A steam pipe, made of carbon steel (k = 50 W/m.C) is covered with three colored insulators of 1.5 cm thick each. The thermal conductivity (k) for insulators is:
Blue = 0.01 W/m.C, Red = 0.03 W/m.C, and Green = 0.05 W/m.C.
The pipe has an in-diameter of D1 Cm, a thickness of 1 cm, and a length of 50m.
For the following cases: How much energy is lost every day when the steam temperature is maintained at 200oC, and the surrounding average air temperature is 20.0oC, and the surroundings average air temperature is 20.0oC? Neglect losses though the ends of the pipe.
Case 1: the pipe is covered by Blue-Red-Green
Case 2: the pipe is covered by Red-Green-Blue
Case 3: the pipe is covered by Green-Blue-Red
Case 4: the pipe is covered by Red-Green-Blue
If the price of insulators per m3 is: $200 Blue-$250 Red- $100 Green.
Calculate the total cost of each case and which case you think is the best.
For Steam hi = 80 W/m2.C, ambient air h0 = 22 W/m2.C
