Natural convective heat transfer from a horizontal cylinder in the presence of nearby walls

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Abstract

This work deals with thc influence of unheated vertical walls, symnietrically placed with respect to a single heated horizontal cylinder, upon the natural convection heat transfer froni a heated cylinder. The study is experimental. By using air, water and Frecon 113 as working flnids, a Rayleigh number range of 10 to 500,000 lias been investigated. Various conibiuations of wall spacing and wall height have been examined. Empirical correlations of Nussclt number with Rayleigh nnmber and geometric parameters are presented. The presence of walls enhances heat transfer froni the cylinder for certain geometries. Wall spacings smaller than two diameters have not been investigated.

Abstract

Le present travail a trait à l'inflocnce dc lxirois verticalcs et non cliauffkes (disposkes synikttriquement par rapport h uii sciil cylindre horizontal ct chauffk) siir le transfert de la chaleiir par convection natnrelle A partir du cylinclrc chaiiffit. Dans l'ktude expkrinieiitale, on a employit l'air, I'caii et Ic “Freon 11 3” conime fluides actifs, ainsi que des iioiiibres Kavleigli kchclorin6s entre 10 et 500,000; on a aussi utilist divcrses coiiihinaisoiis dc hauteur dc parois et d'espaceiiiciit entre celles-ci. On prhsente des correlations einpiriquc entrc le nonibre de Niissclt ct celuide Rayleigh et des paranigéométriqiics. La présciice cles parois favorise le transfert de la claleur á piirtir chi cyliiidre dam le c as de certaincs fornies géométriqiics. on n'i pas étudie dcs cspacenieirts entre les parois qui étaient inlkrieurc d la longuciir dc deiix cliaiidtres.

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