The Experts below are selected from a list of 13131 Experts worldwide ranked by ideXlab platform
Heidrun Mehling - One of the best experts on this subject based on the ideXlab platform.
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Thermal performance of sodium acetate trihydrate thickened with different materials as phase change energy storage material
Applied Thermal Engineering, 2003Co-Authors: Luisa F Cabeza, Gustav Svensson, S. Hiebler, Heidrun MehlingAbstract:The use of phase change materials (PCMs) in energy storage has the advantage of high energy density and isothermal operation. Although the use of only non-segregating PCMs is a good commercial approach, some desirable PCM melting points do not seem attainable with non-segregating salt hydrates at a reasonable price. The addition of gellants and Thickeners can avoid segregation of these materials. In this paper, sodium acetate trihydrate is successfully thickened with bentonite and starch. Cellulose gives an even better thickened PCM, but temperatures higher than 65 ??C give phase separation. The mixtures would show a similar thermal behavior as the salt hydrate, with the same melting point and an enthalpy decrease between 20% and 35%, depending on the type and amount of thickening material used. ?? 2003 Elsevier Ltd. All rights reserved.
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Thermal performance of soduim acetate trihydratethickened with different materials as phase change energy storage material
Applied Thermal Engineering, 2003Co-Authors: Luisa F Cabeza, G Svenson, S. Hiebler, Heidrun MehlingAbstract:The use of phase change materials (PCMs) in energy storage has the advantage of high energy density and isothermal operation. Although the use of only non-segregating PCMs is a good commercial approach, some desirable PCM melting points do not seem attainable with non-segregating salt hydrates at a reasonable price. The addition of gellants and Thickeners can avoid segregation of these materials. In this paper, sodium acetate trihydrate is successfully thickened with bentonite and starch. Cellulose gives an even better thickened PCM, but temperatures higher than 65 C give phase separation. The mixtures would show a similar thermal behavior as the salt hydrate, with the same melting point and an enthalpy decrease between 20% and 35%, depending on the type and amount of thickening material used. 2003 Elsevier Ltd. All rights reserved.
Luisa F Cabeza - One of the best experts on this subject based on the ideXlab platform.
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Thermal performance of sodium acetate trihydrate thickened with different materials as phase change energy storage material
Applied Thermal Engineering, 2003Co-Authors: Luisa F Cabeza, Gustav Svensson, S. Hiebler, Heidrun MehlingAbstract:The use of phase change materials (PCMs) in energy storage has the advantage of high energy density and isothermal operation. Although the use of only non-segregating PCMs is a good commercial approach, some desirable PCM melting points do not seem attainable with non-segregating salt hydrates at a reasonable price. The addition of gellants and Thickeners can avoid segregation of these materials. In this paper, sodium acetate trihydrate is successfully thickened with bentonite and starch. Cellulose gives an even better thickened PCM, but temperatures higher than 65 ??C give phase separation. The mixtures would show a similar thermal behavior as the salt hydrate, with the same melting point and an enthalpy decrease between 20% and 35%, depending on the type and amount of thickening material used. ?? 2003 Elsevier Ltd. All rights reserved.
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Thermal performance of soduim acetate trihydratethickened with different materials as phase change energy storage material
Applied Thermal Engineering, 2003Co-Authors: Luisa F Cabeza, G Svenson, S. Hiebler, Heidrun MehlingAbstract:The use of phase change materials (PCMs) in energy storage has the advantage of high energy density and isothermal operation. Although the use of only non-segregating PCMs is a good commercial approach, some desirable PCM melting points do not seem attainable with non-segregating salt hydrates at a reasonable price. The addition of gellants and Thickeners can avoid segregation of these materials. In this paper, sodium acetate trihydrate is successfully thickened with bentonite and starch. Cellulose gives an even better thickened PCM, but temperatures higher than 65 C give phase separation. The mixtures would show a similar thermal behavior as the salt hydrate, with the same melting point and an enthalpy decrease between 20% and 35%, depending on the type and amount of thickening material used. 2003 Elsevier Ltd. All rights reserved.
David Gon??alves - One of the best experts on this subject based on the ideXlab platform.
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Friction torque in thrust ball bearings lubricated with polymer greases of different Thickener content
Tribology International, 2016Co-Authors: David Gon??alves, Armando V. Campos, Samuel Pinho, Beatriz Gra??a, Jorge H.o. SeabraAbstract:In this work a series of experimental tests were performed in thrust ball bearings lubricated with polymer greases. The tested greases were formulated with the same base oil but different Thickener content. A multi-purpose lithium thickened grease was also tested as reference. The friction torque was measured at constant temperature and load, while varying the rotational speed. The coefficients of friction under boundary and full film lubrication were numerically calculated through the optimization of a rolling bearing friction torque model to the experimental measurements. The results show that the higher the Thickener content, the smaller is the friction torque generated by the lubricating greases, phenomenon which was found to be especially important at low speeds and low specific film thickness.
