EXPERIMENTAL-STUDY OF CRITICAL HEAT-FLUX IN OPEN 2-PHASE THERMOSIPHON

Critical heat flux in an open two-phase thermosyphon has been measured employing water, R113 and R22 for a wide range of L/D=4.8 to 960 and density ratio of rho(L)/rho(G)=6.17 to 1602. The CHF data measured, ar e found to be in fairly good agreement with those calculated from a cr iterion that the CHF takes place when reaches a maximum liquid falling rate in counter-current annular flow of liquid and vapor. Normal oper ation of the thermosyphon cannot be obtained at any liquid of water, R 113 and R22 for a small tube diameter of less than 2 mm.