THEORICAL INVESTIGATION ON THE EFFECTS OF THE FIN-TUBE CONTACT ZONES ON THE EXCHANGED CONVECTIVE HEAT FLUX BETWEEN A FINNED-TUBE AIR-COOLED CONDENSER AND ITS SURROUNDING ENVIRONMENT

Abstract

Adding fins on the tubes of an air-cooled condenser allows to increase its heat transfer area.The purpose of this work is to investigate on the effects of the tube-fin contact zones on thecondenserconvectiveheattransferwiththesurroundingair.Itproposesamethodofdetermining the condenser outer surface and a ratio which compares the losses to the heat fluxgainsduetotheinputoffins.Thisratiocharacterizestheinfluenceofthefin-tubecontactzoneson the exchanged convective heat flux and informs whether or not their effect has to be takeninto account. The developed model allowed to obtain relations which give the condensereffective exchange outer surface which participates to convective heat transfers. The obtainedresults using Matlab software show that the ratio of the losses to the heat flux gains does notdepend on the number of fins. However, it increases with the number of tubes, with their outerdiameterandwiththefinthickness.Itisfoundthat,whenthisratioislessthan0.026,theeffectsof the fin-tube contact zones on the condenser convective heat transfer can be neglected.Otherwise,theseeffectshavetobetakenintoaccountwhendeterminingthecondenserexchanged heat fluxwith its outer environment.