Abstract
Presented in this abstract are the considerations and results of an investigation of forced convective heat loss from the surface of flat-plate model collectors flush mounted on the roof of a model residential house. Forced convection with air as the external fluid was treated.
The study was motivated by the need to better understand heat transfer from the top surface of flat-plate solar energy collectors. The experimental work dealt with heat transfer from the top of rectangular parallelpipeds flush mounted on roof of a model residential house. The smallest collector was 7.62×10−2 m long by 7.62×10−2 m wide by 3.3×10−2 m deep, and the largest collector was 15.875×10−2 m long by 15.875×10−2 m wide by 3.3×10−2 m deep. These small scale units are expected to simulate heat loss pattern from a flat-plate solar collector placed over the roof of a residential dwelling. Experiments were performed to determine the average heat transfer coefficients for forced convective air flow over the surface of the model collector which was inclined and yawed relative to the incoming air flow. The wind speeds varied approximately from 2.5 m/sec to 15 m/sec, the flow was laminar for all wind speeds.
Zusammenfassung
Es werden Vorüberlegungen und Ergebnisse bezüglich einer Untersuchung mitgeteilt, deren Ziel es war, die Wärmeverluste infolge Zwangskonvektion von Flachplatten-Kollektoren auf den Dächern von Wohnhäusern im Kleinmodell zu bestimmen. Angeregt wurde die Studie durch den Bedarf an genaueren Berechnungsunterlagen für den Wärmeübergang an Flachplatten-Solarkollektoren. Die für das Experiment verwendeten zwei Kollektoren waren quadratisch, mit den Seitenlägen 7,62 bzw. 15,9 cm, bei jeweils 3,3 cm Tiefe. Die Versuche lieferten unter Zwangskonvektion mittlere Wärmeübergangskoeffizienten an den Oberflächen der Modellkollektoren, welche zur ankommenden Luftströmung sowohl geneigt als auch gedreht orientiert waren. Bei laminarer Strömung lagen die Anströmgeschwindigkeiten zwischen 2,5 and 15 m/s.
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Onur, N. Forced convection heat transfer from a flat-plate model collector on roof of a model house. Warme - und Stoffubertragung 28, 141–145 (1993). https://doi.org/10.1007/BF01541111
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DOI: https://doi.org/10.1007/BF01541111