Natural-Convection Heat Transfer in Liquids Confined by Two Horizontal Plates and Heated From Below

Abstract

This paper presents results of an experimental investigation of convective heat transfer in liquids placed between two horizontal plates and heated from below. The liquids used were water, silicone oils of 1.5, 50, and 1000 centistoke kinematic viscosities, and mercury. The experiments covered a range of Rayleigh numbers between 1.51(10)5 and 6.76(10)8. and Prandtl numbers between 0.02 and 8750. Tests were made in cylindrical containers having copper tops and bottoms and insulating walls. For water and silicone oils the container was 5 in. in diam and 2 in. high. For mercury, two containers were used, both 5.28 in. in diameter, but one 1.39 in. high and another 2.62 in. high. In all cases the bottom plates were heated by electric heaters. The top plates were air-cooled for the water and silicone-oil experiments and water-cooled for the mercury tests. To prevent amalgamation, the copper plates of the mercury container were chromium plated. Surface temperatures were measured by thermocouples embedded in the plates. The test results indicate that the heat-transfer coefficients for all liquids investigated may be determined from the relationship Nu=0.069Ra13Pr0.074 In this equation the Nusselt and Rayleigh numbers are based on the distance between the copper plates. The results of this experiment are in reasonable agreement with the data reported by others who used larger containers and different fluids.

A study of the Sherwood–Rayleigh relation for water undergoing natural convection-driven evaporation

“…This confirms prior work which has shown that n ¼ 1=4 for low Ra, but increases at larger Ra [20]. There is abundant research in the heat transfer literature to suggest that above a relatively low value of Ra; m ffi 0:3 with relatively small changes in m with increasing Ra, similar to what is seen here with evaporation [26][27][28][29].…”

“…For example, Globe and Dropkin [26] found m ¼ 1=3, Chu and Goldstein [27] show m ¼ 0:278, and Niemela et al [28] give m ¼ 0:309 for a range of Ra spanning 11 orders of magnitude. Many other studies exist, and a good review is provided in Chavanne et al [29] who show that with few exceptions m ffi 0:3.…”

Minimum friction velocity and heat transfer in the rough surface layer of a convective boundary layer

“…found by Globe and Dropkin (1959) for turbulent Rayleigh-Benard convection between two horizontal plane plates with gap H heated uniformly from below. The measurements were obtained for 0.025 m < H < 0.13 m. This indicates that Equations (6, 10) describe the heat transfer over smooth surfaces while Equation (5) is designed for rough surfaces.…”

Research on the possibility of material mixing and interaction in the lower head based on specific corium relocation process

“…The heat transfer from the metal layer to the vessel wall is calculated from Churchill-Chu and Globe-Dropkin correlations (Churchill and Chu, 1975;Globe and Dropkin, 1959) in AP1000 PRA report. Table 7 makes the comparison of several parameters obtained by CFD code and correlations.…”