The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Stephan Havemann - One of the best experts on this subject based on the ideXlab platform.
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The dependence of retrieved cirrus Ice‐Crystal effective dimension on assumed Ice‐Crystal geometry and size‐distribution function at solar wavelengths
Quarterly Journal of the Royal Meteorological Society, 2004Co-Authors: Anthony J Baran, Stephan HavemannAbstract:The dependence of retrieved Ice-Crystal effective dimension on assumed Ice-Crystal shape and size-distribution function is investigated at solar wavelengths (0.87, 1.6 and 3.7 µm). The dual viewing Along Track Scanning Radiometer is used to retrieve Ice-Crystal effective dimension using a method of Optimal Estimation over semi-transparent cirrus located in the tropics and mid-latitudes. The Ice-Crystal effective dimension is defined in terms of the effective diameter and it is retrieved assuming roughened hexagonal Ice aggregates, pristine hexagonal Ice columns, and four-branched bullet rosettes. It is shown that if a phase function that well represents the scattering properties of cirrus is applied to each Crystal type then the retrieved Ice-Crystal effective diameter is only weakly dependent on Ice-Crystal shape and size-distribution function. Absolute differences between retrieved Ice-Crystal effective diameter assuming hexagonal Ice columns and Ice aggregates combined with a representative phase function are generally well within ±5 µm. The findings of this paper have the important implication that, in climate models, simulation of cirrus cloudy radiances at solar wavelengths might be made to be independent of assumed Ice-Crystal shape and size-distribution function. © Crown copyright, 2004.
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the dependence of retrieved cirrus Ice Crystal effective dimension on assumed Ice Crystal geometry and size distribution function at solar wavelengths
Quarterly Journal of the Royal Meteorological Society, 2004Co-Authors: Anthony J Baran, Stephan HavemannAbstract:The dependence of retrieved Ice-Crystal effective dimension on assumed Ice-Crystal shape and size-distribution function is investigated at solar wavelengths (0.87, 1.6 and 3.7 µm). The dual viewing Along Track Scanning Radiometer is used to retrieve Ice-Crystal effective dimension using a method of Optimal Estimation over semi-transparent cirrus located in the tropics and mid-latitudes. The Ice-Crystal effective dimension is defined in terms of the effective diameter and it is retrieved assuming roughened hexagonal Ice aggregates, pristine hexagonal Ice columns, and four-branched bullet rosettes. It is shown that if a phase function that well represents the scattering properties of cirrus is applied to each Crystal type then the retrieved Ice-Crystal effective diameter is only weakly dependent on Ice-Crystal shape and size-distribution function. Absolute differences between retrieved Ice-Crystal effective diameter assuming hexagonal Ice columns and Ice aggregates combined with a representative phase function are generally well within ±5 µm. The findings of this paper have the important implication that, in climate models, simulation of cirrus cloudy radiances at solar wavelengths might be made to be independent of assumed Ice-Crystal shape and size-distribution function. © Crown copyright, 2004.
Alain Le-bail - One of the best experts on this subject based on the ideXlab platform.
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Ice-Crystal formation in gelatin gel during pressure shift versus conventional freezing
Journal of Food Engineering, 2005Co-Authors: Songming Zhu, Hosahalli S Ramaswamy, Alain Le-bailAbstract:Cylindrical specimens (7.8 mm diameter, 35 mm length) of gelatin gel (2% gelatin, w/w) were frozen by pressure shift freezing (PSF) at 100 MPa (-8.4 ??C), 150 MPa (-14 ??C) and 200 MPa (-20 ??C) as well as conventional air freezing (CAF) and liquid immersion freezing (LIF) at -20 ??C. Pressure and temperature profiles of gel samples were gathered during the freezing process. The ovoid microstructure of Ice Crystals in frozen gelatin gels after freeze-drying was evaluated for area, equivalent diameter, roundness and elongation. Equivalent diameter (mean??s.d.) of the Ice Crystals was 145??66, 84??26, 91??30, 73??29, and 44??16 ??m for test samples subjected to CAF, LIF and PSF at 100, 150 and 200 MPa, respectively. Roundness and elongation were somewhat variable and did not show a clear trend with the different freezing techniques. Results from this study with a model food (gelatin gel) confirm that the PSF process promotes the production of larger number of smaller Ice Crystal in the frozen sample that help to retain a better texture in the product. ?? 2004 Elsevier Ltd. All rights reserved.
