Science.gov

Sample records for pan evaporation rates

  1. Differences in evaporation between a floating pan and class a pan on land

    USGS Publications Warehouse

    Masoner, J.R.; Stannard, D.I.; Christenson, S.C.

    2008-01-01

    Research was conducted to develop a method for obtaining floating pan evaporation rates in a small (less than 10,000 m2) 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. ?? 2008 American Water Resources Association.

  2. A mathematical model of pan evaporation under steady state conditions

    NASA Astrophysics Data System (ADS)

    Lim, Wee Ho; Roderick, Michael L.; Farquhar, Graham D.

    2016-09-01

    In the context of changing climate, global pan evaporation records have shown a spatially-averaged trend of ∼ -2 to ∼ -3 mm a-2 over the past 30-50 years. This global phenomenon has motivated the development of the "PenPan" model (Rotstayn et al., 2006). However, the original PenPan model has yet to receive an independent experimental evaluation. Hence, we constructed an instrumented US Class A pan at Canberra Airport (Australia) and monitored it over a three-year period (2007-2010) to uncover the physics of pan evaporation under non-steady state conditions. The experimental investigations of pan evaporation enabled theoretical formulation and parameterisation of the aerodynamic function considering the wind, properties of air and (with or without) the bird guard effect. The energy balance investigation allowed for detailed formulation of the short- and long-wave radiation associated with the albedos and the emissivities of the pan water surface and the pan wall. Here, we synthesise and generalise those earlier works to develop a new model called the "PenPan-V2" model for application under steady state conditions (i.e., uses a monthly time step). Two versions (PenPan-V2C and PenPan-V2S) are tested using pan evaporation data available across the Australian continent. Both versions outperformed the original PenPan model with better representation of both the evaporation rate and the underlying physics of a US Class A pan. The results show the improved solar geometry related calculations (e.g., albedo, area) for the pan system led to a clear improvement in representing the seasonal cycle of pan evaporation. For general applications, the PenPan-V2S is simpler and suited for applications including an evaluation of long-term trends in pan evaporation.

  3. 7 CFR 58.913 - Evaporators and vacuum pans.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Evaporators and vacuum pans. 58.913 Section 58.913....913 Evaporators and vacuum pans. All equipment used in the removal of moisture from milk or milk... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans....

  4. 7 CFR 58.913 - Evaporators and vacuum pans.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Evaporators and vacuum pans. 58.913 Section 58.913....913 Evaporators and vacuum pans. All equipment used in the removal of moisture from milk or milk... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans....

  5. 7 CFR 58.913 - Evaporators and vacuum pans.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Evaporators and vacuum pans. 58.913 Section 58.913....913 Evaporators and vacuum pans. All equipment used in the removal of moisture from milk or milk... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans....

  6. 7 CFR 58.913 - Evaporators and vacuum pans.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Evaporators and vacuum pans. 58.913 Section 58.913....913 Evaporators and vacuum pans. All equipment used in the removal of moisture from milk or milk... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans....

  7. 7 CFR 58.913 - Evaporators and vacuum pans.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Evaporators and vacuum pans. 58.913 Section 58.913....913 Evaporators and vacuum pans. All equipment used in the removal of moisture from milk or milk... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans....

  8. Early Pan-African evolution of the basement around Elat, Israel, and the Sinai Peninsula revealed by single-zircon evaporation dating, and implications for crustal accretion rates

    SciTech Connect

    Kroener, A. ); Eyal, M.; Eyal, Y. )

    1990-06-01

    The authors report {sup 207}Pb/{sup 206}Pb single-zircon evaporation ages for early Pan-African rocks from southern Israel and the northeastern Sinai Peninsula, the northernmost extension of the Arabian-Nubian shield. The oldest rocks are metamorphic schists of presumed island-arc derivation; detrital zircons date the source terrain at ca. 800-820 Ma. A major phase of tonalite-trondhjemite plutonism occurred at ca. 760-780 Ma; more evolved granitic rocks were emplaced at about 745 Ma. A metagabbro-metadiorite complex reflects the youngest igneous phase at ca. 640 Ma. We find no evidence for pre-Pan-African crust, and our data document important crust-forming events that correlate with similar episodes elsewhere in the shield. The widespread presence of early Pan-African juvenile rocks (i.e., ca. 760-850 Ma) in many parts of the Arabian-Nubian shield makes this period the most important in the magmatic history of the shield and supports earlier suggestions for unusually high crust-production rates.

  9. Evaporation from the shallow Lake Massaciuccoli (Tuscany, Italy) studied using stable isotopes and evaporation pan data

    NASA Astrophysics Data System (ADS)

    Baneschi, I.; Gonfiantini, R.; Guidi, M.

    2009-04-01

    Oxygen and hydrogen isotope variations monitored in Lake Massaciuccoli (7 km2, 2 m deep, seasonally variable water level) during summer 2008, were compared with those observed in a Class A evaporation pan (diameter 120.6 cm, depth 25.4 cm) placed on the lake eastern shore. Air temperature, pressure, relative humidity, wind speed and direction, solar radiation, water temperature in the lake and the pan were also measured. The pluviometer indicated that no precipitation occurred during the study period. The pan was initially filled with groundwater up to the level of 19.2 cm (219 L), depleted in heavy isotopes with respect to tha lake water. Sodium chloride was added up to the concentration of 1 g×L-1, which is assumed do not affect significantly the evaporation rate till the water volume is reduced to less than 10 %. The Cl- concentration was used to provide an estimation of the evaporated water fraction, in addition to the micrometer measuring the water level variations. The pan water was sampled every 2-3 days and Cl- and stable isotopes determined. The set of stable isotope and evaporation data enabled us to compute the parameters governing the evaporation process and the isotopic exchanges with the atmospheric moisture, according to the procedure proposed by Gonfiantini (1986). The values were applied to test three working hypotheses of water balance of Lake Massaciuccoli: (i) surface inflow and outflow of liquid water are negligible and only evaporation is important; (ii) the inflow is negligible and outflow and evaporation are both significant; (iii) the three terms of balance are all important but the losses by evaporation and outflow exceed inflow (as the lake water level was decreasing). Water exchanges with groundwater are considered negligible. The best agreement between lake and pan data was obtained with the second hypothesis, for which the fraction of water removed by evaporation was estimated to be about 40 % ot he total water losses. This residual

  10. Groundwater evaporation from salt pans: Examples from the eastern Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Schulz, Stephan; Horovitz, Marcel; Rausch, Randolf; Michelsen, Nils; Mallast, Ulf; Köhne, Maximilian; Siebert, Christian; Schüth, Christoph; Al-Saud, Mohammed; Merz, Ralf

    2015-12-01

    The major groundwater resources of the Arabian Peninsula are stored in the large sedimentary basins in its eastern part. Evaporation from continental salt pans (playas) is an important process in water resources assessments of its upper principal aquifers - the Upper Mega Aquifer system - as it constitutes a significant sink. However, literature values on evaporation rates vary widely and usually report about coastal salt pans where seawater evaporation is assumed. The present study applies different methods to provide a comprehensive picture of groundwater evaporation from salt pans of the Upper Mega Aquifer system. A remote sensing approach provided the spatial distribution and total salt pan area of about 36,500 km2. Hydrochemical and isotopic investigations revealed that from about 10% (3600 km2 ± 1600 km2) of the mapped salt pan area seawater evaporates. To estimate the groundwater evaporation rate from continental salt pans a laboratory column experiment was set up, implying a mean annual evaporation rate of about 42 mm ± 13 mm. In-situ analysis of water table fluctuations in the field suggested about 3 mm a-1 originate from recently infiltrated rainwater leading to an annual net groundwater evaporation of 39 mm ± 13 mm. Relating this number to the mapped salt pan area, from which groundwater evaporates, provides a total annual groundwater loss of 1.3 km3 ± 0.5 km3 for the Upper Mega Aquifer system.

  11. Modeling monthly pan evaporations using fuzzy genetic approach

    NASA Astrophysics Data System (ADS)

    Kişi, Özgür; Tombul, Mustafa

    2013-01-01

    SummaryThis study investigates the ability of fuzzy genetic (FG) approach in estimation of monthly pan evaporations. Various monthly climatic data, that are, solar radiation, air temperature, relative humidity and wind speed from two stations, Antalya and Mersin, in Mediterranean Region of Turkey, were used as inputs to the FG technique so as to estimate monthly pan evaporations. In the first part of the study, FG models were compared with neuro-fuzzy (ANFIS), artificial neural networks (ANNs) and Stephens-Stewart (SS) methods in estimating pan evaporations of Antalya and Mersin stations, separately. Comparison of the models revealed that the FG models generally performed better than the ANFIS, ANN and SS models. In the second part of the study, models were compared to each other in two different applications. In the first application the input data of Antalya Station were used as inputs to the models to estimate pan evaporation data of Mersin Station. The pan evaporation data of Mersin Station were estimated using the input data of Antalya and Mersin stations in the second application. Comparison results indicated that the FG models performed better than the ANFIS and ANN models. Comparison of the accuracy of the applied models in estimating total pan evaporations showed that the FG model provided the closest estimate. It was concluded that monthly pan evaporations could be successfully estimated by the FG approach.

  12. On the theory relating changes in area-average and pan evaporation (Invited)

    NASA Astrophysics Data System (ADS)

    Shuttleworth, W.; Serrat-Capdevila, A.; Roderick, M. L.; Scott, R.

    2009-12-01

    Theory relating changes in area-average evaporation with changes in the evaporation from pans or open water is developed. Such changes can arise by Type (a) processes related to large-scale changes in atmospheric concentrations and circulation that modify surface evaporation rates in the same direction, and Type (b) processes related to coupling between the surface and atmospheric boundary layer (ABL) at the landscape scale that usually modify area-average evaporation and pan evaporation in different directions. The interrelationship between evaporation rates in response to Type (a) changes is derived. They have the same sign and broadly similar magnitude but the change in area-average evaporation is modified by surface resistance. As an alternative to assuming the complementary evaporation hypothesis, the results of previous modeling studies that investigated surface-atmosphere coupling are parameterized and used to develop a theoretical description of Type (b) coupling via vapor pressure deficit (VPD) in the ABL. The interrelationship between appropriately normalized pan and area-average evaporation rates is shown to vary with temperature and wind speed but, on average, the Type (b) changes are approximately equal and opposite. Long-term Australian pan evaporation data are analyzed to demonstrate the simultaneous presence of Type (a) and (b) processes, and observations from three field sites in southwestern USA show support for the theory describing Type (b) coupling via VPD. England's victory over Australia in 2009 Ashes cricket test match series will not be mentioned.

  13. Evolutionary neural networks for monthly pan evaporation modeling

    NASA Astrophysics Data System (ADS)

    Kişi, Özgür

    2013-08-01

    Estimating pan evaporation is very important for monitoring, survey and management of water resources. This study proposes the application evolutionary neural networks (ENN) for modeling monthly pan evaporations. Solar radiation, air temperature, relative humidity, wind speed and pan evaporation data from two stations, Antalya and Mersin, in Mediterranean Region of Turkey are used in the study. In the first part of the study, ENN models are compared with those of the fuzzy genetic (FG), neuro-fuzzy (ANFIS), artificial neural networks (ANN) and Stephens-Stewart (SS) methods in estimating pan evaporations of Antalya and Mersin stations, separately. Comparison results indicate that the ENN models generally perform better than the FG, ANFIS, ANN and SS models. In the second part of the study, models are compared with each other in estimating Mersin’s pan evaporations using input data of both stations. Results reveal that the ENN models performed better than the FG, ANFIS and ANN models. It was concluded that monthly pan evaporations can be successfully estimated by the ENN method. The performance of the ENN model with full weather data as inputs presents 0.749 and 0.759 mm of mean absolute error for the Antalya and Mersin stations, respectively.

  14. 7 CFR 58.217 - Evaporators and/or vacuum pans.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Evaporators and/or vacuum pans. 58.217 Section 58.217....217 Evaporators and/or vacuum pans. Evaporators or vacuum pans or both, with open type condensers... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans. When enclosed type...

  15. 7 CFR 58.217 - Evaporators and/or vacuum pans.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Evaporators and/or vacuum pans. 58.217 Section 58.217....217 Evaporators and/or vacuum pans. Evaporators or vacuum pans or both, with open type condensers... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans. When enclosed type...

  16. 7 CFR 58.217 - Evaporators and/or vacuum pans.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Evaporators and/or vacuum pans. 58.217 Section 58.217....217 Evaporators and/or vacuum pans. Evaporators or vacuum pans or both, with open type condensers... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans. When enclosed type...

  17. 7 CFR 58.217 - Evaporators and/or vacuum pans.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Evaporators and/or vacuum pans. 58.217 Section 58.217....217 Evaporators and/or vacuum pans. Evaporators or vacuum pans or both, with open type condensers... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans. When enclosed type...

  18. 7 CFR 58.217 - Evaporators and/or vacuum pans.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Evaporators and/or vacuum pans. 58.217 Section 58.217....217 Evaporators and/or vacuum pans. Evaporators or vacuum pans or both, with open type condensers... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans. When enclosed type...

  19. From evaporating pans to transpiring plants (John Dalton Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Roderick, Michael

    2013-04-01

    The name of the original inventor of irrigated agriculture is lost to antiquity. Nevertheless, one can perhaps imagine an inquisitive desert inhabitant noting the greener vegetation along a watercourse and putting two and two together. Once water was being supplied and food was being produced it would be natural to ask a further question: how much water can we put on? No doubt much experience was gained down through the ages, but again, one can readily imagine someone inverting a rain gauge, filling it with water and measuring how fast the water evaporated. The inverted rain gauge measures the demand for water by the atmosphere. We call it the evaporative demand. I do not know if this is what actually happened but it sure makes an interesting start to a talk. Evaporation pans are basically inverted rain gauges. The rain gauge and evaporation pan measure the supply and demand respectively and these instruments are the workhorses of agricultural meteorology. Rain gauges are well known. Evaporation pans are lesser known but are in widespread use and are a key part of several national standardized meteorological networks. Many more pans are used for things like scheduling irrigation on farms or estimating evaporation from lakes. Analysis of the long records now available from standardized networks has revealed an interesting phenomenon, i.e., pan evaporation has increased in some places and decreased in other but when averaged over large numbers of pans there has been a steady decline. These independent reports from, for example, the US, Russia, China, India, Thailand, are replicated in the southern hemisphere in, for example, Australia, New Zealand and South Africa. One often hears the statement that because the earth is expected to warm with increasing greenhouse gas emissions then it follows that water will evaporate faster. The pan evaporation observations show that this widely held expectation is wrong. When expectations disagree with observations, it is the

  20. Monthly pan evaporation modeling using linear genetic programming

    NASA Astrophysics Data System (ADS)

    Guven, Aytac; Kisi, Ozgur

    2013-10-01

    This study compares the accuracy of linear genetic programming (LGP), fuzzy genetic (FG), adaptive neuro-fuzzy inference system (ANFIS), artificial neural networks (ANN) and Stephens-Stewart (SS) methods in modeling pan evaporations. Monthly climatic data including solar radiation, air temperature, relative humidity, wind speed and pan evaporation from Antalya and Mersin stations, in Turkey are used in the study. The study composed of two parts. First part of the study focuses the comparison of LGP models with those of the FG, ANFIS, ANN and SS models in estimating pan evaporations of Antalya and Mersin stations, separately. From the comparison results, the LGP models are found to be better than the other models. Comparison of LGP models with the other models in estimating pan evaporations of the Mersin Station by using both stations' inputs is focused in the second part of the study. The results indicate that the LGP models better accuracy than the FG, ANFIS, ANN and SS models. It is seen that the pan evaporations can be successfully estimated by the LGP method.

  1. Application of thermal model for pan evaporation to the hydrology of a defined medium, the sponge

    NASA Technical Reports Server (NTRS)

    Trenchard, M. H.; Artley, J. A. (Principal Investigator)

    1981-01-01

    A technique is presented which estimates pan evaporation from the commonly observed values of daily maximum and minimum air temperatures. These two variables are transformed to saturation vapor pressure equivalents which are used in a simple linear regression model. The model provides reasonably accurate estimates of pan evaporation rates over a large geographic area. The derived evaporation algorithm is combined with precipitation to obtain a simple moisture variable. A hypothetical medium with a capacity of 8 inches of water is initialized at 4 inches. The medium behaves like a sponge: it absorbs all incident precipitation, with runoff or drainage occurring only after it is saturated. Water is lost from this simple system through evaporation just as from a Class A pan, but at a rate proportional to its degree of saturation. The contents of the sponge is a moisture index calculated from only the maximum and minium temperatures and precipitation.

  2. Isotopic composition of atmospheric moisture from pan water evaporation measurements.

    PubMed

    Devi, Pooja; Jain, Ashok Kumar; Rao, M Someshwer; Kumar, Bhishm

    2015-01-01

    A continuous and reliable time series data of the stable isotopic composition of atmospheric moisture is an important requirement for the wider applicability of isotope mass balance methods in atmospheric and water balance studies. This requires routine sampling of atmospheric moisture by an appropriate technique and analysis of moisture for its isotopic composition. We have, therefore, used a much simpler method based on an isotope mass balance approach to derive the isotopic composition of atmospheric moisture using a class-A drying evaporation pan. We have carried out the study by collecting water samples from a class-A drying evaporation pan and also by collecting atmospheric moisture using the cryogenic trap method at the National Institute of Hydrology, Roorkee, India, during a pre-monsoon period. We compared the isotopic composition of atmospheric moisture obtained by using the class-A drying evaporation pan method with the cryogenic trap method. The results obtained from the evaporation pan water compare well with the cryogenic based method. Thus, the study establishes a cost-effective means of maintaining time series data of the isotopic composition of atmospheric moisture at meteorological observatories. The conclusions drawn in the present study are based on experiments conducted at Roorkee, India, and may be examined at other regions for its general applicability. PMID:26332982

  3. Modeling Pan Evaporation for Kuwait by Multiple Linear Regression

    PubMed Central

    Almedeij, Jaber

    2012-01-01

    Evaporation is an important parameter for many projects related to hydrology and water resources systems. This paper constitutes the first study conducted in Kuwait to obtain empirical relations for the estimation of daily and monthly pan evaporation as functions of available meteorological data of temperature, relative humidity, and wind speed. The data used here for the modeling are daily measurements of substantial continuity coverage, within a period of 17 years between January 1993 and December 2009, which can be considered representative of the desert climate of the urban zone of the country. Multiple linear regression technique is used with a procedure of variable selection for fitting the best model forms. The correlations of evaporation with temperature and relative humidity are also transformed in order to linearize the existing curvilinear patterns of the data by using power and exponential functions, respectively. The evaporation models suggested with the best variable combinations were shown to produce results that are in a reasonable agreement with observation values. PMID:23226984

  4. Rate of runaway evaporative cooling

    SciTech Connect

    Groep, J. van de; Straten, P. van der; Vogels, J. M.

    2011-09-15

    Evaporative cooling is a process that is essential in creating Bose-Einstein condensates in dilute atomic gasses. This process has often been simulated based on a model using a truncated Boltzmann distribution. This model assumes that the energy distribution up to the threshold energy can still be described by a Boltzmann distribution: it assumes detailed balance up to the threshold energy. However, the evolution of the distribution function in time is not taken into account. Here we solve the kinetic Boltzmann equation for a gas undergoing evaporative cooling in a harmonic and linear trap in order to determine the evolution of the energy distribution. The magnitude of the discrepancy with the truncated Boltzmannmodel is calculated by including a polynomial expansion of the distribution function. We find that up to 35% fewer particles are found in the high-energy tail of the distribution with respect to the truncated Boltzmann distribution and up to 15% more collisions are needed to reach quantum degeneracy. Supported by a detailed investigation of the particle loss rate at different energies, we conclude that the limited occupation of high-energy states during the evaporation process causes the lowering of the evaporation speed and efficiency.

  5. ON THE THEORY RELATING CHANGES IN AREA-AVERAGE AND PAN EVAPORATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Theory relating changes in the area-average evaporation from a landscape with changes in the evaporation from pans or open water within the landscape is developed. Such changes can arise in two ways, by Type (a) processes related to large-scale changes in atmospheric concentrations and circulation t...

  6. Evaporation variability under climate warming in five reanalyses and its association with pan evaporation over China

    NASA Astrophysics Data System (ADS)

    Su, Tao; Feng, Taichen; Feng, Guolin

    2015-08-01

    With the motivation to identify actual evapotranspiration (AE) variability under climate warming over China, an assessment is made from five sets of reanalysis data sets [National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR), NCEP-Department of Energy (NCEP-DOE), Modern-Era Retrospective Analysis for Research and Applications (MERRA), Interim Reanalysis, and Japanese 55-year Reanalysis (JRA-55)]. Based on comparison with AE estimates calculated using the Budyko equation, all five reanalysis data sets reasonably reproduce the spatial patterns of AE over China, with a clearly southeast-northwest gradient. Overall, JRA-55 (NCEP-DOE) gives the lowest (highest) reanalysis evaporation (RE) values. From 1979 to 2013, dominant modes of RE among five reanalyses are extracted using multivariate empirical orthogonal function analysis. Accordingly, the interdecadal variation of RE is likely driven by the change of temperature, and the interannual variation is constrained by the water supply conditions. Under climate warming, RE increase in the Northwest China, Yangtze-Huaihe river basin, and South China, while they decrease in Qinghai-Tibet Plateau, and northern and Northeast China. Moreover, the relationship between RE and pan evaporation (PE) are comprehensively evaluated in space-time. Negative correlations are generally confirmed in nonhumid environments, while positive correlations exist in the humid regions. Our analysis supports the interpretation that the relationship between PE and AE was complementary with water control and proportional with energy control. In view of data availability, important differences in spatial variability and the amount of RE can be found in Northwest China, the Qinghai-Tibet Plateau, and the Yangtze River Basin. Generally speaking, NCEP-NCAR and MERRA have substantial problems on describing the long-term change of RE; however, there are some inaccuracies in the JRA-55 estimates when focusing on

  7. Turkish Undergraduates' Misconceptions of Evaporation, Evaporation Rate, and Vapour Pressure

    ERIC Educational Resources Information Center

    Canpolat, Nurtac

    2006-01-01

    This study focused on students' misconceptions related to evaporation, evaporation rate, and vapour pressure. Open-ended diagnostic questions were used with 107 undergraduates in the Primary Science Teacher Training Department in a state university in Turkey. In addition, 14 students from that sample were interviewed to clarify their written…

  8. Estimating daily pan evaporation using adaptive neural-based fuzzy inference system

    NASA Astrophysics Data System (ADS)

    Keskin, M. Erol; Terzi, Özlem; Taylan, Dilek

    2009-09-01

    Estimation of evaporation is important for water planning, management, and hydrological practices. There are many available methods to estimate evaporation from a water surface, comprising both direct and indirect methods. All the evaporation models are based on crisp conceptions with no uncertainty element coupled into the model structure although in daily evaporation variations there are uncontrollable effects to a certain extent. The probabilistic, statistical, and stochastic approaches require large amounts of data for the modeling purposes and therefore are not practical in local evaporation studies. It is therefore necessary to adopt a better approach for evaporation modeling, which is the fuzzy sets and adaptive neural-based fuzzy inference system (ANFIS) as used in this paper. ANFIS and fuzzy sets have been evaluated for its applicability to estimate evaporation from meteorological data which is including air and water temperatures, solar radiation, and air pressure obtained from Automated GroWheather meteorological station located near Lake Eğirdir and daily pan evaporation values measured by XVIII. District Directorate of State Hydraulic Works. Results of ANFIS and fuzzy logic approaches were analyzed and compared with measured daily pan evaporation values. ANFIS approach could be employed more successfully in modeling the evaporation process than fuzzy sets.

  9. Trends in Pan Evaporation and Application of the Complimentary Relationship of Evaporation in the Great Basin, USA

    NASA Astrophysics Data System (ADS)

    Huntington, J. L.; Caldwell, T.; Naranjo, R.; Burak, S.; Tyler, S.

    2007-12-01

    Evaluating available water resources in the Great Basin is an increasing topic of discussion by several local, State, and Federal government agencies due to proposals for water importation into areas of rapid population growth. In estimating a water budget for a particular flow system in the Great Basin, groundwater evapotranspiration (ET) from phreatophyte vegetation is often the most important as it is the only water budget component that can be estimated with some certainty, opposed to mountain block recharge and interbasin subsurface flow. Bouchet's complimentary relationship of evaporation has drawn noteworthy attention in recent years, not only because of its use in explaining observed changes in the hydrologic cycle, but also for its use in predicting ET using readily available meteorological data. The objective of this presentation is twofold: 1) to discuss pan evaporation trends in the Great Basin, and 2) discuss results from the application of the complimentary relationship for predicting evapotranspiration from phreatophyte shrubs when compared to measured ET at several U.S. Geological Survey eddy correlation and Bowen ratio sites. Initial findings indicate a decrease of pan evaporation in Death Valley, CA, the lowest, hottest, and driest location in North America, an opposite trend from analysis of several other sites in the Great Basin that indicate an increase of pan evaporation. It is believed that these opposing trends are likely the result of local water availability surrounding the pan, and or data quality. The application of a symmetric complimentary relationship indicate satisfactory results when compared to measured evapotranspiration, however, during the hottest months of the year the predicted ET over estimates the measured. Further investigation of micrometeorological data suggests that an asymmetric complimentary relationship between potential and actual ET exists, and when taken into account, improves the predictions markedly.

  10. A spatial neural fuzzy network for estimating pan evaporation at ungauged sites

    NASA Astrophysics Data System (ADS)

    Chung, C.-H.; Chiang, Y.-M.; Chang, F.-J.

    2011-11-01

    Evaporation is an essential reference to the management of water resources. In this study, a hybrid model that integrates a spatial neural fuzzy network with the kringing method is developed to estimate pan evaporation at ungauged sites. The adaptive network-based fuzzy inference system (ANFIS) can extract the nonlinear relationship of observations, while kriging is an excellent geostatistical interpolator. Three-year daily data collected from nineteen meteorological stations covering the whole of Taiwan are used to train and test the constructed model. The pan evaporation (Epan) at ungauged sites can be obtained through summing up the outputs of the spatially weighted ANFIS and the residuals adjusted by kriging. Results indicate that the proposed AK model (hybriding ANFIS and kriging) can effectively improve the accuracy of Epan estimation as compared with that of empirical formula. This hybrid model demonstrates its reliability in estimating the spatial distribution of Epan and consequently provides precise Epan estimation by taking geographical features into consideration.

  11. A spatial neural fuzzy network for estimating pan evaporation at ungauged sites

    NASA Astrophysics Data System (ADS)

    Chung, C.-H.; Chiang, Y.-M.; Chang, F.-J.

    2012-01-01

    Evaporation is an essential reference to the management of water resources. In this study, a hybrid model that integrates a spatial neural fuzzy network with the kringing method is developed to estimate pan evaporation at ungauged sites. The adaptive network-based fuzzy inference system (ANFIS) can extract the nonlinear relationship of observations, while kriging is an excellent geostatistical interpolator. Three-year daily data collected from nineteen meteorological stations covering the whole of Taiwan are used to train and test the constructed model. The pan evaporation (Epan) at ungauged sites can be obtained through summing up the outputs of the spatially weighted ANFIS and the residuals adjusted by kriging. Results indicate that the proposed AK model (hybriding ANFIS and kriging) can effectively improve the accuracy of Epan estimation as compared with that of empirical formula. This hybrid model demonstrates its reliability in estimating the spatial distribution of Epan and consequently provides precise Epan estimation by taking geographical features into consideration.

  12. Estimating actual, potential, reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis

    NASA Astrophysics Data System (ADS)

    McMahon, T. A.; Peel, M. C.; Lowe, L.; Srikanthan, R.; McVicar, T. R.

    2013-04-01

    This guide to estimating daily and monthly actual, potential, reference crop and pan evaporation covers topics that are of interest to researchers, consulting hydrologists and practicing engineers. Topics include estimating actual evaporation from deep lakes and from farm dams and for catchment water balance studies, estimating potential evaporation as input to rainfall-runoff models, and reference crop evapotranspiration for small irrigation areas, and for irrigation within large irrigation districts. Inspiration for this guide arose in response to the authors' experiences in reviewing research papers and consulting reports where estimation of the actual evaporation component in catchment and water balance studies was often inadequately handled. Practical guides using consistent terminology that cover both theory and practice are not readily available. Here we provide such a guide, which is divided into three parts. The first part provides background theory and an outline of the conceptual models of potential evaporation of Penman, Penman-Monteith and Priestley-Taylor, as well as discussions of reference crop evapotranspiration and Class-A pan evaporation. The last two sub-sections in this first part include techniques to estimate actual evaporation from (i) open-surface water and (ii) landscapes and catchments (Morton and the advection-aridity models). The second part addresses topics confronting a practicing hydrologist, e.g. estimating actual evaporation for deep lakes, shallow lakes and farm dams, lakes covered with vegetation, catchments, irrigation areas and bare soil. The third part addresses six related issues: (i) automatic (hard wired) calculation of evaporation estimates in commercial weather stations, (ii) evaporation estimates without wind data, (iii) at-site meteorological data, (iv) dealing with evaporation in a climate change environment, (v) 24 h versus day-light hour estimation of meteorological variables, and (vi) uncertainty in evaporation

  13. Black hole evaporation rates without spacetime.

    PubMed

    Braunstein, Samuel L; Patra, Manas K

    2011-08-12

    Verlinde recently suggested that gravity, inertia, and even spacetime may be emergent properties of an underlying thermodynamic theory. This vision was motivated in part by Jacobson's 1995 surprise result that the Einstein equations of gravity follow from the thermodynamic properties of event horizons. Taking a first tentative step in such a program, we derive the evaporation rate (or radiation spectrum) from black hole event horizons in a spacetime-free manner. Our result relies on a Hilbert space description of black hole evaporation, symmetries therein which follow from the inherent high dimensionality of black holes, global conservation of the no-hair quantities, and the existence of Penrose processes. Our analysis is not wedded to standard general relativity and so should apply to extended gravity theories where we find that the black hole area must be replaced by some other property in any generalized area theorem. PMID:21902381

  14. Evaporation rate of emulsion and oil-base emulsion pheromones

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of pheromone evaporation rate is critical to distribute pheromone containers effectively in the forest, orchard and field. There are several factors influencing the pheromone evaporation rate that include wind speed, container size and porosity, release area, temperature, humidity, pherom...