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Formulation, rheology and thermal ageing of polymer greases - Part I: Influence of the Thickener content
Tribology International, 2015Co-Authors: David Gon??alves, Armando V. Campos, Beatriz Graça, Jorge H.o. Seabra, René WestbroekAbstract:The aim of this work is to show the correlation between polymer greases' rheology and its formulation. The tested polypropylene (PP) thickened greases were evaluated regarding their Thickener content and its effect on the rheological properties. An artificial ageing procedure was performed by heating fresh grease samples in an oven to study the thermal degradation. The ageing evaluation was performed through rheological measurements, FT-IR spectra, oil loss, bleed-oil viscosity changes and bleed rate. The rheology measurements were performed on a rotational rheometer, emphasizing on the storage and loss moduli values at the Linear Visco-Elastic (LVE) region. The flow curve of each grease was also measured. A modified Herschel-Buckley model was applied and the data was correlated to the Thickener content.
Jorge H.o. Seabra - One of the best experts on this subject based on the ideXlab platform.
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Friction torque in thrust ball bearings lubricated with polymer greases of different Thickener content
Tribology International, 2016Co-Authors: David Gon??alves, Armando V. Campos, Samuel Pinho, Beatriz Gra??a, Jorge H.o. SeabraAbstract:In this work a series of experimental tests were performed in thrust ball bearings lubricated with polymer greases. The tested greases were formulated with the same base oil but different Thickener content. A multi-purpose lithium thickened grease was also tested as reference. The friction torque was measured at constant temperature and load, while varying the rotational speed. The coefficients of friction under boundary and full film lubrication were numerically calculated through the optimization of a rolling bearing friction torque model to the experimental measurements. The results show that the higher the Thickener content, the smaller is the friction torque generated by the lubricating greases, phenomenon which was found to be especially important at low speeds and low specific film thickness.
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On the film thickness behaviour of polymer greases at low and high speeds
Tribology International, 2015Co-Authors: David Gonçalves, Jorge H.o. Seabra, Beatriz Graça, A. Campos, Johan Leckner, René WestbroekAbstract:Abstract Experimental batches of polymer thickened greases, as well as their base and bleed-oils were tribologically characterized through film thickness measurements over a wide range of entrainment speeds on a ball-on-disc test rig using optical interferometry. The results are in agreement with previous observations of several authors. Under fully flooded conditions and low speed it was observed that Thickener lumps enter the contact producing a high film thickness plateau. The transition speed at which the film thickness increases with decreasing speed is dependent on the Thickener content and operating temperature. At moderate to high speeds, all the tested greases show a film thickness much higher than the base and bleed-oils, even though the bleed-oil׳s film thickness is closer to the grease׳s.
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Formulation, rheology and thermal ageing of polymer greases - Part I: Influence of the Thickener content
Tribology International, 2015Co-Authors: David Gon??alves, Armando V. Campos, Beatriz Graça, Jorge H.o. Seabra, René WestbroekAbstract:The aim of this work is to show the correlation between polymer greases' rheology and its formulation. The tested polypropylene (PP) thickened greases were evaluated regarding their Thickener content and its effect on the rheological properties. An artificial ageing procedure was performed by heating fresh grease samples in an oven to study the thermal degradation. The ageing evaluation was performed through rheological measurements, FT-IR spectra, oil loss, bleed-oil viscosity changes and bleed rate. The rheology measurements were performed on a rotational rheometer, emphasizing on the storage and loss moduli values at the Linear Visco-Elastic (LVE) region. The flow curve of each grease was also measured. A modified Herschel-Buckley model was applied and the data was correlated to the Thickener content.
René Westbroek - One of the best experts on this subject based on the ideXlab platform.
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On the film thickness behaviour of polymer greases at low and high speeds
Tribology International, 2015Co-Authors: David Gonçalves, Jorge H.o. Seabra, Beatriz Graça, A. Campos, Johan Leckner, René WestbroekAbstract:Abstract Experimental batches of polymer thickened greases, as well as their base and bleed-oils were tribologically characterized through film thickness measurements over a wide range of entrainment speeds on a ball-on-disc test rig using optical interferometry. The results are in agreement with previous observations of several authors. Under fully flooded conditions and low speed it was observed that Thickener lumps enter the contact producing a high film thickness plateau. The transition speed at which the film thickness increases with decreasing speed is dependent on the Thickener content and operating temperature. At moderate to high speeds, all the tested greases show a film thickness much higher than the base and bleed-oils, even though the bleed-oil׳s film thickness is closer to the grease׳s.
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Formulation, rheology and thermal ageing of polymer greases - Part I: Influence of the Thickener content
Tribology International, 2015Co-Authors: David Gon??alves, Armando V. Campos, Beatriz Graça, Jorge H.o. Seabra, René WestbroekAbstract:The aim of this work is to show the correlation between polymer greases' rheology and its formulation. The tested polypropylene (PP) thickened greases were evaluated regarding their Thickener content and its effect on the rheological properties. An artificial ageing procedure was performed by heating fresh grease samples in an oven to study the thermal degradation. The ageing evaluation was performed through rheological measurements, FT-IR spectra, oil loss, bleed-oil viscosity changes and bleed rate. The rheology measurements were performed on a rotational rheometer, emphasizing on the storage and loss moduli values at the Linear Visco-Elastic (LVE) region. The flow curve of each grease was also measured. A modified Herschel-Buckley model was applied and the data was correlated to the Thickener content.
