Thermal Management
One of the important characteristics of aluminum, and therefore of aluminum extrusion, is thermal conductivity. With a coefficient of thermal conductivity of 239, aluminum conducts heat much more easily than does steel (coefficient of thermal conductivity of 50) and even approaches copper (386). Note that the higher the coefficient of thermal conductivity the more heat a given material conducts; the lower the coefficient, the better the thermal insulator material.
Aluminum’s high conductivity can be an asset—or a liability—depending on the application.
Heat Dissipation
Aluminum's thermal conductivity is an asset when you are trying to move heat away from a heat-generating source; for example, when you want to use an extruded heat sink to dissipate the heat generated by an electric motor, electronic device or LED light. Or if you want to dissipate heat from the battery pack for a Battery Electric Vehicle (BEV).
Thermal Insulation
Aluminum's conductivity is a liability when you want to keep heat or cold at bay. For window framing, you want the heat to stay on the outside in the summer and the cold to stay on the outside in the winter to maximize energy efficiency and occupant comfort. Similarly, if you are designing a door for a supermarket freezer cabinet, you want the cabinet to stay cold and the aisle to remain temperate. For such applications, a variety of thermal breaks or barriers are typically employed.
Such thermal barriers typically employ a plastic material with a low coefficient of thermal conductivity to separate the inner and outer sections of extrusion, thereby providing insulation to minimize heat transfer from one side to the other. PVC, polyurethane and polyamide are often used; all have a coefficient below 0.5.
For more information, see “Thermal Barrier” in this section.
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