Accurate analytical modeling of flat plate solar collectors: Extended correlation for convective heat loss across the air gap between absorber and cover plate
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Autor:innen
Autor:in (Körperschaft)
Publikationsdatum
2015
Typ der Arbeit
Studiengang
Typ
01A - Beitrag in wissenschaftlicher Zeitschrift
Herausgeber:innen
Herausgeber:in (Körperschaft)
Betreuer:in
Übergeordnetes Werk
Solar Energy
Themenheft
DOI der Originalpublikation
Link
Reihe / Serie
Reihennummer
Jahrgang / Band
122
Ausgabe / Nummer
Seiten / Dauer
1214-1224
Patentnummer
Verlag / Herausgebende Institution
Elsevier
Verlagsort / Veranstaltungsort
Auflage
Version
Programmiersprache
Abtretungsempfänger:in
Praxispartner:in/Auftraggeber:in
Zusammenfassung
The well-established correlation of Hollands et al. (1976), which is applicable to isothermal boundaries and Rayleigh numbers up to 105, underestimates the convective heat loss across the air gap of flat plate solar collectors with tube-and-sheet type absorbers both in normal operation and at stagnation. Two reasons for this discrepancy were identified. (1) The Rayleigh number of the air gap above absorbers with highly selective coatings can be three times as high as the application limit. (2) The absorber is not isothermal during normal operation. Based on a literature study and theoretical considerations the application limit of the correlation was extended to Ra =3 105. By means of an analytically derived correction parameter, the correlation was adapted to non-isothermal boundary conditions. For the cost- and efficiency optimization of flat-plate collectors an accurate analytical model was developed, based on the model of Duffie and Beckman (1991), enhanced by the new correlation for convective heat loss between absorber and cover plate. The model was validated against data of standardized collector tests. It is able to predict both the thermal efficiency and the stagnation temperature within the uncertainty limit of the standardized test method EN 12975-2 (CEN, 2006).
Schlagwörter
Solar collector, Convective heat loss, Analytical model, Thermal efficiency, Stagnation temperature, Cost reduction
Fachgebiet (DDC)
Veranstaltung
Startdatum der Ausstellung
Enddatum der Ausstellung
Startdatum der Konferenz
Enddatum der Konferenz
Datum der letzten Prüfung
ISBN
ISSN
0375-9865
1471-1257
0038-092X
1471-1257
0038-092X
Sprache
Englisch
Während FHNW Zugehörigkeit erstellt
Nein
Publikationsstatus
Veröffentlicht
Begutachtung
Peer-Review der ganzen Publikation
Open Access-Status
Lizenz
Zitation
EISMANN, Ralph, 2015. Accurate analytical modeling of flat plate solar collectors: Extended correlation for convective heat loss across the air gap between absorber and cover plate. Solar Energy. 2015. Bd. 122, S. 1214–1224. DOI 10.1016/j.solener.2015.10.037. Verfügbar unter: https://irf.fhnw.ch/handle/11654/32269