Study of Critical Heat Flux during Natural Convective Boiling in Vertical Tubes and Vertical Annular Tubes Submerged in Saturated Liquids

An experimental and theoretical study was carried out for the critical heat flux (CHF) during natural convective boiling in uniformly heated vertical tubes and vertical annular tubes submerged in saturated liquids. By adopting a simple mixing in-tube flow model, a generalized approximate formula was derived which agrees well with the CHF data of the tubes, annular tubes and rectangular channels submerged in water or other liquids under various pressure conditions. The common faults of various experimantal correlations were also discussed theoretically.