CRITICAL HEAT FLUX IN A LONG, CURVED CHANNEL SUBJECTED TO CONCAVE HEATING

摘要

A theoretical model to predict critical heat flux in long, rectangular, curved channels is presented. Development is analogous to a model for long, straight channels previously proposed by the present authors. The model is based on the observation from a flow visualization study that vapor assumes a wavy, periodic distribution along the heated concave wall just prior to CHF such that liquid-surface contact is restricted to the troughs of the wave, called wetting fronts. When the idealized oscillatory liquid-vapor interface is lifted off the surface liquid can no longer rewet the surface to remove heat and CHF ensues. This lift-off of hte interface occurs when vapor momentum emanating from a wetting front due to vigorous boiling overcomes the pressure force which serves to hold the interface in contact with the surface.