  15. Utility of coactive neuro-fuzzy inference system for pan evaporation modeling in comparison with multilayer perceptron

    NASA Astrophysics Data System (ADS)

    Tabari, Hossein; Hosseinzadeh Talaee, P.; Abghari, Hirad

    2012-05-01

    Estimation of pan evaporation ( E pan) using black-box models has received a great deal of attention in developing countries where measurements of E pan are spatially and temporally limited. Multilayer perceptron (MLP) and coactive neuro-fuzzy inference system (CANFIS) models were used to predict daily E pan for a semi-arid region of Iran. Six MLP and CANFIS models comprising various combinations of daily meteorological parameters were developed. The performances of the models were tested using correlation coefficient ( r), root mean square error (RMSE), mean absolute error (MAE) and percentage error of estimate (PE). It was found that the MLP6 model with the Momentum learning algorithm and the Tanh activation function, which requires all input parameters, presented the most accurate E pan predictions ( r = 0.97, RMSE = 0.81 mm day-1, MAE = 0.63 mm day-1 and PE = 0.58 %). The results also showed that the most accurate E pan predictions with a CANFIS model can be achieved with the Takagi-Sugeno-Kang (TSK) fuzzy model and the Gaussian membership function. Overall performances revealed that the MLP method was better suited than CANFIS method for modeling the E pan process.

  16. Statistical rate theory examination of ethanol evaporation.

    PubMed

    Persad, A H; Ward, C A

    2010-05-13

    A series of low-temperature (246 < T(I)(L) < 267 K) steady-state ethanol evaporation experiments have been conducted to determine the saturation vapor pressure of metastable ethanol. The measured interfacial conditions have been used with statistical rate theory (SRT) to develop an expression for the saturation vapor pressure as a function of temperature, f(srt)(eth). This expression is shown to be thermodynamically consistent because it gives predictions of both the evaporative latent heat and the liquid constant-pressure specific heat that are in agreement with independent measurements of these properties. In each experiment, the interfacial vapor temperature was measured to be greater than the interfacial liquid temperature, [triple bond]DeltaT(I)(LV). When f(srt)(eth) is used in SRT to predict DeltaT(I)(LV), the results are shown to be consistent with the measurements. Other expressions for the saturation vapor pressure that are in the literature are examined and found to be thermodynamically inconsistent and do not lead to valid predictions of DeltaT(I)(LV). PMID:20405870

  17. PREDICTING EVAPORATION RATES AND TIMES FOR SPILLS OF CHEMICAL MIXTURES

    EPA Science Inventory


    Spreadsheet and short-cut methods have been developed for predicting evaporation rates and evaporation times for spills (and constrained baths) of chemical mixtures. Steady-state and time-varying predictions of evaporation rates can be made for six-component mixtures, includ...

  18. Comparison of artificial neural network and empirical equations for daily reference evapotranspiration estimation from pan evaporation

    NASA Astrophysics Data System (ADS)

    Mosaedi, Abolfazl; Ghabaei S., Mohammad

    2010-05-01

    Evaporation and Evapotranspiration Process are the major components of the hydrologic cycle which play an important role in agricultural studies such as design of irrigation and drainage systems, and irrigation scheduling. Evapotranspiration is a complex non-linear phenomenon which depends on several climatologic factors. It can be measured directly by high-cost micrometeorological techniques. Hence, many mathematical models and empirical equations were developed to estimate this phenomenon. One conventional method to estimate reference crop evapotranspiration (ET0) is converting the class A pan evaporation (EPan) into ETo by using a pan coefficient (KPan) according to following this equation. ETo = Kpan * Epan PIC Another alternative method to estimate ETo is the application of mathematical models like artificial neural networks (ANNs). ANNs are mathematical models whose architecture has been inspired by biological neural networks. ANNs are very appropriate for the modeling of nonlinear processes, i.e. the case of ETo.Kpan is the important factor for computation of ETo from Epan, There for several empirical equations purposed to determine KPan, using wind speed, relative humidity and fetch length conditions by many researchers. The main objective of this study was to comparison between ability of ANNs and empirical equations for estimation daily ET0 from Epan. For this object Daily measured weather data for a 16 year (from 1992 to 2007) period were obtained from the Shiraz synoptic station (latitude 29o 36' N, longitude 52o 32' E, elevation 1480 m) that located in Fars province of Iran. The climate in the study area is semi-arid with an average annual rainfall of 346 mm year-1. In This paper first, we use seven empirical equations: Cuenca (1989), Snyder (1992), Modified Snyder (1992), Doorenbos and Pruitt (1977), Pereira et al. (1995), Orang (1998) and Raghuwanshi and Wallender (1998) for estimation KPan values and second then we use ANNs for converting Epan to

  19. Evaporation Rates of Brine on Mars

    NASA Technical Reports Server (NTRS)

    Sears, D. W. G.; Chittenden, J.; Moore, S. R.; Meier, A.; Kareev, M.; Farmer, C. B.

    2004-01-01

    While Mars is now largely a dry and barren place, recent data have indicated that water has flowed at specific locations within the last approx. 10(exp 6) y. This had led to a resurgence of interest in theoretical and experimental work aimed at understanding the behavior of water on Mars. There are several means whereby the stability of liquid water on Mars could be increased, one being the presence solutes that would depress the freezing point. Salt water on Earth is about 0.5M NaCl, but laboratory experiments suggest that martian salt water is quite different. We recently began a program of laboratory measurements of the stability of liquid water, ice and ice-dust mixtures under martian conditions and here report measurements of the evaporation rate of 0.25M brine.

  20. Evaluation of pan evaporation modeling with two different neural networks and weather station data

    NASA Astrophysics Data System (ADS)

    Kim, Sungwon; Singh, Vijay P.; Seo, Youngmin

    2014-07-01

    This study evaluates neural networks models for estimating daily pan evaporation for inland and coastal stations in Republic of Korea. A multilayer perceptron neural networks model (MLP-NNM) and a cascade correlation neural networks model (CCNNM) are developed for local implementation. Five-input models (MLP 5 and CCNNM 5) are generally found to be the best for local implementation. The optimal neural networks models, including MLP 4, MLP 5, CCNNM 4, and CCNNM 5, perform well for homogeneous (cross-stations 1 and 2) and nonhomogeneous (cross-stations 3 and 4) weather stations. Statistical results of CCNNM are better than those of MLP-NNM during the test period for homogeneous and nonhomogeneous weather stations except for MLP 4 being better in BUS-DAE and POH-DAE, and MLP 5 being better in POH-DAE. Applying the conventional models for the test period, it is found that neural networks models perform better than the conventional models for local, homogeneous, and nonhomogeneous weather stations.

  1. Evaporation rate and vapor pressure of selected polymeric lubricating oils.

    NASA Technical Reports Server (NTRS)

    Gardos, M. N.

    1973-01-01

    A recently developed ultrahigh-vacuum quartz spring mass sorption microbalance has been utilized to measure the evaporation rates of several low-volatility polymeric lubricating oils at various temperatures. The evaporation rates are used to calculate the vapor pressures by the Langmuir equation. A method is presented to accurately estimate extended temperature range evaporation rate and vapor pressure data for polymeric oils, incorporating appropriate corrections for the increases in molecular weight and the change in volatility of the progressively evaporating polymer fractions. The logarithms of the calculated data appear to follow linear relationships within the test temperature ranges, when plotted versus 1000/T. These functions and the observed effusion characteristics of the fluids on progressive volatilization are useful in estimating evaporation rate and vapor pressure changes on evaporative depletion.

  2. Instructions for measuring the rate of evaporation from water surfaces

    USGS Publications Warehouse

    U.S. Geological Survey

    1898-01-01

    The ·rate of evaporation from water surfaces varies with the temperature of the water, the velocity of the wind at the water surface, and the dryness of the air. Consequently, the rate of evaporation from rivers, lakes, canals, or reservoirs varies widely in different localities and for the same locality in different seasons.

  3. Utility of Penman-Monteith, Priestley-Taylor, reference evapotranspiration, and pan evaporation methods to estimate pasture evapotranspiration

    USGS Publications Warehouse

    Sumner, D.M.; Jacobs, J.M.

    2005-01-01

    Actual evapotranspiration (ETa) was measured at 30-min resolution over a 19-month period (September 28, 2000-April 23, 2002) from a nonirrigated pasture site in Florida, USA, using eddy correlation methods. The relative magnitude of measured ETa (about 66% of long-term annual precipitation at the study site) indicates the importance of accurate ET a estimates for water resources planning. The time and cost associated with direct measurements of ETa and the rarity of historical measurements of ETa make the use of methods relying on more easily obtainable data desirable. Several such methods (Penman-Monteith (PM), modified Priestley-Taylor (PT), reference evapotranspiration (ET 0), and pan evaporation (Ep)) were related to measured ETa using regression methods to estimate PM bulk surface conductance, PT ??, ET0 vegetation coefficient, and Ep pan coefficient. The PT method, where the PT ?? is a function of green-leaf area index (LAI) and solar radiation, provided the best relation with ET a (standard error (SE) for daily ETa of 0.11 mm). The PM method, in which the bulk surface conductance was a function of net radiation and vapor-pressure deficit, was slightly less effective (SE=0.15 mm) than the PT method. Vegetation coefficients for the ET0 method (SE=0.29 mm) were found to be a simple function of LAI. Pan coefficients for the Ep method (SE=0.40 mm) were found to be a function of LAI and Ep. Historical or future meteorological, LAI, and pan evaporation data from the study site could be used, along with the relations developed within this study, to provide estimates of ETa in the absence of direct measurements of ETa. Additionally, relations among PM, PT, and ET0 methods and ETa can provide estimates of ETa in other, environmentally similar, pasture settings for which meteorological and LAI data can be obtained or estimated. ?? 2004 Elsevier B.V. All rights reserved.

  4. PLS regression-based pan evaporation and minimum-maximum temperature projections for an arid lake basin in India

    NASA Astrophysics Data System (ADS)

    Goyal, Manish Kumar; Ojha, C. S. P.

    2011-10-01

    Climate change information required for impact studies is of a much finer scale than that provided by Global circulation models (GCMs). This paper presents an application of partial least squares (PLS) regression for downscaling GCMs output. Statistical downscaling models were developed using PLS regression for simultaneous downscaling of mean monthly maximum and minimum temperatures ( T max and T min) as well as pan evaporation to lake-basin scale in an arid region in India. The data used for evaluation were extracted from the NCEP/NCAR reanalysis dataset for the period 1948-2000 and the simulations from the third-generation Canadian Coupled Global Climate Model (CGCM3) for emission scenarios A1B, A2, B1, and COMMIT for the period 2001-2100. A simple multiplicative shift was used for correcting predictand values. The results demonstrated that the downscaling method was able to capture the relationship between the premises and the response. The analysis of downscaling models reveals that (1) the correlation coefficient for downscaled versus observed mean maximum temperature, mean minimum temperature, and pan evaporation was 0.94, 0.96, and 0.89, respectively; (2) an increasing trend is observed for T max and T min for A1B, A2, and B1 scenarios, whereas no trend is discerned with the COMMIT scenario; and (3) there was no trend observed in pan evaporation. In COMMIT scenario, atmospheric CO2 concentrations are held at year 2000 levels. Furthermore, a comparison with neural network technique shows the efficiency of PLS regression method.

  5. Abnormal evaporation rate of ethanol from low concentration aqueous solutions

    SciTech Connect

    Spedding, P.L.; Grimshaw, J. ); O'Hare, K.D. )

    1993-05-01

    Evaporation of aqueous ethanol solutions was studied in a wind tunnel using a circular cell design which ensured control of all the major conditions of mass transfer. At lower concentrations of alcohol, the evaporation rate of alcohol per unit of alcohol showed a dramatic increase over that at higher concentrations. Various explanations for the effect were sought but it was concluded that preferential adsorption of alcohol at the interface in low alcohol concentrations solutions as suggested by the Gibbs adsorption allowed ethanol to evaporate more readily compared to that obtained at higher concentrations. 55 refs., 6 figs., 1 tab.

  6. Evaporation Rate and Saturated Vapor Pressure of Functional Organic Materials

    NASA Astrophysics Data System (ADS)

    Yase, Kiyoshi; Takahashi, Yoshikazu; Ara-kato, Norihiko; Kawazu, Akira

    1995-02-01

    The evaporation rate and saturated vapor pressure (p) for functional organic materials have been evaluated by thermogravimetry in vacuum. A series of metal phthalocyanines (M-Pc) such as Cu-Pc, Ni-Pc, Pb-Pc and TiO-Pc, Tris(8-hydroxy-quinoline) aluminum complex ( Alq3), fullerene (C60) and tetrathiafulvalene (TTF), tetracyanoquinodimethane (TCNQ) and TTF-TCNQ are examined, together with the relationship between p and the enthalpy of evaporation.

  7. Simulation of temporal and spatial distribution of required irrigation water by crop models and the pan evaporation coefficient method

    NASA Astrophysics Data System (ADS)

    Yang, Yan-min; Yang, Yonghui; Han, Shu-min; Hu, Yu-kun

    2009-07-01

    Hebei Plain is the most important agricultural belt in North China. Intensive irrigation, low and uneven precipitation have led to severe water shortage on the plain. This study is an attempt to resolve this crucial issue of water shortage for sustainable agricultural production and water resources management. The paper models distributed regional irrigation requirement for a range of cultivated crops on the plain. Classic crop models like DSSAT- wheat/maize and COTTON2K are used in combination with pan-evaporation coefficient method to estimate water requirements for wheat, corn, cotton, fruit-trees and vegetables. The approach is more accurate than the static approach adopted in previous studies. This is because the combination use of crop models and pan-evaporation coefficient method dynamically accounts for irrigation requirement at different growth stages of crops, agronomic practices, and field and climatic conditions. The simulation results show increasing Required Irrigation Amount (RIA) with time. RIA ranges from 5.08×109 m3 to 14.42×109 m3 for the period 1986~2006, with an annual average of 10.6×109 m3. Percent average water use by wheat, fruit trees, vegetable, corn and cotton is 41%, 12%, 12%, 11%, 7% and 17% respectively. RIA for April and May (the period with the highest irrigation water use) is 1.78×109 m3 and 2.41×109 m3 respectively. The counties in the piedmont regions of Mount Taihang have high RIA while the central and eastern regions/counties have low irrigation requirement.

  8. Calculation of Reactive-evaporation Rates of Chromia

    SciTech Connect

    Holcomb, G.R.

    2008-04-01

    A methodology is developed to calculate Cr-evaporation rates from Cr2O3 with a flat planar geometry. Variables include temperature, total pressure, gas velocity, and gas composition. The methodology was applied to solid-oxide, fuel cell conditions for metallic interconnects and to advanced-steam turbines conditions. The high velocities and pressures of the advanced steam turbine led to evaporation predictions as high as 5.18 9 10-8 kg/m2/s of CrO2(OH)2(g) at 760 °C and 34.5 MPa. This is equivalent to 0.080 mm per year of solid Cr loss. Chromium evaporation is expected to be an important oxidation mechanism with the types of nickel-base alloys proposed for use above 650 °C in advanced-steam boilers and turbines. It is shown that laboratory experiments, with much lower steam velocities and usually much lower total pressure than found in advanced steam turbines, would best reproduce chromium-evaporation behavior with atmospheres that approach either O2 + H2O or air + H2O with 57% H2O.

  9. Mechanisms of solvent evaporation encapsulation processes: prediction of solvent evaporation rate.

    PubMed

    Wang, J; Schwendeman, S P

    1999-10-01

    The mechanism of organic solvent evaporation during microencapsulation and its role during microsphere hardening has been investigated. Evaporation and encapsulation studies were carried out in a jacketed beaker, filled with aqueous hardening solution, which was maintained at constant temperature and constant stirring rate in the turbulent regime. Evaporation of dissolved methylene chloride (MC), ethyl acetate (EA), and acetonitrile (ACN) was examined by the decline in organic solvent concentration in the hardening bath, which was monitored by gas chromatography. The evaporation from the bath followed first-order kinetics under dilute conditions (e.g., MC < 3 mg/mL), yielding an overall permeability coefficient, P. The value of P was theoretically related to the Kolmogorov length-scale of turbulence under conditions that favor liquid-side transport control. According to theory, factors that favored liquid-phase control (as opposed to gas-phase control) were those that favored a high Henry's law constant [i.e., elevated temperature near the normal boiling point (bp) of the organic solvent] and properties of the dissolved organic solvent (i.e., low normal bp and low aqueous solubility). These theoretical hypotheses were confirmed by (1) correlating the experimentally determined P with process variables raised to the appropriate power according to theory, r(2) = 0.95 (i.e., P approximately rotational speed, omega(3/4), impeller diameter, d (5/4), volume of hardening bath, V(-1/4), and the product of kinematic viscosity and diffusion coefficient, nu(-5/12)D (2/3)), and (2) illustrating that at constant temperature, the tendency of the evaporation system to obey liquid-side transport control follows the same order of increasing Henry's law constant (i.e., MC > EA > ACN). To establish the relationship of evaporation with microsphere hardening, the decline in MC concentration was determined in both the continuous and dispersed polymer phases during microencapsulation. By

  10. Correlation of chemical evaporation rate with vapor pressure.

    PubMed

    Mackay, Donald; van Wesenbeeck, Ian

    2014-09-01

    A new one-parameter correlation is developed for the evaporation rate (ER) of chemicals as a function of molar mass (M) and vapor pressure (P) that is simpler than existing correlations. It applies only to liquid surfaces that are unaffected by the underlying solid substrate as occurs in the standard ASTM evaporation rate test and to quiescent liquid pools. The relationship has a sounder theoretical basis than previous correlations because ER is correctly correlated with PM rather than P alone. The inclusion of M increases the slope of previous log ER versus log P regressions to a value close to 1.0 and yields a simpler one-parameter correlation, namely, ER (μg m(-1) h(-1)) = 1464P (Pa) × M (g mol(-1)). Applications are discussed for the screening level assessment and ranking of chemicals for evaporation rate, such as pesticides, fumigants, and hydrocarbon carrier fluids used in pesticide formulations, liquid consumer products used indoors, and accidental spills of liquids. The mechanistic significance of the single parameter as a mass-transfer coefficient or velocity is discussed. PMID:25105222

  11. Studying biofuel aerosol evaporation rates with single particle manipulation

    NASA Astrophysics Data System (ADS)

    Corsetti, S.; Miles, R. E. H.; Reid, J. P.; Kiefer, J.; McGloin, D.

    2014-09-01

    The significant increase in the air pollution, and the impact on climate change due to the burning of fossil fuel has led to the research of alternative energies. Bio-ethanol obtained from a variety of feedstocks can provide a feasible solution. Mixing bio-ethanol with gasoline leads to a reduction in CO emission and in NOx emissions compared with the use of gasoline alone. However, adding ethanol leads to a change in the fuel evaporation. Here we present a preliminary investigation of evaporation times of single ethanol-gasoline droplets. In particular, we investigated the different evaporation rate of the droplets depending on the variation in the percentage of ethanol inside them. Two different techniques have been used to trap the droplets. One makes use of a 532nm optical tweezers set up, the other of an electrodynamics balance (EDB). The droplets decreasing size was measured using video analysis and elastic light scattering respectively. In the first case measurements were conducted at 293.15 K and ambient humidity. In the second case at 280.5 K and a controlled environment has been preserved by flowing nitrogen into the chamber. Binary phase droplets with a higher percentage of ethanol resulted in longer droplet lifetimes. Our work also highlights the advantages and disadvantages of each technique for such studies. In particular it is challenging to trap droplets with low ethanol content (such as pure gasoline) by the use of EDB. Conversely such droplets are trivial to trap using optical tweezers.

  12. A comparison of methods for estimating open-water evaporation in small wetlands

    USGS Publications Warehouse

    Masoner, Jason R.; Stannard, David I.

    2010-01-01

    We compared evaporation measurements from a floating pan, land pan, chamber, and the Priestley-Taylor (PT) equation. Floating pan, land pan, and meteorological data were collected from June 6 to July 21, 2005, at a small wetland in the Canadian River alluvium in central Oklahoma, USA. Evaporation measured with the floating pan compared favorably to 12 h chamber measurements. Differences between chamber and floating pan rates ranged from −0.2 to 0.3 mm, mean of 0.1 mm. The difference between chamber and land pan rates ranged from 0.8 to 2.0 mm, mean of 1.5 mm. The mean chamber-to-floating pan ratio was 0.97 and the mean chamber-to-land pan ratio was 0.73. The chamber-to-floating pan ratio of 0.97 indicates the use of a floating pan to measure evaporation in small limited-fetch water bodies is an appropriate and accurate method for the site investigated. One-sided Paired t-Tests indicate daily floating pan rates were significantly less than land pan and PT rates. A two-sided Paired t-Test indicated there was no significant difference between land pan and PT values. The PT equation tends to overestimate evaporation during times when the air is of low drying power and tends to underestimate as drying power increases.

  13. Evaporation rates of pasture-mesquite vegetation in central Mexico

    NASA Astrophysics Data System (ADS)

    Sosa, E. G.; Escobar, A. G.

    2004-12-01

    from 1.1 to 2.0 mm d-1, maximum E was 4.3 mm d-1 on sunny days and the average E was 3.1 mm d-1. Average daily E increased during the measuring period at a rate of 0.05 mm d-1 (r2=0.2, p<0.05). Data suggest that evaporation from a pasture-mesquite vegetation is an important component in the water balance considering the limited rainfall occurring.

  14. On the remote measurement of evaporation rates from bare wet soil under variable cloud cover

    NASA Technical Reports Server (NTRS)

    Auer, S.

    1976-01-01

    Evaporation rates from a natural wet soil surface are calculated from an energy balance equation at 0.1-hour intervals. A procedure is developed for calculating the heat flux through the soil surface from a harmonic analysis of the surface temperature curve. The evaporation integrated over an entire 24-hour period is compared with daily evaporation rates obtained from published models.

  15. Pan evaporation modeling using least square support vector machine, multivariate adaptive regression splines and M5 model tree

    NASA Astrophysics Data System (ADS)

    Kisi, Ozgur

    2015-09-01

    Pan evaporation (Ep) modeling is an important issue in reservoir management, regional water resources planning and evaluation of drinking-water supplies. The main purpose of this study is to investigate the accuracy of least square support vector machine (LSSVM), multivariate adaptive regression splines (MARS) and M5 Model Tree (M5Tree) in modeling Ep. The first part of the study focused on testing the ability of the LSSVM, MARS and M5Tree models in estimating the Ep data of Mersin and Antalya stations located in Mediterranean Region of Turkey by using cross-validation method. The LSSVM models outperformed the MARS and M5Tree models in estimating Ep of Mersin and Antalya stations with local input and output data. The average root mean square error (RMSE) of the M5Tree and MARS models was decreased by 24-32.1% and 10.8-18.9% using LSSVM models for the Mersin and Antalya stations, respectively. The ability of three different methods was examined in estimation of Ep using input air temperature, solar radiation, relative humidity and wind speed data from nearby station in the second part of the study (cross-station application without local input data). The results showed that the MARS models provided better accuracy than the LSSVM and M5Tree models with respect to RMSE, mean absolute error (MAE) and determination coefficient (R2) criteria. The average RMSE accuracy of the LSSVM and M5Tree was increased by 3.7% and 16.5% using MARS. In the case of without local input data, the average RMSE accuracy of the LSSVM and M5Tree was respectively increased by 11.4% and 18.4% using MARS. In the third part of the study, the ability of the applied models was examined in Ep estimation using input and output data of nearby station. The results reported that the MARS models performed better than the other models with respect to RMSE, MAE and R2 criteria. The average RMSE of the LSSVM and M5Tree was respectively decreased by 54% and 3.4% using MARS. The overall results indicated that

  16. Trends in evaporation of a large subtropical lake

    NASA Astrophysics Data System (ADS)

    Hu, Cheng; Wang, Yongwei; Wang, Wei; Liu, Shoudong; Piao, Meihua; Xiao, Wei; Lee, Xuhui

    2016-03-01

    How rising temperature and changing solar radiation affect evaporation of natural water bodies remains poor understood. In this study, evaporation from Lake Taihu, a large (area 2400 km2) freshwater lake in the Yangtze River Delta, China, was simulated by the CLM4-LISSS offline lake model and estimated with pan evaporation data. Both methods were calibrated against lake evaporation measured directly with eddy covariance in 2012. Results show a significant increasing trend of annual lake evaporation from 1979 to 2013, at a rate of 29.6 mm decade-1 according to the lake model and 25.4 mm decade-1 according to the pan method. The mean annual evaporation during this period shows good agreement between these two methods (977 mm according to the model and 1007 mm according to the pan method). A stepwise linear regression reveals that downward shortwave radiation was the most significant contributor to the modeled evaporation trend, while air temperature was the most significant contributor to the pan evaporation trend. Wind speed had little impact on the modeled lake evaporation but had a negative contribution to the pan evaporation trend offsetting some of the temperature effect. Reference evaporation was not a good proxy for the lake evaporation because it was on average 20.6 % too high and its increasing trend was too large (56.5 mm decade-1).

  17. Measuring the rate of local evaporation from the liquid surface under the action of gas flow

    NASA Astrophysics Data System (ADS)

    Lyulin, Yu. V.; Feoktistov, D. V.; Afanas'ev, I. A.; Chachilo, E. S.; Kabov, O. A.; Kuznetsov, G. V.

    2015-07-01

    The dynamics of evaporation from the surface of a liquid layer under the action of a gas flow has been studied. Correlation dependences of the rate of liquid evaporation on the gas flow rate and temperature for the ethanol-air system have been obtained and compared to other published experimental data. It is established that, for the two-phase systems studied, the evaporation rate growth with increasing temperature exhibits an almost identical character independently of the thermal properties of particular liquids and gases. In contrast, the character of the evaporation rate growth with increasing gas flow velocity significantly depends on these properties.

  18. Strengthened PAN-based carbon fibers obtained by slow heating rate carbonization

    PubMed Central

    Kim, Min-A; Jang, Dawon; Tejima, Syogo; Cruz-Silva, Rodolfo; Joh, Han-Ik; Kim, Hwan Chul; Lee, Sungho; Endo, Morinobu

    2016-01-01

    Large efforts have been made over the last 40 years to increase the mechanical strength of polyacrylonitrile (PAN)-based carbon fibers (CFs) using a variety of chemical or physical protocols. In this paper, we report a new method to increase CFs mechanical strength using a slow heating rate during the carbonization process. This new approach increases both the carbon sp3 bonding and the number of nitrogen atoms with quaternary bonding in the hexagonal carbon network. Theoretical calculations support a crosslinking model promoted by the interstitial carbon atoms located in the graphitic interlayer spaces. The improvement in mechanical performance by a controlled crosslinking between the carbon hexagonal layers of the PAN based CFs is a new concept that can contribute further in the tailoring of CFs performance based on the understanding of their microstructure down to the atomic scale. PMID:27004752

  19. Strengthened PAN-based carbon fibers obtained by slow heating rate carbonization

    NASA Astrophysics Data System (ADS)

    Kim, Min-A.; Jang, Dawon; Tejima, Syogo; Cruz-Silva, Rodolfo; Joh, Han-Ik; Kim, Hwan Chul; Lee, Sungho; Endo, Morinobu

    2016-03-01

    Large efforts have been made over the last 40 years to increase the mechanical strength of polyacrylonitrile (PAN)-based carbon fibers (CFs) using a variety of chemical or physical protocols. In this paper, we report a new method to increase CFs mechanical strength using a slow heating rate during the carbonization process. This new approach increases both the carbon sp3 bonding and the number of nitrogen atoms with quaternary bonding in the hexagonal carbon network. Theoretical calculations support a crosslinking model promoted by the interstitial carbon atoms located in the graphitic interlayer spaces. The improvement in mechanical performance by a controlled crosslinking between the carbon hexagonal layers of the PAN based CFs is a new concept that can contribute further in the tailoring of CFs performance based on the understanding of their microstructure down to the atomic scale.

  20. Strengthened PAN-based carbon fibers obtained by slow heating rate carbonization.

    PubMed

    Kim, Min-A; Jang, Dawon; Tejima, Syogo; Cruz-Silva, Rodolfo; Joh, Han-Ik; Kim, Hwan Chul; Lee, Sungho; Endo, Morinobu

    2016-01-01

    Large efforts have been made over the last 40 years to increase the mechanical strength of polyacrylonitrile (PAN)-based carbon fibers (CFs) using a variety of chemical or physical protocols. In this paper, we report a new method to increase CFs mechanical strength using a slow heating rate during the carbonization process. This new approach increases both the carbon sp(3) bonding and the number of nitrogen atoms with quaternary bonding in the hexagonal carbon network. Theoretical calculations support a crosslinking model promoted by the interstitial carbon atoms located in the graphitic interlayer spaces. The improvement in mechanical performance by a controlled crosslinking between the carbon hexagonal layers of the PAN based CFs is a new concept that can contribute further in the tailoring of CFs performance based on the understanding of their microstructure down to the atomic scale. PMID:27004752

  1. The Effect of Dynamic Evaporation Rates on the Mobility of Pharmaceuticals in Unsaturated Environments

    NASA Astrophysics Data System (ADS)

    Normile, H.; Papelis, C.; Kibbey, T. C. G.

    2015-12-01

    The focus of this work was on investigating how dynamic rates of evaporation affect the fate and transport of pharmaceutical compounds in unsaturated porous media. The environmental processes of saturation and evaporation control local concentrations of contaminants in pore water of porous media. Specifically, the rate of evaporation can affect the identity and extent of solid formation of a pharmaceutical compound. A range of experiments with different evaporation rates were conducted on sand columns saturated with a solution of ciprofloxacin, a fluoroquinolone antibiotic. Experiments were designed to simulate increased and decreased pore-water concentrations of a compound due to evaporation and resaturation, respectively. Results suggest that varied rates of evaporation cause differences in compound adsorption behavior. This result has significant implications for understanding fate and transport within the unsaturated zone. Preliminary models exploring the impact on contaminant mobility are discussed.

