The Experts below are selected from a list of 3693 Experts worldwide ranked by ideXlab platform
Yasuhito Nakatake - One of the best experts on this subject based on the ideXlab platform.
-
increase in distillate productivity by inclining the flat plate external reflector of a tilted wick solar still in Winter
Solar Energy, 2009Co-Authors: Hiroshi Tanaka, Yasuhito NakatakeAbstract:Abstract This paper presents a theoretical analysis of a tilted-wick solar still with an inclined flat plate external reflector on a Winter Solstice day at 30°N latitude. The daily amount of distillate of a still with an inclined reflector would be about 15% or 27% greater than that with a vertical reflector when the reflector’s length is a half of or the same as the still’s length.
-
improvement of the tilted wick solar still by using a flat plate reflector
Desalination, 2007Co-Authors: Hiroshi Tanaka, Yasuhito NakatakeAbstract:This paper presents a numerical analysis to investigate the effect of the vertical flat plate external reflector on the distillate productivity of the tilted wick solar still. We propose a geometrical method to calculate the solar radiation reflected by the external reflector and absorbed on the evaporating wick, and also performed numerical analysis of heat and mass transfer in the still to predict the distillate productivity on four days (spring and autumn equinox and summer and Winter Solstice days) at 30°N latitude. We found that the external reflector can increase the distillate productivity in all but the summer seasons, and the increase in the daily amount of distillate averaged over the four days is predicted to be about 9%.
-
a simple and highly productive solar still a vertical multiple effect diffusion type solar still coupled with a flat plate mirror
Desalination, 2005Co-Authors: Hiroshi Tanaka, Yasuhito NakatakeAbstract:Abstract This paper presents a newly designed simple solar still: a vertical multiple-effect diffusion-type solar still consisting of a flat-plate mirror, a number of vertical parallel partitions in contact with saline-soaked wicks with narrow air gaps between partitions, and casters for azimuth tracking by human power. The proposed still is designed so that non-skilled persons can construct it with common materials in developing countries. We theoretically analyzed the dependence of the solar absorption on the first (or heated) partition on the angle of the flat-plate mirror and the azimuth angle of the still, and found that the solar absorption on the first partition can be significantly increased by rotating the still at southing of the sun just once a day, and the daily solar absorption would be about 85% or 99% of the daily solar radiation on a horizontal surface on the spring equinox or Winter Solstice, respectively. We also theoretically analyzed the heat and mass transfer in the proposed still, and found that a proposed still of 10 partitions with 10 mm diffusion gaps between partitions was predicted to produce 29.2 34.5 kg/m2d on sunny spring equinox and Winter Solstice days respectively at the equator.
-
parametric study on a vertical multiple effect diffusion typesolar still coupled with a heat pipe solar collector
Desalination, 2005Co-Authors: Hiroshi Tanak, Yasuhito Nakatake, Katsuhiro WatanabeAbstract:A parametric investigation was theoretically performed for the vertical multiple-effect diffusion-type solar still, which consists of a number of vertical partitions in contact with saline-soaked wicks with narrow gaps between the partitions, coupled with a heat-pipe solar collector. The proposed still has some advantages: the still's size is compact, the still can produce distilled water without electricity, and the productivity is greater than that of conventional multiple-effect diffusion-type solar stills. We theoretically predicted the optimum angle of the solar collector on the spring and autumn equinox and the summer and Winter Solstice days, and also performed parametric investigations of the design and operation conditions; it was found that productivity increased with an increase in the number of partitions and the temperature of the saline water fed to the wicks, and with a decrease in the ratio of the solar collector area to each partition area, the thickness of the diffusion gaps between partitions, and the feeding rate of saline water to the wicks.
Hiroshi Tanaka - One of the best experts on this subject based on the ideXlab platform.
