Heat Transfer to Mercury Flowing In-Line Through a Bundle of Circular Rods

Abstract

Experimental results were obtained for the case of in-line flow of mercury through an unbaffled bundle of circular rods, and they were compared with theoretical predictions. The bundle consisted of 13 one-half-in-dia rods arranged in an equilateral triangular pattern, the pitch:diameter ratio being 1.750. Measurements were taken only on the central rod. Six different rods were tested. All rods in the bundle were electrically heated to provide equal and uniform heat fluxes throughout the bundle. The rods were of the Calrod type. The test rods had copper sheaths with fine thermocouples imbedded below the surface for measuring surface temperatures. Some rods were plated with a layer of nickel, followed by a very thin layer of copper, to provide “wetting” conditions, while others were chromeplated to provide “nonwetting” conditions. Heat-transfer coefficients were obtained under the following conditions: (a) Prandtl number, 0.02; (b) Reynolds number range, 7500 to 200,000; (c) Peclet number range, 150 to 4000; (d) “Wetting” versus “nonwetting”; (e) Both transition and fully established flow; (f) Variation of Lf/De ratio from 4 to 46. The precision of the results is estimated to be within 2 to 3 percent. An interesting finding, consistent with earlier predictions, was that the Nusselt number, under fully established turbulent-flow conditions, remained essentially constant, at the lower end of the turbulent flow regime, until a Reynolds number of about 40,000 was reached.

CFD analysis of thermal–hydraulic behavior of heavy liquid metals in sub-channels

“…20 presents the effect of turbulent Prandtl number on the calculated Nusselt number in rod bundles. For comparison the results from the heat transfer correlation of Maresca and Dwyer (1964) is also indicated in this figure. In the range of low turbulent Prandtl number, the CFD results show a sharp decrease in the Nusselt number with increasing turbulent Prandtl number.…”

“…To verify the CFX application to HLM heat transfer in rod bundles, numerical analysis was carried out for the experimental condition in (Maresca and Dwyer, 1964). This experiment was carried out in a vertically arranged triangular rod bundle cooled by mercury with a rod diameter of 12.7 mm and a pitchto-diameter ratio of 1.75.…”

Thermal Hydraulic Experimental Test Article (FY2020 Status Report)

“…9. = 4.82 + 0.0185 • 0.827 (9) On the shell side, the Nusselt number was found using a correlation for in-line flow through unbaffled rod bundles in wide spaced arrays (tube pitch / tube diameter = P/D > 1.35) [10], Eq. 10.…”

Investigation of Local Heat Transfer Enhancement in Generic Liquid Metal–Cooled Fuel Assemblies with Empirical Models

“…This is the ε coefficient, depicted in Eqs. (7,8,10,11). The pin diameters are between 5 and 25 mm, while the pitch-to-diameter ratio is in the range of 1.1 to 2.0.…”

“…Nu∞•RNE as a function of the dimensionless distance from the entrance for different Péclet numbers (Figure adopted from[9]. Experimental data taken from[10])…”