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Ice Crystal formation in gelatin gel during pressure shift versus conventional freezing
Journal of Food Engineering, 2005Co-Authors: Hosahalli S Ramaswamy, Alain Le-bailAbstract:Abstract Cylindrical specimens (7.8 mm diameter, 35 mm length) of gelatin gel (2% gelatin, w/w) were frozen by pressure shift freezing (PSF) at 100 MPa (−8.4 °C), 150 MPa (−14 °C) and 200 MPa (−20 °C) as well as conventional air freezing (CAF) and liquid immersion freezing (LIF) at −20 °C. Pressure and temperature profiles of gel samples were gathered during the freezing process. The ovoid microstructure of Ice Crystals in frozen gelatin gels after freeze-drying was evaluated for area, equivalent diameter, roundness and elongation. Equivalent diameter (mean ± s.d.) of the Ice Crystals was 145 ± 66, 84 ± 26, 91 ± 30, 73 ± 29, and 44 ± 16 μm for test samples subjected to CAF, LIF and PSF at 100, 150 and 200 MPa, respectively. Roundness and elongation were somewhat variable and did not show a clear trend with the different freezing techniques. Results from this study with a model food (gelatin gel) confirm that the PSF process promotes the production of larger number of smaller Ice Crystal in the frozen sample that help to retain a better texture in the product.
Marcela Arellano - One of the best experts on this subject based on the ideXlab platform.
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Online Ice Crystal size measurements during sorbet freezing by means of the focused beam reflectance measurement (FBRM) technology. Influence of operating conditions
Journal of Food Engineering, 2012Co-Authors: Marcela Arellano, Hayat Benkhelifa, Denis Flick, Graciela ÁlvarezAbstract:In Ice cream and sorbet manufacturing small Ice Crystals are desired to deliver a product with a smooth texture and good palatability. This research studied the influence of the operating conditions on the Ice Crystal size and the draw temperature of the sorbet during the freezing process. The evolution of Ice Crystal size was tracked with the focused beam reflectance measurement (FBRM) technique, which uses an in situ sensor that makes it possible to monitor online the chord length distribution (CLD) of Ice Crystals in sorbets containing up to 40% of Ice. The refrigerant fluid temperature had the most significant influence on the mean Ice Crystal chord length, followed by the dasher speed, whereas the mix flow rate had no significant influence. A decrease in the refrigerant fluid temperature led to a reduction in Ice Crystal size, due to the growth of more small Ice Crystals left behind on the scraped wall from previous scrapings. Increasing the dasher speed slightly reduced the mean Ice Crystal chord length, due to the production of new small Ice nuclei by secondary nucleation. For a given refrigerant fluid temperature and dasher speed, low mix flow rates resulted in lower draw temperatures, due to the fact that the product remains in contact with the freezer wall longer. High dasher speeds warmed the product slightly, due to the dissipation of frictional energy in the product, the effect of which was in part moderated by the improvement in the heat transfer coefficient between the product and the freezer wall. © 2012 Elsevier Ltd. All rights reserved.
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EFFECT OF SORBET FREEZING PROCESS ON DRAW TEMPERATURE AND Ice Crystal SIZE USING FOCUSED BEAM REFLECTANCE METHOD (FBRM) ONLINE MEASUREMENTS
The 23rd IIR (International Institute of Refrigeration) International Congress of Refrigeration, 2011Co-Authors: Marcela Arellano, J Enrique GONZALEZAbstract:During sorbet and Ice cream manufacturing is desired to obtain, a narrow Ice Crystal size distribution with a small mean size, in order to get a smooth texture in the final product. We studied the influence of the mix flow rate, the evaporation temperature of the refrigerant fluid and the dasher speed the draw temperature and on the Ice Crystal size during sorbet freezing in order to identify optimal operating conditions. We used the focused beam reflectance method (FBRM) to follow the evolution of the Ice Crystal size. The FBRM probe, provides accurate and repeatable information about the chord length distribution (CLD) of Ice Crystals. With this probe it is possible to follow online the development of the Ice Crystals in sorbets or slurries containing up to 40% of Ice. The effect of refrigerant fluid temperature was very important; by decreasing refrigerant temperature we reduce significantly the Ice Crystal size and we obtain as expected lower draw temperature. High dasher speeds slightly decrease the Ice Crystal chord length, due to the attrition of the bigger Ice Crystals, which produces new smaller Ice nuclei by secondary nucleation. Also, an increase of the dasher speed slightly warms the product, due to the dissipation of frictional energy into the product. As expected low mix flow rates result in lower draw temperatures because the product remains longer in contact with the freezer wall, extracting thus more heat from the product. Nevertheless, the mix flow rate did not show a significant effect on the Ice Crystal size.