-
tilted wick solar still with flat plate bottom reflector
Desalination, 2011Co-Authors: Hiroshi TanakaAbstract:This paper presents a theoretical analysis of a tilted wick solar still with a flat plate bottom reflector extending from the lower edge of the still on four days (the spring and autumn equinox and summer and Winter Solstices) at 30°N latitude when the still's inclination is fixed at 30° and the reflector's length is the same as the still's length. We propose a geometrical model to calculate the solar radiation reflected by the bottom reflector and then absorbed on the evaporating wick. We also performed a numerical analysis of heat and mass transfer in the still. We found that the bottom reflector can reflect the sunrays to the evaporating wick and increase distillate productivity of the tilted wick still when the reflector's inclination is larger than about 15° on the spring and autumn equinox and Winter Solstice, and 25° on the summer Solstice, and the average distillate value for four days is greatest when the reflector's inclination is about 35° and would be about 13% greater than that of a conventional tilted wick still.
-
increase in distillate productivity by inclining the flat plate external reflector of a tilted wick solar still in Winter
Solar Energy, 2009Co-Authors: Hiroshi Tanaka, Yasuhito NakatakeAbstract:Abstract This paper presents a theoretical analysis of a tilted-wick solar still with an inclined flat plate external reflector on a Winter Solstice day at 30°N latitude. The daily amount of distillate of a still with an inclined reflector would be about 15% or 27% greater than that with a vertical reflector when the reflector’s length is a half of or the same as the still’s length.
-
improvement of the tilted wick solar still by using a flat plate reflector
Desalination, 2007Co-Authors: Hiroshi Tanaka, Yasuhito NakatakeAbstract:This paper presents a numerical analysis to investigate the effect of the vertical flat plate external reflector on the distillate productivity of the tilted wick solar still. We propose a geometrical method to calculate the solar radiation reflected by the external reflector and absorbed on the evaporating wick, and also performed numerical analysis of heat and mass transfer in the still to predict the distillate productivity on four days (spring and autumn equinox and summer and Winter Solstice days) at 30°N latitude. We found that the external reflector can increase the distillate productivity in all but the summer seasons, and the increase in the daily amount of distillate averaged over the four days is predicted to be about 9%.
-
a simple and highly productive solar still a vertical multiple effect diffusion type solar still coupled with a flat plate mirror
Desalination, 2005Co-Authors: Hiroshi Tanaka, Yasuhito NakatakeAbstract:Abstract This paper presents a newly designed simple solar still: a vertical multiple-effect diffusion-type solar still consisting of a flat-plate mirror, a number of vertical parallel partitions in contact with saline-soaked wicks with narrow air gaps between partitions, and casters for azimuth tracking by human power. The proposed still is designed so that non-skilled persons can construct it with common materials in developing countries. We theoretically analyzed the dependence of the solar absorption on the first (or heated) partition on the angle of the flat-plate mirror and the azimuth angle of the still, and found that the solar absorption on the first partition can be significantly increased by rotating the still at southing of the sun just once a day, and the daily solar absorption would be about 85% or 99% of the daily solar radiation on a horizontal surface on the spring equinox or Winter Solstice, respectively. We also theoretically analyzed the heat and mass transfer in the proposed still, and found that a proposed still of 10 partitions with 10 mm diffusion gaps between partitions was predicted to produce 29.2 34.5 kg/m2d on sunny spring equinox and Winter Solstice days respectively at the equator.
Huiqun Wang - One of the best experts on this subject based on the ideXlab platform.
