An annular flow model for predicting liquid carryover into austenitic superheaters

A singular integro-differential equation model for dryout in LMFBR boiler tubes

“…Both droplet deposition from the gas core and the undercutting of any small waves present on the free surface and subsequent entrainment may add to or subtract from evaporative mass exchange. Deposition, as one might expect, seems to be directly proportional to the concentration of liquid droplets in the gas core (see (Fisher & Pearce, 1993), (Whalley, 1977) and (Whalley, 1987)); mass entrainment is an altogether more complicated phenomenon. At the operating conditions of interest the results of (Collier, 1972) suggest that neither entrainment nor deposition occurs rapidly.…”

“…At the dryout point the pipe wall temperature increases sharply since the thermal conductivity of the gas phase, which is now in direct contact with the wall, is much less than that of the liquid phase. The determination of the position of the dryout point is not a trivial problem (see (Fisher & Pearce, 1993)) since, for example, in the event that deposition of liquid drops occurs rapidly, the liquid film may reform, causing rewetting and a consequent drop in the temperature of the pipe wall. If the processes of dryout and rewetting occur periodically, thermal stresses may be set up in the wall which could lead to cracking of the pipe.…”