  2. Effect of the Heat Flux Density on the Evaporation Rate of a Distilled Water Drop

    NASA Astrophysics Data System (ADS)

    Ponomarev, Konstantin; Orlova, Evgeniya; Feoktistov, Dmitry

    2016-02-01

    This paper presents the experimental dependence of the evaporation rate of a nondeaerated distilled water drop from the heat flux density on the surfaces of non-ferrous metals (copper and brass). A drop was placed on a heated substrate by electronic dosing device. To obtain drop profile we use a shadow optical system; drop symmetry was controlled by a high-speed video camera. It was found that the evaporation rate of a drop on a copper substrate is greater than on a brass. The evaporation rate increases intensively with raising volume of a drop. Calculated values of the heat flux density and the corresponding evaporation rates are presented in this work. The evaporation rate is found to increase intensively on the brass substrate with raising the heat flux density.

  3. Low internal pressure in femtoliter water capillary bridges reduces evaporation rates

    NASA Astrophysics Data System (ADS)

    Cho, Kun; Hwang, In Gyu; Kim, Yeseul; Lim, Su Jin; Lim, Jun; Kim, Joon Heon; Gim, Bopil; Weon, Byung Mook

    2016-03-01

    Capillary bridges are usually formed by a small liquid volume in a confined space between two solid surfaces. They can have a lower internal pressure than the surrounding pressure for volumes of the order of femtoliters. Femtoliter capillary bridges with relatively rapid evaporation rates are difficult to explore experimentally. To understand in detail the evaporation of femtoliter capillary bridges, we present a feasible experimental method to directly visualize how water bridges evaporate between a microsphere and a flat substrate in still air using transmission X-ray microscopy. Precise measurements of evaporation rates for water bridges show that lower water pressure than surrounding pressure can significantly decrease evaporation through the suppression of vapor diffusion. This finding provides insight into the evaporation of ultrasmall capillary bridges.

  4. Low internal pressure in femtoliter water capillary bridges reduces evaporation rates

    PubMed Central

    Cho, Kun; Hwang, In Gyu; Kim, Yeseul; Lim, Su Jin; Lim, Jun; Kim, Joon Heon; Gim, Bopil; Weon, Byung Mook

    2016-01-01

    Capillary bridges are usually formed by a small liquid volume in a confined space between two solid surfaces. They can have a lower internal pressure than the surrounding pressure for volumes of the order of femtoliters. Femtoliter capillary bridges with relatively rapid evaporation rates are difficult to explore experimentally. To understand in detail the evaporation of femtoliter capillary bridges, we present a feasible experimental method to directly visualize how water bridges evaporate between a microsphere and a flat substrate in still air using transmission X-ray microscopy. Precise measurements of evaporation rates for water bridges show that lower water pressure than surrounding pressure can significantly decrease evaporation through the suppression of vapor diffusion. This finding provides insight into the evaporation of ultrasmall capillary bridges. PMID:26928329

  5. Low internal pressure in femtoliter water capillary bridges reduces evaporation rates.

    PubMed

    Cho, Kun; Hwang, In Gyu; Kim, Yeseul; Lim, Su Jin; Lim, Jun; Kim, Joon Heon; Gim, Bopil; Weon, Byung Mook

    2016-01-01

    Capillary bridges are usually formed by a small liquid volume in a confined space between two solid surfaces. They can have a lower internal pressure than the surrounding pressure for volumes of the order of femtoliters. Femtoliter capillary bridges with relatively rapid evaporation rates are difficult to explore experimentally. To understand in detail the evaporation of femtoliter capillary bridges, we present a feasible experimental method to directly visualize how water bridges evaporate between a microsphere and a flat substrate in still air using transmission X-ray microscopy. Precise measurements of evaporation rates for water bridges show that lower water pressure than surrounding pressure can significantly decrease evaporation through the suppression of vapor diffusion. This finding provides insight into the evaporation of ultrasmall capillary bridges. PMID:26928329

  6. Evaporation of Liquid Droplet in Nano and Micro Scales from Statistical Rate Theory.

    PubMed

    Duan, Fei; He, Bin; Wei, Tao

    2015-04-01

    The statistical rate theory (SRT) is applied to predict the average evaporation flux of liquid droplet after the approach is validated in the sessile droplet experiments of the water and heavy water. The steady-state experiments show a temperature discontinuity at the evaporating interface. The average evaporation flux is evaluated by individually changing the measurement at a liquid-vapor interface, including the interfacial liquid temperature, the interfacial vapor temperature, the vapor-phase pressure, and the droplet size. The parameter study shows that a higher temperature jump would reduce the average evaporation flux. The average evaporation flux can significantly be influenced by the interfacial liquid temperature and the vapor-phase pressure. The variation can switch the evaporation into condensation. The evaporation flux is found to remain relative constant if the droplet is larger than a micro scale, while the smaller diameters in nano scale can produce a much higher evaporation flux. In addition, a smaller diameter of droplets with the same liquid volume has a larger surface area. It is suggested that the evaporation rate increases dramatically as the droplet shrinks into nano size. PMID:26353528

  7. Effects on evaporation rates from different water-permeable pavement designs.

    PubMed

    Starke, P; Göbel, P; Coldewey, W G

    2011-01-01

    The urban water balance can be attenuated to the natural by water-permeable pavements (WPPs). Furthermore, WPPs have a 16% higher evaporation rate than impermeable pavements, which can lead to a better urban climate. Evaporation rates from pavements are influenced by the pavement surface and by the deeper layers. By a compared evaporation measurement between different WPP designs, the grain size distribution of the sub-base shows no influence on the evaporation rates in a significant way. On the contrary, a sub-base made of a twin-layer decreases the evaporation by 16% compared to a homogeneous sub-base. By a change in the colour of the paving stone, 19% higher evaporation rates could be achieved. A further comparison shows that the transpiration-effect of the grass in grass pavers increases the evaporation rates more than threefold to pervious concrete pavements. These high evapotranspiration rates can not be achieved with a pervious concrete paving stone. In spite of this, the broad field of application of the pervious concrete paving stone increases the importance in regard to the urban climate. PMID:22049757

  8. Water budgets of Italian and Dutch gravel pit lakes: a study using a fen as a natural evaporation pan, stable isotopes and conservative tracer modeling.

    NASA Astrophysics Data System (ADS)

    Nella Mollema, Pauline; Antonellini, Marco

    2015-04-01

    Gravel pits are excavated in aquifers to fulfill the need for construction materials. Flow-through lakes form where the gravel pits are below the water table and fill with groundwater. Their presence changes the drainage patterns, water- and hydrochemical budgets of a watershed. We have studied the water budget of two gravel pit lakes systems using stable H and O isotopes of water as well as conservative tracer (Cl) modeling. The Dutch gravel pit lakes are a fluvial fresh water system of 70 lakes along the Meuse River and the Italian gravel pit lakes are a brackish system along the Adriatic coast. Surface water evaporation from the gravel pit lakes is larger than the actual evapotranspiration of the grass land and forests that were replaced. The ratio of evaporation to total flow into the Dutch lakes was determined by using a Fen as a natural evaporation pan: the isotope content of the Tuspeel Fen, filled with rain water and sampled in a dry and warm summer period (August 2012), is representative for the limiting isotopic enrichment under local hydro meteorological conditions. The Local Evaporation line (LEL) was determined δ2 H = 4.20 δ 18O - 14.10 (R² = 0.99) and the ratio of total inflow to evaporation for three gravel pit lakes were calculated to be 22.6 for the De Lange Vlieter lake used for drinking water production, 11.3 for the Boschmolen Lake and 8.9 for the Anna's Beemd lake showing that groundwater flow is much larger than evaporation. The Italian gravel pit lakes are characterized by high salinity (TDS = 4.6-12.3 g L-1). Stable isotope data show that these latter gravel pit lakes are fed by groundwater, which is a mix between fresh Apennine River water and brackish (Holocene) Adriatic Sea water. The local evaporation line is determined: δ2H = 5.02 δ18O - 10.49. The ratio of total inflow to evaporation is 5. Conservative tracer modeling indicates that the chloride concentration in the Italian gravel pit lakes stabilizes after a short period of rapid

  9. Effect of UV irradiation on the evaporation rate of alcohols droplets

    NASA Astrophysics Data System (ADS)

    Korobko, O. V.; Britan, A. V.; Verbinskaya, G. H.; Gavryushenko, D. A.

    2015-06-01

    The effect of ultraviolet irradiation with a wavelength of 390 nm on the evaporation of droplets of the homologous series of alcohols ( n-propanol, n-butanol, n-pentanol, n-heptanol, n-octanol, and n-decanol) at 10, 30, 50, 100, and 200 mm Hg in an atmosphere of dry nitrogen is studied. The values of the evaporation rate of alcohols are calculated with and without irradiation. Starting from n-pentanol, the rate of evaporation grows strongly for droplets of higher alcohols under the effect of low-power irradiation not associated with the heating of the evaporating droplets of alcohols. The obtained results are analyzed by comparing them to experimental data on neutron scattering by alcohols. It is shown that free convection must be considered in order to describe the evaporation process. Expressions of different authors for describing this effect are analyzed.

  10. A model to predict evaporation rates in habitats used by container-dwelling mosquitoes.

    PubMed

    Bartlett-Healy, Kristen; Healy, Sean P; Hamilton, George C

    2011-05-01

    Container-dwelling mosquitoes use a wide variety of container habitats. The bottle cap is often cited as the smallest container habitat used by container species. When containers are small, the habitat conditions can greatly affect evaporation rates that in turn can affect the species dynamics within the container. An evaporation rate model was adapted to predict evaporation rates in mosquito container habitats. In both the laboratory and field, our model was able to predict actual evaporation rates. Examples of how the model may be applied are provided by examining the likelihood of Aedes albopictus (Skuse), Aedes aegypti (L.), and Culex pipiens pipiens (L.) completing their development within small-volume containers under typical environmental conditions and a range of temperatures. Our model suggests that under minimal direct sunlight exposure, both Ae. aegypti and Ae. albopictus could develop within a bottle cap before complete evaporation. Our model shows that under the environmental conditions when a plastic field container was sampled, neither Ae. albopictus or Cx. p. pipiens could complete development in that particular container before the water evaporated. Although rainfall could replenish the habitat, the effects of evaporation would increase larval density, which could in turn further decrease developmental rates. PMID:21661337

  11. Atmospheric sugar alcohols: evaporation rates and saturation vapor pressures

    NASA Astrophysics Data System (ADS)

    Bilde, M.; Zardini, A. A.; Hong, J.; Tschiskale, M.; Emanuelsson, E.

    2014-12-01

    The atmospheric partitioning between gas and condensed phase of organic molecules is poorly understood, and discrepancies exist between predicted and observed concentrations of secondary organic aerosols. A key problem is the lack of information about thermodynamic properties of semi- and low volatile organic molecules. Saturation vapor pressure and the associated temperature dependence (dH) are key parameters for improving predictive atmospheric models. In this work we combine experiments and thermodynamic modeling to investigate these parameters for a series of polyols, so-called sugar alcohols. These polyols are common in the water soluble fraction of atmospheric aerosols. In our experimental system sub-micron particles are generated by nebulization from aqueous solution, and a mono disperse fraction of the aerosol is selected using a differential mobility analyzer. The particles are allowed to evaporate in a laminar flow reactor, and changes in particle size as function of evaporation time are determined using a scanning mobility particle sizer system. In this work saturation vapor pressures of sugar alcohols at several temperatures have been inferred from such measurements using thermodynamic modeling. Results are presented and discussed in context of atmospheric gas to particle partitioning.

  12. Water evaporation rates across hydrophobic acid monolayers at equilibrium spreading pressure.

    PubMed

    Tsuji, Minami; Nakahara, Hiromichi; Moroi, Yoshikiyo; Shibata, Osamu

    2008-02-15

    The effect of alkanoic acid [CH(3)(CH(2))(n-2)COOH; HCn] and perfluoroalkanoic acid [CF(3)(CF(2))(n-2)COOH; FCn] monolayers on the water evaporation rate was investigated by thermogravimetry tracing the decrease in amount of water with time. The evaporation rate from the surface covered by a monolayer was measured as a function of temperature and hydrophobic chain length of the acids, where the monolayer was under an equilibrium spreading pressure. From thermal behavior of the crystallized acids, their solid states are C-type in crystalline state over the temperature range from 298.2 to 323.2 K. The dry air was flowed through a furnace tube of a thermogravimetry apparatus at the flow rate of 80 mL min(-1), where the evaporation rate becomes almost constant irrespective of the flow rate. The temperature dependence of the evaporation rate was analyzed kinetically to evaluate the activation energy and thermodynamics values for the activated complex, which demonstrated that these values were almost the same for both alkanoic acids and perfluoroalkanoic acids, although the effect of perfluoroalkanoic acids on the evaporation rate was smaller than that of corresponding hydrogenated fatty acids. The difference in the evaporation rate between FCn and HCn was examined by atomic force microscopy (AFM), Brewster angle microscopy (BAM), surface potential (DeltaV) at equilibrium spreading pressure, and Langmuir curve (pi-A isotherm), and their results were consistent and supported the difference. PMID:18048050

  13. Atmospheric evaporative demand observations, estimates and driving factors in Spain (1961-2011)

    NASA Astrophysics Data System (ADS)

    Azorin-Molina, Cesar; Vicente-Serrano, Sergio M.; Sanchez-Lorenzo, Arturo; McVicar, Tim R.; Morán-Tejeda, Enrique; Revuelto, Jesús; El Kenawy, Ahmed; Martín-Hernández, Natalia; Tomas-Burguera, Miquel

    2015-04-01

    We analyzed the spatio-temporal evolution of evaporation observations from Piché atmometers (1961-2011; 56 stations) and Pan evaporimeters (1984-2011; 21 stations) across Spain, and compared both measurements with evaporation estimates obtained by four physical models: i.e., Food and Agricultural Organization-56 Penman-Monteith, Food and Agricultural Organization-Pan, PenPan and Penman, based on climate data. In this study we observed a positive and statistically significant correlation between Piché and Pan evaporation measurements during the common period (1984-2011; 19 stations), mainly in summer. When evaporation observations and estimates were compared, we detected positive and statistically significant correlations with the four methods, except for winter. Among the four physical models, the FAO-Pan showed the best fitting to both Piché and Pan evaporation measurements; the PenPan model overestimated evaporation rates; and the FAO-Penman-Monteith and Penman methods underestimated evaporation observations. We also observed a better spatial agreement between Pan evaporation and estimates than that obtained by Piché measurements. Annual and seasonal trends of evaporation estimates show a statistically significant increase for 1961-2011, which do not agree with long-term Piché evaporation trends; e.g. a discontinuity was found around the 1980s. Radiative and aerodynamic driving factors suggest that this discontinuity, and the observed evaporation trends across Spain could be associated with the abrupt increase in air temperature observed during last few decades (i.e., global warming). Further investigations using available Piché evaporation observations for other regions are needed to better understand physical components influencing long-term trends of evaporation.

  14. Evaporation Loss of Light Elements as a Function of Cooling Rate: Logarithmic Law

    NASA Technical Reports Server (NTRS)

    Xiong, Yong-Liang; Hewins, Roger H.

    2003-01-01

    Knowledge about the evaporation loss of light elements is important to our understanding of chondrule formation processes. The evaporative loss of light elements (such as B and Li) as a function of cooling rate is of special interest because recent investigations of the distribution of Li, Be and B in meteoritic chondrules have revealed that Li varies by 25 times, and B and Be varies by about 10 times. Therefore, if we can extrapolate and interpolate with confidence the evaporation loss of B and Li (and other light elements such as K, Na) at a wide range of cooling rates of interest based upon limited experimental data, we would be able to assess the full range of scenarios relating to chondrule formation processes. Here, we propose that evaporation loss of light elements as a function of cooling rate should obey the logarithmic law.

  15. Modeling the evaporation rate of cesium off tungsten based controlled porosity dispenser photocathodes

    NASA Astrophysics Data System (ADS)

    Pan, Z.; Jensen, K. L.

    2013-04-01

    The evaporation of cesium from a tungsten surface is modeled using an effective one-dimensional potential well representation of the binding energy. The model accounts for both local and global interactions of cesium with the surface metal as well as with other cesium atoms. The theory is compared with the data of Taylor and Langmuir [Phys. Rev. 44, 423 (1933), 10.1103/PhysRev.44.423] comparing evaporation rates to sub-monolayer surface coverage of cesium, gives good agreement, and reproduces the nonlinear behavior of evaporation with varying coverage and temperature.

  16. Evaporation through a capillary allows electrically determined rate

    NASA Astrophysics Data System (ADS)

    Lawson, Lawrence R.

    1998-10-01

    Using a capillary to suppress diffusion allowed construction of an electrically calibrated vapor dispenser for organic solvent vapors. The rate of flow was essentially the applied electric power divided by the heat of vaporization.

  17. Surface composition and barium evaporation rate of ``pedigreed'' impregnated tungsten dispenser cathodes during accelerated life testing

    NASA Astrophysics Data System (ADS)

    Tomich, D. H.; Mescher, J. A.; Grant, J. T.

    1987-03-01

    A study has been made of the surface composition and barium evaporation rate of "pedigreed" impregnated tungsten dispenser cathodes. The effect of air exposure on coated cathodes was examined and was found to have no significant effect on barium evaporation rate although in some cases longer reactivation times were required. No changes in surface topography were apparent following air exposure and reactivation. Life testing was done at 100°C above the typical operating temperature for the cathode, where the typical operating temperature was taken to be 950°C for coated cathodes and 1050°C for uncoated cathodes. The cathodes were examined at different stages of life testing, up to 1200 h. Significant decreases in barium evaporation rates were found after as few as 500 h of life testing. After 1000 h the evaporation rate had decreased more than an order of magnitude. Changes in surface composition were also found. The effects of tungsten particle size, used in manufacture of the billet, on barium evaporation rate were also studied but no correlation was found.

  18. Reservoir evaporation in central Colorado

    USGS Publications Warehouse

    Spahr, N.E.; Ruddy, B.C.

    1983-01-01

    Evaporation losses from seven reservoirs operated by the Denver Water Department in central Colorado were determined during various periods from 1974 to 1980. The reservoirs studies were Ralston, Cheesman, Antero, Williams Fork, Elevenmile Canyon, Dillon, and Gross. Energy-budget and mass-transfer methods were used to determine evaporation. Class-A pan data also were collected at each reservoir. The energy-budget method was the most accurate of the methods used to determine evaporation. At Ralston, Cheesman, Antero, and Williams Fork Reservoirs the energy-budget method was used to calibrate the mass-transfer coefficients. Calibrated coefficients already were available for Elevenmile Canyon, Dillon, and Gross Reservoirs. Using the calibrated coefficients, long-term mass-transfer evaporation rates were determined. Annual evaporation values were not determined because the instrumentation was not operated for the entire open-water season. Class-A pan data were used to determine pan coefficients for each season at each reservoir. The coefficients varied from season to season and between reservoirs, and the seasonal values ranged from 0.29 to 1.05. (USGS)

  19. The evaporative requirement for heat balance determines whole-body sweat rate during exercise under conditions permitting full evaporation.

    PubMed

    Gagnon, Daniel; Jay, Ollie; Kenny, Glen P

    2013-06-01

    Although the requirements for heat dissipation during exercise are determined by the necessity for heat balance, few studies have considered them when examining sweat production and its potential modulators. Rather, the majority of studies have used an experimental protocol based on a fixed percentage of maximum oxygen uptake (% ). Using multiple regression analysis, we examined the independent contribution of the evaporative requirement for heat balance (Ereq) and % to whole-body sweat rate (WBSR) during exercise. We hypothesised that WBSR would be determined by Ereq and not by % . A total of 23 males performed two separate experiments during which they exercised for 90 min at different rates of metabolic heat production (200, 350, 500 W) at a fixed air temperature (30°C, n = 8), or at a fixed rate of metabolic heat production (290 W) at different air temperatures (30, 35, 40°C, n = 15 and 45°C, n = 7). Whole-body evaporative heat loss was measured by direct calorimetry and used to calculate absolute WBSR in grams per minute. The conditions employed resulted in a wide range of Ereq (131-487 W) and % (15-55%). The individual variation in non-steady-state (0-30 min) and steady-state (30-90 min) WBSR correlated significantly with Ereq (P < 0.001). In contrast, % correlated negatively with the residual variation in WBSR not explained by Ereq, and marginally increased (∼2%) the amount of total variability in WBSR described by Ereq alone (non-steady state: R(2) = 0.885; steady state: R(2) = 0.930). These data provide clear evidence that absolute WBSR during exercise is determined by Ereq, not by % . Future studies should therefore use an experimental protocol which ensures a fixed Ereq when examining absolute WBSR between individuals, irrespective of potential differences in relative exercise intensity. PMID:23459754

  20. The evaporative requirement for heat balance determines whole-body sweat rate during exercise under conditions permitting full evaporation

    PubMed Central

    Gagnon, Daniel; Jay, Ollie; Kenny, Glen P

    2013-01-01

    Although the requirements for heat dissipation during exercise are determined by the necessity for heat balance, few studies have considered them when examining sweat production and its potential modulators. Rather, the majority of studies have used an experimental protocol based on a fixed percentage of maximum oxygen uptake (%). Using multiple regression analysis, we examined the independent contribution of the evaporative requirement for heat balance (Ereq) and % to whole-body sweat rate (WBSR) during exercise. We hypothesised that WBSR would be determined by Ereq and not by %. A total of 23 males performed two separate experiments during which they exercised for 90 min at different rates of metabolic heat production (200, 350, 500 W) at a fixed air temperature (30°C, n= 8), or at a fixed rate of metabolic heat production (290 W) at different air temperatures (30, 35, 40°C, n= 15 and 45°C, n= 7). Whole-body evaporative heat loss was measured by direct calorimetry and used to calculate absolute WBSR in grams per minute. The conditions employed resulted in a wide range of Ereq (131–487 W) and % (15–55%). The individual variation in non-steady-state (0–30 min) and steady-state (30–90 min) WBSR correlated significantly with Ereq (P < 0.001). In contrast, % correlated negatively with the residual variation in WBSR not explained by Ereq, and marginally increased (∼2%) the amount of total variability in WBSR described by Ereq alone (non-steady state: R2= 0.885; steady state: R2= 0.930). These data provide clear evidence that absolute WBSR during exercise is determined by Ereq, not by %. Future studies should therefore use an experimental protocol which ensures a fixed Ereq when examining absolute WBSR between individuals, irrespective of potential differences in relative exercise intensity. PMID:23459754

  1. Evaporation rates of water from concentrated oil-in-water emulsions.

    PubMed

    Aranberri, I; Binks, B P; Clint, J H; Fletcher, P D I

    2004-03-16

    We have investigated the rate of water evaporation from concentrated oil-in-water (o/w) emulsions containing an involatile oil. Evaporation of the water continuous phase causes compression of the emulsion with progressive distortion of the oil drops and thinning of the water films separating them. Theoretically, the vapor pressure of water is sensitive to the interdroplet interactions, which are a function of the film thickness. Three main possible situations are considered. First, under conditions when the evaporation rate is controlled by mass transfer across the stagnant vapor phase, model calculations show that evaporation can, in principle, be slowed by repulsive interdroplet interactions. However, significant retardation requires very strong repulsive forces acting over large separations for typical emulsion drop sizes. Second, water evaporation may be limited by diffusion in the network of water films within the emulsion. In this situation, water loss by evaporation from the emulsion surface leads to a gradient in the water concentration (and in the water film thickness). Third, compression of the drops may lead to coalescence of the emulsion drops and the formation of a macroscopic oil film at the emulsion surface, which serves to prevent further water evaporation. Water mass-loss curves have been measured for silicone o/w emulsions stabilized by the anionic surfactant SDS as a function of the water content, the thickness of the stagnant vapor-phase layer, and the concentration of electrolyte in the aqueous phase, and the results are discussed in terms of the three possible scenarios just described. In systems with added salt, water evaporation virtually ceases before all the water present is lost, probably as a result of oil-drop coalescence resulting in the formation of a water-impermeable oil film at the emulsion surface. PMID:15835653

  2. What determines drying rates at the onset of diffusion controlled stage-2 evaporation from porous media?

    NASA Astrophysics Data System (ADS)

    Shokri, N.; Or, D.

    2011-09-01

    Early stages of evaporation from porous media are marked by relatively high evaporation rates supplied by capillary liquid flow from a receding drying front to vaporization surface. At a characteristic drying front depth, hydraulic continuity to the surface is disrupted marking the onset of stage-2 evaporation where a lower evaporative flux is supported by vapor diffusion. Observations suggest that in some cases the transition is accompanied by a jump in the vaporization plane from the surface to a certain depth below. The resulting range of evaporation rates at the onset of stage-2 is relatively narrow (0.5-2.5 mm d-1). The objective is to estimate the depth of the vaporization plane that defines vapor diffusion length at the onset of stage-2. The working hypothesis is that the jump length is determined by a characteristic length of connected clusters at the secondary drying front that obeys a power law with the system's Bond number. We conducted evaporation experiments using sands and glass beads of different particle size distributions and extracted experimental data from the literature for model comparison. Results indicate the jump length at the end of stage-1 was affected primarily by porous media properties and less so by boundary conditions. Results show power law relationships between the length of the vaporization plane jump and Bond number with an exponent of -0.48 in good agreement with the percolation theory theoretical exponent of -0.47. The results explain the origins of a relatively narrow range of evaporation rates at the onset of stage-2, and provide a means for estimating these rates.

  3. Material Properties and Plasma Display Panel Discharging Characteristics Depending on MgO Evaporation Rate

    NASA Astrophysics Data System (ADS)

    Kwon, Sang Jik; Kim, Yong Jae; Lee, Seong Eui

    2006-11-01

    MgO thin film is most widely used as a protecting layer in ac Plasma Display Panel. The film is deposited using electron beam evaporation. The effects of the evaporation rate of MgO film deposited using an electron beam on the MgO properties and the discharge characteristics of the plasma display panel (PDP) were investigated. The evaporation rate was changed from 3 to 15 Å/s at a substrate temperature of 300 °C. MgO properties such as crystal orientation, surface roughness, contact angle, and film structure were inspected using X-ray diffraction (XRD), analysis atomic force microscopy (AFM), drop shape analysis, and secondary electron microscopy (SEM). The MgO properties were shown to be strongly dependent on the evaporation rate. We also studied the relation between MgO properties and PDP discharging characteristics. The minimum firing voltage and maximum luminous efficiency were obtained at an evaporation rate of 5 Å/s. In the MgO film deposited at 5 Å/s, the (200) orientation was most intensive and surface roughness was minimum.

  4. Influence of solvent evaporation rate and formulation factors on solid dispersion physical stability.

    PubMed

    Wu, Jian X; Yang, Mingshi; Berg, Frans van den; Pajander, Jari; Rades, Thomas; Rantanen, Jukka

    2011-12-18

    New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical process factor (solvent evaporation rate) and two formulation factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (P(MW))) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in factors contributing to a decrease in the extent of PRX nucleation being evaporation rate>PVP:PRX>P(MW). The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12days the rank became PVP:PRX>evaporation rate>P(MW). The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from P(MW) was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald's step rule, and an increase in the three factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multifactorial analysis. PMID:22024381

  5. A generalized complementary relationship between actual and potential evaporation defined by a reference surface temperature

    NASA Astrophysics Data System (ADS)

    Aminzadeh, Milad; Roderick, Michael L.; Or, Dani

    2016-01-01

    The definition of potential evaporation remains widely debated despite its centrality for hydrologic and climatic models. We employed an analytical pore-scale representation of evaporation from terrestrial surfaces to define potential evaporation using a hypothetical steady state reference temperature that is common to both air and evaporating surface. The feedback between drying land surfaces and overlaying air properties, central in the Bouchet (1963) complementary relationship, is implicitly incorporated in the hypothetical steady state where the sensible heat flux vanishes and the available energy is consumed by evaporation. Evaporation rates predicted based on the steady state reference temperature hypothesis were in good agreement with class A pan evaporation measurements suggesting that evaporation from pans occurs with negligible sensible heat flux. The model facilitates a new generalization of the asymmetric complementary relationship with the asymmetry parameter b analytically predicted for a wide range of meteorological conditions with initial tests yielding good agreement between measured and predicted actual evaporation.

  6. EFFECT OF HEATING RATE ON EVAPORATIVE HEAT LOSS IN THE MICROWAVE-EXPOSED MOUSE

    EPA Science Inventory

    Male CBA/J mice were administered heat loads of 0-28 J. per g at specific absorption rates (SARs) of either 47 or 93 W. per kg by exposure to 2,450-MHz microwave radiation at an ambient temperature of 30 C while evaporative heat loss (EHL) was continuously monitored with dew-poin...

  7. PREDICTIONS OF EVAPORATIVE LOSS RATES OF SOLUTES IN STAGNANT AND TURBENT WATERS IN RELATION TO RATES OF REFERENCE MATERIALS

    EPA Science Inventory

    A previously published kinetic model for evaporative rates of substances into air leads to the estimation of the dependence of solute transfer coefficients on turbulence applied to the system. The ratios of the transfer coefficients of all solutes become insensitive to air turbul...

  8. Investigation of annular flow at high evaporation rates in view of liquid film cooling

    NASA Astrophysics Data System (ADS)

    Nahstoll, Juergen

    1988-01-01

    The process of liquid film cooling of combustion chamber walls which are subjected to extremely high heat rates was investigated. A theoretical model was developed for a reliable prediction of the film cooling length. The mass transfer at the liquid-gas interface results from evaporated liquid and entrained liquid droplets. The film cooling length analysis, which includes the physical effects in detail, is separated into two regions: heating the liquid and evaporating the liquid. The theoretical results were experimentally verified at high pressures and temperatures using a modified H2/O2-rocket motor. There is a good agreement between the theoretical and the experimental results over the experimental range.

