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It is proposed to convert existing Robert evaporators into Trebor evaporators. Trebor evaporators work as falling film evaporators with the well-known thermal and technological advantages. When converting a Robert evaporator into ...
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It is proposed to convert existing Robert evaporators into Trebor evaporators. Trebor evaporators work as falling film evaporators with the well-known thermal and technological advantages. When converting a Robert evaporator into a Trebor evaporator, the heating steam inlet and the vapour outlet as well as the condensate drain remain in their original positions. If necessary, the positions of the juice inlet and outlet nozzles are changed, and two additional nozzles and a circulation juice pump are required. These changes are cheaper than installing a new falling film evaporator.
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We have systematically studied the interaction of ultrapure, de-ionized water droplets with chemically amplified, deep-ultraviolet photoresist layers during evaporation by means of experiments. The contact lines of the evaporating...
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We have systematically studied the interaction of ultrapure, de-ionized water droplets with chemically amplified, deep-ultraviolet photoresist layers during evaporation by means of experiments. The contact lines of the evaporating droplets undergo two pinning events. The footprint diameters during pinning D-1,D-2 scale with the initial droplet diameter D-0 approximately as D-1,D-2 similar to D-0(4/3). Evaporated droplets leave a residue behind, generally in the form of an ultrathin layer (order 1-10 nm) with a sub-micron thick mound in the center. We have systematically characterized the residue dimensions as a function of the initial droplet size, the photoresist composition and process conditions. Post-evaporation rinsing steps were found to be unable to completely remove a deposit, depending on how long after droplet evaporation they were performed. Our results indicate that the occurrence of so-called watermark defects might be related to deliquescence induced by ionic residues.
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Evaporation from nanopores plays an important role in various natural and industrial processes that require efficient heat and mass transfer. The ultimate performance of nanopore-evaporation-based processes is dictated by evaporat...
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Evaporation from nanopores plays an important role in various natural and industrial processes that require efficient heat and mass transfer. The ultimate performance of nanopore-evaporation-based processes is dictated by evaporation kinetics at the liquid-vapor interface, which has yet to be experimentally studied down to the single nanopore level. Here we report unambiguous measurements of kinetically limited intense evaporation from individual hydrophilic nanopores with both hydrophilic and hydrophobic top outer surfaces at 22 degrees C using nanochannel-connected nanopore devices. Our results show that the evaporation fluxes of nanopores with hydrophilic outer surfaces show a strong diameter dependence with an exponent of nearly -1.5, reaching up to 11-fold of the maximum theoretical predication provided by the classical Hertz-Knudsen relation at a pore diameter of 27 nm. Differently, the evaporation fluxes of nanopores with hydrophobic outer surfaces show a different diameter dependence with an exponent of -0.66, achieving 66% of the maximum theoretical predication at a pore diameter of 28 nm. We discover that the ultrafast diameter-dependent evaporation from nanopores with hydrophilic outer surfaces mainly stems from evaporating water thin films outside of the nanopores. In contrast, the diameter-dependent evaporation from nanopores with hydrophobic outer surfaces is governed by evaporation kinetics inside the nanopores, which indicates that the evaporation coefficient varies in different nanoscale confinements, possibly due to surface-charge-induced concentration changes of hydronium ions. This study enhances our understanding of evaporation at the nanoscale and demonstrates great potential of evaporation from nanopores.
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We investigated the organization of micrometric hydrophilic beads (glass or basalt) immersed in Leidenfrost drops. Starting from a large volume of water compared to the volume of the beads, while the liquid evaporates, we observed...
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We investigated the organization of micrometric hydrophilic beads (glass or basalt) immersed in Leidenfrost drops. Starting from a large volume of water compared to the volume of the beads, while the liquid evaporates, we observed that the grains are eventually trapped at the interface of the droplet and accumulate. At a moment, the grains entirely cover the droplet. We measured the surface area at this moment as a function of the total mass of particles inserted in the droplet. We concluded that the grains form a monolayer around the droplet assuming (i) that the packing of the beads at the surface is a random close packing and (ii) that the initial surface of the drop is larger than the maximum surface that the beads can cover. Regarding the evaporation dynamics, the beads are found to reduce the evaporation rate of the drop. The slowdown of the evaporation is interpreted as being the consequence of the dewetting of the particles located at the droplet interface which makes the effective surface of evaporation smaller. As a matter of fact, contact angles of the beads with the water deduced from the evaporation rates are consistent with contact angles of beads directly measured at a flat air–water interface of water in a container.
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Reliable estimates of evaporative water loss are required to assess the urban water budget in support of division of water resources among various needs, including heat mitigation measures in cities relying on evaporative cooling....
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Reliable estimates of evaporative water loss are required to assess the urban water budget in support of division of water resources among various needs, including heat mitigation measures in cities relying on evaporative cooling. We report on urban evaporative water loss from Arnhem and Rotterdam in the Netherlands, using eddy covariance, scintillometer and sapflow observations. Evaporation is assessed at daily to seasonal and annual timescale. For the summer half-year (April-September), observations from Arnhem and Rotterdam are consistent regarding magnitude and variability of evaporation that typically varies between 0.5 and 1.0 mm of evaporation per day. The mean daily evaporative cooling rate was 20 -25 Wm~(-2),11-14% of the average incoming solar radiation. Evaporation by trees related to sapflow was found to be a small term on the water budget at the city or neighbourhood scale. However, locally the contribution may be significant, given observed maxima of daily sap flows up to 170 1 per tree. In Arnhem, evaporation is strongly linked with precipitation, possibly owing to building style. During the summer season, 60% of the precipitation evaporated again. In Rotterdam, the link between evaporation and precipitation is much weaker. An analysis of meteorological observations shows that estimation of urban evaporation from routine weather data using the concept of reference evaporation would be a particularly challenging task. City-scale evaporation may not scale with reference evaporation and the urban fabric results in strong microweather variability. Observations like the ones presented here can be used to evaluate and improve methods for routine urban evaporation estimates.
