Exercise -2

1. A long electricity heated cylinder 3 cm in diameter is covered with 8cm of insulation. Thermal conductivity of insulation is  . The temperature is the insulation varies from  at the inside surface to  at outside surface. Calculate heat loss in .

Heat loss  

     2.  Vary the insulation thickness from 5 to 8 cm at the interval of 1 cm and calculate in each case           the outside surface temperature.

Exercise -3 (Self study)

In laying refractory bricks in a furnace it is observes that two courses of firebricks  are poorly joined so that they are separated by a crack of air space averaging 2mm in width. The brick temperature in the vicinity of the joint is 

Estimate the additional brick thickness in inches to which the thermal resistance of the joint is equivalent.