Turbulent natural convection in an enclosure formed by an array of vertical cylinders
A number of situations can be hypothesized to occur in an advanced or special purpose nuclear reactor such that the core is filled with a gas but there is no forced flow to remove the thermal energy evolved. Typically, the dimensions are so large that the magnitudes of the governing parameters indicate that the flow regime is probably turbulent. The generic situation considered in the present work is natural convection between heated, slender, vertical, circular cylinders and a surrounding array of cooler vertical cylinders in a triangular pattern. Experiments were conducted by resistively heating a vertical circular cylinder of length-to-diameter ratio of about 160 centered inside a concentric perforated tube which was, in turn, surrounded by three larger diameter tubes cooled internally with water flow. The medium was air. In order to deduce the contribution due to thermal radiation, thermal emissivities of the tubes were determined in-situ during the experiment and the emissivities of samples of the surfaces involved were measured separately. The ratio of the test section temperature to the cooling tube temperature was varied up to 2.6 by adjusting the electrical power. The Rayleigh number, based on tube diameter and properties evaluated at the cooling tube temperature, ranged from 2.9 {times} 10{sup 4} to 9.2 {times} 10{sup 5}. Results indicate that the convective heat transfer parameters for the perforated tube are about fifteen per cent higher than for the smooth bare tube centered in the same position relative to the array. The Nusselt number for convective heat transfer across the annulus-between the heated test section and the perforated tube corresponded to parallel laminar flow. Data with water films flowing down the outside surfaces of the cooling tubes demonstrated no significant change in the convective heat transfer parameters deduced.
- Research Organization:
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 10163468
- Report Number(s):
- EGG-NE-10237; ON: DE92017994
- Resource Relation:
- Other Information: PBD: Apr 1992
- Country of Publication:
- United States
- Language:
- English
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Turbulent natural convection between a perforated vertical cylinder and a surrounding array
Turbulent natural convection between a perforated vertical cylinder and a surrounding array
Related Subjects
22 GENERAL STUDIES OF NUCLEAR REACTORS
REACTOR CORES
NATURAL CONVECTION
CYLINDERS
HEAT TRANSFER
HYDRAULICS
NUSSELT NUMBER
TUBES
LOSS OF COOLANT
DESIGN BASIS ACCIDENTS
ENGINEERING DRAWINGS
EXPERIMENTAL DATA
420400
220200
220100
HEAT TRANSFER AND FLUID FLOW
COMPONENTS AND ACCESSORIES
THEORY AND CALCULATION