25-08-2017, 09:32 PM
Testing of thermal insulation
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What is thermal Insulation ?
A provision made to retard heat flow from a hot surface to a cold environment or from a warm environment to a cold surface is called Thermal Insulation.
Insulation is defined as a material or combination of materials, which retard the flow of heat.
The materials can be adapted to any size, shape or surface.
A variety of finishes are used to protect the insulation from mechanical and environmental damage, and to enhance appearance.
Economic reasons for Thermal insulation in industry :-
Reduces fuel consumption, and hence overall cost of operation. Benefits of higher profits to owner.
Reduces capacity requirements for heating/cooling systems (e.g., boilers/ refrigeration units, etc).
Savings in Project Capital costs
Prevent or reduce condensation on surfaces.
Reduce heat loss or heat gain to achieve energy conservation.
Types of insulation
Mass Insulation : Air or another gas with thermal properties similar to air within the interstices inside the material. Many cellular insulations, and all fibrous and granular insulations are of this type.
Reflective Insulation : It bounding one or both sides of an air space.
Why Testing of Thermal Insulation
To acquire the following parameters it is must for the insulation to be tested :-
Insulation system should perform to the expected level, undiminished over its life.
This needs full data on material behaviour under all conditions of exposure.
In particular, designers need to know what would make a material lose its properties.
Features of a material are important-but their limitations are even more so.
Apparatus :-
The heating plate consist of a corrosion resistant plate with exposed area of 36 by 18 inch. but having a minimum test area of 18 by 18 inch.
The heated area has an insulated heated guard area having a minimum width of 3 inch around the entire periphery of test area.
The plate is supported in a horizontal plane at a sufficient number of points to prevent sagging. It is heated by six Heaters placed underside.
The surface temperature is measured by a thermocouple at the centre of the plate.