Critical Radius Of Insulation In Heat Transfer. The use of thermal insulation is to avoid or lower the rate of heat. Critical radius of insulation.
Rcrcylinder frackh the critical radius of insulation for a spherical shell. Critical radius of insulation kh0 015 002 m 20 mm. Addition of asbestos insulation will increase the heat transfer rate and that is not desirable.
As can be seen if r 1 r cr as it is in this case the total resistance decreases and the heat rate therefore increases with the addition of insulation.
Note that the critical radius of insulation depends on the thermal conductivity of the insulation k and the external convection heat transfer coefficient h. To examine this critical radius parameterand whether it even existsfor other simple. Insulating a cylinder or sphere larger than the critical radius has the expected effect of retarding heat loss. The rate of heat transfer from the cylinder increases with the addition of insulation for r 2 r cr reaches a maximum when r 2 r cr and starts to decrease for r 2 r cr.