Documents disponibles écrits par cet auteur

Negatively buoyant plume flow in a baffled heat exchanger / Sandra K. S. Boetcher in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 3 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [034502/1-7] Titre : Negatively buoyant plume flow in a baffled heat exchanger Type de document : texte imprimé Auteurs : Sandra K. S. Boetcher, Auteur ; F. A. Kulacki, Auteur ; Jane H. Davidson, Auteur Année de publication : 2011 Article en page(s) : pp. [034502/1-7] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Thermal  stores  Immersed  heat  exchanger  Negatively  buoyant  flow Index. décimale : 621.47 Résumé : A numerical simulation of transient two-dimensional negatively buoyant flow into a straight baffle situated below an isothermal circular cylinder in an initially isothermal enclosure is presented for both an adiabatic and a highly conducting baffle for Rayleigh numbers from 106 to 107. Results show the effects of baffle offset, width, and length on the point where viscous flow develops and on velocity profiles within the baffle. Results are interpreted to guide the design of straight baffles to reduce destruction of stratification in thermal stores using an immersed heat exchanger. The preferred geometry is a low-conductivity baffle of width equal to the effective width of the heat exchanger and 15 or more cylinder diameters in length to ensure nearly fully developed flow at the baffle outlet. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Negatively buoyant plume flow in a baffled heat exchanger [texte imprimé] / Sandra K. S. Boetcher, Auteur ; F. A. Kulacki, Auteur ; Jane H. Davidson, Auteur . - 2011 . - pp. [034502/1-7]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [034502/1-7] Mots-clés : Thermal  stores  Immersed  heat  exchanger  Negatively  buoyant  flow Index. décimale : 621.47 Résumé : A numerical simulation of transient two-dimensional negatively buoyant flow into a straight baffle situated below an isothermal circular cylinder in an initially isothermal enclosure is presented for both an adiabatic and a highly conducting baffle for Rayleigh numbers from 106 to 107. Results show the effects of baffle offset, width, and length on the point where viscous flow develops and on velocity profiles within the baffle. Results are interpreted to guide the design of straight baffles to reduce destruction of stratification in thermal stores using an immersed heat exchanger. The preferred geometry is a low-conductivity baffle of width equal to the effective width of the heat exchanger and 15 or more cylinder diameters in length to ensure nearly fully developed flow at the baffle outlet. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Use of a shroud and baffle to improve natural convection to immersed heat exchangers / Sandra K. S. Boetcher in Transactions of the ASME. Journal of solar energy engineering, Vol. 133 N° 1 (Fevrier 2011) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 1 (Fevrier 2011) . - 07 p. Titre : Use of a shroud and baffle to improve natural convection to immersed heat exchangers Type de document : texte imprimé Auteurs : Sandra K. S. Boetcher, Auteur ; F. A. Kulacki, Auteur ; Jane H. Davidson, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Heat  exchangers  Natural  convection  Numerical  analysis  Solar  power  Tanks  (containers)  Thermal  energy  storage  Transient  analysis  Water  storage Index. décimale : 621.47 Résumé : Optimizing heat transfer during the charge and discharge of thermal stores is crucial for high performance of solar thermal systems for domestic and commercial applications. This study models a sensible water storage tank for which discharge is accomplished using a heat exchanger immersed in the storage fluid. The heat exchanger is a two-dimensional isothermal cylinder in an adiabatic enclosure with no initial stratification. An adiabatic shroud and baffle whose geometry is parametrically varied is placed around and below the cylinder. Transient numerical simulations of the discharge process are obtained for 105 < RaD < 107, and estimates of the time needed to discharge a given fraction of the initial stored energy are obtained. We find that a short baffle is least effective in increasing heat transfer rates. The performance benefit is greatest early in the transient discharge period when the buoyant flow in the store is strongest. As with all flow control devices, the benefit decreases as energy is extracted from the tank and the temperature difference driving the flow decreases. The use of a shroud increases the transient Nusselt number by as much as twentyfold. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000134000001 [...] [article] Use of a shroud and baffle to improve natural convection to immersed heat exchangers [texte imprimé] / Sandra K. S. Boetcher, Auteur ; F. A. Kulacki, Auteur ; Jane H. Davidson, Auteur . - 2012 . - 07 p. Solar energy Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 1 (Fevrier 2011) . - 07 p. Mots-clés : Heat  exchangers  Natural  convection  Numerical  analysis  Solar  power  Tanks  (containers)  Thermal  energy  storage  Transient  analysis  Water  storage Index. décimale : 621.47 Résumé : Optimizing heat transfer during the charge and discharge of thermal stores is crucial for high performance of solar thermal systems for domestic and commercial applications. This study models a sensible water storage tank for which discharge is accomplished using a heat exchanger immersed in the storage fluid. The heat exchanger is a two-dimensional isothermal cylinder in an adiabatic enclosure with no initial stratification. An adiabatic shroud and baffle whose geometry is parametrically varied is placed around and below the cylinder. Transient numerical simulations of the discharge process are obtained for 105 < RaD < 107, and estimates of the time needed to discharge a given fraction of the initial stored energy are obtained. We find that a short baffle is least effective in increasing heat transfer rates. The performance benefit is greatest early in the transient discharge period when the buoyant flow in the store is strongest. As with all flow control devices, the benefit decreases as energy is extracted from the tank and the temperature difference driving the flow decreases. The use of a shroud increases the transient Nusselt number by as much as twentyfold. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000134000001 [...]