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Research was conducted to develop a method for obtaining floating pan evaporation rates in a small (less than 10,000 m~2) wetland, lagoon, or pond. Floating pan and land pan evaporation data were collected from March 1 to August 3...
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Research was conducted to develop a method for obtaining floating pan evaporation rates in a small (less than 10,000 m~2) wetland, lagoon, or pond. Floating pan and land pan evaporation data were collected from March 1 to August 31, 2005, at a small natural wetland located in the alluvium of the Canadian River near Norman, Oklahoma, at the U.S. Geological Survey Norman Landfill Toxic Substances Hydrology Research Site. Floating pan evaporation rates were compared with evaporation rates from a nearby standard Class A evaporation pan on land. Floating pan evaporation rates were significantly less than land pan evaporation rates for the entire period and on a monthly basis. Results indicated that the use of a floating evaporation pan in a small free-water surface better simulates actual physical conditions on the water surface that control evaporation. Floating pan to land pan ratios were 0.82 for March, 0.87 for April, 0.85 for May, 0.85 for June, 0.79 for July, and 0.69 for August.
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Estimating evaporation from standard meteorological data continues to be an active area of research and practical application. Here we report on recent progress in using standard meteorology data to estimate potential, reference a...
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Estimating evaporation from standard meteorological data continues to be an active area of research and practical application. Here we report on recent progress in using standard meteorology data to estimate potential, reference and actual evaporation from terrestrial landscapes as well as evaporation from lakes and reservoirs. We also address recent enhancements to standard methodologies through use of remote sensing and data-driven procedures. From our report we observe that remote sensing offers significant potential for mapping spatial variations in evaporation. There has been limited progress in estimating actual evaporation via the complementary relationship, whereas applications of the Penman-Monteith and related equations incorporating actual surface resistance term(s) have dominated the recent literature.
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We demonstrate runaway evaporative cooling directly with a tightly confining optical-dipole trap andachieve fast production of condensates of 1.5 X 105 87Rb atoms. Our scheme uses a misaligned crossed-beamfar off-resonance optical...
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We demonstrate runaway evaporative cooling directly with a tightly confining optical-dipole trap andachieve fast production of condensates of 1.5 X 105 87Rb atoms. Our scheme uses a misaligned crossed-beamfar off-resonance optical-dipole trap (MACRO-FORT). It is characterized by independent control of the trapconfinement and depth allowing forced all-optical evaporation in the runaway regime. Although our configu-ration is particularly well suited to the case of 87Rb atoms in a 1565 nm optical trap, where an efficient initialloading is possible, our scheme is general and will allow all-optical evaporative cooling at constant stiffness forevery optically trappable atomic or even molecular species.
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Declining trends in pan and lake evaporation have been reported. It is important to study this trend in every region to evaluate
the validity of the trend and water management implications. Data from nine pan evaporation sites in ...
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Declining trends in pan and lake evaporation have been reported. It is important to study this trend in every region to evaluate
the validity of the trend and water management implications. Data from nine pan evaporation sites in South Florida were
evaluated to see if there is a trend and if the quality of the data is sufficient for such analysis. The conclusion is that pan
evaporation measurements are prone to too many sources of errors to be used for trend analysis. This condition is demonstrated
in South Florida and in other regions by differences in magnitude and direction between spatially related pan stations and
unexplainable observations. Also, potential evapotranspiration (ETp) was estimated with the Simple (Abtew equation) and the
Penman–Monteith method. Both cases indicated no decline in evapotranspiration for the period of analysis. Based on the
decline in humidity and the increasing trend in vapor pressure deficit for the short period of analysis, 1992–2009, it appears
that South Florida is experiencing increase in evaporation and evapotranspiration at this time assuming no systematic error in
the weather stations’ observations.
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Potential (wet surface) evaporation is the basis for many methods to estimate actual evaporation. Penman's (1948, ) combination of energy budget with mass and energy transfer equations can be depicted on temperature-vapor pressure...
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Potential (wet surface) evaporation is the basis for many methods to estimate actual evaporation. Penman's (1948, ) combination of energy budget with mass and energy transfer equations can be depicted on temperature-vapor pressure graphs. Key to this depiction is two straight lines on the graph representing constant enthalpy of the air at measurement height and at the surface skin, with the gap between the lines representing a combination of aerodynamic resistance variables and available energy. The equations on which Penman based his formula are easily solved numerically (without need for Penman's famous assumption) for T-0w, the temperature the surface would have if it was saturated, keeping all other variables constant. Wet surface evaporation is proportional to the vapor pressure difference between the measurement height and the surface skin. Equilibrium evaporation, based on the slope of the vapor pressure curve at T-0w, is also easily represented in the graph. The difference between the correct wet surface evaporation rate and Penman's approximation is immediately visible on the graphs. The different wet surface evaporation rates are compared using data from a tropical savanna in Australia. Implications for the classic two-component interpretation of Penman's equation are discussed.
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