  9. Cold {sup 52}Cr elastic and inelastic collision-rate determination using evaporative cooling analysis

    SciTech Connect

    Nguyen, Scott V.; Carvalho, Robert de; Doyle, John M.

    2007-06-15

    Elastic and inelastic collision-rate constants of {sup 52}Cr in the temperature range of 20 mK to 1 K are inferred from the evaporative cooling of buffer gas loaded atomic chromium. Using a model that describes the dynamics of the trapped chromium cloud during evaporation, we find g{sub el}=2.15(+2.5,-1.2)x10{sup -10} cm{sup 3}/s and g{sub in}=1.36(+1.2,-0.7)x10{sup -12} cm{sup 3}/s, consistent with theory but in disagreement with previously reported measurements.

  10. Relationship between the evaporation rate and vapor pressure of moderately and highly volatile chemicals.

    PubMed

    van Wesenbeeck, Ian; Driver, Jeffrey; Ross, John

    2008-04-01

    Volatilization of chemicals can be an important form of dissipation in the environment. Rates of evaporative losses from plant and soil surfaces are useful for estimating the potential for food-related dietary residues and operator and bystander exposure, and can be used as source functions for screening models that predict off-site movement of volatile materials. A regression of evaporation on vapor pressure from three datasets containing 82 pesticidal active ingredients and co-formulants, ranging in vapor pressure from 0.0001 to >30,000 Pa was developed for this purpose with a regression correlation coefficient of 0.98. PMID:18344074

  11. Estimating steady-state evaporation rates from bare soils under conditions of high water table

    USGS Publications Warehouse

    Ripple, C.D.; Rubin, J.; Van Hylckama, T. E. A.

    1970-01-01

    A procedure that combines meteorological and soil equations of water transfer makes it possible to estimate approximately the steady-state evaporation from bare soils under conditions of high water table. Field data required include soil-water retention curves, water table depth and a record of air temperature, air humidity and wind velocity at one elevation. The procedure takes into account the relevant atmospheric factors and the soil's capability to conduct 'water in liquid and vapor forms. It neglects the effects of thermal transfer (except in the vapor case) and of salt accumulation. Homogeneous as well as layered soils can be treated. Results obtained with the method demonstrate how the soil evaporation rates·depend on potential evaporation, water table depth, vapor transfer and certain soil parameters.

  12. The effect of ambient pressure on the evaporation rate of materials

    NASA Technical Reports Server (NTRS)

    Naumann, R. J.; Russell, W. M.

    1972-01-01

    A simple expression is obtained using a diffusion model for the effect of ambient pressure on the outgassing or evaporation rate of materials. The correctness of the expression is demonstrated by comparing the estimates from this expression with actual weight loss measurements. It is shown that the rate of mass loss is governed by the ratio of mean free path to the characteristic dimension of the surface in question.

  13. Evaporation Rates for Liquid Water and Ice Under Current Martian Conditions

    NASA Technical Reports Server (NTRS)

    Sears, D. W. G.; Moore, S. R.; Meier, A.; Chittenden, J.; Kareev, M.; Farmer, C. B.

    2004-01-01

    A number of studies have been concerned with the evaporation rates under martian conditions in order to place limits on the possible survival time of both liquid water and ice exposed on the surface of Mars. Such studies also aid in assessing the efficacy of an overlying layer of dust or loose regolith material in providing a barrier to free evaporation and thus prolong the lifetime of water in locations where its availability to putative living organisms would be significant. A better quantitative understanding of the effects of phase changes of water in the near surface environment would also aid the evaluation of the possible role of water in the formation of currently observed features, such as gullies in cliff walls and relatively short-term changes in the albedo of small surface areas ('dark stains'). Laboratory measurements aimed at refinement of our knowledge of these values are described here. The establishment of accurate values for evaporation rates and their dependence on the physical conditions of temperature, pressure and energy input, is an important benchmark for the further investigation of the efficacy of barriers to free evaporation in providing a prolonged period of survival of the water, particularly as a liquid.

  14. Peter Pan.

    ERIC Educational Resources Information Center

    Storr, Catherine

    1992-01-01

    Offers a contemporary view of J. M. Barrie's life and his classic story, "Peter Pan." Suggests that "Peter Pan" does not really speak for today's children and that the time for Peter Pan's retirement has come. (PRA)

  15. Maximum Evaporation Rates of Water Droplets Approaching Obstacles in the Atmosphere Under Icing Conditions

    NASA Technical Reports Server (NTRS)

    Lowell, H. H.

    1953-01-01

    When a closed body or a duct envelope moves through the atmosphere, air pressure and temperature rises occur ahead of the body or, under ram conditions, within the duct. If cloud water droplets are encountered, droplet evaporation will result because of the air-temperature rise and the relative velocity between the droplet and stagnating air. It is shown that the solution of the steady-state psychrometric equation provides evaporation rates which are the maximum possible when droplets are entrained in air moving along stagnation lines under such conditions. Calculations are made for a wide variety of water droplet diameters, ambient conditions, and flight Mach numbers. Droplet diameter, body size, and Mach number effects are found to predominate, whereas wide variation in ambient conditions are of relatively small significance in the determination of evaporation rates. The results are essentially exact for the case of movement of droplets having diameters smaller than about 30 microns along relatively long ducts (length at least several feet) or toward large obstacles (wings), since disequilibrium effects are then of little significance. Mass losses in the case of movement within ducts will often be significant fractions (one-fifth to one-half) of original droplet masses, while very small droplets within ducts will often disappear even though the entraining air is not fully stagnated. Wing-approach evaporation losses will usually be of the order of several percent of original droplet masses. Two numerical examples are given of the determination of local evaporation rates and total mass losses in cases involving cloud droplets approaching circular cylinders along stagnation lines. The cylinders chosen were of 3.95-inch (10.0+ cm) diameter and 39.5-inch 100+ cm) diameter. The smaller is representative of icing-rate measurement cylinders, while with the larger will be associated an air-flow field similar to that ahead of an airfoil having a leading-edge radius

  16. Mechanical tuning of the evaporation rate of liquid on crossed fibers.

    PubMed

    Boulogne, François; Sauret, Alban; Soh, Beatrice; Dressaire, Emilie; Stone, Howard A

    2015-03-17

    We investigate experimentally the drying of a small volume of perfectly wetting liquid on two crossed fibers. We characterize the drying dynamics for the three liquid morphologies that are encountered in this geometry: drop, column, and a mixed morphology, in which a drop and a column coexist. For each morphology, we rationalize our findings with theoretical models that capture the drying kinetics. We find that the evaporation rate significantly depends upon the liquid morphology and that the drying of the liquid column is faster than the evaporation of the drop and the mixed morphology for a given liquid volume. Finally, we illustrate that shearing a network of fibers reduces the angle between them, changes the morphology toward the column state, and therefore, enhances the drying rate of a volatile liquid deposited on it. PMID:25716158

  17. Effect of heating rate on evaporative heat loss in the microwave-exposed mouse

    SciTech Connect

    Gordon, C.J.

    1982-08-01

    Mice were exposed to microwave radiation at 2.450 MHz at varying intensities and heat loads to determine if the animals thermoregulate or temperature regulate in conditions of varying heat load. The mice were exposed to whole-body doses of microwave radiation and power not reflected back was regarded as absorbed by the mouse. Incident powers of three to six watts were used, resulting in specific absorption rates of 47.4-93.4 W/kg. Deep body temperatures and the evaporated heat loss were monitored, and results demonstrated that mice thermoregulate, i.e., dissipate heat loads through evaporative heat loss at a rate which is modeled numerically. It is concluded that a significant portion of the microwave energy is deposited internally.

  18. Friction, Wear, and Evaporation Rates of Various Materials in Vacuum to 10(exp -7) mm Hg

    NASA Technical Reports Server (NTRS)

    Buckley, Donald H.; Swikert, Max; Johnson, Robert L.

    1961-01-01

    The requirements for bearings and seals to operate in the environment of space dictate a new area for lubrication research. The low ambient pressures encountered in space can be expected to influence the behavior of oil, grease, and solid-film lubricants. The property of these materials most significantly affected by low ambient pressures is the evaporation rate. Various investigators have therefore measured the evaporation rates of oils and greases in vacuum as one method of establishing their relative merit for space applications (1-3). The results of this work have given some indication as to the oils and greases with the greatest stability at reduced ambient pressures. Only limited experimental work, however, has been reported in the literature for inorganic solids and soft metals which have potential use as solid lubricant films or coatings for hard alloy substrates [e.g. Reference ( 4 )]. In general, the evaporation rates of these materials would be lower than those of oils and greases. These films might therefore be very attractive as lubricants for high vacuum service.

  19. Determination of barium and calcium evaporation rates from impregnated tungsten dispenser cathodes

    NASA Astrophysics Data System (ADS)

    Jones, G. L.; Grant, J. T.

    The evaporation rates of barium and calcium from impregnated tungsten dispenser cathodes have been determined by both a vapor-collect method and line-of-sight mass spectrometry. Cathodes having molar ratios of BaO, CaO, and Al 2O 3 of 4:1:1, 5:3:2, and 1:1:1 have been studied. All measurements were conducted in ultrahigh vacuum. For the vapor-collect method, a W(110) collector was found to be suitable for monolayer growth. The procedure involved plotting the ratio of the adsorbate Auger peak-to-peak height to that from the collector as a function of collection time. Break-points in these plots characterized the collection of one monolayer of adsorbate. A geometrical correction then allowed the evaporation rates to be determined. Evaporation rates were determined at cathode temperatures of 1050, 1100, and 1150°C. For the line-of-sight mass spectrometry an Extranuclear quadrupole was used. The quadrupole was capable of measuring species up to 300 amu. Measurements with the quadrupole were made on a 5:3:2 and a 4:1:1 cathode. Results obtained using these two methods are compared.

  20. Effects Of Evaporation Rate of Some Common Organic Contaminants on Hydraulic Conductivity of Aquifer Sand

    NASA Astrophysics Data System (ADS)

    Saud, Q. J.; Hasan, S. E.

    2014-12-01

    As part of a larger study to investigate potential effects of hydrocarbons on the geotechnical properties of aquifer solids, a series of laboratory experiments were carried out to ascertain the influence of evaporation rate of some common and widespread organic contaminants on the hydraulic conductivity of aquifer sand. Gasoline and its constituent chemicals-benzene, toluene, ethylbenzene, xylene (BTEX), isooctane- and trichloroethylene (TCE) were used to contaminate sand samples collected from the aquifer and vadose zone, at varying concentrations for extended periods of time. The goal was to study any change in the chemical makeup of the contaminants and its control on hydraulic conductivity of the sand. It was found that: (a) gasoline breaks down into constituent compounds when subjected to evaporation, e.g. during oil spills and leaks; and (b) lighter compounds volatilize faster and in the following order: TCE> benzene > isooctane > toluene > gasoline> ethylbenzene > xylene. In addition, these contaminants also caused a decrease in hydraulic conductivity of sand by up to 60% as compared to the uncontaminated sand. The inherent differences in the chemical structure of contaminating chemicals influenced hydraulic conductivity such that the observed decrease was greater for aliphatic than aromatic and chlorinated hydrocarbons. The presentation includes details of the experimental set up; evaporation rate, and geotechnical tests; X-ray diffraction and scanning electron microscope studies; and data analyses and interpretation. Rate of evaporation test indicates that residual LNAPLs will occupy a certain portion of the pores in the soil either as liquid or vapor phase in the vadose zone, and will create a coating on the adjacent solid mineral grains in the aquifer. Replacement of air by the LNAPLs along with grain coatings and the intramolecular forces would impede groundwater movement, thus affecting overall permeability of contaminated aquifers. Keywords: aquifer

  1. Effect of Thickness of a Water Repellent Soil Layer on Soil Evaporation Rate

    NASA Astrophysics Data System (ADS)

    Ahn, S.; Im, S.; Doerr, S.

    2012-04-01

    A water repellent soil layer overlying wettable soil is known to affect soil evaporation. This effect can be beneficial for water conservation in areas where water is scarce. Little is known, however, about the effect of the thickness of the water repellent layer. The thickness of this layer can vary widely, and particularly after wildfire, with the soil temperature reached and the duration of the fire. This study was conducted to investigate the effect of thickness of a top layer of water repellent soil on soil evaporation rate. In order to isolate the thickness from other possible factors, fully wettable standard sand (300~600 microns) was used. Extreme water repellency (WDPT > 24 hours) was generated by 'baking' the sand mixed with oven-dried pine needles (fresh needles of Pinus densiflora) at the mass ratio of 1:13 (needle:soil) at 185°C for 18 hours. The thicknesses of water repellent layers were 1, 2, 3 and 7 cm on top of wettable soil. Fully wettable soil columns were prepared as a control. Soil columns (8 cm diameter, 10 cm height) were covered with nylon mesh. Tap water (50 ml, saturating 3 cm of a soil column) was injected with hypoderm syringes from three different directions at the bottom level. The injection holes were sealed with hot-melt adhesive immediately after injection. The rate of soil evaporation through the soil surface was measured by weight change under isothermal condition of 40°C. Five replications were made for each. A trend of negative correlation between the thickness of water repellent top layer and soil evaporation rate is discussed in this contribution.

  2. Vapor pressure and evaporation rate of certain heat-resistant compounds in a vacuum at high temperatures

    NASA Technical Reports Server (NTRS)

    Bolgar, A. S.; Verkhoglyadova, T. S.; Samsonov, G. V.

    1985-01-01

    The vapor pressure and evaporation rate of borides of titanium, zirconium, and chrome; and of strontium and carbides of titanium, zirconium, and chrome, molybdenum silicide; and nitrides of titanium, niobium, and tantalum in a vacuum were studied. It is concluded that all subject compounds evaporate by molecular structures except AlB sub 12' which dissociates, losing the aluminum.

  3. A new limit on the rate-density of evaporating black holes

    SciTech Connect

    The CYGNUS Collaboration

    1993-05-01

    Data taken with the CYGNUS detector between 1989 and 1993 have been used to search for 1 second bursts of ultra-high energy (UHE) gamma rays from any point in the northern sky. There is no evidence for such bursts. Therefore the theory-dependent upper limit on the rate-density of evaporating black holes is 6.1 {times} 10{sup 5}pc{sup {minus}3}yr{sup {minus}1} at the 99% C.L.. After renormalizing previous direct searches to the same theory, this limit is the most restrictive by more than 2 orders of magnitude.

  4. A new limit on the rate-density of evaporating black holes

    SciTech Connect

    Not Available

    1993-01-01

    Data taken with the CYGNUS detector between 1989 and 1993 have been used to search for 1 second bursts of ultra-high energy (UHE) gamma rays from any point in the northern sky. There is no evidence for such bursts. Therefore the theory-dependent upper limit on the rate-density of evaporating black holes is 6.1 [times] 10[sup 5]pc[sup [minus]3]yr[sup [minus]1] at the 99% C.L.. After renormalizing previous direct searches to the same theory, this limit is the most restrictive by more than 2 orders of magnitude.

  5. Evaporation Rate Study and NDMA Formation from UDMH/NO2 Reaction Products

    NASA Technical Reports Server (NTRS)

    Buchanan, Vanessa D.; Dee, Louis A.; Baker, David L.

    2003-01-01

    Laboratory samples of uns-dimethylhydrazine (UDMH) fuel/oxidizer (nitrogen dioxide) non-combustion reaction products (UFORP) were prepared using a unique permeation tube technology. Also, a synthetic UFORP was prepared from UDMH, N-nitrosodimethylamine (NDMA), dimethylammonium nitrate, sodium nitrite and purified water. The evaporation rate of UFORP and synthetic UFORP was determined under space vacuum (approx 10(exp -3) Torr) at -40 ?C and 0 ?C. The material remaining was analyzed and showed that the UFORP weight and NDMA concentration decreased over time; however, NDMA had not completely evaporated. Over 85% of the weight was removed by subjecting the UFORP to 10(-3) Torr for 7 hours at -40 ?C and 4 hours at 0 ?C. A mixture of dimethylammonium nitrate and sodium nitrite formed NDMA at a rapid rate in a moist air environment. A sample of UFORP residue was analyzed for formation of NDMA under various conditions. It was found that NDMA was not formed unless nitrite was added.

  6. An experimental investigation on the effects of surface gravity waves on the water evaporation rate in different air flow regimes

    NASA Astrophysics Data System (ADS)

    Jodat, Amin; Moghiman, Mohammad; Shirkhani, Golshad

    2013-12-01

    Estimating rate of evaporation from undisturbed water surfaces to moving and quiet air has been the topic a vast number of research activities. The obvious presence of various shapes of gravity waves on the water body surfaces was the motivation of this experimental investigation. In this investigation experimental measurements have been done to quantify evaporation rate from wavy water surfaces in free, mixed and forced convection regimes. The effects of a wide range of surface gravity waves from low steepness, round shaped crest with slow celerity, to steep and very slight spilling crest waves, on the water evaporation rate have been investigated. A wide range of was achieved by applying different air flow velocities on a large heated wave flume equipped with a wind tunnel. Results reveal that wave motion on the water surface increase the rate of evaporation for all air flow regimes. For free convection, due to the effect of wave motion for pumping rotational airflows at the wave troughs and the dominant effect of natural convection for the air flow advection, the maximum evaporation increment percentage from wavy water surface is about 70 %. For mixed and forced convection, water evaporation rate increment is more sensitive to the air flow velocity for the appearance of very slight spilling on the steep wave crests and the leeward air flow structures.

  7. Milagro limits and HAWC sensitivity for the rate-density of evaporating primordial black holes

    SciTech Connect

    Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Alvarez, J. D.; Arceo, R.; Arteaga-Velazquez, J. C.; Aune, T.; H. A. Ayala Solares; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Gonzalez, J. Becerra; Belmont, E.; BenZvi, S. Y.; Berley, D.; Bonilla Rosales, M.; Braun, J.; Caballero-Lopez, R. A.; Caballero-Mora, K. S.; Carraminana, A.; Castillo, M.; Christopher, G. E.; Cotti, U.; Cotzomi, J.; de la Fuente, E.; De León, C.; DeYoung, T.; Diaz Hernandez, R.; Diaz-Cruz, L.; Díaz-Vélez, J. C.; Dingus, B. L.; DuVernois, M. A.; Ellsworth, R. W.; Fiorino, D. W.; Fraija, N.; Galindo, A.; Garfias, F.; González, M. M.; Goodman, J. A.; Grabski, V.; Gussert, M.; Hampel-Arias, Z.; Harding, J. P.; Hays, E.; Hoffman, C. M.; Hui, C. M.; Hüntemeyer, P.; Imran, A.; Iriarte, A.; Karn, P.; Kieda, D.; Kolterman, B. E.; Kunde, G. J.; Lara, A.; Lauer, R. J.; Lee, W. H.; Lennarz, D.; Vargas, H. Leon; Linares, E. C.; Linnemann, J. T.; Longo, M.; Luna-GarcIa, R.; MacGibbon, J. H.; Marinelli, A.; Marinelli, S. S.; Martinez, H.; Martinez, O.; Martínez-Castro, J.; J. A.J. Matthews; McEnery, J.; Mendoza Torres, E.; Mincer, A. I.; Miranda-Romagnoli, P.; Moreno, E.; Morgan, T.; Mostafa, M.; Nellen, L.; Nemethy, P.; Newbold, M.; Noriega-Papaqui, R.; Oceguera-Becerra, T.; Patricelli, B.; Pelayo, R.; Perez-Perez, E. G.; Pretz, J.; Riviere, C.; Rosa-Gonzalez, D.; Ruiz-Velasco, E.; Ryan, J.; Salazar, H.; Salesa, F.; Sandoval, A.; Saz Parkinson, P. M.; Schneider, M.; Silich, S.; Sinnis, G.; Smith, A. J.; Stump, D.; Sparks Woodle, K.; Springer, R. W.; Taboada, I.; Toale, P. A.; Tollefson, K.; Torres, I.; Ukwatta, T. N.; Vasileiou, V.; Villasenor, L.; Weisgarber, T.; Westerhoff, S.; Williams, D. A.; Wisher, I. G.; Wood, J.; Yodh, G. B.; Younk, P. W.; Zaborov, D.; Zepeda, A.; Zhou, H.

    2015-04-01

    Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ~ 5.0 × 10¹⁴ g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV – TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.

  8. Milagro limits and HAWC sensitivity for the rate-density of evaporating primordial black holes

    DOE PAGESBeta

    Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Alvarez, J. D.; Arceo, R.; Arteaga-Velazquez, J. C.; Aune, T.; H. A. Ayala Solares; et al

    2015-04-01

    Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ~ 5.0 × 10¹⁴ g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV – TeV energy range. The Milagro high energy observatory, which operated from 2000 tomore » 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.« less

  9. Milagro limits and HAWC sensitivity for the rate-density of evaporating Primordial Black Holes

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Aune, T.; Ayala Solares, H. A.; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Becerra Gonzalez, J.; Belmont, E.; BenZvi, S. Y.; Berley, D.; Bonilla Rosales, M.; Braun, J.; Caballero-Lopez, R. A.; Caballero-Mora, K. S.; Carramiñana, A.; Castillo, M.; Christopher, G. E.; Cotti, U.; Cotzomi, J.; de la Fuente, E.; De León, C.; DeYoung, T.; Diaz Hernandez, R.; Diaz-Cruz, L.; Díaz-Vélez, J. C.; Dingus, B. L.; DuVernois, M. A.; Ellsworth, R. W.; Fiorino, D. W.; Fraija, N.; Galindo, A.; Garfias, F.; González, M. M.; Goodman, J. A.; Grabski, V.; Gussert, M.; Hampel-Arias, Z.; Harding, J. P.; Hays, E.; Hoffman, C. M.; Hui, C. M.; Hüntemeyer, P.; Imran, A.; Iriarte, A.; Karn, P.; Kieda, D.; Kolterman, B. E.; Kunde, G. J.; Lara, A.; Lauer, R. J.; Lee, W. H.; Lennarz, D.; León Vargas, H.; Linares, E. C.; Linnemann, J. T.; Longo, M.; Luna-GarcIa, R.; MacGibbon, J. H.; Marinelli, A.; Marinelli, S. S.; Martinez, H.; Martinez, O.; Martínez-Castro, J.; Matthews, J. A. J.; McEnery, J.; Mendoza Torres, E.; Mincer, A. I.; Miranda-Romagnoli, P.; Moreno, E.; Morgan, T.; Mostafá, M.; Nellen, L.; Nemethy, P.; Newbold, M.; Noriega-Papaqui, R.; Oceguera-Becerra, T.; Patricelli, B.; Pelayo, R.; Pérez-Pérez, E. G.; Pretz, J.; Rivière, C.; Rosa-González, D.; Ruiz-Velasco, E.; Ryan, J.; Salazar, H.; Salesa, F.; Sandoval, A.; Saz Parkinson, P. M.; Schneider, M.; Silich, S.; Sinnis, G.; Smith, A. J.; Stump, D.; Sparks Woodle, K.; Springer, R. W.; Taboada, I.; Toale, P. A.; Tollefson, K.; Torres, I.; Ukwatta, T. N.; Vasileiou, V.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Williams, D. A.; Wisher, I. G.; Wood, J.; Yodh, G. B.; Younk, P. W.; Zaborov, D.; Zepeda, A.; Zhou, H.

    2015-04-01

    Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ∼5.0 × 1014 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.

  10. Milagro Limits and HAWC Sensitivity for the Rate-Density of Evaporating Primordial Black Holes

    NASA Technical Reports Server (NTRS)

    Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Alvarez, J. D.; Arceo, R.; Arteaga-Velazquez, J. C.; Aune, T.; Ayala Solares, H. A.; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Becerra Gonzalez, J.; Belmont, E.; BenZvi, S. Y.; Berley, D.; Rosales, M. Bonilla; Braun, J.; Hays, E.

    2014-01-01

    Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of approx.5.0 x 10(exp 14) g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.

  11. Milagro Limits and HAWC Sensitivity for the Rate-Density of Evaporating Primordial Black Holes

    NASA Technical Reports Server (NTRS)

    Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B.T.; Alvarez, C.; Alvarez, J. D.; Arceo, R.; Arteaga-Velazquez, J. C.; Aune, T.; Ayala Solares, H. A.; Hays, E.

    2014-01-01

    Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of approximately 5.0 x 10 (sup 14) grams should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the gigaelectronvolt - teraelectronvolt energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90 percent duty cycle and sensitivity up to 100 teraelectronvolt gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.

  12. Estimation of barium evaporation rate from emission measurement of dispenser cathodes

    NASA Astrophysics Data System (ADS)

    Ravi, M.; Bhat, K. S.

    2003-06-01

    Dispenser cathodes of type M (Os-Ru coated) have been fabricated in the laboratory and tested for their emission characteristics in a sealed glass bulb in a closely spaced diode configuration. It is observed that the pulsed emission current in the temperature limited region decreased with time during the first few hours of operation and later stabilized at a constant value. This initial fall of emission current is attributed to the back bombardment of barium atoms from the anode resulting in an increase in the effective work function of the cathode surface. The decrease in emission current with time was found to follow a t1/2 relation. It was also observed that when the anode was baked at about 800 °C B for a few minutes the original emission current was restored, thus suggesting that the barium evaporated on the anode was responsible for such a behavior. A theoretical model has been suggested for estimation of barium evaporation rate from the above time dependent emission phenomenon observed.

  13. 76 FR 362 - Pan American Energy, LLC ; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-04

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Pan American Energy, LLC ; Supplemental Notice That Initial Market-Based... supplemental notice in the above-referenced proceeding of Pan American Energy, LLC's application for...

  14. Simulation of lake ice and its effect on the late-Pleistocene evaporation rate of Lake Lahontan

    USGS Publications Warehouse

    Hostetler, S.W.

    1991-01-01

    A model of lake ice was coupled with a model of lake temperature and evaporation to assess the possible effect of ice cover on the late-Pleistocene evaporation rate of Lake Lahontan. The simulations were done using a data set based on proxy temperature indicators and features of the simulated late-Pleistocene atmospheric circulation over western North America. When a data set based on a mean-annual air temperature of 3?? C (7?? C colder than present) and reduced solar radiation from jet-stream induced cloud cover was used as input to the model, ice cover lasting ??? 4 months was simulated. Simulated evaporation rates (490-527 mm a-1) were ??? 60% lower than the present-day evaporation rate (1300 mm a-1) of Pyramid Lake. With this reduced rate of evaporation, water inputs similar to the 1983 historical maxima that occurred in the Lahontan basin would have been sufficient to maintain the 13.5 ka BP high stand of Lake Lahontan. ?? 1991 Springer-Verlag.

  15. Environmental and Groundwater Controls on Evaporation Rates of A Shallow Saline Lake in the Western Sandhills Nebraska, USA

    NASA Astrophysics Data System (ADS)

    Peake, C.; Riveros-Iregui, D.; Lenters, J. D.; Zlotnik, V. A.; Ong, J.

    2013-12-01

    The western Sand Hills of Nebraska exhibit many shallow saline lakes that actively mediate groundwater-lake-atmospheric exchanges. The region is home to the largest stabilized dune field in the western hemisphere. Most of the lakes in the western Sand Hills region are saline and support a wide range of ecosystems. However, they are also highly sensitive to variability in evaporative and groundwater fluxes, which makes them a good laboratory to examine the effects of climate on the water balance of interdunal lakes. Despite being semiarid, little is known about the importance of groundwater-surface water interactions on evaporative rates, or the effects of changes in meteorological and energy forcings on the diel, and seasonal dynamics of evaporative fluxes. Our study is the first to estimate evaporation rates from one of the hundreds of shallow saline lakes that occur in the western Sand Hills region. We applied the energy balance Bowen ratio method at Alkali Lake, a typical saline western Sand Hills lake, over a three-year period (2007-2009) to quantify summer evaporation rates. Daily evaporation rates averaged 5.5 mm/day from July through September and were largely controlled by solar radiation on a seasonal and diel scales. Furthermore, the range of annual variability of evaporation rates was low. Although less pronounced, groundwater level effects on evaporation rates were also observed, especially from August through October when solar radiation was lower. The lake exhibits significant fluctuation in lake levels and combined with a shallow lake bed, large changes in lake surface area are observed. Our findings also show that with the onset of summer conditions, lake surface area can change very rapidly (e.g. 24% of its surface area or ~16.6 hectares were lost in less than ~2 months). In every year summer evaporation exceeded annual rainfall by an average of 28.2% suggesting that groundwater is a significant component of the lake water balance, it is important

  16. Evaporation mitigation using floating modular devices

    NASA Astrophysics Data System (ADS)

    Hassan, M. Mahmudul; Peirson, William Leslie; Neyland, Bryce M.; Fiddis, Nicholas McQuistan

    2015-11-01

    Reducing evaporation losses from open water storages is of paramount importance in the improvement of water security in arid countries, including Australia. Widespread adoption of evaporation mitigation techniques has been prevented by their high capital and maintenance or operating costs. The use of clean, floating recycled materials to mitigate evaporation technique has been investigated systematically at sites within both the coastal and semi-arid zones of Australia. Evaporation reduction systematically increases with the proportion of covered surface. Evaporation is reduced by 43% at coastal site and 37% at arid zone site at the maximum packing densities achievable for a single layer of floating devices. The study highlights the importance of both long-term investigations and the climatic influences in the robust quantification of evaporation mitigation. The effects of solar radiation, temperature, wind speed and relative humidity on the evaporation rate at both study sites have been determined in terms of both the classical Penman model and FAO Penman Monteith model with corresponding pan coefficients quantified. FAO Penman Monteith model better estimates evaporation from the open reference tank.

