Control of Heat Flow

The flow of heat by each method can be controlled. That is, the transfer of heat by each of the methods can be aided or restricted according to the particular need. Radiation, or rather the transfer of heat by radiation, may be aided by making the radiating surfaces of a material, or of a color known to be a good radiator of heat, and by making the receiving surfaces of a material or color is known to be a good absorber (or poor reflector) of radiated heat. Conversely, it may be impeded by reversing this application. Dark materials or colors absorb and radiate readily. Light-colored or shiny materials have the opposite properties.

Conduction may be aided by providing large conducting surfaces and good con­ducting materials, such as copper, alumi­num, and iron. Cork, wood, mineral wool, and many other similar materials are poor conductors of heat. Poor conductors of heat are often referred to as heat in­sulators (insulation). Convection may be aided by speeding the flow of the conveying medium; for example, forced-air circulation heating systems. Conversely, it can be impeded by retarding the flow of circulation.