HEAT TRANSFER
Heat transfer is the study of heat or energy crossing the boundaries of one system to another, or many others. Heat Transfer happens in one of 3 ways:
Conduction
Heat Conduction is a form of heat transfer the transfer of heat from one place ot another place within the same substance, or across another system in physical contact. An example of this would be a length of metal heated at one end, will conduct the heat through the part to the other end of the pipe. Conduction is the only form of heat transfer to take place within a solid body. Scroll down for Fouriers law of conduction



ConvectionConvection is the transfer of heat by mixing a heated fluid with a cooler fluid. By mixing the fluid, either naturally or forced convection, the temperature differential is reduced.
Natural convection is the mixing of the fluid by density change across the fluid, as a higher temperature fluid tends to be less dense than a cooler one, the heat tends to flow through the cool fluid, thus cooling the fluid, and causing it to fall once again. Forced convection can better be described as being two fluids which are propelled into each other by external forces. A good example is a fan heater, a heater warms the air around the element, and the fan forces the air out of the heater into the room. Often, the heat transfer between a solid and a fluid will be by conduction and convection. 
Radiation
Fourierâ€™s Law of Conduction Calculator
Fourier’s law states that the flow of heat through a body is directly proportional to the area perpendicular the heat flow. It is also proportional to the length of the heat flow path:
The rate of heat transfer can be found from the following equation:
Where: Q = Heat Flow Rate −λ = Thermal Conductivity A = Area perpendicular to heat flow dx = Material Thickness dx = Temperature Differential (t1−t2) 
