Methods of heat transfer
Heat energy can be transferred in three basic ways: conduction, convection and radiation. Thermal imagers, or infrared cameras, can only detect radiated heat energy, so it’s important to understand the distinction so you know the limitations of your thermal imaging device.
- Conduction is the transfer of thermal energy from one object to another through direct contact. Heat transfer by conduction occurs primarily in solids, and to some extent in fluids, as warmer molecules transfer their energy directly to cooler, adjacent ones. For example, you experience conduction when touching a warm mug of coffee or a cold soft drink can.
- Convection is the transfer of heat that occurs when molecules move and/or currents circulate between the warm and cool regions of air, gas, or fluid. Convection occurs in both liquids and gases, and involves the mass movement of molecules at different temperatures. For example, a thundercloud is convection that occurs on a large scale because as masses of warm air rise, cool air sinks.
- Radiation is the transfer of heat energy that occurs by electromagnetic waves, which is similar to light transmission. An example of radiation is feeling the heat of the sun.
All objects radiate electromagnetic energy at the speed of light. Electromagnetic energy is radiated in waves with electric and magnetic properties. It can take on several forms including light, radio waves, and infrared radiation. The primary difference among all of the wave types is their wavelength. Normal eyesight detects visible light wavelengths, while infrared cameras detect radiated heat (or infrared radiation) wavelengths.
To understand this topic more thoroughly, we recommend you seek out training, which can provide you with the theoretical and practical tools to get the best results out of your thermal camera.