  17. Characteristics of CIGS photovoltaic devices co-evaporated with various Se flux rates at low temperatures

    NASA Astrophysics Data System (ADS)

    Huang, Chia-Hua; Lin, Chun-Ping; Jan, Yueh-Lin

    2016-08-01

    Cu(In,Ga)Se2 (CIGS) films were prepared by a single-stage co-evaporation process at Se flux rates of 10 Å s‑1, 20 Å s‑1, and 30 Å s‑1 and substrate temperatures ranging from 400 °C to 500 °C. The flux rates of the Cu, In, Ga, and Se were kept constant throughout each deposition of the films. The grain sizes, surface morphologies, and crystallinity of the CIGS films improved with increasing substrate temperatures or Se flux rates. The causes of the formation of voids on the surface of CIGS films deposited with a low Se flux rate of 10 Å s‑1 at substrate temperatures of 475 °C and 500 °C were addressed. The higher Se flux rates of 20 Å s‑1 and 30 Å s‑1 repressed the formation of voids for the CIGS films deposited at the relatively higher substrate temperatures of 475 °C and 500 °C. The conversion efficiencies of CIGS solar cells were significantly improved by increasing the substrate temperatures or the Se flux rates, largely contributed from the enhancement of the open-circuit voltage and fill factor because of the restraint of the carrier recombination. The short-circuit current densities were slightly enhanced by the increment of the substrate temperatures or the Se flux rates, resulting from the improved crystalline quality of the CIGS films. Moreover, the EQE results suggest that the effective carrier-diffusion lengths of the films deposited at the relatively high substrate temperatures were increased, leading to the enhancement of the short-circuit current density. The efficiencies of CIGS solar cells prepared with a Se flux rate of 10 Å s‑1 improved from 10% to 12.4% when the substrate temperatures increased from 400 °C to 500 °C. The efficiencies of cells deposited at the substrate temperature of 500 °C improved to 15.4% as the Se flux rates increased from 10 Å s‑1 to 30 Å s‑1.

  18. Laboratory studies in planetary science and quantitative analysis of evaporation rates under current Martian conditions

    NASA Astrophysics Data System (ADS)

    Moore, Shauntae

    2005-12-01

    Laboratory measurements have been performed that are intended to shed light on several problems in planetary science. Thermoluminescence measurements of ordinary chondrites have been performed as part of an effort to identify the most primitive materials in the solar system. Experiments to study the fractionation of metal and silicate grains on asteroid surfaces have been performed on NASA's microgravity facility because of its relevance to meteorite origins and the exploration of asteroids by robotic spacecraft. The results of these studies are presented in this thesis as a conference presentation whose summary appeared in the journal Meteoritics and Planetary Science and a paper that appeared in the journal Geophysical Research Letters. The rest of the thesis describes measurements on the stability of water on the surface of Mars and is submitted in normal thesis format, although at the time of submission some of this work has appeared in Geophysical Research Letters and some has been submitted to the journal Astrobiology. The thermoluminescence studies were used to derive petrologic classifications for several type 3 ordinary chondrites from North Africa, some of which are very low and have the potential to provide new insights to the early solar system and its formation. The metal-silicate fractionation work suggests that the differences in composition observed among the major chondrite groups, the H, L and LL chondrites, could be the result of processes occurring on the surface of the meteorite parent body, probably an asteroid. They also suggest that minor disturbances of the surface will cause separation of components in the asteroid regolith and this should be borne in mind in robotics exploration of asteroids. The stability of water on Mars was investigated by measuring the evaporation rate of liquid water in a Mars-like environment produced in a large chamber on Earth. The evaporation rates measured are in good agreement with model-dependent theoretical

  19. Emergent relation between surface vapor conductance and relative humidity profiles yields evaporation rates from weather data

    PubMed Central

    Salvucci, Guido D.; Gentine, Pierre

    2013-01-01

    The ability to predict terrestrial evapotranspiration (E) is limited by the complexity of rate-limiting pathways as water moves through the soil, vegetation (roots, xylem, stomata), canopy air space, and the atmospheric boundary layer. The impossibility of specifying the numerous parameters required to model this process in full spatial detail has necessitated spatially upscaled models that depend on effective parameters such as the surface vapor conductance (Csurf). Csurf accounts for the biophysical and hydrological effects on diffusion through the soil and vegetation substrate. This approach, however, requires either site-specific calibration of Csurf to measured E, or further parameterization based on metrics such as leaf area, senescence state, stomatal conductance, soil texture, soil moisture, and water table depth. Here, we show that this key, rate-limiting, parameter can be estimated from an emergent relationship between the diurnal cycle of the relative humidity profile and E. The relation is that the vertical variance of the relative humidity profile is less than would occur for increased or decreased evaporation rates, suggesting that land–atmosphere feedback processes minimize this variance. It is found to hold over a wide range of climate conditions (arid–humid) and limiting factors (soil moisture, leaf area, energy). With this relation, estimates of E and Csurf can be obtained globally from widely available meteorological measurements, many of which have been archived since the early 1900s. In conjunction with precipitation and stream flow, long-term E estimates provide insights and empirical constraints on projected accelerations of the hydrologic cycle. PMID:23576717

  20. Evaporation Rate of Water as a Function of a Magnetic Field and Field Gradient

    PubMed Central

    Guo, Yun-Zhu; Yin, Da-Chuan; Cao, Hui-Ling; Shi, Jian-Yu; Zhang, Chen-Yan; Liu, Yong-Ming; Huang, Huan-Huan; Liu, Yue; Wang, Yan; Guo, Wei-Hong; Qian, Ai-Rong; Shang, Peng

    2012-01-01

    The effect of magnetic fields on water is still a highly controversial topic despite the vast amount of research devoted to this topic in past decades. Enhanced water evaporation in a magnetic field, however, is less disputed. The underlying mechanism for this phenomenon has been investigated in previous studies. In this paper, we present an investigation of the evaporation of water in a large gradient magnetic field. The evaporation of pure water at simulated gravity positions (0 gravity level (ab. g), 1 g, 1.56 g and 1.96 g) in a superconducting magnet was compared with that in the absence of the magnetic field. The results showed that the evaporation of water was indeed faster in the magnetic field than in the absence of the magnetic field. Furthermore, the amount of water evaporation differed depending on the position of the sample within the magnetic field. In particular, the evaporation at 0 g was clearly faster than that at other positions. The results are discussed from the point of view of the evaporation surface area of the water/air interface and the convection induced by the magnetization force due to the difference in the magnetic susceptibility of water vapor and the surrounding air. PMID:23443127

  1. Evaporation in the Atacama Desert: An empirical study of spatio-temporal variations and their causes

    NASA Astrophysics Data System (ADS)

    Houston, John

    2006-11-01

    SummaryThe Atacama Desert is hyper-arid, and areas where adequate moisture exists for evaporation are spatially highly restricted. Nevertheless, water resources exist and their evaluation requires knowledge of this elusive but important component of the hydrological cycle. Evaporation may occur in four typical areas: rivers and associated riparian zones, localized springs, large playas and extensive areas of bare soil after infrequent precipitation events. Transpiration is locally possible where moisture is sufficiently close to the surface to allow phreatophytes or scarce grass cover to grow, but virtually no information is available for quantification. Pan evaporation data from 11 stations for the period 1977-1991 is analyzed and complemented by analysis of an evaporation study conducted in the Salar de Atacama during 1987/1988. The results show that pan evaporation, and hence maximum potential evaporation may be considered largely a function of maximum temperature and elevation as well as density of the evaporating fluid. Actual evaporation is limited by available moisture and diminishes rapidly as the level of soil moisture saturation drops below the soil surface, extinguishing at ca. 2 m depth. Evaporation is greatest during the summer, but at higher elevations convective cloudiness develops during January and February reducing evaporating rates at a time when significant precipitation may occur. Inter-annual variations in pan evaporation are considerable and weakly correlated with ENSO, but variations in actual evaporation are damped by comparison. Regression equations are developed which have widespread applicability and may be used to estimate evaporation in areas where no site-specific data exists.

  2. Pan-Svalbard growth rate variability and environmental regulation in the Arctic bivalve Serripes groenlandicus

    NASA Astrophysics Data System (ADS)

    Carroll, Michael L.; Ambrose, William G.; Levin, Benjamin S.; Locke V, William L.; Henkes, Gregory A.; Hop, Haakon; Renaud, Paul E.

    2011-11-01

    Growth histories contained in the shells of bivalves provide continuous records of environmental and biological information over lifetimes spanning decades to centuries, thereby linking ecosystem responses to both natural and anthropogenic climatic variations over a range of scales. We examined growth rates and temporal growth patterns of 260 individuals of the circumpolar Greenland Smooth Cockle ( Serripes groenlandicus) collected between 1997 and 2009 from 11 sites around the Svalbard Archipelago. These sites encompass a range of oceanographic and environmental conditions, from strongly Atlantic-influenced conditions on the west coast to high-Arctic conditions in northeast Svalbard. Absolute growth was up to three times greater at the most strongly Atlantic-influenced locations compared to the most Arctic-influenced areas, and growth performance was highest at sites closest to the West Spitsbergen Current. We also developed growth chronologies up to 34 years in length extending back to 1974. Standardized growth indices (SGI) exhibited substantial inter-site variability, but there were also common temporal features including steadily increasing growth from the late 1980's to the mid-1990's followed by a marked shift from relatively greater to poorer growth in the mid-1990's and from 2004 to 2008. This pattern was consistent with phase-shifts in large-scale climatic drivers. Interannual variability in SGI was also related to local manifestations of the large-scale drivers, including sea temperature and sea ice extent. The temporal growth pattern at Rijpfjorden, on northeast Svalbard, was broadly representative (R = 0.81) of the entire dataset. While there were site-related differences in the specific relationships between growth and environmental parameters, the aggregated dataset indicated an overriding regional driver of bivalve growth: the Arctic Climate Regime Index (ACRI). These results demonstrate that sclerochronological proxies can be useful retrospective

  3. Comparison of diurnal dynamics in evaporation rate between bare soil and moss-crusted soil within a revegetated desert ecosystem of northwestern China

    NASA Astrophysics Data System (ADS)

    Zhang, Ya-Feng; Wang, Xin-Ping; Pan, Yan-Xia; Hu, Rui

    2016-02-01

    Effects of biological soil crusts (BSCs) on soil evaporation is quite controversial in literature, being either facilitative or inhibitive, and therein few studies have actually conducted direct evaporation measurements. Continuous field measurements of soil water evaporation were conducted on two microlysimeters, i.e., one with sand soil collected from bare sand dune area and the other with moss-crusted soil collected from an area that was revegetated in 1956, from field capacity to dry, at the southeastern edge of the Tengger Desert. We mainly aimed to quantify the diurnal variations of evaporation rate from two soils, and further comparatively discuss the effects of BSCs on soil evaporation after revegetation. Results showed that in clear days with high soil water content (Day 1 and 2), the diurnal variation of soil evaporation rate followed the typical convex upward parabolic curve, reaching its peak around mid-day. Diurnal evaporation rate and the accumulated evaporation amount of moss-crusted soil were lower (an average of 0.90 times) than that of sand soil in this stage. However, as soil water content decreased to a moderately low level (Day 3 and 4), the diurnal evaporation rate from moss-crusted soil was pronouncedly higher (an average of 3.91 times) than that of sand soil, prolonging the duration of this higher evaporation rate stage; it was slightly higher in the final stage (Day 5 and 6) when soil moisture was very low. We conclude that the effects of moss crusts on soil evaporation vary with different evaporation stages, which is closely related to soil water content, and the variation and transition of evaporation rate between bare soil and moss-crusted soil are expected to be predicted by soil water content.

  4. Effects of Carbonyl Bond and Metal Cluster Dissociation and Evaporation Rates on Predictions of Nanotube Production in HiPco

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Smalley, Richard E.

    2002-01-01

    The high-pressure carbon monoxide (HiPco) process for producing single-wall carbon nanotubes (SWNT) uses iron pentacarbonyl as the source of iron for catalyzing the Boudouard reaction. Attempts using nickel tetracarbonyl led to no production of SWNTs. This paper discusses simulations at a constant condition of 1300 K and 30 atm in which the chemical rate equations are solved for different reaction schemes. A lumped cluster model is developed to limit the number of species in the models, yet it includes fairly large clusters. Reaction rate coefficients in these schemes are based on bond energies of iron and nickel species and on estimates of chemical rates for formation of SWNTs. SWNT growth is measured by the co-formation of CO2. It is shown that the production of CO2 is significantly greater for FeCO due to its lower bond energy as compared with that ofNiCO. It is also shown that the dissociation and evaporation rates of atoms from small metal clusters have a significant effect on CO2 production. A high rate of evaporation leads to a smaller number of metal clusters available to catalyze the Boudouard reaction. This suggests that if CO reacts with metal clusters and removes atoms from them by forming MeCO, this has the effect of enhancing the evaporation rate and reducing SWNT production. The study also investigates some other reactions in the model that have a less dramatic influence.

  5. Out of the frying pan into the air--emersion behaviour and evaporative heat loss in an amphibious mangrove fish (Kryptolebias marmoratus).

    PubMed

    Gibson, Daniel J; Sylvester, Emma V A; Turko, Andy J; Tattersall, Glenn J; Wright, Patricia A

    2015-10-01

    Amphibious fishes often emerse (leave water) when faced with unfavourable water conditions. How amphibious fishes cope with the risks of rising water temperatures may depend, in part, on the plasticity of behavioural mechanisms such as emersion thresholds. We hypothesized that the emersion threshold is reversibly plastic and thus dependent on recent acclimation history rather than on conditions during early development. Kryptolebias marmoratus were reared for 1 year at 25 or 30°C and acclimated as adults (one week) to either 25 or 30°C before exposure to an acute increase in water temperature. The emersion threshold temperature and acute thermal tolerance were significantly increased in adult fish acclimated to 30°C, but rearing temperature had no significant effect. Using a thermal imaging camera, we also showed that emersed fish in a low humidity aerial environment (30°C) lost significantly more heat (3.3°C min(-1)) than those in a high humidity environment (1.6°C min(-1)). In the field, mean relative humidity was 84%. These results provide evidence of behavioural avoidance of high temperatures and the first quantification of evaporative cooling in an amphibious fish. Furthermore, the avoidance response was reversibly plastic, flexibility that may be important for tropical amphibious fishes under increasing pressures from climatic change. PMID:26490418

  6. A New Approach to Measure Contact Angle and Evaporation Rate with Flow Visualization in a Sessile Drop

    NASA Technical Reports Server (NTRS)

    Zhang, Nengli; Chao, David F.

    1999-01-01

    The contact angle and the spreading process of sessile droplet are very crucial in many technological processes, such as painting and coating, material processing, film-cooling applications, lubrication, and boiling. Additionally, as it is well known that the surface free energy of polymers cannot be directly, measured for their elastic and viscous restraints. The measurements of liquid contact angle on the polymer surfaces become extremely important to evaluate the surface free energy of polymers through indirect methods linked with the contact angle data. Due to the occurrence of liquid evaporation is inevitable, the effects of evaporation on the contact angle and the spreading become very important for more complete understanding of these processes. It is of interest to note that evaporation can induce Marangoni-Benard convection in sessile drops. However, the impacts of the inside convection on the wetting and spreading processes are not clear. The experimental methods used by previous investigators cannot simultaneously measure the spreading process and visualize the convection inside. Based on the laser shadowgraphic system used by the present author, a very simple optical procedure has been developed to measure the contact angle, the spreading speed, the evaporation rate, and to visualize inside convection of a sessile drop simultaneously. Two CCD cameras were used to synchronously record the real-time diameter of the sessile drop, which is essential for determination of both spreading speed and evaporation rate, and the shadowgraphic image magnified by the sessile drop acting as a thin plano-convex lens. From the shadowgraph, the inside convection of the drop can be observed if any and the image outer diameter, which linked to the drop profile, can be measured. Simple equations have been derived to calculate the drop profile, including the instantaneous contact angle, height, and volume of the sessile drop, as well as the evaporation rate. The influence of

  7. Operation of a low temperature absorption chiller at rating point and at reduced evaporator temperature

    NASA Astrophysics Data System (ADS)

    Best, R.; Biermann, W.; Reimann, R. C.

    1985-01-01

    The returned fifteen ton Solar Absorption Machine (SAM) 015 chiller was given a cursory visual inspection, some obvious problems were remedied, and then it was placed on a test stand to get a measure of dirty performance. It was then given a standard acid clean, the water side of the tubes was brushed clean, and then the machine was retested. The before and after cleaning data were compared to equivalent data taken before the machine was shipped. The second part of the work statement was to experimentally demonstrate the technical feasibility of operating the chiller at evaporator temperatures below 0(0)C (32(0)F) and identify any operational problems.

  8. Effects of deposition rate on the structure and electron density of evaporated BaSi2 films

    NASA Astrophysics Data System (ADS)

    Hara, Kosuke O.; Trinh, Cham Thi; Arimoto, Keisuke; Yamanaka, Junji; Nakagawa, Kiyokazu; Kurokawa, Yasuyoshi; Suemasu, Takashi; Usami, Noritaka

    2016-07-01

    In order to control the electrical properties of an evaporated BaSi2 film, which is an emerging candidate for the absorber-layer material of earth-abundant thin-film solar cells, we have investigated the effects of deposition rate on the produced phases, microstructure, and carrier density of the thin films grown by thermal evaporation of BaSi2. X-ray diffraction results show that a high substrate temperature is necessary for BaSi2 formation at a high deposition rate, which is discussed from viewpoints of vapor composition and diffusion time. Microstructural characteristics such as grain size of 30-120 nm, oxide particle arrays present around the interface, and partial oxidation at a low substrate temperature are revealed by cross-sectional transmission electron microscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy combined with an energy-dispersive X-ray spectroscopy. With increasing deposition rate, the crystalline quality of BaSi2 is found to improve, as evidenced by a decrease in full-width at half maximum of a [ Si 4 ] 4 - vibration band in Raman spectra. At the same time, electron density, which is determined by Hall measurement, decreases with deposition rate. The variation of electron density is discussed on the basis of microstructural characteristics and BaSi2 formation mechanism. The most probable reason is concluded to be composition deviation from stoichiometry.

  9. Effect of pervaporation plate thickness on the rate of methanol evaporation in a passive vapor-feed direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Fauzi, N. F. I.; Hasran, U. A.; Kamarudin, S. K.

    2015-09-01

    In a passive vapor-feed direct methanol fuel cell (DMFC), methanol vapor is typically obtained using a pervaporation plate in a process by which liquid methanol contained in the fuel reservoir undergoes a phase change to vapor in the anodic vapor chamber. This work investigates the effect of pervaporation plate thickness on the rate of methanol evaporation using a three-dimensional simulation model developed by varying the plate thickness. A. The rate of methanol evaporation was measured using Darcy's law. The rate of methanol evaporation was found to be inversely proportional to the plate thickness, where the decrease in thickness inevitably lowers the resistance along the plate and consequently increases the methanol transport through the plate. This shows that the plate thickness has a significant influence on the rate of methanol evaporation and thereby plays an important role in improving the performance of the passive vapor-feed direct methanol fuel cell.

  10. Metabolic rate, evaporative water loss and thermoregulatory state in four species of bats in the Negev desert.

    PubMed

    Muñoz-Garcia, Agustí; Larraín, Paloma; Ben-Hamo, Miriam; Cruz-Neto, Ariovaldo; Williams, Joseph B; Pinshow, Berry; Korine, Carmi

    2016-01-01

    Life in deserts is challenging for bats because of their relatively high energy and water requirements; nevertheless bats thrive in desert environments. We postulated that bats from desert environments have lower metabolic rates (MR) and total evaporative water loss (TEWL) than their mesic counterparts. To test this idea, we measured MR and TEWL of four species of bats, which inhabit the Negev desert in Israel, one species mainly restricted to hyper-arid deserts (Otonycteris hemprichii), two species from semi-desert areas (Eptesicus bottae and Plecotus christii), and one widespread species (Pipistrellus kuhlii). We also measured separately, in the same individuals, the two components of TEWL, respiratory water loss (RWL) and cutaneous evaporative water loss (CEWL), using a mask. In all the species, MR and TEWL were significantly reduced during torpor, the latter being a consequence of reductions in both RWL and CEWL. Then, we evaluated whether MR and TEWL in bats differ according to their geographic distributions, and whether those rates change with Ta and the use of torpor. We did not find significant differences in MR among species, but we found that TEWL was lowest in the species restricted to desert habitats, intermediate in the semi-desert dwelling species, and highest in the widespread species, perhaps a consequence of adaptation to life in deserts. Our results were supported by a subsequent analysis of data collected from the literature on rates of TEWL for 35 bat species from desert and mesic habitats. PMID:26459985

  11. Flow Visualization in Evaporating Liquid Drops and Measurement of Dynamic Contact Angles and Spreading Rate

    NASA Technical Reports Server (NTRS)

    Zhang, Neng-Li; Chao, David F.

    2001-01-01

    A new hybrid optical system, consisting of reflection-refracted shadowgraphy and top-view photography, is used to visualize flow phenomena and simultaneously measure the spreading and instant dynamic contact angle in a volatile-liquid drop on a nontransparent substrate. Thermocapillary convection in the drop, induced by evaporation, and the drop real-time profile data are synchronously recorded by video recording systems. Experimental results obtained from this unique technique clearly reveal that thermocapillary convection strongly affects the spreading process and the characteristics of dynamic contact angle of the drop. Comprehensive information of a sessile drop, including the local contact angle along the periphery, the instability of the three-phase contact line, and the deformation of the drop shape is obtained and analyzed.

  12. Quantifying the feedback of evaporation and transpiration rates to soil moisture dynamics and meteorological condition changes by a numerical model

    NASA Astrophysics Data System (ADS)

    Su, Ye; Shao, Wei; Vlček, Lukáš; Langhammer, Jakub

    2015-04-01

    Evapotranspiration drives the hydrological process through energy-driven water-phase changes between systems of soil-vegetation-atmosphere. Evapotranspiration performs a rather complex process attributable to the spatial and temporal variation of soil-vegetation-atmosphere system. For vegetation-covered land surfaces, the transpiration process is governed by the stomatal behavior and water uptake from the root zone, and evaporation is related with the interception of rainfall and radiation on the canopy and soil surface. This study is emphasized on describing the hydrological process and energy cycle in a basic hydrological response unit, a hillslope. The experimental hillslope is located in an experimental catchment of the Bohemian Forest Mountains' headwaters in the Czech Republic, where is mostly covered by dead Norway spruce forest (Picea abies) stands caused by balk beetle outbreak. High-frequency monitoring network of the hydro-climatic data, soil pore water pressure and soil temperature has been launched since 2012. To conceptualize the land-surface energy and water fluxes in a complex hillslope, a soil-vegetation-atmosphere transport (SVAT) model, coupled with a multi-phase soil physics process (i.e. the water, vapor and heat flow transport) is used. We selected an 8-week basis dataset from 2013 as a pilot for partitioning the evapotranspiration into three interactive components: transpiration (Et), canopy interception evaporation (Ei), and soil evaporation (Es), by using this numerical model. Within such model framework, the sensitive feedback of evapotranspiration rates to rainfall intensity, soil moisture, and solar radiation will be examined by conducting numerical experiments to better understand the mechanism of evapotranspiration process under various influencing factors. Such application study and followed numerical simulations provide a new path for quantifying the behaviors of the soil-vegetation-atmosphere system.

  13. Effect of DOC on evaporation from small Wisconsin lakes

    NASA Astrophysics Data System (ADS)

    Watras, C. J.; Morrison, K. A.; Rubsam, J. L.

    2016-09-01

    Evaporation (E) dominates the loss of water from many small lakes, and the balance between precipitation and evaporation (P-E) often governs water levels. In this study, evaporation rates were estimated for three small Wisconsin lakes over several years using 30-min data from floating evaporation pans (E-pans). Measured E was then compared to the output of mass transfer models driven by local conditions over daily time scales. The three lakes were chosen to span a range of dissolved organic carbon (DOC) concentrations (3-20 mg L-1), a solute that imparts a dark, tea-stain color which absorbs solar energy and limits light penetration. Since the lakes were otherwise similar, we hypothesized that a DOC-mediated increase in surface water temperature would translate directly to higher rates of evaporation thereby informing climate response models. Our results confirmed a DOC effect on surface water temperature, but that effect did not translate to enhanced evaporation. Instead the opposite was observed: evaporation rates decreased as DOC increased. Ancillary data and prior studies suggest two explanatory mechanisms: (1) disproportionately greater radiant energy outflux from high DOC lakes, and (2) the combined effect of wind speed (W) and the vapor pressure gradient (es - ez), whose product [W(es - ez)] was lowest on the high DOC lake, despite very low wind speeds (<1.5 m s-1) and steep forested uplands surrounding all three lakes. Agreement between measured (E-pan) and modeled evaporation rates was reasonably good, based on linear regression results (r2: 0.6-0.7; slope: 0.5-0.7, for the best model). Rankings based on E were similar whether determined by measured or modeled criteria (high DOC < low DOC). Across the 3 lakes and 4 years, E averaged ∼3 mm d-1 (C.V. 9%), but statistically significant differences between lakes resulted in substantial differences in cumulative E that were consistent from year to year. Daily water budgets for these lakes show that inputs

  14. Hydrogen capacity and absorption rate of the SAES St707 non-evaporable getter at various temperatures.

    SciTech Connect

    Hsu, Irving; Mills, Bernice E.

    2010-08-01

    A prototype of a tritium thermoelectric generator (TTG) is currently being developed at Sandia. In the TTG, a vacuum jacket reduces the amount of heat lost from the high temperature source via convection. However, outgassing presents challenges to maintaining a vacuum for many years. Getters are chemically active substances that scavenge residual gases in a vacuum system. In order to maintain the vacuum jacket at approximately 1.0 x 10{sup -4} torr for decades, nonevaporable getters that can operate from -55 C to 60 C are going to be used. This paper focuses on the hydrogen capacity and absorption rate of the St707{trademark} non-evaporable getter by SAES. Using a getter testing manifold, we have carried out experiments to test these characteristics of the getter over the temperature range of -77 C to 60 C. The results from this study can be used to size the getter appropriately.

  15. Soil Evaporation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil evaporation can significantly influence energy flux partitioning of partially vegetated surfaces, ultimately affecting plant transpiration. While important, quantification of soil evaporation, separately from canopy transpiration, is challenging. Techniques for measuring soil evaporation exis...

  16. Group evaporation

    NASA Technical Reports Server (NTRS)

    Shen, Hayley H.

    1991-01-01

    Liquid fuel combustion process is greatly affected by the rate of droplet evaporation. The heat and mass exchanges between gas and liquid couple the dynamics of both phases in all aspects: mass, momentum, and energy. Correct prediction of the evaporation rate is therefore a key issue in engineering design of liquid combustion devices. Current analytical tools for characterizing the behavior of these devices are based on results from a single isolated droplet. Numerous experimental studies have challenged the applicability of these results in a dense spray. To account for the droplets' interaction in a dense spray, a number of theories have been developed in the past decade. Herein, two tasks are examined. One was to study how to implement the existing theoretical results, and the other was to explore the possibility of experimental verifications. The current theoretical results of group evaporation are given for a monodispersed cluster subject to adiabatic conditions. The time evolution of the fluid mechanic and thermodynamic behavior in this cluster is derived. The results given are not in the form of a subscale model for CFD codes.

  17. 14. RW Meyer Sugar Mill: 18761889. Sorghum Pan. Manufactured by ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. RW Meyer Sugar Mill: 1876-1889. Sorghum Pan. Manufactured by John Nott & Co., Honolulu, Hawaii, 1878. View: In the sorghum pan, heat was applied to the cane juice to clarify it, evaporate its water content, and concentrate the sugar crystals. The pan was set on a slope so that the juice would move through the compartments by gravity. The hand-lever sluice valves in the partition walls between the compartments permitted the sugar boiler to regulate the movement of batches of cane juice flowing through the pan. The metal fins projecting from the bottom of the pan imparted a circuitous route to the juice as it flowed through the pan--this made it flow over a much greater heated surface. The fins also supplemented the pan's heating surface by ... - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

  18. Liquid-particle dynamics and rate of evaporation in the rotating field of centrifugal compressors

    SciTech Connect

    Pinkus, O.

    1981-01-01

    A model is presented which consists of injecting a liquid coolant into the vapor of centrifugal compressors via slots in the rotating blades. The aim of the injection is to achieve isothermal compression and thus minimal work input. The 3-dimensional analysis determines the relative velocities and trajectories of the liquid particles, and their rate of vaporization as a function of the prevailing flow field and inlet conditions. Inertia, viscous drag, centrifugal and Coriolis forces are all included. The computer-obtained results show that for optimum conditions and to avoid collision with the blades it is desirable that injection occur at the suction side of the blades and close to the hub; that low rather than high initial particle velocities are preferred; and that small droplet sizes are required both to avoid blade erosion and to assure the highest rate of vaporization. The analysis also shows that vaporization levels will remain low unless the compressed vapor is at relatively high temperatures.

  19. Global distribution of moisture, evaporation-precipitation, and diabatic heating rates

    NASA Technical Reports Server (NTRS)

    Christy, John R.

    1989-01-01

    Global archives were established for ECMWF 12-hour, multilevel analysis beginning 1 January 1985; day and night IR temperatures, and solar incoming and solar absorbed. Routines were written to access these data conveniently from NASA/MSFC MASSTOR facility for diagnostic analysis. Calculations of diabatic heating rates were performed from the ECMWF data using 4-day intervals. Calculations of precipitable water (W) from 1 May 1985 were carried out using the ECMWF data. Because a major operational change on 1 May 1985 had a significant impact on the moisture field, values prior to that date are incompatible with subsequent analyses.

