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Modelling of Heat Transfer for Convection-boosted Flat Vertical Radiator Surfaces : An investigation of how heat transfer is influenced by radiator height and freestream air velocity

In this thesis, a calculation model is created to study a theoretical radiator-like configuration, consisting of a flat vertical plate heated with a constant capacity rate. This lumped capacitance model is partly created to more theoretically look at radiators with add-on-fans, but also to in such a setting look at fundamental heat transfer relationships. System heat transfer is studied for various heights, H (m), and freestream velocities, u (m/s). These results are then subject to validation, where comparison is made with values derived from two relevant reference studies. It is found that polynomial fits well describe the results obtained from calculation. The relationships for heat transfer Q (W), heat flux q (W/m2) thus become: 𝑄(𝐻,𝑒) = π‘Ž00Β + π‘Ž01𝑒 + π‘Ž10𝐻 + π‘Ž11𝐻𝑒 + π‘Ž02𝑒2Β (W) π‘ž(𝐻,𝑒) =𝑄/𝐻= π‘Ž00𝐻-1Β + π‘Ž01𝐻-1𝑒 + π‘Ž10Β + π‘Ž11𝑒 + π‘Ž02𝐻-1𝑒2Β (W/m2) For these relationships, polynomial coefficients π‘Ž00, π‘Ž01, π‘Ž10, π‘Ž11Β and π‘Ž02Β are found for three temperature set-ups of system supply and return temperature at zero freestream velocity: 55/45, 45/35 and 35/25 (Β°C). These values are chosen as they correspond to standard temperatures for low-temperature heating set-ups. Model validation is successful for the case of natural convection (u = 0), whereas difficulties are encountered for the cases of mixed and forced convection. Reasons for these difficulties are discussed and it is concluded that there is a need for more experimental studies of flat vertical plates with non-isothermal wall temperature profiles.

Identiferoai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-220138
Date January 2017
CreatorsScheibe, Oskar
PublisherKTH, StrΓΆmnings- och klimatteknik
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeStudent thesis, info:eu-repo/semantics/bachelorThesis, text
Formatapplication/pdf
Rightsinfo:eu-repo/semantics/openAccess
RelationTRITA-STKL ; 2017:02

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