3 Types of Heat Transfer

The process of heat transmission can take place through solid substances (conduction), or via fluids such as liquids and gases (convection). Alternatively, it can occur through the propagation of electromagnetic waves (radiation). Typically, heat doesn’t transfer through just one of these processes, but rather, it’s a blend of these three methods, happening naturally without a specific order.

Conduction is the transfer of heat through a solid material without any actual movement of the material itself. It occurs when molecules within the material collide and transfer their kinetic energy to neighboring molecules. The rate of heat transfer through conduction depends on the material’s thermal conductivity, which is a measure of how easily heat can flow through it.

For example, metals like copper and aluminum have high thermal conductivities, making them efficient conductors of heat. In contrast, materials such as wood and insulation have low thermal conductivities, acting as thermal insulators that reduce heat transfer.

Convection is the transfer of heat through the movement of fluids, such as gases and liquids. In this process, warmer, less dense fluid rises, while cooler, denser fluid sinks. This circulation creates a continuous flow that transports heat throughout the fluid. Convection can be either natural, driven by temperature differences within the fluid, or forced, driven by external forces like fans or pumps.

Convection plays a vital role in heating and cooling systems, such as air conditioners and radiators. For instance, in a radiator, hot water flows through pipes, transferring heat to the surrounding air through convection. The warmed air then rises and circulates throughout the room, providing even heating.

So how do we measure heat?

There are many ways to measure heat. You could use something as simple as a thermometer. Here at HuksefluxUSA we measure something called Heat Flux. To measure heat flux we use heat flux sensors. Heat Flux is the transfer of heat through a surface or substance. Usually from a heat source to a heat sink. Heat flux sensors are made by connecting thermocouple pairs wired together in series across a thin layer of insulation. This will create a voltage differential between both sides of the insulation. The direction in which the heat is flowing is measurable by the positive or negative readings from the lead wires.