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• 1. [Article] An experimental investigation of natural convection heat transfer from an array of uniformly heated vertical cylinders to mercury

  An experimental investigation was conducted for natural convection heat transfer in an array of uniformly heated vertical cylinders in mercury. The test section consisted of seven electrically heated cylinders ...

  Citation × Citation Citation Abstract Copy Title: An experimental investigation of natural convection heat transfer from an array of uniformly heated vertical cylinders to mercury Author: Dutton, Jonathan Craig, 1951- An experimental investigation was conducted for natural convection heat transfer in an array of uniformly heated vertical cylinders in mercury. The test section consisted of seven electrically heated cylinders of 1.365 inch diameter and 3.825 inch heated length arranged in an equilateral triangular pattern. In order to preclude side flow effects, each seven pin bundle was surrounded by an enclosure tube with unheated half cylinders attached to the tube. Temperatures were measured with a stretched wire thermocouple probe which was designed to minimize flow disturbance effects. Four geometries were studied: the single vertical cylinder (P/D = ∞), and three bundle spacings, P/D = 1.5, 1.3, and 1.1, where P/D is the pitch-to-diameter ratio. The heat transfer results are presented in terms of the local Nusselt number and local modified Grashof number with the range on the Grashof number being 10⁵ < Gr[superscript *][subscript x] < 10¹⁰. The stretched wire probe results for the single cylinder are in agreement with those taken with an L-shaped probe and with previous experimental work. The bundle results were found to depend parametrically on both the heat flux and cylinder spacing. For the range investigated, the spacing effect was found to be much more significant than that of heat flux. The heat transfer results were found to depend significantly on circumferential position for P/D = 1.1, however circumferential dependence for the wider bundles was negligible. Rod-average correlations for the four geometries are also presented. The characteristics of the fluid temperature field were also studied. The trends observed in the mean temperature profiles for the various conditions are in agreement with those expected for this confined flow situation. In addition, fluctuations in the fluid temperatures were encountered and recorded. The trends shown by these disturbances are similar to those found for the previously studied vertical channel. The fluctuations were of largest amplitude for P/D = 1. 5, while those for P/D = 1.3 were slightly less severe, and those for the single cylinder and P/D = 1. 1 were negligible. The flow regimes thought to be encountered were the unstable laminar regime for P/D = 1.5 and 1.3, and the stable laminar one for the single cylinder and P/D = 1.1. Title: An experimental investigation of natural convection heat transfer from an array of uniformly heated vertical cylinders to mercury Author: Dutton, Jonathan Craig, 1951- An experimental investigation was conducted for natural convection heat transfer in an array of uniformly heated vertical cylinders in mercury. The test section consisted of seven electrically heated cylinders of 1.365 inch diameter and 3.825 inch heated length arranged in an equilateral triangular pattern. In order to preclude side flow effects, each seven pin bundle was surrounded by an enclosure tube with unheated half cylinders attached to the tube. Temperatures were measured with a stretched wire thermocouple probe which was designed to minimize flow disturbance effects. Four geometries were studied: the single vertical cylinder (P/D = ∞), and three bundle spacings, P/D = 1.5, 1.3, and 1.1, where P/D is the pitch-to-diameter ratio. The heat transfer results are presented in terms of the local Nusselt number and local modified Grashof number with the range on the Grashof number being 10⁵ < Gr[superscript *][subscript x] < 10¹⁰. The stretched wire probe results for the single cylinder are in agreement with those taken with an L-shaped probe and with previous experimental work. The bundle results were found to depend parametrically on both the heat flux and cylinder spacing. For the range investigated, the spacing effect was found to be much more significant than that of heat flux. The heat transfer results were found to depend significantly on circumferential position for P/D = 1.1, however circumferential dependence for the wider bundles was negligible. Rod-average correlations for the four geometries are also presented. The characteristics of the fluid temperature field were also studied. The trends observed in the mean temperature profiles for the various conditions are in agreement with those expected for this confined flow situation. In addition, fluctuations in the fluid temperatures were encountered and recorded. The trends shown by these disturbances are similar to those found for the previously studied vertical channel. The fluctuations were of largest amplitude for P/D = 1. 5, while those for P/D = 1.3 were slightly less severe, and those for the single cylinder and P/D = 1. 1 were negligible. The flow regimes thought to be encountered were the unstable laminar regime for P/D = 1.5 and 1.3, and the stable laminar one for the single cylinder and P/D = 1.1. Close