A double-pipe heat exchanger is used to condense steam at 40°Csaturation temperature. Water at an average bulk temperature of20°C flows at 2 m/s through the inner tube (copper, 2.54 cm ID,3.05 cm OD). Steam at its saturation temperature flows in theannulus formed between the outer surface of the inner tube andouter tube of 6 cm ID. The average heat transfer coefficient of thecondensing steam is 6,000 W/m2 ? K, and the thermalresistance of a surface scale on the outer surface of the copperpipe is 0.000176 m2 ? K/W. a. Determine the overall heattransfer coefficient between the steam and the water based on theouter area of the copper tube. b. Evaluate the temperature at theinner surface of the tube. c. Estimate the length required tocondense 0.5 kg/s of steam.
