Introduction to thermal insulation materials
Thermal insulation materials are substances used for making a place or an object resistant to incoming and outgoing heat. They almost stop all flow of heat from and to an object. This causes the temperature of the object to be maintained almost at a constant value for some time.
Thermal insulation materials are used for insulation. insulation is the process of making an object or a place safe from temperature changes.
Common thermal insulation materials are cotton, wool, wood, paper, cardboard, clay, foam, insulating paint, mineral wool, polystyrene, fiber glass, glass wool, cementitious, vermiculite, cork, etc.
How Thermal Insulation Materials Minimize Heat Flow
Thermal insulation materials minimize heat flow by minimizing one or all of the three processes by which heat flows from one point to another. These three processes are conduction, convection and radiation:
Conduction : It is the flow of heat from one object to another when the two objects are in physical contact. Heat flow can be stopped by conduction by placing an insulation material in between the two objects. The two objects can be separated by air or any other insulating material like wool, polystyrene etc.
Convection: It is the flow of heat in fluids (gases and liquids), for example in air. In this type of heat flow, the heat is distributed throughout the mass of the fluid by convection currents, which are currents of warmer fluid flowing up and thus reaching the cooler parts of the fluid. The cooler fluid in reaction flows near to the source of heat. Heat flow from convection can be stopped by limiting the convection through covering by insulating materials.
Radiation: It is the flow of heat from one object to another through electromagnetic radiation, which does not require any medium in between for propagation. Radiation can be limited by the use of reflecting surfaces which reflect the radiation and prevent it from entering or leaving a particular object.
Desirable Characteristics in Thermal Insulation Materials
Low thermal conductivity
The insulation material should have low conductivity. Lower thermal conductivity means that it can insulate heat more efficiently.
Low moisture and water absorption
The thermal insulation material should have low permeability for water vapor and water, otherwise it will be easily corroded and will last for a smaller period of time.
Desirable physical and chemical properties
The thermal insulation material should be resistant to water and other chemicals. It should be durable, not affected by micro-organisms, easy to install, cost efficient, and should not release odors.
The insulating material should be non-flammable and non-explosive. It should not catch fire quickly and should not release toxic gases on burning.