ANALYTICAL STUDY OF CRITICAL HEAT-FLUX IN 2-PHASE THERMOSIPHON - RELATIONSHIP BETWEEN MAXIMUM FALLING LIQUID RATE AND CRITICAL HEAT-FLUX

An analytical study has been done on the critical heat flux of a two-p hase thermosyphon, in which a liquid film and a vapor flow exist in a countercurrent annular flow. The CHF point on the thermosyphon is prov ed to correspond to a maximum falling liquid rate fed to the thermosyp hon, which can be determined from three equations of momentum, its par tial derivative with void fraction, and mass balance in the thermosyph on. This maximum point, furthermore, becomes identical to the point at which an envelope line generated from the momentum equation and its p artial derivative intersects the mass balance line. The CHF calculated from the maximum liquid rare is found to be in fairly good agreement with the existing CHF data.