1be Effect of Partial Baffles on Natural Convection in an Inclined Rectangular Enclosure

Complete partitioning wilb boneyoomb-Iike struetuIes bas previously been proposed to reduce heat transfer by natural convection. at the expense of direct oonduction through the Struet\I.fe. in Ihe thin rectangular enclosures used for solar colleclors. 11tis paper presents the results of a sludy of the use of partial ballles for this purpose. 1be heat transfer rate was measured in glycerol using heal !Iw< meters in both the heated and cooled surfaces. and three-ions of 254 x lbis paper apparently presents the first results for the eflect 177.8 x 19.05 mm served as the lap and bonom 01 the enof a partial baffle DOnna! to the heated and cooled surfaces closwe and also of the vacuum chamber. Waler jackets ofan iDclined rectangularenclosure. Streak.Jineswere photowere attached to these plates to maintain thc:m at differ.enl. graphed and heal transler rales were measured lor six batnear-unilonn temperarures. The periphery of both oopper Oe-r0n6gurations at a series of inclinations of the enclosure plales was milled our to provide space for a silver-roated. abow the shorter horizontal dimension. front-swface mirror. The purpose of tbe-:;c mirrors was to minimize radiative beat transfer betweeD the vertical surThe internal dimensions 01 !be test enclosure ....re 63.50 x fa<= of !he test end","", and the portion of the copper 31.75 x 31.75 mrn, the latter being the height, giving plates comprising the top and bonom surf.... of the ..peel ratios of 2/1 (width!heighl) and 1/1 (depthlheighl). vacuum chamber. Tbe wrtial sides of !be tesl ceO ....re Plexiglas with a thickIntroduction and radiant inlerchange between the partitions and the enclosing surfaces were taken inlO aa:ounL Tbe wort reported herein is part ala oonrinuing investigaEmery [51 found thai a central, wrtical. parJaI baffle in a tion 01 narural oonvecrion in enclosures. with the primary ralI, lW<>-dimensional enclosure, heated and cooled on the objective of reducing heal losses across Ihe air film in solar opposing vertical sides, had a negligible elfeCl on the flow ooUector>.1n reoenl prior wort [1. 21. il was found thaI nonfield and on the rate of heal uansfer. This geometry wn uniformities in the sucf.ace temperatures generally had an chosen to simulate the cooling cbanllel of a nuclear reactor. adverse eflect, i.e., they increased the rare of heal transfer. His results are nol surprising because the baffIe, although The specific objective 01 the currenl work is 10 investigate extending over 90,"0 of the height of the enclosure. was in experimenlally the effect 01 partial baffles in suppressing the stagnanl cenlral .:ore 01 the fluid. convective heat transfer. Prior work on !be effect of battles Probert and Ward [6J and Janikowski cl al [7) in'estigated on natural oonvection in encloswes has generally been for the effect of short baffles extending ~rti. Cane el a1. [3) and Aroold el al. [41 found ,hat placed near the cold wall and Ihe lower baffle near the hot existing correlations for single enclosures were applicable wall. for the individual cells if conduction along the partitions_ Several, recent inves.ligalions (e.g.. 18) and [9) are concerned wilh (he effect of partial room-Jividers on nalural con• Mobil Research. and nc...elopment CorporatiCin. P'aulsboro. vection; but the boundar~.... condiliuns are not relc ... ant 10 NJ. CSA Ihis im,·cstigation. HO\l,e ..er. !he: following Iwo more: d()~ly •• Dep3r1m~n( of IndU5lrial and Mechanica.l Engin~ering. rdall:d P3~PII have arr~~red ,inee (hi" inn: ..lig;l!inn u:;.1'> Ola..a.ma L'ni1o'entlv. Oka1/.1m~. Japan complctl·t.i. Ch.mg 1.:1 at 1111\ 1.1.>i,.:d 1\l'\i~c:-Jilf..:r~nt:C: cakula••• 1bc ·Cm\..~rsiIY of ·PennsYh'ama. Phiiaddphia. fA. 191(~. lions 10 JCIl:rminc the lamin~r tll)\\," palh:rn.. am.l ratl: of USA