Vertical natural convection heat transfer data for an enclosed fluid

摘要

Natural convection flow of enclosed fluids with high temperature gradients can result in extremely high heat transfer rates. This phenomenon must be accurately modeled in order to predict the correct temperature distribution of structures in contact with the convecting flow. Ignoring the heat transfer by natural convection and assuming only the normal molecular heat conduction of stagnant water can result in an underestimate of the heat transfer by several orders of magnitude. Natural convection of enclosed fluids is different than free convection to a non-enclosed (i.e., open) ambient atmosphere since the recirculating fluid flow pattern can have a significant influence on the resultant heat transfer. Rayleigh numbers extending the entire range from conditions where free convection is a second order effect (e.g., Ra < 3000) to those where turbulent free convection dominates (e.g., Ra > 10(sup 5)) were tested and the results described. Inconsistencies between earlier investigations reported in the literature are resolved because of the wide test range capability. Correlations of the data in the form of Nusselt number as a function of Rayleigh number are provided for 0 < Ra < 10(sup l2).