Compare the rate of condensate flow from the pipe in Problem 5.24 (air pressure = 2.0 atm) with that for a 3.89-cm-OD pipe and 2.0 atm air pressure. What is the rate of condensate flow if the 2 cm pipe is submerged in a 20°C constant-temperature water bath?

From Problem 5.24: Long, 2-cm-OD horizontal copper pipe carries dry saturated steam at 1.2 atm absolute pressure. The pipe is contained within an environmental testing chamber in which the ambient air pressure can be adjusted form 0.5 to 2.0 atm, absolute while the ambient air temperature is held constant at 20°C. Assume that the pressure change does not affect the absolute viscosity, thermal conductivity, or specific heat of the air.

GIVEN

• A long horizontal copper pipe carrying saturated steam within an environmental testing chamber or a water bath
• Steam pressure = 1.2 atm
• Ambient pressure (P) = 2 atm
• Ambient air or water temperature (T_∞) = 20°C

ASSUMPTIONS

• Pressure change has no effect on absolute viscosity, thermal conductivity, or specific heat of the air
• Air is still
• Convective thermal resistance on the inside of the pipe is negligible
• Thermal resistance of the copper pipe is negligible
• The air behaves as an ideal gas