Insulation is defined as a medium that impedes the transfer of heat from one item to another. Insulation serves the purpose of preventing or slowing down temperature changes in a substance, area or object. The above definition means that insulation can keep a substance or item hot by preventing heat from leaking out of it into the surrounding environment, or keep it cold by preventing outside heat from getting into it. Due to the fact that it restricts the flow of heat, insulation has a low thermal conductivity. No human-produced insulator is perfect. Therefore insulation reduces, rather than entirely blocks the transfer of heat.
Common Applications Of Insulation
Keeping food or liquids hot or cold
A common application of insulation is a thermos. A thermos keeps drinks cold or slow the melting of ice, and it keeps soup or food hot. Thermos bottles are usually lined with a hidden layer of insulation in their walls. In some cases, it is vacuum insulation.
Keeping Refrigerators Warm
The walls of refrigerators contain insulation that help to keep their contents cool after the fridge has reached its desired temperature and shut off. This extends the amount of time that the refrigerator can remain off before its contents heat back up, conserving energy.
Keeping Buildings Warm Or Cool
Insulation is sometimes installed in the attics and walls of buildings to keep them cool during summer and warm during winter. During summer, insulation reduces the amount of work your air conditioner has to do (therefore reducing energy usage) by reducing the amount of heat that re-enters the house after the air conditioner cools it off. It keeps heat outside (to a limited degree by slowing it down). During winter, insulation slows down the leakage of heat from your home to the outside environment. A key detail to remember about all this is that heat tries to move to cooler surfaces if it gets on opportunity to. Therefore the heat inside tries to transfer itself outside during winter, and vice versa during summer.
Keeping Automobiles Warm Or Cool
Insulation in the doors of automobiles helps to keep heat out of the car during summer, and in during winter. However, the large window area of cars parked out in the sun allows a great deal of sunlight (and therefore heat) into the car. The insulation may end up trapping the heat in a fashion similar to a solar oven.
Types Of Insulation
Materials With Low Thermal Conductivity: Fiberglass, foam, aerogel, and other materials are used as insulation due to their ability to block the transfer of heat.
Vacuum Insulation: This concept uses the lack of substances to impede the transfer of heat. Heat needs some form of matter (solid, liquid, or gas) to travel through. Vacuum insulators consist of two layers of a solid material such as glass or a metal with a gap between them. The gap contains no air nor any other substances (which makes it a vacuum). One alternative to preserving a vacuum is to fill the gap with an inert gas (for example: argon).