  20. Calculations of evaporative losses using stable water isotope composition in dry climates

    NASA Astrophysics Data System (ADS)

    Skrzypek, Grzegorz; Mydlowski, Adam; Dogramaci, Shawan; Hedley, Paul; Gibson, John; Grierson, Pauline

    2014-05-01

    Evaporative loss from surface waters is a major component of the hydrological cycle in arid zones, restricting recharge to aquifers and limiting the persistence of surface water bodies. Calculation of evaporative loss is founded on the so-called Craig-Gordon model (C-G), and the stable hydrogen and oxygen isotope composition of water can be successfully used to estimate progressive evaporation. The advantage of this approach is that it does not require monitoring of water levels, inflow and outflow rates. However, the precision and reliability of calculations in very hot and dry climates can be compromised by variable isotope composition of air moisture, which thus needs to be calibrated for C-G model calculations. In this study, we tested the range of uncertainty in the estimation of evaporative losses by cross-validating a simplified stable isotope model with field pan evaporation experiments. The use of standardized pans (1.2 m diameter, max volume 300 dm3) allowed simulation of fast evaporation from shallow water bodies in hot and dry climates (mean daily temperature 29° C and relative humidity between 19 and 26% RH during an 11 day experiment). The stable isotope composition of water in pans changed from -8.23o (δ18O) and -56o (δ2H) to approximately +6.0o (δ18O) and +2.4o (δ2H), reflecting evaporative losses of 56% in sun and 53% in shade. The maximum difference between observed (measured in the field) and calculated evaporative losses was

  1. Field-measured, hourly soil water evaporation stages in relation to reference evapotranspiration rate and soil to air temperature ratio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil water evaporation takes critical water supplies away from crops, especially in areas where both rainfall and irrigation water are limited. This study measured bare soil water evaporation from clay loam, silt loam, sandy loam, and fine sand soils. It found that on average almost half of the ir...

  2. An Energy Partitioning Perspective on Lake Evaporation Variations to Climate Change

    NASA Astrophysics Data System (ADS)

    Lee, X.; WANG, W.; Zhao, L.; Subin, Z. M.

    2015-12-01

    Lake evaporation, nexus between lake hydrological cycle and energy balance, is very sensitive to climate change. Despite considerable observational and modeling studies on water surface evaporation, mechanisms underlying the response of long-term lake evaporation variations to climate change are still uncertain. Two hypotheses have been proposed to explain interannual variations in lake evaporation. In the first hypothesis, water surface evaporation will increase as air temperature rises, at a rate of about 7% K-1 predicted by the Clausius-Clapeyron equation. The second hypothesis, supported by the universal decline trends in pan evaporation tied to global diming, is that evaporation variabilities are controlled by variabilities in the surface solar radiation. In this study, we firstly validated the evaporation simulations of NCAR's CLM4.5-LISSS (Lake, Ice, Snow, and Sediment Simulator) against 28 lake observations. Then historical (1991-2010) and future (2005-2100, RCP8.5) lake evaporation were simulated by the same lake model. Results show that global lake evaporation increases with air temperature at a rate faster under the RCP8.5 scenario (3.72 W m-2 oC-1) than in the historical case (3.03 W m-2 oC-1). With normalization of energy constrains, both observed and modeled lake evaporation fraction (the ratio of latent heat flux to net radiation minus heat storage) increase as air temperature rises at a rate perfectly captured by the Priestley-Taylor model with the model parameter of 1.26. From the energy partitioning perspective, the lake evaporation variations are explained primary by air temperature not by surface solar radiation.

  3. Evaporative Cooling Membrane Device

    NASA Technical Reports Server (NTRS)

    Lomax, Curtis (Inventor); Moskito, John (Inventor)

    1999-01-01

    An evaporative cooling membrane device is disclosed having a flat or pleated plate housing with an enclosed bottom and an exposed top that is covered with at least one sheet of hydrophobic porous material having a thin thickness so as to serve as a membrane. The hydrophobic porous material has pores with predetermined dimensions so as to resist any fluid in its liquid state from passing therethrough but to allow passage of the fluid in its vapor state, thereby, causing the evaporation of the fluid and the cooling of the remaining fluid. The fluid has a predetermined flow rate. The evaporative cooling membrane device has a channel which is sized in cooperation with the predetermined flow rate of the fluid so as to produce laminar flow therein. The evaporative cooling membrane device provides for the convenient control of the evaporation rates of the circulating fluid by adjusting the flow rates of the laminar flowing fluid.

  4. Evaporation estimates from the Dead Sea and their implications on its water balance

    NASA Astrophysics Data System (ADS)

    Oroud, Ibrahim M.

    2011-12-01

    The Dead Sea (DS) is a terminal hypersaline water body situated in the deepest part of the Jordan Valley. There is a growing interest in linking the DS to the open seas due to severe water shortages in the area and the serious geological and environmental hazards to its vicinity caused by the rapid level drop of the DS. A key issue in linking the DS with the open seas would be an accurate determination of evaporation rates. There exist large uncertainties of evaporation estimates from the DS due to the complex feedback mechanisms between meteorological forcings and thermophysical properties of hypersaline solutions. Numerous methods have been used to estimate current and historical (pre-1960) evaporation rates, with estimates differing by ˜100%. Evaporation from the DS is usually deduced indirectly using energy, water balance, or pan methods with uncertainty in many parameters. Accumulated errors resulting from these uncertainties are usually pooled into the estimates of evaporation rates. In this paper, a physically based method with minimum empirical parameters is used to evaluate historical and current evaporation estimates from the DS. The more likely figures for historical and current evaporation rates from the DS were 1,500-1,600 and 1,200-1,250 mm per annum, respectively. Results obtained are congruent with field observations and with more elaborate procedures.

  5. Effects of carbonyl bond, metal cluster dissociation, and evaporation rates on predictions of nanotube production in high-pressure carbon monoxide

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Smalley, Richard E.

    2003-01-01

    The high-pressure carbon monoxide (HiPco) process for producing single-wall carbon nanotubes (SWNTs) uses iron pentacarbonyl as the source of iron for catalyzing the Boudouard reaction. Attempts using nickel tetracarbonyl led to no production of SWNTs. This paper discusses simulations at a constant condition of 1300 K and 30 atm in which the chemical rate equations are solved for different reaction schemes. A lumped cluster model is developed to limit the number of species in the models, yet it includes fairly large clusters. Reaction rate coefficients in these schemes are based on bond energies of iron and nickel species and on estimates of chemical rates for formation of SWNTs. SWNT growth is measured by the conformation of CO2. It is shown that the production of CO2 is significantly greater for FeCO because of its lower bond energy as compared with that of NiCO. It is also shown that the dissociation and evaporation rates of atoms from small metal clusters have a significant effect on CO2 production. A high rate of evaporation leads to a smaller number of metal clusters available to catalyze the Boudouard reaction. This suggests that if CO reacts with metal clusters and removes atoms from them by forming MeCO, this has the effect of enhancing the evaporation rate and reducing SWNT production. The study also investigates some other reactions in the model that have a less dramatic influence.

  6. Evaporation from seven reservoirs in the Denver water-supply system, central Colorado

    USGS Publications Warehouse

    Ficke, John F.; Adams, D. Briane; Danielson, T.W.

    1977-01-01

    Seven reservoirs in central Colorado, operated by the Denver Board of Water Commissioners, were studied during 1967-73 to determine evaporation losses. These reservoirs, Elevenmile Canyon, Dillon, Gross, Antero, Cheesman, Williams Fork, and Ralston, are located on both sides of the Continental Divide. Methods for computing evaporation include energy-budget, mass-transfer, and pan relationships. Three reservoirs, Elevenmile Canyon, Dillon, and Gross, had mass-transfer coefficients calibrated by energy-budget studies. At the remaining reservoirs, an empirical technique was used to estimate the mass-transfer coefficient. The enery-budget-calibrated methods give the most accurate evaporation values; the empirical coefficients give only a best estimate of evaporation. All reservoirs should be calibrated by energy-budget studies. The pan method of computing evaporation is the least reliable method because of problems of advected energy through the sides of the pan, representative pan exposure , and the irregularity of ratios of reservoir to pan evaporation. (Woodard-USGS)

  7. Development of Statistical Typhoon Intensity Prediction: Application to Satellite-Observed Surface Evaporation and Rain Rate (STIPER)

    NASA Astrophysics Data System (ADS)

    Gao, S.; Chiu, L.

    2012-12-01

    A statistical-dynamical model has been used for operational guidance for tropical cyclone (TC) intensity prediction. In this study, several multiple linear regression models and neural network (NN) models are developed for the intensity prediction of western North Pacific TCs at 24-, 48-, and 72-h intervals. The multiple linear regression models include a model of climatology and persistence (CLIPER), a model based on the Statistical Typhoon Intensity Prediction System (STIPS), which serves as the base regression model (BASE), and a model of STIPS with additional satellite estimates of surface evaporation (SLHF) and innercore rain rate (IRR, STIPER model). A revised equation for the TC maximum potential intensity is derived using Tropical Rainfall Measuring Mission Microwave Imager optimally interpolated sea surface temperature data, which have higher temporal and spatial resolutions. Analyses of the resulting models show the marginal improvement of STIPER over BASE. However, IRR and SLHF are found to be significant predictors in the predictor pool. Neural network models using the same predictors as STIPER show reductions of the mean absolute errors of 7%, 11%, and 16% relative to STIPER for 24-, 48-, and 72-h forecasts, respectively. The largest improvement is found for the intensity forecasts of the rapidly intensifying and rapidly decaying TCs. (top) The 24-h BASE, STIPER, and NN24 model mean absolute errors (MAEs) stratified by best-track initial intensity (MWS0) in 5-kt bins and (bottom) 24-h intensity change (DELV) in 5-kt bins for all nine verification years. Lower values of MAEs represent better forecasts. Dashed dotted lines represent the numbers of valid observations within a particular bin.

  8. Comparison of energy-budget evaporation losses from two morphometrically different Florida seepage lakes

    USGS Publications Warehouse

    Sacks, L.A.; Lee, T.M.; Radell, M.J.

    1994-01-01

    Evaporation was computed by the energy-budget method for two north Florida lakes with similar surface areas but different depths, for the period May 1989 to December 1990. Lake Barco, in north-central Florida, is shallow, with an average depth of 3 m; Lake Five-O, in the Florida panhandle, is considerably deeper, with an average depth of 9.5 m. As a result, the thermal regime and seasonal evaporation rates of the lakes are different. Evaporation from the shallower lake was higher than that from the deeper lake in the winter and spring. In the late summer and autumn, however, the situation is reversed. Evaporation from the shallow lake is directly related to the amount of incoming shortwave radiation because of its limited ability to store energy. The lag in evaporation at the deeper lake is a function of the greater amount of heat that it seasonally stores and releases. The difference in annual evaporation between Lake Barco (151 cm year-1) and Lake Five-O (128 cm year-1) is related to differences in regional climatic conditions between the two sites. Additionally, higher than normal evaporation rates at the two lakes are probably related to drought conditions experienced in north Florida during 1990, which resulted in higher temperatures and more incoming radiation. Monthly evaporation at Lake Barco could usually be estimated within 10% of the energy-budget evaporation using a constant pan coefficient. This lake may be representative of other shallow lakes that do not store considerable heat. Monthly evaporation at Lake Five-O, however, could not be estimated accurately by using an annual pan coefficient because of the large seasonal influence of change in stored heat. Monthly mass-transfer evaporation compared well with energy-budget evaporation at Lake Barco, but did not compare well at Lake Five-O. These errors may also be associated with changes in heat storage. Thus, the thermal regime of the lake must be considered to estimate accurately the seasonal

  9. Phase, Viscosity, Morphology, and Room Temperature Evaporation Rates of SOA Particles Generated from Different Precursors, at Low and High Relative Humidities, and their Interaction with Hydrophobic Organics

    NASA Astrophysics Data System (ADS)

    Wilson, J. M.; Zelenyuk, A.; Imre, D. G.; Beranek, J.; Abramson, E.; Shrivastava, M.

    2012-12-01

    Formation, properties, transformations, and temporal evolution of secondary organic aerosol (SOA) particles strongly depend on particle phase. Semi-volatile molecules that comprise SOA particles were assumed to form a low viscosity solution that maintains equilibrium with the evolving gas phase by rapid evaporation condensation. However, studies by our group indicate that laboratory-generated alpha-pinene SOA particles and ambient SOA characterized in a recent field campaign are in a semi-solid, highly viscous phase, and their evaporation rates are orders of magnitude slower than predicted. We present the results of recent studies in which we have extended our work to include SOA particles generated by oxidation of a number of precursors including limonene, n-alkenes, cyclo-alkenes and isoprene. The resulting particles are characterized by their phase, morphology and room temperature evaporation rates. We conclude that, while the detailed properties of SOA particles depend of their precursor, all studied SOA particles are highly viscous semi-solids that exhibit very slow evaporation rates. Given that atmospheric relative humidity (RH) can change particle phase, it is important to investigate the effect of RH on the phase and evaporation kinetics of SOA particles. To this end SOA particles were generated at low and high (~90%) RH, and their evaporation kinetics and phase were characterized as a function of RH. In the ambient atmosphere SOA particles form in the presence of a mixture of different organic compounds, which are present at or below their equilibrium vapor pressure, and thus have been ignored. However, our data show that these compounds can adsorb to the surface of particles during SOA formation, becoming trapped in the highly viscous SOA, and affect particle properties. We examine the interaction between SOA particles and different hydrophobic organics representing typical anthropogenic emissions by making SOA in the presence of the vapors of these

  10. Electrochemical treatment of evaporated residue of soak liquor generated from leather industry.

    PubMed

    Boopathy, R; Sekaran, G

    2013-09-15

    The organic and suspended solids present in soak liquor, generated from leather industry, demands treatment. The soak liquor is being segregated and evaporated in solar evaporation pans/multiple effect evaporator due to non availability of viable technology for its treatment. The residue left behind in the pans/evaporator does not carry any reuse value and also faces disposal threat due to the presence of high concentration of sodium chloride, organic and bacterial impurities. In the present investigation, the aqueous evaporated residue of soak liquor (ERSL) was treated by electrochemical oxidation. Graphite/graphite and SS304/graphite systems were used in electrochemical oxidation of organics in ERSL. Among these, graphite/graphite system was found to be effective over SS304/graphite system. Hence, the optimised conditions for the electrochemical oxidation of organics in ERSL using graphite/graphite system was evaluated by response surface methodology (RSM). The mass transport coefficient (km) was calculated based on pseudo-first order rate kinetics for both the electrode systems (graphite/graphite and SS304/graphite). The thermodynamic properties illustrated the electrochemical oxidation was exothermic and non-spontaneous in nature. The calculated specific energy consumption at the optimum current density of 50 mA cm(-2) was 0.41 kWh m(-3) for the removal of COD and 2.57 kWh m(-3) for the removal of TKN. PMID:23770619

  11. Quantitative Microbiological Analysis of Bacterial Community Shifts in a High-Rate Anaerobic Bioreactor Treating Sulfite Evaporator Condensate

    PubMed Central

    Ney, U.; Macario, A. J. L.; de Macario, E. Conway; Aivasidis, A.; Schoberth, S. M.; Sahm, H.

    1990-01-01

    The bacterial population of a high-rate, anaerobic, fixed-bed loop reactor treating sulfite evaporator condensate from the pulp industry was studied over a 14-month period. This period was divided into seven cycles that included a startup at the beginning of each cycle. Some 82% of the total biomass was immobilized on and between the porous glass rings filling the reactor. The range of the total number of microorganisms in these biofilms was 2 × 109 to 7 × 109 cells per ml. Enumeration and characterization by microbiological methods and by phase-contrast, epifluorescence, and electron microscopy showed that the samples consisted mainly of the following methanogens: a Methanobacterium sp., a Methanosarcina sp., a Methanobrevibacter sp., and a Methanothrix sp., as well as furfural-degrading sulfate-reducing bacteria resembling Desulfovibrio furfuralis. Viable counts of hydrogenotrophic methanogens were relatively stable (mostly within the range of 3.2 × 108 to 7.5 × 108 cells per ml), but Methanobrevibacter cells increased from <5 to 30% of the total hydrogenotrophic count after transfer of the fixed bed into a second reactor vessel. Acetotrophic methanogens reached their highest numbers of 1.3 × 108 to 2.6 × 108 cells per ml in the last fermentation cycles. They showed a morphological shift from sarcinalike packets in early samples to single coccoid forms in later phases of the fermentation. Furfural-degrading sulfate reducers reached counts of 1 × 107 to 5.8 × 107 cells per ml. The distribution of the chief metabolic groups between free fluid and biofilms was analyzed in the fifth fermentation cycle: 4.5 times more furfural degraders were found in the free fluid than in the biofilms. In contrast, 5.8 times more acetotrophic and 16.6 times more hydrogenotrophic methanogens were found in the biofilms than in the free liquid. The data concerning time shifts of morphotypes among the trophic groups of methanogens corroborated the trends observed by using

  12. Streamer Evaporation

    NASA Technical Reports Server (NTRS)

    Suess, Steven T.; Wang, A. H.; Wu, Shi T.; Nerney, S.

    1998-01-01

    Evaporation is the consequence of slow plasma heating near the tops of streamers where the plasma is only weakly contained by the magnetic field. The form it takes is the slow opening of field lines at the top of the streamer and transient formation of new solar wind. It was discovered in polytropic model calculations, where due to the absence of other energy loss mechanisms in magnetostatic streamers, its ultimate endpoint is the complete evaporation of the streamer. This takes, for plausible heating rates, weeks to months in these models. Of course streamers do not behave this way, for more than one reason. One is that there are losses due to thermal conduction to the base of the streamer and radiation from the transition region. Another is that streamer heating must have a characteristic time constant and depend on the ambient physical conditions. We use our global Magnetohydrodynamics (MHD) model with thermal conduction to examine a few examples of the effect of changing the heating scale height and of making ad hoc choices for how the heating depends on ambient conditions. At the same time, we apply and extend the analytic model of streamers, which showed that streamers will be unable to contain plasma for temperatures near the cusp greater than about 2xl0(exp 6) K. Slow solar wind is observed to come from streamers through transient releases. A scenario for this that is consistent with the above physical process is that heating increases the near-cusp temperature until field lines there are forced open. The subsequent evacuation of the flux tubes by the newly forming slow wind decreases the temperature and heating until the flux tubes are able to reclose. Then, over a longer time scale, heating begins to again refill the flux tubes with plasma and increase the temperature until the cycle repeats itself. The calculations we report here are first steps towards quantitative evaluation of this scenario.

  13. 3. RW Meyer Sugar Mill: 18761889. Sorghum pan and boiling ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. RW Meyer Sugar Mill: 1876-1889. Sorghum pan and boiling range flue. Manufactured by John Nott & Co., Honolulu, Hawaii, 1878. View: South side of sorghum pan and boiling range flue. In the sorghum pan heat was applied to the cane juice to clarify it, evaporate its water content, and concentrate the sugar crystals. Hot gasses moved through the flue underneath the entire copper bottom of the sorghum pan from the furnace (east) end to the smokestack (west) end of the boiling range. The sorghum pan sides are of redwood. The flue is built of fire-brick, masonry, and portland cement. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

  14. Evaporation study at Warm Springs Reservoir, Oregon

    USGS Publications Warehouse

    Harris, D.D.

    1968-01-01

    The mass transfer-water budget method of computing reservoir evaporation was tested on Warm Springs Reservoir, whose contents and surface area change greatly from early spring to late summer. The mass-transfer coefficient computed for the reservoir is two to three times greater than expected and results in a computed evaporation much greater than that from a land pan. Because of the remoteness of the area, the recommended study technique was modified, which could have reduced the accuracy of the results.

  15. Evaporation and reference evapotranspiration trends in Spain

    NASA Astrophysics Data System (ADS)

    Sanchez-Lorenzo, Arturo; Vicente-Serrano, Sergio M.; Wild, Martin; Azorin-Molina, Cesar; Calbó, Josep; Revuelto, Jesús; López-Moreno, Juan I.; Moran-Tejeda, Enrique; Martín-Hernández, Natalia; Peñuelas, Josep

    2015-04-01

    Interest is growing in the trends of atmospheric evaporation demand, increasing the need for long-term time series. In this study, we first describe the development of a dataset on evaporation in Spain based on long-term series of Piché and pan measurement records. Piché measurements have been reported for >50 stations since the 1960s. Measurements of pan evaporation, which is a much more widely studied variable in the literature, are also available, but only since 1984 for 21 stations. Particular emphasis was placed on the homogenization of this dataset (for more details, we refer to Sanchez-Lorenzo et al., 2014, Clim Res, 61: 269-280). Both the mean annual Piché and pan series over Spain showed evaporative increases during the common study period (1985-2011). Furthermore, using the annual Piché records since the 1960s, an evaporation decline was detected from the 1960s to the mid-1980s, which resulted in a non-significant trend over the entire 1961-2011 period. Our results indicate agreement between the decadal variability of reference evapotranspiration (Vicente-Serrano et al., 2014, Glob Planet Chang, 121: 26-40) and surface solar radiation (Sanchez-Lorenzo et al., 2013, Glob Planet Chang, 100: 343-352) and the evaporation from Piché and pan measurements since the mid-1980s, especially during summer. Nevertheless, this agreement needs attention, as Piché evaporimeters are inside meteorological screens and not directly exposed to radiation. Thus, as Piché readings are mainly affected by the aerodynamic term in Penman's evaporation equation and pan records are affected by both the heat balance and aerodynamic terms, the results suggest that both terms must be highly and positively correlated in Spain. In order to check this hypothesis, the radiative and aerodynamic components were estimated using the Penman's equation. The results show that the relationship with the radiative components is weaker than that with the aerodynamic component for both pan and

  16. PanDAR: a wide-area, frame-rate, and full color lidar with foveated region using backfilling interpolation upsampling

    NASA Astrophysics Data System (ADS)

    Mundhenk, T. Nathan; Kim, Kyungnam; Owechko, Yuri

    2015-01-01

    LIDAR devices for on-vehicle use need a wide field of view and good fidelity. For instance, a LIDAR for avoidance of landing collisions by a helicopter needs to see a wide field of view and show reasonable details of the area. The same is true for an online LIDAR scanning device placed on an automobile. In this paper, we describe a LIDAR system with full color and enhanced resolution that has an effective vertical scanning range of 60 degrees with a central 20 degree fovea. The extended range with fovea is achieved by using two standard Velodyne 32-HDL LIDARs placed head to head and counter rotating. The HDL LIDARS each scan 40 degrees vertical and a full 360 degrees horizontal with an outdoor effective range of 100 meters. By positioning them head to head, they overlap by 20 degrees. This creates a double density fovea. The LIDAR returns from the two Velodyne sensors do not natively contain color. In order to add color, a Point Grey LadyBug panoramic camera is used to gather color data of the scene. In the first stage of our system, the two LIDAR point clouds and the LadyBug video are fused in real time at a frame rate of 10 Hz. A second stage is used to intelligently interpolate the point cloud and increase its resolution by approximately four times while maintaining accuracy with respect to the 3D scene. By using GPGPU programming, we can compute this at 10 Hz. Our backfilling interpolation methods works by first computing local linear approximations from the perspective of the LIDAR depth map. The color features from the image are used to select point cloud support points that are the best points in a local group for building the local linear approximations. This makes the colored point cloud more detailed while maintaining fidelity to the 3D scene. Our system also makes objects appearing in the PanDAR display easier to recognize for a human operator.

  17. Determining the virtual surface in the thermal evaporation process of magnesium fluoride from a tungsten boat for different deposition rates, to be used in precision optical components

    NASA Astrophysics Data System (ADS)

    Tejada Esteves, A.; Gálvez de la Puente, G.

    2013-11-01

    Vacuum thermal evaporation has, for some time now, been the principal method for the deposition of thin films, given, among other aspects, its simplicity, flexibility, and relatively low cost. Therefore, the development of models attempting to predict the deposition patterns of given thin film materials in different locations of a vacuum evaporation chamber are arguably important. With this in mind, we have designed one of such models for the thermal evaporation process of magnesium fluoride (MgF2), a common material used in optical thin films, originating from a tungsten boat source. For this we took several deposition samples in glass slide substrates at different locations in the vacuum chamber, considering as independent variables the mean deposition rate, and the axial and vertical distances of the source to the substrate. After a careful analysis by matrix method from the spectral transmittance data of the samples, while providing as output data the spectral transmittance, as well as the physical thickness of the films, both as functions of the aforementioned variables, the virtual surface of the source was determined.

  18. Loving Peter Pan.

    ERIC Educational Resources Information Center

    Kinkaid, James R.

    2003-01-01

    Explores the story of "Peter Pan." Considers its creation, its role on the stage, and its impact on society. Considers how "Peter Pan" is about the inability to have make-believe and the true stick together: it dramatizes an artistic failure, the failure to make the vision of the play successful. (SG)

  19. Evaluation of Pan Coefficients for Estimating Reference Evapotranspiration in Southern Taiwan

    NASA Astrophysics Data System (ADS)

    Yeh, H.

    2006-12-01

    Evapotranspiration is an important process of water transfer in the hydrosphere and atmosphere, which plays an active role in the hydrological cycle. Evaporation pan (Epan) data are often used to estimate reference evapotranspiration (ETref) for use in water resource planning. Generally, ETref is estimated as the product of the Epan data and a pan coefficient (Kpan). However, reliable estimation of ETref using Epan depends on the accurate determination of pan coefficients Kpan. Many different methods for estimating ETref have been developed, among which the Penman-Monteith method is demonstrated to be especially excellent by the Food and Agriculture Organization (FAO). In this study, the Penman-Monteith reference evapotranspiration, pan evaporation, and pan coefficient are calculated, compared and regionally mapped at nine meteorological stations during 1990-2004 in Southern Taiwan. The results show the reference evapotranspiration and pan evaporation have similar regional distribution patterns in the southern Taiwan both with the highest values being in the lower region and the lowest values being in the upper region. In addition, the pan coefficient, Kpan, varies both regionally and seasonally. Smallest Kpan values are found in the upper reach of the southern Taiwan, meaning that the relative difference between the reference evapotranspiration and pan evaporation is the biggest in the region, the largest Kpan values are obtained in the western area of southern Taiwan. This distribution pattern provides valuable information for regional hydrological studies since it is one of the most important factors determining regional actual evapotranspiration.

  20. Effect of argon gas flow rate on properties of film electrodes prepared by thermal vacuum evaporation from synthesized Cu{sub 2}SnSe{sub 3} source

    SciTech Connect

    Sabli, Nordin; Talib, Zainal Abidin; Yunus, Wan Mahmood Mat; Zainal, Zulkarnain; Hilal, Hikmat S.; Fujii, Masatoshi

    2014-03-05

    This work describes a new technique to enhance photoresponse of metal chalcogenide-based semiconductor film electrodes deposited by thermal vacuum evaporation under argon gas flow from synthesized Cu{sub 2}SnSe{sub 3} sources. SnSe formation with Cu-doped was obtained under higher argon gas flow rate (V{sub A} = 25 cm{sup 3}/min). Higher value of photoresponse was observed for films deposited under V{sub A} = 25 cm{sup 3}/min which was 9.1%. This finding indicates that Cu atoms inside the SnSe film were important to increase carrier concentrations that promote higher photoresponse.

  1. EFFECTS OF ADDITION RATE AND ACID MATRIX ON THE DESTRUCTION OF AMMONIUM BY THE SEMI-CONTINUOUS ADDITION OF SODIUM NITRITE DURING EVAPORATION

    SciTech Connect

    Kyser, E

    2007-08-27

    The destruction of ammonium by the semi-continuous addition of sodium nitrite during acidic evaporation can be achieved with a wide range of waste compositions. The efficiency of nitrite utilization for ammonium destruction was observed to vary from less than 20% to 60% depending on operating conditions. The effects of nitric acid concentration and nitrite addition rate are dominant factors that affect the efficiency of nitrite utilization for ammonium destruction. Reducing the acid concentration by performing acid recovery via steam stripping prior to performing nitrite destruction of ammonium will require more nitrite due to the low destruction efficiency. The scale-up of the baseline rate nitrite addition rate from the 100 mL to the 1600 gallon batch size has significant uncertainty and poses the risk of lower efficiency at the plant scale. Experience with plant scale processing will improve confidence in the application of nitrite destruction of ammonium to different waste streams.

  2. Effect of sweating set rate on clothing real evaporative resistance determined on a sweating thermal manikin in a so-called isothermal condition ( T manikin = T a = T r)

    NASA Astrophysics Data System (ADS)

    Lu, Yehu; Wang, Faming; Peng, Hui; Shi, Wen; Song, Guowen

    2016-04-01

    The ASTM F2370 (2010) is the only standard with regard to measurement of clothing real evaporative resistance by means of a sweating manikin. However, the sweating set-point is not recommended in the standard. In this study, the effect of sweating rate on clothing real evaporative resistance was investigated on a 34-zone "Newton" sweating thermal manikin in a so-called isothermal condition ( T manikin = T a = T r). Four different sweating set rates (i.e., all segments had a sweating rate of 400, 800, 1200 ml/hr•m2, respectively, and different sweating rates were assigned to different segments) were applied to determine the clothing real evaporative resistance of five clothing ensembles and the boundary air layer. The results indicated that the sweating rate did not affect the real evaporative resistance of clothing ensembles with the absence of strong moisture absorbent layers. For the clothing ensemble with tight cotton underwear, a sweating rate of lower than 400 ml/hr•m2 is not recommended. This is mainly because the wet fabric "skin" might not be fully saturated and thus led to a lower evaporative heat loss and thereby a higher real evaporative resistance. For vapor permeable clothing, the real evaporative resistance determined in the so-called isothermal condition should be corrected before being used in thermal comfort or heat strain models. However, the reduction of wet thermal insulation due to moisture absorption in different test scenarios had a limited contribution to the effect of sweating rate on the real evaporative resistance.

  3. Effect of sweating set rate on clothing real evaporative resistance determined on a sweating thermal manikin in a so-called isothermal condition (T manikin = T a = T r).

