Discuss the below:
Q: Steam having a quality of 98% at a pressure of 1.37 A? 105 N/m2 is flowing at a velocity of 1 m/s through a steel pipe of 2.7 cm OD and 2.1 cm ID. The heat transfer coefficient at the inner surface, where condensation occurs, is 567 W/(m2 K). A dirt film at the inner surface adds a unit thermal resistance of 0.18 (m2 K)/W. Estimate the rate of heat loss per meter length of pipe if;
(a) the pipe is bare,
(b) the pipe is covered with a 5 cm layer of 85% magnesia insulation. For both cases assume that the convective heat transfer coefficient at the outer surface is 11 W/(m2 K) and that the environmental temperature is 21°C. Also estimate the quality of the steam after a 3-m length of pipe in both cases.
GIVEN
A steel pipe with steam condensing on the inside
Diameters
Outside (Do) = 2.7 cm = 0.027 m
Inside (Di) = 2.1 cm = 0.021 m
Velocity of the steam (V) = 1 m/s
Initial steam quality (Xi) = 98%
Steam pressure = 1.37 A? 105 N/m2
Heat transfer coefficients
Inside (hci) = 567 W/(m2 K)
Outside (hco) = 11 W/(m2 K)
Thermal resistance of dirt film on inside surface (Rf) = 0.18 (m2 K)/W
Ambient temperature (TA) = 21°C
ASSUMPTIONS
Steady state conditions exist
Constant thermal conductivity
Steel is 1% carbon steel
Radiative heat transfer from the pipe is negligible
Neglect the pressure drop of thesteam
