Infrared Explained through Thermal Imaging

Have you ever seen a thermal image with the various colors denoting different temperatures? If you have, you are peering into the spectrum of infrared. An infrared camera can sense and photograph temperatures of its surroundings. How can it do this? The objects, people, animals, etc. are giving off thermal radiation. If that sounds scary, rest assured it’s innocuous and here’s why. Any object that is above absolute zero (that’s -459.67 degrees F!) gives off infrared. And, since absolute zero is impossible to reach, all objects give off thermal radiation. It is only the intensity (i.e. temperature) that varies. Thermal radiation is non-ionizing and cannot give you cancer. That’s a good thing since we’re barraged with thermal radiation from the ground, trees, rocks, houses, and everything else that surrounds us!

infrared heater panel comparison

Campfire-like Warmth

The physiological effect of infrared (the warmth that you feel) is predominately correlated to how hot the other object is (temperature and total heat output), and how close you are to it. We feel the warmth of the sun via infrared even though we’re 93 million miles away, because the sun is massive and is about 10,000 degrees. If you’ve ever sat next to a campfire and felt the intense warmth, this is from its thermal radiation i.e. infrared. Thermal energy transfers from hot to cold, and since you’re colder than the campfire, you’re receiving the infrared. To demonstrate the opposite effect, if you hold your hand a couple of inches from a window when it’s cold out, you can feel the cold from the window. This is actually thermal radiation from you that is going to the window.

 
With infrared heaters, one of the main goals is to maximize the surface temperature of a panel and make that temperature consistent (evenly spread) so that the panel gives off infrared heat which you will then feel as warmth. Since objects in the room are colder than the heater too, they also absorb the warmth from the infrared panel. As those objects warm up, they re-radiate the heat which causes warm air to be generated, and this raises the air temperature in the room. With infrared heaters the primary effect is the warmth that you feel and absorb, and the secondary effect is the air temperature which rises as a result of objects warming around you.
 
For a broader explanation of Infrared, check out this post of the Basics of Infrared Heating
 
Written by: Jeff Abel, VP of Sales, Heating Green