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Détail de l'auteur
Auteur Jane H. Davidson
Documents disponibles écrits par cet auteur
Affiner la rechercheBuoyant convection in superposed metal foam and water layers / V. Kathare in Journal of heat transfer, Vol. 132 N° 1 (Janvier 2010)
in Journal of heat transfer > Vol. 132 N° 1 (Janvier 2010) . - pp. [014503-1/4]
Titre : Buoyant convection in superposed metal foam and water layers Type de document : texte imprimé Auteurs : V. Kathare, Auteur ; F. A. Kulacki, Auteur ; Jane H. Davidson, Auteur Article en page(s) : pp. [014503-1/4] Note générale : Physique Langues : Anglais (eng) Mots-clés : Natural convection Metal foam Heat transfer enhancement Index. décimale : 536 Chaleur. Thermodynamique Résumé : Heat transfer measurements for natural convection in superposed metal foam and water layers are reported. Two systems heated at the lower boundary are considered: a water-filled cavity with a foam layer on the heated surface and a water-filled cavity with foam layers on the upper and lower surfaces. The present experiments use open cell copper foams with a nominal porosity of 92%, and the relative thicknesses of the water and foam layers are varied. Steady state Nusselt numbers show that the presence of foam on the boundaries enhances overall heat transfer coefficients over that for the water-only layer. Enhancement of overall Nusselt numbers varies from 12% to 60% depending on Rayleigh number. Sublayer configurations with foam on both heat transfer surfaces are more effective for enhancement than a configuration with foam only on the heated surface.
DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Buoyant convection in superposed metal foam and water layers [texte imprimé] / V. Kathare, Auteur ; F. A. Kulacki, Auteur ; Jane H. Davidson, Auteur . - pp. [014503-1/4].
Physique
Langues : Anglais (eng)
in Journal of heat transfer > Vol. 132 N° 1 (Janvier 2010) . - pp. [014503-1/4]
Mots-clés : Natural convection Metal foam Heat transfer enhancement Index. décimale : 536 Chaleur. Thermodynamique Résumé : Heat transfer measurements for natural convection in superposed metal foam and water layers are reported. Two systems heated at the lower boundary are considered: a water-filled cavity with a foam layer on the heated surface and a water-filled cavity with foam layers on the upper and lower surfaces. The present experiments use open cell copper foams with a nominal porosity of 92%, and the relative thicknesses of the water and foam layers are varied. Steady state Nusselt numbers show that the presence of foam on the boundaries enhances overall heat transfer coefficients over that for the water-only layer. Enhancement of overall Nusselt numbers varies from 12% to 60% depending on Rayleigh number. Sublayer configurations with foam on both heat transfer surfaces are more effective for enhancement than a configuration with foam only on the heated surface.
DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]
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 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041011/1-8]
Titre : Renewable hydrogen from the Zn/ZnO solar thermochemical cycle : a cost and policy analysis Type de document : texte imprimé Auteurs : Julia F. Haltiwanger, Auteur ; Jane H. Davidson, Auteur ; Elizabeth J. Wilson, Auteur Année de publication : 2011 Article en page(s) : pp. [041011/1-8] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Carbon Chemical energy conversion Hydrogen production II-VI semiconductors Renewable energy sources Solar energy conversion Zinc compounds Index. décimale : 621.47 Résumé : Flexible energy carriers are a crucial element of our energy portfolio. In a future in which a significant fraction of our energy comes from renewable sources, renewably produced fuels will be vital. The zinc/zinc-oxide thermochemical redox cycle is one approach for producing hydrogen using solar energy. This paper explores the level of carbon taxation necessary to make the cycle competitive with hydrogen production via methane reforming. In addition, the time frame for economic viability is assessed through the use of experience curves under minimal input, midrange, and aggressive incentive policy scenarios. Prior work projects that hydrogen produced by the zinc/zinc-oxide cycle will cost between $5.02/kg and $14.75/kg, compared with $2.40–3.60/kg for steam methane reforming. Overcoming this cost difference would require a carbon tax of ($119–987)/tCO2, which is significantly higher than is likely to be implemented in most countries. For the technology to become cost competitive, incentive policies that lead to early implementation of solar hydrogen plants will be necessary to allow the experience effect to draw down the price. Under such policies, a learning curve analysis suggests that hydrogen produced via the Zn/ZnO cycle could become economically viable between 2032 and 2069, depending on how aggressively the policies encourage the emerging technology. Thus, the Zn/ZnO cycle has the potential to be economically viable by midcentury if incentive policies—such as direct financial support, purchase guarantees, low interest rate loans, and tax breaks—are used to support initial projects.
DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Renewable hydrogen from the Zn/ZnO solar thermochemical cycle : a cost and policy analysis [texte imprimé] / Julia F. Haltiwanger, Auteur ; Jane H. Davidson, Auteur ; Elizabeth J. Wilson, Auteur . - 2011 . - pp. [041011/1-8].
Energie Solaire
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041011/1-8]
Mots-clés : Carbon Chemical energy conversion Hydrogen production II-VI semiconductors Renewable energy sources Solar energy conversion Zinc compounds Index. décimale : 621.47 Résumé : Flexible energy carriers are a crucial element of our energy portfolio. In a future in which a significant fraction of our energy comes from renewable sources, renewably produced fuels will be vital. The zinc/zinc-oxide thermochemical redox cycle is one approach for producing hydrogen using solar energy. This paper explores the level of carbon taxation necessary to make the cycle competitive with hydrogen production via methane reforming. In addition, the time frame for economic viability is assessed through the use of experience curves under minimal input, midrange, and aggressive incentive policy scenarios. Prior work projects that hydrogen produced by the zinc/zinc-oxide cycle will cost between $5.02/kg and $14.75/kg, compared with $2.40–3.60/kg for steam methane reforming. Overcoming this cost difference would require a carbon tax of ($119–987)/tCO2, which is significantly higher than is likely to be implemented in most countries. For the technology to become cost competitive, incentive policies that lead to early implementation of solar hydrogen plants will be necessary to allow the experience effect to draw down the price. Under such policies, a learning curve analysis suggests that hydrogen produced via the Zn/ZnO cycle could become economically viable between 2032 and 2069, depending on how aggressively the policies encourage the emerging technology. Thus, the Zn/ZnO cycle has the potential to be economically viable by midcentury if incentive policies—such as direct financial support, purchase guarantees, low interest rate loans, and tax breaks—are used to support initial projects.
DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 1 (Janvier 2010) . - pp. [011013/1-9]
Titre : Shear induced removal of calcium carbonate scale from polypropylene and copper tubes Type de document : texte imprimé Auteurs : Matt Royer, Auteur ; Jane H. Davidson, Auteur ; Lorraine F. Francis, Auteur Année de publication : 2010 Article en page(s) : pp. [011013/1-9] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Adhesion Calcium compounds Laminar flow Scanning electron microscopy Shear turbulence Index. décimale : 621.47 Résumé : This paper presents an analytical model and an experimental study of adhesion and fluid shear removal of calcium carbonate scale on polypropylene and copper tubes in laminar and turbulent water flows, with a view toward understanding how scale can be controlled in solar absorbers and heat exchangers. The tubes are first coated with scale and then inserted in a flow-through apparatus. Removal is measured gravimetrically for Reynolds numbers from 525 to 5550, corresponding to wall shear stresses from 0.16 Pa to 6.0 Pa. The evolutionary structure of the scale is visualized with scanning electron microscopy. Consistent with the predictive model, calcium carbonate is more easily removed from polypropylene than copper. In a laminar flow with a wall shear stress of 0.16 Pa, 65% of the scale is removed from polypropylene while only 10% is removed from copper. Appreciable removal of scale from copper requires higher shear stresses. At Reynolds number of 5500, corresponding to a wall shear stress of 6.0 Pa, 30% of the scale is removed from the copper tubes. The results indicate scale will be more easily removed from polypropylene, and by inference other polymeric materials, than from copper by flushing with water.
DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Shear induced removal of calcium carbonate scale from polypropylene and copper tubes [texte imprimé] / Matt Royer, Auteur ; Jane H. Davidson, Auteur ; Lorraine F. Francis, Auteur . - 2010 . - pp. [011013/1-9].