    PubMed

    Lu, Yehu; Wang, Faming; Peng, Hui; Shi, Wen; Song, Guowen

    2016-04-01

    The ASTM F2370 (2010) is the only standard with regard to measurement of clothing real evaporative resistance by means of a sweating manikin. However, the sweating set-point is not recommended in the standard. In this study, the effect of sweating rate on clothing real evaporative resistance was investigated on a 34-zone "Newton" sweating thermal manikin in a so-called isothermal condition (T manikin = T a = T r). Four different sweating set rates (i.e., all segments had a sweating rate of 400, 800, 1200 ml/hr ∙ m(2), respectively, and different sweating rates were assigned to different segments) were applied to determine the clothing real evaporative resistance of five clothing ensembles and the boundary air layer. The results indicated that the sweating rate did not affect the real evaporative resistance of clothing ensembles with the absence of strong moisture absorbent layers. For the clothing ensemble with tight cotton underwear, a sweating rate of lower than 400 ml/hr ∙ m(2) is not recommended. This is mainly because the wet fabric "skin" might not be fully saturated and thus led to a lower evaporative heat loss and thereby a higher real evaporative resistance. For vapor permeable clothing, the real evaporative resistance determined in the so-called isothermal condition should be corrected before being used in thermal comfort or heat strain models. However, the reduction of wet thermal insulation due to moisture absorption in different test scenarios had a limited contribution to the effect of sweating rate on the real evaporative resistance. PMID:26150329

  4. 15. RW Meyer Sugar Mill: 18761889. Sorghum pan and boiling ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. RW Meyer Sugar Mill: 1876-1889. Sorghum pan and boiling range flue. Manufactured by John Nott & Co., Honolulu, Hawaii, 1878. View: North side of sorghum pan and boiling range flue, with furnace-end in background. In the sorghum pan heat was applied to the cane juice to clarify it, evaporate its water content, and concentrate the sugar crystals. Hot gasses moved through the flue underneath the entire copper bottom of the sorghum pan from the furnace end (in background) to the smokestack end (in foreground). After the hot cane juice moved through the separate compartments until it reached the final compartment (now missing two sides) where it was drawn out from the copper lip in the corner. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

  5. Analytical Complementary Relationship Between Actual and Potential Evaporation Defined by Steady State Reference Surface Temperature

    NASA Astrophysics Data System (ADS)

    Or, D.; Aminzadeh, M.; Roderick, M. L.

    2015-12-01

    The definition of potential evaporation remains widely debated despite its centrality for hydrologic and climatic models. We employed an analytical pore-scale representation of evaporation from porous surfaces to define potential evaporation using a hypothetical steady-state reference temperature for air and evaporating surface. The feedback between drying land surfaces and overlaying air properties is implicitly incorporated in the hypothetical steady-state where the sensible heat flux vanishes and available energy is consumed by evaporation. Potential evaporation based on steady-state surface temperature was in surprisingly good agreement with class A pan evaporation measurements suggesting that pan evaporation occurs with negligible sensible heat flux. The model facilitates a new analytical generalization of the asymmetric complementary relationship across a wide range of meteorological conditions with good agreement between measured and predicted actual evaporation.

  6. Evaporating firewalls

    NASA Astrophysics Data System (ADS)

    Van Raamsdonk, Mark

    2014-11-01

    In this note, we begin by presenting an argument suggesting that large AdS black holes dual to typical high-energy pure states of a single holographic CFT must have some structure at the horizon, i.e. a fuzzball/firewall, unless the procedure to probe physics behind the horizon is state-dependent. By weakly coupling the CFT to an auxiliary system, such a black hole can be made to evaporate. In a case where the auxiliary system is a second identical CFT, it is possible (for specific initial states) that the system evolves to precisely the thermofield double state as the original black hole evaporates. In this case, the dual geometry should include the "late-time" part of the eternal AdS black hole spacetime which includes smooth spacetime behind the horizon of the original black hole. Thus, if a firewall is present initially, it evaporates. This provides a specific realization of the recent ideas of Maldacena and Susskind that the existence of smooth spacetime behind the horizon of an evaporating black hole can be enabled by maximal entanglement with a Hawking radiation system (in our case the second CFT) rather than prevented by it. For initial states which are not finely-tuned to produce the thermofield double state, the question of whether a late-time infalling observer experiences a firewall translates to a question about the gravity dual of a typical high-energy state of a two-CFT system.

  7. Streamer Evaporation

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Wang, A.-H.; Wu, S. T.; Nerney, S. F.

    1998-01-01

    Evaporation is the consequence of heating near the top of streamers in ideal Magnetohydrodynamics (MHD) models, where the plasma is weakly contained by the magnetic field. Heating causes slow opening of field lines and release of new solar wind. It was discovered in simulations and, due to the absence of loss mechanisms, the ultimate end point is the complete evaporation of the streamer. Of course streamers do not behave in this way because there are losses by thermal conduction and radiation. Physically, heating is also expected to depend on ambient conditions. We use our global MHD model with thermal conduction to examine the effect of changing the heating scale height. We also apply and extend an analytic model of streamers developed by Pneuman (1968) to show that steady streamers are unable to contain plasma for temperatures near the cusp greater than approximately 2 x 10(exp 6) K.

  8. Reservoir evaporation in Texas, USA

    NASA Astrophysics Data System (ADS)

    Wurbs, Ralph A.; Ayala, Rolando A.

    2014-03-01

    The role of reservoir surface evaporation in river/reservoir water budgets and water management is explored using a modeling system that combines historical natural hydrology with current conditions of water resources development and management. The long-term mean evaporation from the 3415 reservoirs in the Texas water rights permit system is estimated to be 7.53 billion m3/year, which is equivalent to 61% of total agricultural or 126% of total municipal water use in the state during the year 2010. Evaporation varies with the hydrologic conditions governing reservoir surface areas and evaporation rates. Annual statewide total evaporation volumes associated with exceedance probabilities of 75%, 50%, and 25% are 7.07, 7.47, and 7.95 billion m3/year, respectively. Impacts of evaporation are greatest during extended severe droughts that govern water supply capabilities.

  9. Analysis of energy use in tomato evaporation

    SciTech Connect

    Rumsey, T.; Conant, T.

    1980-01-01

    Field performance data for four tomato product evaporators are presented and analyzed. Steam and feed flow rates along with steam economies were measured and are compared to steady state theoretical evaporator models.

  10. Novel approaches to the calculation and comparison of thermoregulatory parameters: Non-linear regression of metabolic rate and evaporative water loss in Australian rodents.

    PubMed

    Tomlinson, Sean

    2016-04-01

    The calculation and comparison of physiological characteristics of thermoregulation has provided insight into patterns of ecology and evolution for over half a century. Thermoregulation has typically been explored using linear techniques; I explore the application of non-linear scaling to more accurately calculate and compare characteristics and thresholds of thermoregulation, including the basal metabolic rate (BMR), peak metabolic rate (PMR) and the lower (Tlc) and upper (Tuc) critical limits to the thermo-neutral zone (TNZ) for Australian rodents. An exponentially-modified logistic function accurately characterised the response of metabolic rate to ambient temperature, while evaporative water loss was accurately characterised by a Michaelis-Menten function. When these functions were used to resolve unique parameters for the nine species studied here, the estimates of BMR and TNZ were consistent with the previously published estimates. The approach resolved differences in rates of metabolism and water loss between subfamilies of Australian rodents that haven't been quantified before. I suggest that non-linear scaling is not only more effective than the established segmented linear techniques, but also is more objective. This approach may allow broader and more flexible comparison of characteristics of thermoregulation, but it needs testing with a broader array of taxa than those used here. PMID:27033039

  11. The Pan Zhichang Incident

    ERIC Educational Resources Information Center

    Yuchen, Zhu

    2007-01-01

    This article examines why Pan Zhichang, a well-known professor and Ph.D. candidate supervisor at Nanjing University, has repeatedly been accused of plagiarism. It may not be difficult to check whether he has committed plagiarism, but seeking the deeper social and systemic reasons for a person's repeated "negligence" is indeed a thought-provoking…

  12. Evaporation dynamics of femtoliter water capillary bridges

    NASA Astrophysics Data System (ADS)

    Cho, Kun; Hwang, In Gyu; Kim, Yeseul; Lim, Su Jin; Lim, Jun; Kim, Joon Heon; Gim, Bopil; Kim, Jung Gu; Weon, Byung Mook

    2015-11-01

    Capillary bridges are usually formed by a small liquid volume in confined space between two solid surfaces and particularly they have lower internal pressure than 1 atm at femtoliter scales. Femtoliter capillary bridges exhibit rapid evaporation rates. To quantify detailed evaporation kinetics of femtoliter bridges, we present a feasible protocol to directly visualize femtoliter water bridges that evaporate in still air between a microsphere and a flat substrate by utilizing transmission X-ray microscopy. Precise measurements of evaporation kinetics for water bridges indicate that lower water pressure than 1 atm can significantly decelerate evaporation by suppression of vapor diffusion. This finding would provide a consensus to understand evaporation of ultrasmall capillary bridges.

  13. Photoluminescence and anti-deliquesce of cesium iodide and its sodium-doped films deposited by thermal evaporation at high deposition rates

    NASA Astrophysics Data System (ADS)

    Hsu, Jin-Cherng; Chiang, Yueh-Sheng; Ma, Yu-Sheng

    2013-03-01

    Cesium iodide (CsI) and sodium iodide (NaI) are good scintillators due to their high luminescence efficiency. These alkali halides can be excited by ultra-violet or by ionizing radiation. In this study, CsI and its Na-doped films about 8 μm thick were deposited by thermal evaporation boat without heating substrates at high deposition rates of 30, 50, 70, 90, and 110 nm/sec, respectively. The as-deposited films were sequentially deposited a silicon dioxide film to protect from deliquesce. And, the films were also post-annealed in vacuum at 150, 200, 250, and 300 °C, respectively. We calculated the packing densities of the samples according to the measurements of Fourier transform infrared spectroscopy (FTIR) and observed the luminescence properties by photoluminescence (PL) system. The surfaces and cross sections of the films were investigated by scanning electron microscope (SEM). From the above measurements we can find the optimal deposition rate of 90 nm/sec and post-annealing temperature of 250 °C in vacuum for the asdeposited cesium iodide and its sodium-doped films.

  14. Pan-Tetris: an interactive visualisation for Pan-genomes

    PubMed Central

    2015-01-01

    Background Large-scale genome projects have paved the way to microbial pan-genome analyses. Pan-genomes describe the union of all genes shared by all members of the species or taxon under investigation. They offer a framework to assess the genomic diversity of a given collection of individual genomes and moreover they help to consolidate gene predictions and annotations. The computation of pan-genomes is often a challenge, and many techniques that use a global alignment-independent approach run the risk of not separating paralogs from orthologs. Also alignment-based approaches which take the gene neighbourhood into account often need additional manual curation of the results. This is quite time consuming and so far there is no visualisation tool available that offers an interactive GUI for the pan-genome to support curating pan-genomic computations or annotations of orthologous genes. Results We introduce Pan-Tetris, a Java based interactive software tool that provides a clearly structured and suitable way for the visual inspection of gene occurrences in a pan-genome table. The main features of Pan-Tetris are a standard coordinate based presentation of multiple genomes complemented by easy to use tools compensating for algorithmic weaknesses in the pan-genome generation workflow. We demonstrate an application of Pan-Tetris to the pan-genome of Staphylococcus aureus. Conclusions Pan-Tetris is currently the only interactive pan-genome visualisation tool. Pan-Tetris is available from http://bit.ly/1vVxYZT PMID:26328606

  15. Remotely monitoring evaporation rate and soil water status using thermal imaging and "three-temperatures model (3T Model)" under field-scale conditions.

    PubMed

    Qiu, Guo Yu; Zhao, Ming

    2010-03-01

    Remote monitoring of soil evaporation and soil water status is necessary for water resource and environment management. Ground based remote sensing can be the bridge between satellite remote sensing and ground-based point measurement. The primary object of this study is to provide an algorithm to estimate evaporation and soil water status by remote sensing and to verify its accuracy. Observations were carried out in a flat field with varied soil water content. High-resolution thermal images were taken with a thermal camera; soil evaporation was measured with a weighing lysimeter; weather data were recorded at a nearby meteorological station. Based on the thermal imaging and the three-temperatures model (3T model), we developed an algorithm to estimate soil evaporation and soil water status. The required parameters of the proposed method were soil surface temperature, air temperature, and solar radiation. By using the proposed method, daily variation in soil evaporation was estimated. Meanwhile, soil water status was remotely monitored by using the soil evaporation transfer coefficient. Results showed that the daily variation trends of measured and estimated evaporation agreed with each other, with a regression line of y = 0.92x and coefficient of determination R(2) = 0.69. The simplicity of the proposed method makes the 3T model a potentially valuable tool for remote sensing. PMID:20445861

  16. Characterization and Compatibility Studies of Different Rate Retardant Polymer Loaded Microspheres by Solvent Evaporation Technique: In Vitro-In Vivo Study of Vildagliptin as a Model Drug

    PubMed Central

    Dewan, Irin; Islam, Swarnali; Rana, Md. Sohel

    2015-01-01

    The present study has been performed to microencapsulate the antidiabetic drug of Vildagliptin to get sustained release of drug. The attempt of this study was to formulate and evaluate the Vildagliptin loaded microspheres by emulsion solvent evaporation technique using different polymers like Eudragit RL100, Eudragit RS100, Ethyl cellulose, and Methocel K100M. In vitro dissolution studies were carried out in 0.1 N HCl for 8 hours according to USP paddle method. The maximum and minimum drug release were observed as 92.5% and 68.5% from microspheres, respectively, after 8 hours. Release kinetics were studied in different mathematical release models to find out the linear relationship and release rate of drug. The SEM, DSC, and FTIR studies have been done to confirm good spheres and smooth surface as well as interaction along with drug and polymer. In this experiment, it is difficult to explain the exact mechanism of drug release. But the drug might be released by both diffusion and erosion as the correlation coefficient (R2) best fitted with Korsmeyer model and release exponent (n) was 0.45–0.89. At last it can be concluded that all in vitro and in vivo experiments exhibited promising result to treat type II diabetes mellitus with Vildagliptin microspheres. PMID:26640713

  17. An eye on small reservoirs: remote sensing of storage volumes, their use as remotely sensed runoff gauges, and evaporation losses

    NASA Astrophysics Data System (ADS)

    Liebe, J. R.; van de Giesen, N.; Andreini, M. S.; Walter, M. T.; Steenhuis, T. S.

    2009-04-01

    Small reservoirs are important sources of water supply for the scattered rural population in semi-arid areas. Due to their small size, and their existence in large numbers, such reservoirs have not been studied much. Little is known about their storage volumes, their impact on their watershed's contribution to runoff downstream, and their evaporation losses are frequently stated to be prohibitive. Satellite remote sensing can be used to assess and monitor small reservoirs' storage volumes with regional area-volume equations. Radar remote sensing of small reservoirs was found suitable especially during the rainy season due to its capability to penetrate clouds, but is affected by wind and lack of vegetation context during the dry season. Reservoirs were extracted most often successfully with a quasi-manual classification approach, as stringent classification rules often failed under less than optimal conditions. Especially wind speeds above 2.6 m s-1 at the time of image acquisition were detrimental (Bragg scattering) to the extraction of reservoirs. Due to lower wind speeds, the use of night time acquisitions was more effective than the use of daytime images. With a time series of radar images, small reservoirs were used as remotely sensed runoff gauges, and to calibrate hydrological rainfall-runoff models. Eight small reservoirs in the Upper East Region of Ghana, and Togo, were monitored to calibrate modified Thornthwaite-Mather models, in which increasing precipitation leads to exponentially increasing contributing areas. Model results indicate that the reservoirs captured, on the average, 34% of the quick flow, and 15% of overall runoff from their watersheds. Reservoir evaporation losses were measured directly with a floating evaporation pan and were compared to evaporation rates determined from the reservoir's energy budget, and Penman's equation. The direct pan measurements were generally lower than the evaporation determined with the energy budget or Penman

  18. Evaporation variability of Nam Co Lake in the Tibetan Plateau and its role in recent rapid lake expansion

    NASA Astrophysics Data System (ADS)

    Ma, Ning; Szilagyi, Jozsef; Niu, Guo-Yue; Zhang, Yinsheng; Zhang, Teng; Wang, Binbin; Wu, Yanhong

    2016-06-01

    Previous studies have shown that the majority of the lakes in the Tibetan Plateau (TP) started to expand rapidly since the late 1990s. However, the causes are still not well known. For Nam Co, being a closed lake with no outflow, evaporation (EL) over the lake surface is the only way water may leave the lake. Therefore, quantifying EL is key for investigating the mechanism of lake expansion in the TP. EL can be quantified by Penman- and/or bulk-transfer-type models, requiring only net radiation, temperature, humidity and wind speed for inputs. However, interpolation of wind speed data may be laden with great uncertainty due to extremely sparse ground meteorological observations, the highly heterogeneous landscape and lake-land breeze effects. Here, evaporation of Nam Co Lake was investigated within the 1979-2012 period at a monthly time-scale using the complementary relationship lake evaporation (CRLE) model which does not require wind speed data. Validations by in-situ observations of E601B pan evaporation rates at the shore of Nam Co Lake as well as measured EL over an adjacent small lake using eddy covariance technique suggest that CRLE is capable of simulating EL well since it implicitly considers wind effects on evaporation via its vapor transfer coefficient. The multi-year average of annual evaporation of Nam Co Lake is 635 mm. From 1979 to 2012, annual evaporation of Nam Co Lake expressed a very slight decreasing trend. However, a more significant decrease in EL occurred during 1998-2008 at a rate of -12 mm yr-1. Based on water-level readings, this significant decrease in lake evaporation was found to be responsible for approximately 4% of the reported rapid water level increase and areal expansion of Nam Co Lake during the same period.

  19. Evaporation effects in elastocapillary aggregation

    NASA Astrophysics Data System (ADS)

    Vella, Dominic; Hadjittofis, Andreas; Singh, Kiran; Lister, John

    2015-11-01

    We consider the effect of evaporation on the aggregation of a number of elastic objects due to a liquid's surface tension. In particular, we consider an array of spring-block elements in which the gaps between blocks are filled by thin liquid films that evaporate during the course of an experiment. Using lubrication theory to account for the fluid flow within the gaps, we study the dynamics of aggregation. We find that a non-zero evaporation rate causes the elements to aggregate more quickly and, indeed, to contact within finite time. However, we also show that the number of elements within each cluster decreases as the evaporation rate increases. We explain these results quantitatively by comparison with the corresponding two-body problem and discuss their relevance for controlling pattern formation in carbon nanotube forests.

  20. Rainfall interception modelling: Is the wet bulb approach adequate to estimate mean evaporation rate from wet/saturated canopies in all forest types?

    NASA Astrophysics Data System (ADS)

    Pereira, F. L.; Valente, F.; David, J. S.; Jackson, N.; Minunno, F.; Gash, J. H.

    2016-03-01

    The Penman-Monteith equation has been widely used to estimate the maximum evaporation rate (E) from wet/saturated forest canopies, regardless of canopy cover fraction. Forests are then represented as a big leaf and interception loss considered essentially as a one-dimensional process. With increasing forest sparseness the assumptions behind this big leaf approach become questionable. In sparse forests it might be better to model E and interception loss at the tree level assuming that the individual tree crowns behave as wet bulbs ("wet bulb approach"). In this study, and for five different forest types and climate conditions, interception loss measurements were compared to modelled values (Gash's interception model) based on estimates of E by the Penman-Monteith and the wet bulb approaches. Results show that the wet bulb approach is a good, and less data demanding, alternative to estimate E when the forest canopy is fully ventilated (very sparse forests with a narrow canopy depth). When the canopy is not fully ventilated, the wet bulb approach requires a reduction of leaf area index to the upper, more ventilated parts of the canopy, needing data on the vertical leaf area distribution, which is seldom-available. In such cases, the Penman-Monteith approach seems preferable. Our data also show that canopy cover does not per se allow us to identify if a forest canopy is fully ventilated or not. New methodologies of sensitivity analyses applied to Gash's model showed that a correct estimate of E is critical for the proper modelling of interception loss.

  1. Marangoni Convection and Deviations from Maxwells' Evaporation Model

    NASA Technical Reports Server (NTRS)

    Segre, P. N.; Snell, E. H.; Adamek, D. H.

    2003-01-01

    We investigate the convective dynamics of evaporating pools of volatile liquids using an ultra-sensitive thermal imaging camera. During evaporation, there are significant convective flows inside the liquid due to Marangoni forces. We find that Marangoni convection during evaporation can dramatically affect the evaporation rates of volatile liquids. A simple heat balance model connects the convective velocities and temperature gradients to the evaporation rates.

  2. Estimation of evaporation from open water - A review of selected studies, summary of U.S. Army Corps of Engineers data collection and methods, and evaluation of two methods for estimation of evaporation from five reservoirs in Texas

    USGS Publications Warehouse

    Harwell, Glenn R.

    2012-01-01

    Organizations responsible for the management of water resources, such as the U.S. Army Corps of Engineers (USACE), are tasked with estimation of evaporation for water-budgeting and planning purposes. The USACE has historically used Class A pan evaporation data (pan data) to estimate evaporation from reservoirs but many USACE Districts have been experimenting with other techniques for an alternative to collecting pan data. The energy-budget method generally is considered the preferred method for accurate estimation of open-water evaporation from lakes and reservoirs. Complex equations to estimate evaporation, such as the Penman, DeBruin-Keijman, and Priestley-Taylor, perform well when compared with energy-budget method estimates when all of the important energy terms are included in the equations and ideal data are collected. However, sometimes nonideal data are collected and energy terms, such as the change in the amount of stored energy and advected energy, are not included in the equations. When this is done, the corresponding errors in evaporation estimates are not quantifiable. Much simpler methods, such as the Hamon method and a method developed by the U.S. Weather Bureau (USWB) (renamed the National Weather Service in 1970), have been shown to provide reasonable estimates of evaporation when compared to energy-budget method estimates. Data requirements for the Hamon and USWB methods are minimal and sometimes perform well with remotely collected data. The Hamon method requires average daily air temperature, and the USWB method requires daily averages of air temperature, relative humidity, wind speed, and solar radiation. Estimates of annual lake evaporation from pan data are frequently within 20 percent of energy-budget method estimates. Results of evaporation estimates from the Hamon method and the USWB method were compared against historical pan data at five selected reservoirs in Texas (Benbrook Lake, Canyon Lake, Granger Lake, Hords Creek Lake, and Sam

  3. Evaporation Rate and Development of Wetted Area of Water Droplets with and without Surfactant at Different Locations on Waxy Leaf Surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The evaporation and formation of deposit patterns from single droplets deposited at various locations on waxy leaves were investigated under controlled conditions. Leaf locations included the interveinal area, midrib and secondary vein on both adaxial and abaxial surfaces. Tests were conducted with ...

  4. Using Photosynthetically Active Radiation (PAR) Observations to Estimate Potential Evaporation with Combination Equations

    NASA Astrophysics Data System (ADS)

    Kim, J.; Freyberg, D. L.

    2011-12-01

    Estimating potential evaporation with combination equations typically depends on observations of solar radiation. In situations where only photosynthetically active radiation (PAR) observations are available, a conversion model is required. We use coincident observations of solar radiation and PAR to build a conversion model for the Santa Cruz Mountains region of California, USA. The model takes advantage of the strong seasonality in cloud cover and albedo, using two seasonal sub-models to improve performance. We examine the uncertainty induced by model error in predictions of potential evaporation and reference crop evaporation using locally calibrated combination equations, and compare with direct observations of pan evaporation and inferred estimates of lake evaporation.

  5. Measuring sub-canopy evaporation in a forested wetland using an ensemble of methods

    NASA Astrophysics Data System (ADS)

    Allen, S. T.; Edwards, B.; Reba, M. L.; Keim, R.

    2013-12-01

    Evaporation from the sub-canopy water surface is an integral but understudied component of the water balance in forested wetlands. Previous studies have used eddy covariance, energy balance approaches, and water-table fluctuations to assess whole-system evapotranspiration. However, partitioning evaporation from transpiration is necessary for modeling the system because of different controls over each process. Sub-canopy evaporation is a physically controlled process driven by relatively small gradients in residual energy transmitted through the canopy. The low-energy sub-canopy environment is characterized by a spatiotemporally varying light environment due to sunflecks, small and often inverse temperature and vapor gradients, and a high capacity for heat storage in flood water, which each present challenges to common evapotranspiration measurement techniques. Previous studies have examined wetland surface evaporation rates with small lysimeter experiments, but this approach does not encapsulate micrometeorological processes occurring at the scale of natural wetlands. In this study, we examine a one year time series of in situ sub-canopy flux measurements from a seasonally flooded cypress-tupelo swamp in southeast Louisiana. Our objective is to apply these data towards modeling sub-canopy energy flux responses to intra-annual hydrologic, phenologic, and climatic cycles. To assess and mitigate potential errors due to the inherent measurement challenges of this environment, we utilized multiple measurement approaches including eddy covariance, Bowen ratio energy balance (with both air to air gradients and water surface to air gradients) and direct measurement using a floating evaporation pan. Preliminary results show that Bowen ratio energy balance measurements are useful for constraining evaporation measurements when low wind speed conditions create a non-ideal setting for eddy covariance. However, Bowen ratios were often highly erratic due to the weak temperature

  6. Simulations of Peroxyacetyl Nitrate (PAN) Photochemistry in the Arctic Surface Layer

    NASA Astrophysics Data System (ADS)

    Dassau, T. M.; Ford, K. M.; Shepson, P. B.; Bottenheim, J. W.

    2002-12-01

    Peroxyacetyl nitrate (PAN) is a reservoir compound of NOx_ that has the ability to transport NOx_ to remote environments, allowing for NOx_ photochemistry and/or deposition of nitrogen to these clean locations. Measurements of PAN have been made at Alert, Nunavut and Summit, Greenland aimed at understanding the nitrogen budget at each site. These measurements show concentrations of PAN that are only slowly varying, even during ozone depletion events at sunrise. However, calculations of [PAN], using its primary sources and sinks, indicate a dramatic production rate for PAN when the surface is sunlit. This is inconsistent with the measurement data, illustrating that we are missing an important sink for atmospheric PAN above snow-covered surfaces. We performed a zero-dimensional model of PAN photochemistry at Alert, Nunavut and Summit, Greenland, which simulated the known gas-phase chemistry of each region, to discern the predicted PAN behavior in each environment. We then adjusted the model sinks to simulate the ambient PAN data, in order to determine the magnitude of the missing PAN sink. Ambient data from Alert, Nunavut (1998 and 2000), and Summit, Greenland (1999) will be presented, as well as the original model simulations based upon the known gas-phase chemistry of each environment. In addition, we will discuss the magnitude of the missing sink, and the potential for PAN interaction with the snowpack.

  7. The Imager for Mars Pathfinder Insurance Pan

    NASA Technical Reports Server (NTRS)

    Herkenhoff, K. E.; Johnson, J. R.; Weller, L. A.

    2003-01-01

    The Imager for Mars Pathfinder (IMP) obtained a full panorama of the Sagan Memorial Station landing site on Sol 2, before the IMP mast was deployed. The images in this panorama were taken in 4 filters (including stereo) and losslessly compressed to provide a high-quality multispectral survey of the landing site even if the IMP mast did not successfully deploy; this data set was therefore called the Insurance Pan. It was completed late in the afternoon of Sol 2, just before the IMP mast was (successfully) deployed. The data were stored in memory and returned to Earth after it became clear that downlink rates were higher than expected. The Insurance Pan horizontal (azimuth) coverage is nearly complete, with gaps caused by pointing errors and data packet losses. Stereo data were acquired in the blue (445 nm) filter, as well as right-eye green (531 nm), orange (600 nm), and near-infrared (752 nm) data.

  8. Nanofluid Drop Evaporation: Experiment, Theory, and Modeling

    NASA Astrophysics Data System (ADS)

    Gerken, William James

    Nanofluids, stable colloidal suspensions of nanoparticles in a base fluid, have potential applications in the heat transfer, combustion and propulsion, manufacturing, and medical fields. Experiments were conducted to determine the evaporation rate of room temperature, millimeter-sized pendant drops of ethanol laden with varying amounts (0-3% by weight) of 40-60 nm aluminum nanoparticles (nAl). Time-resolved high-resolution drop images were collected for the determination of early-time evaporation rate (D2/D 02 > 0.75), shown to exhibit D-square law behavior, and surface tension. Results show an asymptotic decrease in pendant drop evaporation rate with increasing nAl loading. The evaporation rate decreases by approximately 15% at around 1% to 3% nAl loading relative to the evaporation rate of pure ethanol. Surface tension was observed to be unaffected by nAl loading up to 3% by weight. A model was developed to describe the evaporation of the nanofluid pendant drops based on D-square law analysis for the gas domain and a description of the reduction in liquid fraction available for evaporation due to nanoparticle agglomerate packing near the evaporating drop surface. Model predictions are in relatively good agreement with experiment, within a few percent of measured nanofluid pendant drop evaporation rate. The evaporation of pinned nanofluid sessile drops was also considered via modeling. It was found that the same mechanism for nanofluid evaporation rate reduction used to explain pendant drops could be used for sessile drops. That mechanism is a reduction in evaporation rate due to a reduction in available ethanol for evaporation at the drop surface caused by the packing of nanoparticle agglomerates near the drop surface. Comparisons of the present modeling predictions with sessile drop evaporation rate measurements reported for nAl/ethanol nanofluids by Sefiane and Bennacer [11] are in fairly good agreement. Portions of this abstract previously appeared as: W. J

  9. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Ash pans. 230.69 Section 230.69 Transportation... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans § 230.69 Ash pans. Ash pans shall be securely supported from mud-rings or frames with no part less than...

  10. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Ash pans. 230.69 Section 230.69 Transportation... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans § 230.69 Ash pans. Ash pans shall be securely supported from mud-rings or frames with no part less than...

  11. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Ash pans. 230.69 Section 230.69 Transportation... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans § 230.69 Ash pans. Ash pans shall be securely supported from mud-rings or frames with no part less than...

  12. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Ash pans. 230.69 Section 230.69 Transportation... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans § 230.69 Ash pans. Ash pans shall be securely supported from mud-rings or frames with no part less than...

  13. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Ash pans. 230.69 Section 230.69 Transportation... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans § 230.69 Ash pans. Ash pans shall be securely supported from mud-rings or frames with no part less than...

  14. Evaporator Cleaning Studies

    SciTech Connect

    Wilmarth, W.R.