-
zonal wavenumber three traveling waves in the northern hemisphere of mars simulated with a general circulation model
Icarus, 2013Co-Authors: Huiqun Wang, M I Richardson, Anthony D Toigo, C E NewmanAbstract:Abstract Observations suggest a strong correlation between curvilinear shaped traveling dust storms (observed in wide angle camera images) and eastward traveling zonal wave number m = 3 waves (observed in thermal data) in the northern mid and high latitudes during the fall and Winter. Using the MarsWRF General Circulation Model, we have investigated the seasonality, structure and dynamics of the simulated m = 3 traveling waves and tested the hypothesis that traveling dust storms may enhance m = 3 traveling waves under certain conditions. Our standard simulation using a prescribed “MGS dust scenario” can capture the observed major wave modes and strong near surface temperature variations before and after the northern Winter Solstice. The same seasonal pattern is also shown by the simulated near surface meridional wind, but not by the normalized surface pressure. The simulated eastward traveling 1.4 T m = 3 waves are confined near the surface in terms of the temperature perturbation, EP flux and eddy available potential energy, and they extend higher in terms of the eddy winds and eddy kinetic energy. The signature of the simulated m = 3 traveling waves is stronger in the near surface meridional wind than in the near surface temperature field. Compared with the standard simulation, our test simulations show that the prescribed m = 3 traveling dust blobs can enhance the simulated m = 3 traveling waves during the pre- and post-Solstice periods when traveling dust storms are frequently observed in images, and that they have negligible effect during the northern Winter Solstice period when traveling dust storms are absent. The enhancement is even greater in our simulation when dust is concentrated closer to the surface. Our simulations also suggest that dust within the 45–75°N band is most effective at enhancing the simulated m = 3 traveling waves. There are multiple factors influencing the strength of the simulated m = 3 traveling waves. Among those, our study suggests that weaker near surface static stability, larger near surface baroclinic parameter, and wave-form dust forcing for latitudinally extended dust storms are favorable. Further study is needed to fully understand the importance of these factors and others.
-
dust storms originating in the northern hemisphere during the third mapping year of mars global surveyor
Icarus, 2007Co-Authors: Huiqun WangAbstract:Abstract Data from the third Mars Global Surveyor (MGS) mapping year (MY 26, 2003–2005) are used to investigate dust storms originating in the northern hemisphere. Flushing dust storms, which originate as frontal dust storms at the northern polar vortex edge and propagate southward through topographic channels, are observed immediately before and after a quiescent period that occurs around the northern Winter Solstice ( 240 ° L s 300 ° ). Both the pre- and post-Solstice active periods can be further divided into two sub-periods. The most vigorous of these flushing storms occurred during L s 210–220° and L s 310–320°. The lifted dust crossed the equator and accumulated in the southern hemisphere. These major dust storms enhanced the Hadley circulation and suppressed the lower-level baroclinic eddies in the northern mid and high latitudes. The 2–3 sol wave number m = 3 traveling waves show the best correlation with flushing dust storms and can combine with other wave modes to produce storm tracks and fronts within individual sub-periods.
-
relationship between frontal dust storms and transient eddy activity in the northern hemisphere of mars as observed by mars global surveyor
Journal of Geophysical Research, 2005Co-Authors: Huiqun Wang, R W Zurek, M I RichardsonAbstract:We have compiled a catalog of frontal dust storms in the northern hemisphere using Mars Orbiter Camera daily global maps spanning ~2.3 Martian years of Mars Global Surveyor (MGS) observations (from 1999 to 2003). The most vigorous frontal storms that flush dust to the low latitudes occur in early-mid fall and mid-late Winter, away from the northern Winter Solstice. While many streaks are observed in the polar hood during the Winter Solstice period, no frontal dust storms are observed in the vicinity of the north polar region. We have also analyzed simultaneous MGS Thermal Emission Spectrometer (TES) temperature data and found statistically significant negative temperature anomalies associated with frontal storms. In the lowest scale height of the atmosphere, the geographical and seasonal distributions of temperature standard deviations associated with transient variations agree well with the distributions of frontal storms. The correlation deteriorates with increasing altitude, suggesting that lower-level temperature waves are associated with the frontal dust storms. Specifically, eastward traveling m = 3 waves with periods of 2–3 sols appear to be closely related to the development of flushing frontal storms.
M I Richardson - One of the best experts on this subject based on the ideXlab platform.
