ISSN Online: 2377-424X
ISBN Print: 0-89116-130-9
International Heat Transfer Conference 6
POST-NUCLEATE BOILING AND CRITICAL HEAT FLUX FROM HORIZONTAL HEATED SURFACES
Abstract
Based on a study of the mechanics of boiling at the critical heat flux (CHF) on horizontal heated surfaces, hydrodynamic models are suggested to describe the critical heat flux region for horizontal cylinders in saturated and subcooled liquids. The models have been shown to bring out correctly the physical basis for the characteristic variation of critical heat flux with heater diameter. Correlations are developed for the critical heat flux, based on CHF data for water and several viscous and non-viscous organic liquids. In the case of liquids substantially more viscous than water, such as subcooled glycerol or cyclohexanol at atmospheric pressure, the augmentation of the critical heat flux with the degree of subcooling is shown to be offset by the effect of viscosity. At very high subcoolings, even an actual reversal of the trend is observed. It is concluded that the physical basis for the CHFs is well represented by the hydrodynamic prediction methods proposed in this paper.