It is planned to insulate the shell of a heat exchanger. The outside diameter of the shell is 30cm, its outer surface temperature is at 280C and it may be assumed to be remains constant even after applying insulation on the shell. 32. If the outside surface heat transfer coefficient is 2, what is the maximum thermal conductivity of insulating material for effectively reducing heat transfer from shell (a) 0.3 (c) 2.4 (b) 0.24 (d) 1.2 33. If the air temperature of the outer surface of insulation is must not exceed 30 and the loss of heat from heat exchanger is 200 W/m. What is the thickness of insulation provided (a) 1.43 m (b) 1.25 m (c) 0.71 m (d) 0.55 m