Saturated steam at 120oC is transported through a steel pipe of diameter 250 mm. The temperature of the outer surface of the pipe can also be assumed 120oC. The pipe is centeredin concrete of square cross section (400x400 mm). The outer surfaces of the concrete are exposed to ambient air, for which T? = 20oC and h = 25 W/(m2*K). Radiation heat exchange can be neglected.
a. Estimate the heat loss per unit length of the pipe.
b. Plot the quality of steam exiting a 100-m long pipe as a function of steam flow rate. The steam quality at the entrance is 100%. The quality of a wet steam is defined as the mass fraction of the mixture that is vapor.
c. If the quality of steam flowing through this 100-m long pipe is not to fall below 80%, estimate the minimum allowable flow rate of the steam.
Data: k concrete = 1.3 W/(m*K), heat of condensation = 2202.59kJ/kg.