n ADM Milling Company, a 10 m long steel pipe with the inner radius of 2 cm and 0.25 cm thickness is being used to carry steam at 130°C. The convective heat transfer coefficient on the steam side is 11,740 W/m2K, and that on the outside of the pipe to air is 57 W/m2K. Ambient air temperature is 15°C. The thermal conductivity of steel is 54 W/m.K. The pipe is covered with 2 cm thick insulation material which has thermal conductivity of 1.15 W/m.K.
(a) Calculate the heat loss to the surroundings.
(b) The operations manager suggested to add another insulation layer which is 4 cm thick with thermal conductivity of 0.04 W/m.K. How much would you save in one year (365 days @ 24 h/day) due to this additional layer of insulation? Cost of electricity is $0.10/kW-h.