3 Types of Heat Transfer
Conduction is the transfer of heat through a solid object by the movement of atoms and molecules. If you touch a hot pan, for instance, heat is conducted through the pan and into your hand. The rate of heat conduction depends on the material the pan is made of – metals are generally good conductors of heat, while insulators like wood and plastic are poor conductors.
Radiation is the transfer of heat through electromagnetic waves, and it doesn’t need a medium (like a solid or a fluid) to work. The heat you feel from the sun on a warm day is an example of radiation. All objects with a temperature above absolute zero emit thermal radiation, and the amount of radiation emitted depends on the object’s temperature and surface characteristics. Hotter objects emit more radiation than cooler ones.
Another way of understanding radiation is how the CDC describes it: Radiation is energy that comes from a source and travels through space at the speed of light. All radiation has a wavelength or frequency that defines it’s energy output. To understand radiation better think of how a microwave works. When a microwave is on, to heat the object or substance in it, it will use microwaves, hence the name microwave.
Convection is the transfer of heat through a fluid (like water or air) by the movement of currents within the fluid. When a fluid is heated, it becomes less dense and rises to the top. As it cools, it becomes denser and falls back down, creating a current. This process can happen naturally, such as when hot air rises and cool air falls in the atmosphere, or it can be forced, like when a fan blows air over a heating element. Convective heat transfer is important in many natural and man-made systems, like the circulation of the Earth’s atmosphere and the operation of a radiator in a car. A good example of convection would be boiling water in a pot over a flame.
So how do we measure heat?
Heat flux sensors
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.
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