Condensation and Boiling Problems
1. Saturated steam at 68.9 kPa condenses on a vertical tube 0.305 m long and diameter of
0.025 m with surface temperature at 86.1C. Determine surface heat transfer coefficient.
Given: Nu = 1.13[2.g.hfg.L3/.k.T]1/4 for laminar flow
Re = 4m/d for vertical tube
2. Show that the condensation Reynolds number for laminar condensation on a vertical
plate may be expressed as :
Ref
=
3.77{[L3(Tg-Tw)3 f(f-v) g kf3]/(f5hfg3)}1/4
3. A 50 by 50 cm square vertical plate is maintained at 95C and exposed to saturated
steam at 1 atm pressure. Calculated the amount of steam condensed per hour.
4. The surface tension of water at 212F is 58.8 dyn/cm for the vapor in contact with the
liquid. Assuming that the saturated vapor inside a bubble is at 213F while the
surrounding liquid is saturated at 212F, calculate the size of bubble.
5. A 5 mm diameter copper heater rod is submerged in water at 1 atm. The temperature
excess is 11C. Estimate the heat loss per unit length of the rod.
6. A horizontal tube 3 mm in diameter and 7.5 cm long is submerged in water at 1.6 atm.
Calculate the surface temperature necessary to generate a heat flux of 0.2 MW/m 2.