Use of a shroud and baffle to improve natural convection to immersed heat exchangers / Sandra K. S. Boetcher in Transactions of the ASME. Journal of solar energy engineering, Vol. 134 N° 1 (Janvier/Fevrier 2012) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 134 N° 1 (Janvier/Fevrier 2012) . - 7 p. Titre : Use of a shroud and baffle to improve natural convection to immersed heat exchangers Type de document : texte imprimé Auteurs : Sandra K. S. Boetcher, Auteur Année de publication : 2012 Article en page(s) : 7 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Heat  exchangers,  Natural  convection,  Numerical  analysis,  Solar  power,  Tanks  (containers),  Thermal  energy  storage,  Transient  analysis,  Water  storage Résumé : Optimizing heat transfer during the charge and discharge of thermal stores is crucial for high performance of solar thermal systems for domestic and commercial applications. This study models a sensible water storage tank for which discharge is accomplished using a heat exchanger immersed in the storage fluid. The heat exchanger is a two-dimensional isothermal cylinder in an adiabatic enclosure with no initial stratification. An adiabatic shroud and baffle whose geometry is parametrically varied is placed around and below the cylinder. Transient numerical simulations of the discharge process are obtained for 105 < RaD < 107, and estimates of the time needed to discharge a given fraction of the initial stored energy are obtained. We find that a short baffle is least effective in increasing heat transfer rates. The performance benefit is greatest early in the transient discharge period when the buoyant flow in the store is strongest. As with all flow control devices, the benefit decreases as energy is extracted from the tank and the temperature difference driving the flow decreases. The use of a shroud increases the transient Nusselt number by as much as twentyfold. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000134000001 [...] [article] Use of a shroud and baffle to improve natural convection to immersed heat exchangers [texte imprimé] / Sandra K. S. Boetcher, Auteur . - 2012 . - 7 p. Solar energy Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 134 N° 1 (Janvier/Fevrier 2012) . - 7 p. Mots-clés : Heat  exchangers,  Natural  convection,  Numerical  analysis,  Solar  power,  Tanks  (containers),  Thermal  energy  storage,  Transient  analysis,  Water  storage Résumé : Optimizing heat transfer during the charge and discharge of thermal stores is crucial for high performance of solar thermal systems for domestic and commercial applications. This study models a sensible water storage tank for which discharge is accomplished using a heat exchanger immersed in the storage fluid. The heat exchanger is a two-dimensional isothermal cylinder in an adiabatic enclosure with no initial stratification. An adiabatic shroud and baffle whose geometry is parametrically varied is placed around and below the cylinder. Transient numerical simulations of the discharge process are obtained for 105 < RaD < 107, and estimates of the time needed to discharge a given fraction of the initial stored energy are obtained. We find that a short baffle is least effective in increasing heat transfer rates. The performance benefit is greatest early in the transient discharge period when the buoyant flow in the store is strongest. As with all flow control devices, the benefit decreases as energy is extracted from the tank and the temperature difference driving the flow decreases. The use of a shroud increases the transient Nusselt number by as much as twentyfold. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000134000001 [...]