5. (25%) A pipeline transporting cold water is surrounded by stagnant air that is both hot and hurnid, and
moisture continually di ffuses to the cold surface of the pipe to form condensation. The condensed water forms
a liquid film around the pipe, which drops off. At a distance of 10 cm from the exterior of the pipe, the relative
humidity is constant, while close to the pipe the moisture content approaches the vapor pressure of water
evaluated at the temperature of the pipe.
【題組】(a) Which coordinate system best describes this transfer process? List three major assumptions. (5 pts)