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Online Ice Crystal size measurements by the focused beam reflectance method (FBRM) during sorbet freezing
Procedia Food Science, 2011Co-Authors: Marcela Arellano, J Enrique GONZALEZ, Graciela Álvarez, Hayat Benkhelifa, Denis Flick, D. LeducqAbstract:The Ice Crystal size distribution determines in part the textural properties of sorbet and Ice cream. During sorbet and Ice cream manufacturing, a narrow Ice Crystal size distribution with a small mean size is desired, in order to obtain a smooth texture in the final product. This research studied the influence of the mix flow rate, the evaporation temperature of the refrigerant fluid and the dasher speed on the Ice Crystal size and the draw temperature during sorbet freezing, so as to identify optimal operating conditions. The evolution of the Ice Crystal size was followed by the focused beam reflectance method (FBRM), which uses an in situ sensor that provides accurate and repeatable information about the chord length distribution (CLD) of Ice Crystals. Our results showed that the {FBRM} sensor is a promising tool which makes it possible to monitor online the development of the Ice Crystals in sorbets containing up to 40% of Ice. Decreasing the refrigerant fluid temperature allows us to reduce the Ice Crystal size and to lower the product's temperature, due to the increase of the supercooling driving force. High dasher speeds slightly decrease the Ice Crystal chord length, due to the attrition of the bigger Ice Crystals, which produces new smaller Ice nuclei by secondary nucleation. Also, an increase of the dasher speed slightly warms the product, due to the dissipation of frictional energy into the product. Low mix flow rates result in lower draw temperatures because the product remains longer in contact with the freezer wall extracting thus more heat from the product.
Anthony J Baran - One of the best experts on this subject based on the ideXlab platform.
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The dependence of retrieved cirrus Ice‐Crystal effective dimension on assumed Ice‐Crystal geometry and size‐distribution function at solar wavelengths
Quarterly Journal of the Royal Meteorological Society, 2004Co-Authors: Anthony J Baran, Stephan HavemannAbstract:The dependence of retrieved Ice-Crystal effective dimension on assumed Ice-Crystal shape and size-distribution function is investigated at solar wavelengths (0.87, 1.6 and 3.7 µm). The dual viewing Along Track Scanning Radiometer is used to retrieve Ice-Crystal effective dimension using a method of Optimal Estimation over semi-transparent cirrus located in the tropics and mid-latitudes. The Ice-Crystal effective dimension is defined in terms of the effective diameter and it is retrieved assuming roughened hexagonal Ice aggregates, pristine hexagonal Ice columns, and four-branched bullet rosettes. It is shown that if a phase function that well represents the scattering properties of cirrus is applied to each Crystal type then the retrieved Ice-Crystal effective diameter is only weakly dependent on Ice-Crystal shape and size-distribution function. Absolute differences between retrieved Ice-Crystal effective diameter assuming hexagonal Ice columns and Ice aggregates combined with a representative phase function are generally well within ±5 µm. The findings of this paper have the important implication that, in climate models, simulation of cirrus cloudy radiances at solar wavelengths might be made to be independent of assumed Ice-Crystal shape and size-distribution function. © Crown copyright, 2004.
