . . . . . . . . "The rate of heat flow between two systems is measured in watts (joules per second). The formula for rate of heat flow is \\(\\bigtriangleup Q / \\bigtriangleup t = -K \\times A \\times \\bigtriangleup T/x\\), where \\(\\bigtriangleup Q / \\bigtriangleup t\\) is the rate of heat flow; \\(-K\\) is the thermal conductivity factor; A is the surface area; \\(\\bigtriangleup T\\) is the change in temperature and \\(x\\) is the thickness of the material. \\(\\bigtriangleup T/ x\\) is called the temperature gradient and is always negative because of the heat of flow always goes from more thermal energy to less)."^^ . . . .