Energie Solaire
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 1 (Janvier 2010) . - pp. [011013/1-9]
Mots-clés : Adhesion Calcium compounds Laminar flow Scanning electron microscopy Shear turbulence Index. décimale : 621.47 Résumé : This paper presents an analytical model and an experimental study of adhesion and fluid shear removal of calcium carbonate scale on polypropylene and copper tubes in laminar and turbulent water flows, with a view toward understanding how scale can be controlled in solar absorbers and heat exchangers. The tubes are first coated with scale and then inserted in a flow-through apparatus. Removal is measured gravimetrically for Reynolds numbers from 525 to 5550, corresponding to wall shear stresses from 0.16 Pa to 6.0 Pa. The evolutionary structure of the scale is visualized with scanning electron microscopy. Consistent with the predictive model, calcium carbonate is more easily removed from polypropylene than copper. In a laminar flow with a wall shear stress of 0.16 Pa, 65% of the scale is removed from polypropylene while only 10% is removed from copper. Appreciable removal of scale from copper requires higher shear stresses. At Reynolds number of 5500, corresponding to a wall shear stress of 6.0 Pa, 30% of the scale is removed from the copper tubes. The results indicate scale will be more easily removed from polypropylene, and by inference other polymeric materials, than from copper by flushing with water.
DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 2 (Mai 2011) . - 09 p.
Titre : Solar gasification of biomass : kinetics of pyrolysis and steam gasification in molten salt Type de document : texte imprimé Auteurs : Brandon J. Hathaway, Auteur ; Jane H. Davidson, Auteur ; David B. Kittelson, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Electric furnaces Fuel gasification Heat transfer Hydrogen production Lithium Mass transfer Potassium Pyrolysis Reaction kinetics Sodium Solar energy conversion Stability Index. décimale : 621.47 Résumé : The use of concentrated solar energy as a heat source for pyrolysis and gasification of biomass is an efficient means for production of hydrogen rich synthesis gas. Utilizing molten alkali carbonate salts as a reaction and heat transfer media promises enhanced stability to solar transients and faster reaction rates. The present study establishes and compares the reaction kinetics of pyrolysis and gasification of cellulose from 1124 K to 1235 K in an electric furnace. Data are presented in an inert environment and in a bath of a ternary eutectic blend of lithium, potassium, and sodium carbonate salts. Arrhenius rate expressions are derived from the data supported by a numerical model of heat and mass transfer. The molten salt increases the rate of pyrolysis by 74% and increases gasification rates by more than an order of magnitude while promoting a product gas composition nearer to thermodynamic equilibrium predictions. These results justify using molten carbonate salts as a combined catalyst and heat transfer media for solar gasification. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000002 [...] [article] Solar gasification of biomass : kinetics of pyrolysis and steam gasification in molten salt [texte imprimé] / Brandon J. Hathaway, Auteur ; Jane H. Davidson, Auteur ; David B. Kittelson, Auteur . - 2012 . - 09 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 2 (Mai 2011) . - 09 p.
Mots-clés : Electric furnaces Fuel gasification Heat transfer Hydrogen production Lithium Mass transfer Potassium Pyrolysis Reaction kinetics Sodium Solar energy conversion Stability Index. décimale : 621.47 Résumé : The use of concentrated solar energy as a heat source for pyrolysis and gasification of biomass is an efficient means for production of hydrogen rich synthesis gas. Utilizing molten alkali carbonate salts as a reaction and heat transfer media promises enhanced stability to solar transients and faster reaction rates. The present study establishes and compares the reaction kinetics of pyrolysis and gasification of cellulose from 1124 K to 1235 K in an electric furnace. Data are presented in an inert environment and in a bath of a ternary eutectic blend of lithium, potassium, and sodium carbonate salts. Arrhenius rate expressions are derived from the data supported by a numerical model of heat and mass transfer. The molten salt increases the rate of pyrolysis by 74% and increases gasification rates by more than an order of magnitude while promoting a product gas composition nearer to thermodynamic equilibrium predictions. These results justify using molten carbonate salts as a combined catalyst and heat transfer media for solar gasification. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000002 [...]
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