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the dependence of retrieved cirrus Ice Crystal effective dimension on assumed Ice Crystal geometry and size distribution function at solar wavelengths
Quarterly Journal of the Royal Meteorological Society, 2004Co-Authors: Anthony J Baran, Stephan HavemannAbstract:The dependence of retrieved Ice-Crystal effective dimension on assumed Ice-Crystal shape and size-distribution function is investigated at solar wavelengths (0.87, 1.6 and 3.7 µm). The dual viewing Along Track Scanning Radiometer is used to retrieve Ice-Crystal effective dimension using a method of Optimal Estimation over semi-transparent cirrus located in the tropics and mid-latitudes. The Ice-Crystal effective dimension is defined in terms of the effective diameter and it is retrieved assuming roughened hexagonal Ice aggregates, pristine hexagonal Ice columns, and four-branched bullet rosettes. It is shown that if a phase function that well represents the scattering properties of cirrus is applied to each Crystal type then the retrieved Ice-Crystal effective diameter is only weakly dependent on Ice-Crystal shape and size-distribution function. Absolute differences between retrieved Ice-Crystal effective diameter assuming hexagonal Ice columns and Ice aggregates combined with a representative phase function are generally well within ±5 µm. The findings of this paper have the important implication that, in climate models, simulation of cirrus cloudy radiances at solar wavelengths might be made to be independent of assumed Ice-Crystal shape and size-distribution function. © Crown copyright, 2004.
Graciela Álvarez - One of the best experts on this subject based on the ideXlab platform.
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Online Ice Crystal size measurements during sorbet freezing by means of the focused beam reflectance measurement (FBRM) technology. Influence of operating conditions
Journal of Food Engineering, 2012Co-Authors: Marcela Arellano, Hayat Benkhelifa, Denis Flick, Graciela ÁlvarezAbstract:In Ice cream and sorbet manufacturing small Ice Crystals are desired to deliver a product with a smooth texture and good palatability. This research studied the influence of the operating conditions on the Ice Crystal size and the draw temperature of the sorbet during the freezing process. The evolution of Ice Crystal size was tracked with the focused beam reflectance measurement (FBRM) technique, which uses an in situ sensor that makes it possible to monitor online the chord length distribution (CLD) of Ice Crystals in sorbets containing up to 40% of Ice. The refrigerant fluid temperature had the most significant influence on the mean Ice Crystal chord length, followed by the dasher speed, whereas the mix flow rate had no significant influence. A decrease in the refrigerant fluid temperature led to a reduction in Ice Crystal size, due to the growth of more small Ice Crystals left behind on the scraped wall from previous scrapings. Increasing the dasher speed slightly reduced the mean Ice Crystal chord length, due to the production of new small Ice nuclei by secondary nucleation. For a given refrigerant fluid temperature and dasher speed, low mix flow rates resulted in lower draw temperatures, due to the fact that the product remains in contact with the freezer wall longer. High dasher speeds warmed the product slightly, due to the dissipation of frictional energy in the product, the effect of which was in part moderated by the improvement in the heat transfer coefficient between the product and the freezer wall. © 2012 Elsevier Ltd. All rights reserved.
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Online Ice Crystal size measurements by the focused beam reflectance method (FBRM) during sorbet freezing
Procedia Food Science, 2011Co-Authors: Marcela Arellano, J Enrique GONZALEZ, Graciela Álvarez, Hayat Benkhelifa, Denis Flick, D. LeducqAbstract:The Ice Crystal size distribution determines in part the textural properties of sorbet and Ice cream. During sorbet and Ice cream manufacturing, a narrow Ice Crystal size distribution with a small mean size is desired, in order to obtain a smooth texture in the final product. This research studied the influence of the mix flow rate, the evaporation temperature of the refrigerant fluid and the dasher speed on the Ice Crystal size and the draw temperature during sorbet freezing, so as to identify optimal operating conditions. The evolution of the Ice Crystal size was followed by the focused beam reflectance method (FBRM), which uses an in situ sensor that provides accurate and repeatable information about the chord length distribution (CLD) of Ice Crystals. Our results showed that the {FBRM} sensor is a promising tool which makes it possible to monitor online the development of the Ice Crystals in sorbets containing up to 40% of Ice. Decreasing the refrigerant fluid temperature allows us to reduce the Ice Crystal size and to lower the product's temperature, due to the increase of the supercooling driving force. High dasher speeds slightly decrease the Ice Crystal chord length, due to the attrition of the bigger Ice Crystals, which produces new smaller Ice nuclei by secondary nucleation. Also, an increase of the dasher speed slightly warms the product, due to the dissipation of frictional energy into the product. Low mix flow rates result in lower draw temperatures because the product remains longer in contact with the freezer wall extracting thus more heat from the product.
