question 4
air flows at 85 degrees celsius through a copper pipe with an internal diameter of 6 cm and a thickness of 0.4 cm , where it is externally heated by water at 130 degrees celsius . on the external surfaces of the pipe , a scale with a thickness of 0.2 cm is formed. take the thermal conductivity of the copper pipe as 384 W/m.K and of scale as 1.75 W/m.K and the connective coefficient of the inside surface as 221 W/m^2.K and outside surface as 3605 W/m^2.K. Calculate the overall heat transfer coefficient on the outside area basis, the water to air heat transfer and the temperature drop across the scale deposit