Abo Bibliothek: Guest

ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

NATURAL CONVECTION FROM AN ARRAY OF ISOTHERMAL HORIZONTAL CYLINDERS: A COMBINED EXPERIMENTAL AND NUMERICAL INVESTIGATION

Get access (open in a dialog) DOI: 10.1615/IHTC16.cov.023938
pages 3167-3174

Abstrakt

Many industrial and domestic heating applications make use of tubular heat exchangers, where heat is transferred between an array of heated horizontal cylinders and a cooler surrounding fluid. In these situations, there can be significant interaction between the thermal plumes and the thermal boundary layers of nearby cylinders which can lead to an enhancement or a reduction in local heat transfer. In this study an experimental test facility has been designed to approximate the conditions of three isothermal horizontal cylinders of infinite length contained within an infinite fluid medium. The internal dimensions of the enclosure are chosen to minimize horizontal and vertical confinement effects and the enclosure is filled with approximately 200 liters of deoxygenated water to minimize temperature drift. The three heated cylinders are arranged in equilateral triangle configurations and the influence of the distance between cylinder centers on the local heat transfer characteristics is investigated for Rayleigh numbers of 2 × 106, 4 × 106 and 6 × 106. In conjunction with the experiments, a two-dimensional computational model was developed to approximate the experimental conditions using ANSYS Fluent 18.0. A parametric modelling approach enables the configuration and inter-cylinder spacing to be modified between simulations. Validation of the numerical procedure is achieved by comparison with published experimental and numerical studies for a single cylinder and pair of vertically aligned cylinders. For the three-cylinder cases, the simulated time-averaged Nusselt number profiles were found to be sensitive to Rayleigh number, configuration and inter cylinder spacing, and showed reasonable agreement with the experimental data across the parameter range.