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The effect of the angle of inclination on the operation limiting heat flux of long R-134a filled thermosyphons / M. H. M. Grooten in Journal of heat transfer, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 5 (Mai 2010) . - pp. [051501-1/5] Titre : The effect of the angle of inclination on the operation limiting heat flux of long R-134a filled thermosyphons Type de document : texte imprimé Auteurs : M. H. M. Grooten, Auteur ; C. W. M. Van Der Geld, Auteur Article en page(s) : pp. [051501-1/5] Note générale : Physique Langues : Anglais (eng) Mots-clés : Heat  pipes  Thermosyphon  Heat  exchangers  R-134a  Limiting  heat  flux Index. décimale : 536 Chaleur. Thermodynamique Résumé : When traditional air-to-air cooling is too voluminous, long thermosyphons may offer a way out. For safe operation of heat exchangers equipped with thermosyphons, the limiting heat flux qlim[double-prime] is an important design parameter. Some literatures are found to deal with the operation limiting heat flux of closed two-phase thermosyphons. However, R-134a filled thermosyphons with large length-to-diameter (188) are hardly investigated up to now. Extrapolation of existing correlations to predict qlim[double-prime] in this case results in large scatter. The effect of the angle of inclination on qlim[double-prime] has not been considered until now. Dedicated experiments with a single thermosyphon with a large length-to-diameter ratio (188) and filled with R-134a are presented and analyzed. Effects of saturation temperature, filling ratio, and angle of inclination beta on the operational limiting heat flux have been investigated. The thermosyphon functions properly if beta<83 deg, and qlim[double-prime] is found to increase with increasing beta. With decreasing saturation temperature, qlim[double-prime] increases. The filling ratio is found not to be crucial if it exceeds 25%. Correlations are presented to accurately predict the operation limiting heat flux for thermosyphons with a L/d ratio up to 188. Because of the accounting for the above new aspects, these correlations are also relevant for filling refrigerants other than R-134a. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...] [article] The effect of the angle of inclination on the operation limiting heat flux of long R-134a filled thermosyphons [texte imprimé] / M. H. M. Grooten, Auteur ; C. W. M. Van Der Geld, Auteur . - pp. [051501-1/5]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 5 (Mai 2010) . - pp. [051501-1/5] Mots-clés : Heat  pipes  Thermosyphon  Heat  exchangers  R-134a  Limiting  heat  flux Index. décimale : 536 Chaleur. Thermodynamique Résumé : When traditional air-to-air cooling is too voluminous, long thermosyphons may offer a way out. For safe operation of heat exchangers equipped with thermosyphons, the limiting heat flux qlim[double-prime] is an important design parameter. Some literatures are found to deal with the operation limiting heat flux of closed two-phase thermosyphons. However, R-134a filled thermosyphons with large length-to-diameter (188) are hardly investigated up to now. Extrapolation of existing correlations to predict qlim[double-prime] in this case results in large scatter. The effect of the angle of inclination on qlim[double-prime] has not been considered until now. Dedicated experiments with a single thermosyphon with a large length-to-diameter ratio (188) and filled with R-134a are presented and analyzed. Effects of saturation temperature, filling ratio, and angle of inclination beta on the operational limiting heat flux have been investigated. The thermosyphon functions properly if beta<83 deg, and qlim[double-prime] is found to increase with increasing beta. With decreasing saturation temperature, qlim[double-prime] increases. The filling ratio is found not to be crucial if it exceeds 25%. Correlations are presented to accurately predict the operation limiting heat flux for thermosyphons with a L/d ratio up to 188. Because of the accounting for the above new aspects, these correlations are also relevant for filling refrigerants other than R-134a. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...]