Cooling water flows through the 25.4-mm-diameter thin-walled tubes of a steam co

Cooling water flows through the 25.4-mm-diameter thin-walled tubes of a steam condenser at 1 m/s and a surface temperature of 350 K is maintained by the condensing steam. The water inlet temperature is 290 K and the tubes are 5 m long. (a) What is the heat transfer coefficient? Evaluate water properties at an assumed average temperature of 300 K. (b) Was the assumed value for the average temperature of water reasonable? PROBLEM 1
A long uninsulated steam line with a diameter of 89 mm and a surface emissivity of 0.
Cooling water flows through the 25.4-mm-diameter thin-walled tubes of a steam condenser at 1 m/s and a surface temperature of 350 K is maintained by the condensing steam. The water inlet temperature is 290 K and the tubes are 5 m long. (a) What is the heat transfer coefficient? Evaluate water properties at an assumed average temperature of 300 K. (b) Was the assumed value for the average temperature of water reasonable? PROBLEM 1
A long uninsulated steam line with a diameter of 89 mm and a surface emissivity of 0.8 transports steam at 2000 C and is exposed to atmospheric air and large surroundings at a temperature of 200 C. Assuming surface temperature of the steam line is 2000C (a) calculate the heat loss per unit length for a calm day and (b) calculate the heat loss per unit length on a breezy day when the wind speed is 8 m/s. PROBLEM 2
Saturated water vapor at a temperature of 355 K ( hfg = 2304 kJ/kg ) leaves a steam turbine at a flow rate of 1.5 kg/s. The vapor is to be completely condensed to saturated liquid in a shell-and-tube heat exchanger that uses city water as the cold fluid. The water enters the thin-walled tubes at 290 K and is to leave at 330 K. Assuming an overall heat transfer coefficient of 2000 W/(m2 K) determine the required heat exchanger surface area and the flow rate of city water. PROBLEM 3
A very long electrical conductor 10 mm in diameter is concentric with a cooled cylindrical tube 50 mm in diameter whose surface is diffuse and gray with an emissivity of 0.9 and temperature of 27 C. The electrical conductor has a diffuse gray surface with an emissivity of 0.6 and is dissipating 6.0 W per meter of length. Assuming that the space between the two surfaces is evacuated calculate the surface temperature of the conductor. PROBLEM 4
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