The three types of heat transfer have been discussed here and there on this blog before. One of the most common heat transfer methods that I deal with on a day to day basis is radiant heat transfer. Also known as thermal radiation, the process is actually the exchange of energy by photons. The main difference separating radiant heat from convection and conduction is that radiation does not require there to be a medium to permit propagation of the heat. Any item which contains thermal energy, meaning it is above absolute zero and less than 1,000 Kelvin, will have this thermal energy. This thermal energy is radiated to other items causing a transfer of heat energy to those objects that results in an equilibrium between the items. The equilibrium does not stop the transfer of photons however.
The most common occurrence that most of us get to experience for radiant heat is heat from the Sun. As the sun shines it is emitting heat. On a hot day, generally the sun is a little closer to your geographic location and you feel hot because the sun is emitting more heat onto your surface than what is being emitted by your internal temperature, so your core temp will increase. On a cold day, when the sun is further away, while it is still shining you feel cold because the sun is not in fact transferring as much energy to the surface of your body than what you are internally generating. The same kind of radiant heat transfer can be from a campfire, open kiln, maybe even a hot steel slab coming out of a blast furnace.
Understanding where a radiant heat source is being generated can help tremendously when looking at cooling an electrical enclosure or even trying to keep a part or sensor cool. Radiant heat is one of the few times a heat shield or shade structure can help to eliminate a portion of the heat load being introduced. Other methods to combat the heat load would be determined with the application at hand. For cooling enclosures that are absorbing a solar heat load, we would look at an EXAIR Cabinet Cooler System and the factors that help to appropriately size the cooler. If this is a single component or part, we would evaluate one of the many other EXAIR Engineered Solutions to determine the best fit for the application. To do either of these, all it takes is a simple chat, email, or call to an Application Engineer.