Reconsider Prob. 8–82. Using the EES (or other) software, evaluate the effect of the saturated water vapor mass flow rate on needed insulation thickness for keeping the outer surface temperature below 180°C to prevent fire hazard if oil leak happens. By varying the mass flow rate from 0.01 to 0.1 kg/s, plot the insulation layer thickness as a function of the mass flow rate. If the flow rate of the saturated water vapor is adjusted between 0.03 and 0.1 kg/s, determine the insulation layer thickness that is suitable for this flow rate range.

Data from problem 82

A metal pipe (k_pipe = 15 W/m ∙ K, D_i,_pipe = 5 cm, D_o,pipe = 6 cm, and L = 10 m) situated in an engine room is used for transporting hot saturated water vapor at a flow rate of 0.03 kg/s. The water vapor enters and exits the pipe at 325°C and 290°C, respectively. Oil leakage can occur in the engine room, and when leaked oil comes in contact with hot spots above the oil’s autoignition temperature, it can ignite spontaneously. To prevent any fire hazard caused by oil leakage on the hot surface of the pipe, determine the needed insulation (kins = 0.95 W/m ∙ K) layer thickness over the pipe for keeping the outer surface temperature below 180°C.