-
zonal wavenumber three traveling waves in the northern hemisphere of mars simulated with a general circulation model
Icarus, 2013Co-Authors: Huiqun Wang, M I Richardson, Anthony D Toigo, C E NewmanAbstract:Abstract Observations suggest a strong correlation between curvilinear shaped traveling dust storms (observed in wide angle camera images) and eastward traveling zonal wave number m = 3 waves (observed in thermal data) in the northern mid and high latitudes during the fall and Winter. Using the MarsWRF General Circulation Model, we have investigated the seasonality, structure and dynamics of the simulated m = 3 traveling waves and tested the hypothesis that traveling dust storms may enhance m = 3 traveling waves under certain conditions. Our standard simulation using a prescribed “MGS dust scenario” can capture the observed major wave modes and strong near surface temperature variations before and after the northern Winter Solstice. The same seasonal pattern is also shown by the simulated near surface meridional wind, but not by the normalized surface pressure. The simulated eastward traveling 1.4 T m = 3 waves are confined near the surface in terms of the temperature perturbation, EP flux and eddy available potential energy, and they extend higher in terms of the eddy winds and eddy kinetic energy. The signature of the simulated m = 3 traveling waves is stronger in the near surface meridional wind than in the near surface temperature field. Compared with the standard simulation, our test simulations show that the prescribed m = 3 traveling dust blobs can enhance the simulated m = 3 traveling waves during the pre- and post-Solstice periods when traveling dust storms are frequently observed in images, and that they have negligible effect during the northern Winter Solstice period when traveling dust storms are absent. The enhancement is even greater in our simulation when dust is concentrated closer to the surface. Our simulations also suggest that dust within the 45–75°N band is most effective at enhancing the simulated m = 3 traveling waves. There are multiple factors influencing the strength of the simulated m = 3 traveling waves. Among those, our study suggests that weaker near surface static stability, larger near surface baroclinic parameter, and wave-form dust forcing for latitudinally extended dust storms are favorable. Further study is needed to fully understand the importance of these factors and others.
-
relationship between frontal dust storms and transient eddy activity in the northern hemisphere of mars as observed by mars global surveyor
Journal of Geophysical Research, 2005Co-Authors: Huiqun Wang, R W Zurek, M I RichardsonAbstract:We have compiled a catalog of frontal dust storms in the northern hemisphere using Mars Orbiter Camera daily global maps spanning ~2.3 Martian years of Mars Global Surveyor (MGS) observations (from 1999 to 2003). The most vigorous frontal storms that flush dust to the low latitudes occur in early-mid fall and mid-late Winter, away from the northern Winter Solstice. While many streaks are observed in the polar hood during the Winter Solstice period, no frontal dust storms are observed in the vicinity of the north polar region. We have also analyzed simultaneous MGS Thermal Emission Spectrometer (TES) temperature data and found statistically significant negative temperature anomalies associated with frontal storms. In the lowest scale height of the atmosphere, the geographical and seasonal distributions of temperature standard deviations associated with transient variations agree well with the distributions of frontal storms. The correlation deteriorates with increasing altitude, suggesting that lower-level temperature waves are associated with the frontal dust storms. Specifically, eastward traveling m = 3 waves with periods of 2–3 sols appear to be closely related to the development of flushing frontal storms.
Katsuhiro Watanabe - One of the best experts on this subject based on the ideXlab platform.
-
parametric study on a vertical multiple effect diffusion typesolar still coupled with a heat pipe solar collector
Desalination, 2005Co-Authors: Hiroshi Tanak, Yasuhito Nakatake, Katsuhiro WatanabeAbstract:A parametric investigation was theoretically performed for the vertical multiple-effect diffusion-type solar still, which consists of a number of vertical partitions in contact with saline-soaked wicks with narrow gaps between the partitions, coupled with a heat-pipe solar collector. The proposed still has some advantages: the still's size is compact, the still can produce distilled water without electricity, and the productivity is greater than that of conventional multiple-effect diffusion-type solar stills. We theoretically predicted the optimum angle of the solar collector on the spring and autumn equinox and the summer and Winter Solstice days, and also performed parametric investigations of the design and operation conditions; it was found that productivity increased with an increase in the number of partitions and the temperature of the saline water fed to the wicks, and with a decrease in the ratio of the solar collector area to each partition area, the thickness of the diffusion gaps between partitions, and the feeding rate of saline water to the wicks.