    1999-04-15

    Operation of the 242-16H High Level Waste Evaporator proves crucial to liquid waste management in the H-Area Tank Farm. Recent operational history of the Evaporator showed significant solid formation in secondary lines and in the evaporator pot. Additional samples remain necessary to ensure material identity in the evaporator pot. Analysis of these future samples will provide actinide partitioning information and dissolution characteristics of the solid material from the pot to ensure safe chemical cleaning.

  15. 242-A evaporator vacuum condenser system

    SciTech Connect

    Smith, V.A.

    1994-09-28

    This document is written for the 242-A evaporator vacuum condenser system (VCS), describing its purpose and operation within the evaporator. The document establishes the operating parameters specifying pressure, temperature, flow rates, interlock safety features and interfacing sub-systems to support its operation.

  16. The Pan-STARRS1 medium-deep survey: The role of galaxy group environment in the star formation rate versus stellar mass relation and quiescent fraction out to z ∼ 0.8

    SciTech Connect

    Lin, Lihwai; Chen, Chin-Wei; Coupon, Jean; Hsieh, Bau-Ching; Jian, Hung-Yu; Foucaud, Sebastien; Norberg, Peder; Bower, R. G.; Cole, Shaun; Arnalte-Mur, Pablo; Draper, P.; Heinis, Sebastien; Phleps, Stefanie; Chen, Wen-Ping; Lee, Chien-Hsiu; Burgett, William; Chambers, K. C.; Denneau, L.; Flewelling, H.; Hodapp, K. W.; and others

    2014-02-10

    Using a large optically selected sample of field and group galaxies drawn from the Pan-STARRS1 Medium-Deep Survey (PS1/MDS), we present a detailed analysis of the specific star formation rate (SSFR)—stellar mass (M {sub *}) relation, as well as the quiescent fraction versus M {sub *} relation in different environments. While both the SSFR and the quiescent fraction depend strongly on stellar mass, the environment also plays an important role. Using this large galaxy sample, we confirm that the fraction of quiescent galaxies is strongly dependent on environment at a fixed stellar mass, but that the amplitude and the slope of the star-forming sequence is similar between the field and groups: in other words, the SSFR-density relation at a fixed stellar mass is primarily driven by the change in the star-forming and quiescent fractions between different environments rather than a global suppression in the star formation rate for the star-forming population. However, when we restrict our sample to the cluster-scale environments (M > 10{sup 14} M {sub ☉}), we find a global reduction in the SSFR of the star-forming sequence of 17% at 4σ confidence as opposed to its field counterpart. After removing the stellar mass dependence of the quiescent fraction seen in field galaxies, the excess in the quiescent fraction due to the environment quenching in groups and clusters is found to increase with stellar mass, although deeper and larger data from the full PS1/MDS will be required to draw firm conclusions. We argue that these results are in favor of galaxy mergers to be the primary environment quenching mechanism operating in galaxy groups whereas strangulation is able to reproduce the observed trend in the environment quenching efficiency and stellar mass relation seen in clusters. Our results also suggest that the relative importance between mass quenching and environment quenching depends on stellar mass—the mass quenching plays a dominant role in producing quiescent

  17. Salt stains from evaporating droplets.

    PubMed

    Shahidzadeh, Noushine; Schut, Marthe F L; Desarnaud, Julie; Prat, Marc; Bonn, Daniel

    2015-01-01

    The study of the behavior of sessile droplets on solid substrates is not only associated with common everyday phenomena, such as the coffee stain effect, limescale deposits on our bathroom walls , but also very important in many applications such as purification of pharmaceuticals, de-icing of airplanes, inkjet printing and coating applications. In many of these processes, a phase change happens within the drop because of solvent evaporation, temperature changes or chemical reactions, which consequently lead to liquid to solid transitions in the droplets. Here we show that crystallization patterns of evaporating of water drops containing dissolved salts are different from the stains reported for evaporating colloidal suspensions. This happens because during the solvent evaporation, the salts crystallize and grow during the drying. Our results show that the patterns of the resulting salt crystal stains are mainly governed by wetting properties of the emerging crystal as well as the pathway of nucleation and growth, and are independent of the evaporation rate and thermal conductivity of the substrates. PMID:26012481

  18. Salt stains from evaporating droplets

    PubMed Central

    Shahidzadeh, Noushine; Schut, Marthe F. L.; Desarnaud, Julie; Prat, Marc; Bonn, Daniel

    2015-01-01

    The study of the behavior of sessile droplets on solid substrates is not only associated with common everyday phenomena, such as the coffee stain effect, limescale deposits on our bathroom walls , but also very important in many applications such as purification of pharmaceuticals, de-icing of airplanes, inkjet printing and coating applications. In many of these processes, a phase change happens within the drop because of solvent evaporation, temperature changes or chemical reactions, which consequently lead to liquid to solid transitions in the droplets. Here we show that crystallization patterns of evaporating of water drops containing dissolved salts are different from the stains reported for evaporating colloidal suspensions. This happens because during the solvent evaporation, the salts crystallize and grow during the drying. Our results show that the patterns of the resulting salt crystal stains are mainly governed by wetting properties of the emerging crystal as well as the pathway of nucleation and growth, and are independent of the evaporation rate and thermal conductivity of the substrates. PMID:26012481

  19. PanSNPdb: The Pan-Asian SNP Genotyping Database

    PubMed Central

    Ngamphiw, Chumpol; Assawamakin, Anunchai; Xu, Shuhua; Shaw, Philip J.; Yang, Jin Ok; Ghang, Ho; Bhak, Jong; Liu, Edison; Tongsima, Sissades

    2011-01-01

    The HUGO Pan-Asian SNP consortium conducted the largest survey to date of human genetic diversity among Asians by sampling 1,719 unrelated individuals among 71 populations from China, India, Indonesia, Japan, Malaysia, the Philippines, Singapore, South Korea, Taiwan, and Thailand. We have constructed a database (PanSNPdb), which contains these data and various new analyses of them. PanSNPdb is a research resource in the analysis of the population structure of Asian peoples, including linkage disequilibrium patterns, haplotype distributions, and copy number variations. Furthermore, PanSNPdb provides an interactive comparison with other SNP and CNV databases, including HapMap3, JSNP, dbSNP and DGV and thus provides a comprehensive resource of human genetic diversity. The information is accessible via a widely accepted graphical interface used in many genetic variation databases. Unrestricted access to PanSNPdb and any associated files is available at: http://www4a.biotec.or.th/PASNP. PMID:21731755

  20. Evaporation in space manufacturing

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1974-01-01

    'Normal evaporation' equations for predicting the compositional changes with time and temperature have been developed and correlated with actual experimental data. An evaporative congruent temperature is defined and used to explain, predict, or plan space experiments on anomalous constitutional melting (on cooling) or solidification (on heating). Uneven evaporation causes reactive jetting forces capable of initiating new convection currents, nongravitational accelerations, surface vibrations, or other disturbances. Applications of evaporation to space manufacturing are described concerning evaporative purification, surface cooling, specimen selection, particles splitting, freezing data interpretation, material loss and dimensional control, and surface contamination or compositional changes.

  1. A search for fast optical transients in the Pan-STARRS1 medium-deep survey: M-dwarf flares, asteroids, limits on extragalactic rates, and implications for LSST

    SciTech Connect

    Berger, E.; Leibler, C. N.; Chornock, R.; Foley, R. J.; Soderberg, A. M.; Rest, A.; Price, P. A.; Burgett, W. S.; Chambers, K. C.; Flewelling, H.; Huber, M. E.; Magnier, E. A.; Tonry, J. L.; Metcalfe, N.; Stubbs, C. W.

    2013-12-10

    We present a search for fast optical transients (τ ∼ 0.5 hr-1 day) using repeated observations of the Pan-STARRS1 Medium-Deep Survey (PS1/MDS) fields. Our search takes advantage of the consecutive g {sub P1} r {sub P1} observations (16.5 minutes in each filter), by requiring detections in both bands, with non-detections on preceding and subsequent nights. We identify 19 transients brighter than 22.5 AB mag (S/N ≳ 10). Of these, 11 events exhibit quiescent counterparts in the deep PS1/MDS templates that we identify as M4-M9 dwarfs at d ≈ 0.2-1.2 kpc. The remaining eight transients lack quiescent counterparts, exhibit mild but significant astrometric shifts between the g {sub P1} and r {sub P1} images, colors of (g – r){sub P1} ≈ 0.5-0.8 mag, non-varying light curves, and locations near the ecliptic plane with solar elongations of about 130°, which are all indicative of main-belt asteroids near the stationary point of their orbits. With identifications for all 19 transients, we place an upper limit of R {sub FOT}(τ ∼ 0.5 hr) ≲ 0.12 deg{sup –2} day{sup –1} (95% confidence level) on the sky-projected rate of extragalactic fast transients at ≲ 22.5 mag, a factor of 30-50 times lower than previous limits; the limit for a timescale of ∼1 day is R {sub FOT} ≲ 2.4 × 10{sup –3} deg{sup –2} day{sup –1}. To convert these sky-projected rates to volumetric rates, we explore the expected peak luminosities of fast optical transients powered by various mechanisms, and find that non-relativistic events are limited to M ≈ –10 to ≈ – 14 mag for a timescale of ∼0.5 hr to ∼1 day, while relativistic sources (e.g., gamma-ray bursts, magnetar-powered transients) can reach much larger luminosities. The resulting volumetric rates are ≲ 13 Mpc{sup –3} yr{sup –1} (M ≈ –10 mag), ≲ 0.05 Mpc{sup –3} yr{sup –1} (M ≈ –14 mag), and ≲ 10{sup –6} Mpc{sup –3} yr{sup –1} (M ≈ –24 mag), significantly above the nova, supernova

  2. A multimodel simulation of pan-Arctic hydrology

    NASA Astrophysics Data System (ADS)

    Slater, A. G.; Bohn, T. J.; McCreight, J. L.; Serreze, M. C.; Lettenmaier, D. P.

    2007-12-01

    We compare the performance of five land surface models (Chameleon Surface Model (CHASM), Noah, Community Land Model (CLM), Variable Infiltration Capacity Model (VIC), European Centre for Medium Range Weather Forecasts (ECMWF)), in the simulation of hydrological processes across the terrestrial Arctic drainage system for the period 1980-2001. The models represent a wide range of model physics, particularly with respect to high-latitude processes, and are forced with surface meteorology derived from the ERA-40 reanalysis. Models offer great potential for enlightenment regarding large-scale hydrology in this poorly observed region; thus our objective is to assess the ability of the models to capture various aspects of pan-Arctic hydrology as well as identify those features that contain the largest uncertainty. Results reveal up to a 30% difference in annual partitioning of precipitation between evaporation and runoff with major Arctic watersheds such as the Lena. Capturing the correct base flow of the large rivers is a consistent problem. The model hydrographs are often out of phase, peaking too early in comparison to observations. However, allowing for a large uptake in soil moisture as well as moisture movement during frozen periods alleviates this discrepancy. A negative correlation exists between models and observations for annual runoff time series over the Yenesi basin, apparently mostly because of inconsistencies in the input data. Compared to station data, all models produce similar errors in snow water equivalent; yet they differ widely in their snow regimes in terms of snowfall quantity, estimated snow depths, and most importantly, sublimation rates. Additionally, model albedo is consistently higher than observations in the presence of snow. No single model is the best or worst performing when compared to a range of observations.

  3. Quantifying nonisothermal subsurface soil water evaporation

    NASA Astrophysics Data System (ADS)

    Deol, Pukhraj; Heitman, Josh; Amoozegar, Aziz; Ren, Tusheng; Horton, Robert

    2012-11-01

    Accurate quantification of energy and mass transfer during soil water evaporation is critical for improving understanding of the hydrologic cycle and for many environmental, agricultural, and engineering applications. Drying of soil under radiation boundary conditions results in formation of a dry surface layer (DSL), which is accompanied by a shift in the position of the latent heat sink from the surface to the subsurface. Detailed investigation of evaporative dynamics within this active near-surface zone has mostly been limited to modeling, with few measurements available to test models. Soil column studies were conducted to quantify nonisothermal subsurface evaporation profiles using a sensible heat balance (SHB) approach. Eleven-needle heat pulse probes were used to measure soil temperature and thermal property distributions at the millimeter scale in the near-surface soil. Depth-integrated SHB evaporation rates were compared with mass balance evaporation estimates under controlled laboratory conditions. The results show that the SHB method effectively measured total subsurface evaporation rates with only 0.01-0.03 mm h-1difference from mass balance estimates. The SHB approach also quantified millimeter-scale nonisothermal subsurface evaporation profiles over a drying event, which has not been previously possible. Thickness of the DSL was also examined using measured soil thermal conductivity distributions near the drying surface. Estimates of the DSL thickness were consistent with observed evaporation profile distributions from SHB. Estimated thickness of the DSL was further used to compute diffusive vapor flux. The diffusive vapor flux also closely matched both mass balance evaporation rates and subsurface evaporation rates estimated from SHB.

  4. Dry deposition of peroxyacetyl nitrate (PAN): Determination of its deposition velocity at night from measurements of the atmospheric PAN and 222Radon concentration gradient

    NASA Astrophysics Data System (ADS)

    Schrimpf, Wolfram; Lienaerts, Karlheinz; Müller, Klaus Peter; Rudolph, Jochen; Neubert, Rolf; Schüßler, Wolfram; Levin, Ingeborg

    During the field campaign POPCORN (Photooxidant Formation by Plant Emitted Compounds and OH-Radicals in North-Eastern Germany) in August 1994 we measured the nighttime deposition velocities of PAN above a corn field. These are the first absolute measurements of PAN deposition velocities in the field. The deposition velocities were derived using a novel method, which uses measurements of the gradients of PAN and 222Rn and of the emission rates of 222Rn from the soil. A unique data set of about 250 field measurements of the PAN deposition velocity at night was thus obtained. The deposition velocity at night proved to be highly variable with an average of 0.54 cm/s and a standard deviation of 0.94 cm/s. Recent presumptions by Shepson et al. [1992] that the PAN deposition velocity is strongly reduced with increasing relative humidity could not be confirmed by our measurements.

  5. On the evaporation of ammonium sulfate solution

    PubMed Central

    Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

    2009-01-01

    Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 ± 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor–liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly. PMID:19861551

  6. On the evaporation of ammonium sulfate solution

    SciTech Connect

    Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

    2009-07-16

    Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 {+-} 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor-liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly.

  7. Laboratory prototype flash evaporator

    NASA Technical Reports Server (NTRS)

    Gaddis, J. L.

    1972-01-01

    A laboratory prototype flash evaporator that is being developed as a candidate for the space shuttle environmental control system expendable heat sink is described. The single evaporator configuration uses water as an evaporant to accommodate reentry and on-orbit peak heat loads, and Freon 22 for terrestrial flight phases below 120,000 feet altitude. The design features, fabrication techniques used for the prototype unit, redundancy considerations, and the fluid temperature control arrangement are reported in detail. The results of an extensive test program to determine the evaporator operational characteristics under a wide variety of conditions are presented.

  8. Pan-ebolavirus and Pan-filovirus Mouse Monoclonal Antibodies: Protection against Ebola and Sudan Viruses

    PubMed Central

    Holtsberg, Frederick W.; Shulenin, Sergey; Vu, Hong; Howell, Katie A.; Patel, Sonal J.; Gunn, Bronwyn; Karim, Marcus; Lai, Jonathan R.; Frei, Julia C.; Nyakatura, Elisabeth K.; Zeitlin, Larry; Douglas, Robin; Fusco, Marnie L.; Froude, Jeffrey W.; Saphire, Erica Ollmann; Herbert, Andrew S.; Wirchnianski, Ariel S.; Lear-Rooney, Calli M.; Alter, Galit; Dye, John M.; Glass, Pamela J.; Warfield, Kelly L.

    2015-01-01

    ABSTRACT The unprecedented 2014-2015 Ebola virus disease (EVD) outbreak in West Africa has highlighted the need for effective therapeutics against filoviruses. Monoclonal antibody (MAb) cocktails have shown great potential as EVD therapeutics; however, the existing protective MAbs are virus species specific. Here we report the development of pan-ebolavirus and pan-filovirus antibodies generated by repeated immunization of mice with filovirus glycoproteins engineered to drive the B cell responses toward conserved epitopes. Multiple pan-ebolavirus antibodies were identified that react to the Ebola, Sudan, Bundibugyo, and Reston viruses. A pan-filovirus antibody that was reactive to the receptor binding regions of all filovirus glycoproteins was also identified. Significant postexposure efficacy of several MAbs, including a novel antibody cocktail, was demonstrated. For the first time, we report cross-neutralization and in vivo protection against two highly divergent filovirus species, i.e., Ebola virus and Sudan virus, with a single antibody. Competition studies indicate that this antibody targets a previously unrecognized conserved neutralizing epitope that involves the glycan cap. Mechanistic studies indicated that, besides neutralization, innate immune cell effector functions may play a role in the antiviral activity of the antibodies. Our findings further suggest critical novel epitopes that can be utilized to design effective cocktails for broad protection against multiple filovirus species. IMPORTANCE Filoviruses represent a major public health threat in Africa and an emerging global concern. Largely driven by the U.S. biodefense funding programs and reinforced by the 2014 outbreaks, current immunotherapeutics are primarily focused on a single filovirus species called Ebola virus (EBOV) (formerly Zaire Ebola virus). However, other filoviruses including Sudan, Bundibugyo, and Marburg viruses have caused human outbreaks with mortality rates as high as 90%. Thus

  9. Evaporative winds in X-ray binaries

    NASA Technical Reports Server (NTRS)

    Basko, M. M.; Suniaev, R. A.; Hatchett, S.; Mccray, R.

    1977-01-01

    Evaporation of gas from the surface of HZ Her by Her X-1 and its implications regarding the mass transfer process are examined further. The powerful soft X-ray flux results in an evaporation rate greater than previous estimates. The evaporative flow is shown to be subsonic at first, with the result that the capture of evaporated gas by Her X-1 may be efficient, and the self-excited wind mechanism is possible. A criterion for stabilization of mass transfer by stellar wind mass loss is derived. Possible mechanisms for the long-period variability of HZ Her are discussed. Evaporative winds are also estimated for Sco X-1 and Cyg X-2 spectra.

  10. Vapor compression evaporator concentrates, recovers alcohol

    SciTech Connect

    Miller, M.N.; Robe, K.; Bacchetti, J.A.

    1982-11-01

    This article focuses on presenting a solution to the high energy cost of operating a steam heated, single effect evaporator used by Monsanto Industrial Chemical Company at a plant in Seattle, Wash., to produce vanillin from pulp and paper mill sulfite. Use of the single effect flash evaporator resulted in high energy usage due not only to the ''single effect'' use of steam, but also because energy consumption was reduced only slightly at low operating rates. The solution to this problem was the replacement of the single effect evaporator with a vapor recompression evaporator. Operating for over 1 1/2 years, the vapor recompression evaporator system has had no significant maintenance problems. The system operates with only 1/60th the steam consumption and 15% of the total energy consumption of the previous evaporator and has had no tube fouling. Also, since the distillate is condensed within the evaporator, less cooling water is required, allowing two heat exchangers to be taken out of service. When operating at less than design capacity, the energy consumption drops almost linearly with the feed rate. At low feed rates, a by-pass valve unloads the compressor to reduce energy consumption. Total energy consumption, now 15% of the previous level, results in an estimated pay-back of less than three years.

  11. Hard-pan soils - Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hard pans, hard layers, or compacted horizons, either surface or subsurface, are universal problems that limit crop production. Hard layers can be caused by traffic or soil genetic properties that result in horizons with high density or cemented soil particles; these horizons have elevated penetrati...

  12. The Pan-STARRS Moving Object Processing System

    NASA Astrophysics Data System (ADS)

    Denneau, Larry; Jedicke, Robert; Grav, Tommy; Granvik, Mikael; Kubica, Jeremy; Milani, Andrea; Vereš, Peter; Wainscoat, Richard; Chang, Daniel; Pierfederici, Francesco; Kaiser, N.; Chambers, K. C.; Heasley, J. N.; Magnier, Eugene A.; Price, P. A.; Myers, Jonathan; Kleyna, Jan; Hsieh, Henry; Farnocchia, Davide; Waters, Chris; Sweeney, W. H.; Green, Denver; Bolin, Bryce; Burgett, W. S.; Morgan, J. S.; Tonry, John L.; Hodapp, K. W.; Chastel, Serge; Chesley, Steve; Fitzsimmons, Alan; Holman, Matthew; Spahr, Tim; Tholen, David; Williams, Gareth V.; Abe, Shinsuke; Armstrong, J. D.; Bressi, Terry H.; Holmes, Robert; Lister, Tim; McMillan, Robert S.; Micheli, Marco; Ryan, Eileen V.; Ryan, William H.; Scotti, James V.

    2013-04-01

    We describe the Pan-STARRS Moving Object Processing System (MOPS), a modern software package that produces automatic asteroid discoveries and identifications from catalogs of transient detections from next-generation astronomical survey telescopes. MOPS achieves >99.5% efficiency in producing orbits from a synthetic but realistic population of asteroids whose measurements were simulated for a Pan-STARRS4-class telescope. Additionally, using a nonphysical grid population, we demonstrate that MOPS can detect populations of currently unknown objects such as interstellar asteroids. MOPS has been adapted successfully to the prototype Pan-STARRS1 telescope despite differences in expected false detection rates, fill-factor loss, and relatively sparse observing cadence compared to a hypothetical Pan-STARRS4 telescope and survey. MOPS remains highly efficient at detecting objects but drops to 80% efficiency at producing orbits. This loss is primarily due to configurable MOPS processing limits that are not yet tuned for the Pan-STARRS1 mission. The core MOPS software package is the product of more than 15 person-years of software development and incorporates countless additional years of effort in third-party software to perform lower-level functions such as spatial searching or orbit determination. We describe the high-level design of MOPS and essential subcomponents, the suitability of MOPS for other survey programs, and suggest a road map for future MOPS development.

  13. Effects of nanoparticles on nanofluid droplet evaporation

    SciTech Connect

    Chen, Ruey-Hung; Phuoc, Tran X.; Martello, Donald

    2010-09-01

    Laponite, Fe2O3 and Ag nanoparticles were added to deionized water to study their effect of evaporation rates. The results show that these nanofluid droplets evaporate at different rates (as indicated by the evaporation rate constant K in the well known D2-law) from the base fluid. Different particles lead to different values of K. As the particle concentration increases due to evaporation. K values of various Ag and Fe2O3 nanofluids go through a transition from one value to another, further demonstrating the effect of increasing nanoparticle concentration. The implication for the heat of vaporization (hfg) is discussed.

  14. The Effect of Nitrogen Gas Flow Rate on the Properties of TiN-COATED High-Speed Steel (hss) Using Cathodic Arc Evaporation Physical Vapor Deposition (pvd) Technique

    NASA Astrophysics Data System (ADS)

    Mubarak, Ali; Hamzah, Esah Binti; Mohd Toff, Mohd Radzi Hj.; Hashim, Abdul Hakim Bin

    Cathodic arc evaporation (CAE) is a widely-used technique for generating highly ionized plasma from which hard and wear resistant physical vapor deposition (PVD) coatings can be deposited. A major drawback of this technique is the emission of micrometer-sized droplets of cathode material from the arc spot, which are commonly referred to as "macroparticles." In present study, titanium nitride (TiN) coatings on high-speed steel (HSS) coupons were produced with a cathodic arc evaporation technique. We studied and discussed the effect of various nitrogen gas flow rates on microstructural and mechanical properties of TiN-coated HSS coupons. The coating properties investigated in this work included the surface morphology, thickness of deposited coating, adhesion between the coating and substrate, coating composition, coating crystallography, hardness and surface characterization using a field emission scanning electron microscope (FE-SEM) with energy dispersive X-ray (EDX), X-ray diffraction (XRD) with glazing incidence angle (GIA) technique, scratch tester, hardness testing machine, surface roughness tester, and atomic force microscope (AFM). An increase in the nitrogen gas flow rate showed decrease in the formation of macro-droplets in CAE PVD technique. During XRD-GIA studies, it was observed that by increasing the nitrogen gas flow rate, the main peak [1,1,1] shifted toward the lower angular position. Surface roughness decreased with an increase in nitrogen gas flow rate but was higher than the uncoated polished sample. Microhardness of TiN-coated HSS coupons showed more than two times increase in hardness than the uncoated one. Scratch tester results showed good adhesion between the coating material and substrate. Considerable improvement in the properties of TiN-deposited thin films was achieved by the strict control of all operational steps.

  15. The Pan-STARRS Surveys

    NASA Astrophysics Data System (ADS)

    Carter Chambers, Kenneth

    2015-08-01

    The 4 year Pan-STARRS1 Science Mission has now completed and the data will be publicly release by the time of the IAU Assembly. The full data set, including catalogs (100TB database), images (2PB), and metadata, will be available from the STScI MAST archive. The Pan-STARRS1 Surveys include: (1) The 3pi Steradian Survey, (2) The Medium Deep survey of 10 PS1 footprints (7 sq deg each) spaced around the sky; (3) A solar system survey of the ecliptic optimized for the discovery of Near Earth Objects, (4) a Stellar Transit Survey in the galactic bulge; and (5) a time domain Survey of M31.The characteristics of the Pan-STARRS Surveys will be presented, including image quality, depth, cadence, and coverage. Science results span most fields of astronomy from Near Earth Objects to cosmology.The 2nd mission, the Pan-STARRS NEO Survey, is currently underway on PS1 and it will be supplemented by PS2 as it becomes fully operational. PS2 is currently undergoing commissioning and is expected to begin full time science observations with an functional capability similar to PS1 by summer of 2015. The status of PS2 and commissioning data from PS2 will be presented along with a full description of the Pan-STARRS NEO Survey. The prospects for future (beyond 2017) wide field surveys in the Northern Hemisphere will also be discussed.The Pan-STARRS1 Surveys have been made possible through contributions of the Institute for Astronomy of the University of Hawaii; the Pan-STARRS Project Office; the Max-Planck Society and its participating institutes: the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching; The Johns Hopkins University; Durham University; the University of Edinburgh; Queen's University Belfast; the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated; the National Central University of Taiwan; the Space Telescope Science Institute; the National Aeronautics

  16. Measure Guideline: Evaporative Condensers

    SciTech Connect

    German, A; Dakin, B.; Hoeschele, M.

    2012-03-01

    This measure guideline on evaporative condensers provides information on properly designing, installing, and maintaining evaporative condenser systems as well as understanding the benefits, costs, and tradeoffs. This is a prescriptive approach that outlines selection criteria, design and installation procedures, and operation and maintenance best practices.

  17. Evaporation, Boiling and Bubbles

    ERIC Educational Resources Information Center

    Goodwin, Alan

    2012-01-01

    Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The…

  18. Influence of monolayer amounts of HNO3 on the evaporation rate of H2O over ice in the range 179 to 208 K: a quartz crystal microbalance study.

    PubMed

    Delval, Christophe; Rossi, Michel J

    2005-08-18

    The evaporation flux J(ev) of H2O from thin H2O ice films containing between 0.5 and 7 monolayers of HNO3 has been measured in the range 179 to 208 K under both molecular and stirred flow conditions in isothermal experiments. FTIR absorption of the HNO3/H2O condensate revealed the formation of metastable alpha-NAT (HNO(3).3H2O) converting to stable beta-NAT at 205 K. After deposition of HNO3 for 16-80 s on a 1 mum thick pure ice film at a deposition rate in the range (6-60) x 10(12) molecules s(-1) the initial evaporative flux J(ev)(H2O) was always that of pure ice. J(ev)(H2O) gradually decreased with the evaporation of H2O and the concomitant increase of the average mole fraction of HNO3, chi(HNO3), indicating the presence of an amorphous mixture of H2O/HNO3 that is called complexed or (c)-ice whose vapor pressure is that of pure ice. The final value of J(ev) was smaller by factors varying from 2.7 to 65 relative to pure ice. Depending on the doping conditions and temperature of the ice film the pure ice thickness d(D) of the ice film for which J(ev) < 0.85J(ev)(pure ice) varied between 130 and 700 nm compared to the 1000 nm thick original ice film at 208 and 191 K, respectively, in what seems to be an inverse temperature dependence. There exist three different types of H2O molecules under the present experimental conditions, namely (a) free H2O corresponding to pure ice, (b) complexed H2O or c-ice, and (c) H2O molecules originating from the breakup of NAT or amorphous H2O/HNO3 mixtures. The significant decrease of J(ev)(H2O) with increasing chi(HNO3) leads to an increase of the evaporative lifetime of atmospheric ice particles in the presence of HNO3 and may help explain the occurrence of persistent and/or large contaminated ice particles at certain atmospheric conditions. PMID:16834079

  19. Evaporative modeling for idealized lithographic pores

    NASA Astrophysics Data System (ADS)

    Oinuma, Ryoji; Best, Frederick

    2002-01-01

    As a demand for the high performance and small size electronics devices increased, the heat removal from those electronic devices for space use is getting critical factor more than devices on the earth due to the limitation of the size. The purpose of this paper is to show a study of optimized size of coherent pores or slits in the evaporative wick of a heat pipe to cool down the high heat flux density heat source. Our system considered in this paper consists of a plate heat source, the evaporative wick with coherent pores and conducting walls connecting between the heat source and the evaporator. The evaporation rate of working fluid along the meniscus interface in a micro-order pore or slit was calculated based on the kinetic theory and the statistical rate theory to find a proper diameter of pores to cool down the heat source effectively. The results show the smaller diameter of pores is preferred to achieve the smallest total size of the evaporator although it will involve the cost issue. As a demand for the high performance and small size electronics devices increased, the heat removal from those electronic devices for space use is getting critical factor more than devices on the earth due to the limitation of the size. The purpose of this paper is to show a study of optimized size of coherent pores or slits in the evaporative wick of a heat pipe to cool down the high heat flux density heat source. Our system considered in this paper consists of a plate heat source, the evaporative wick with coherent pores and conducting walls connecting between the heat source and the evaporator. The evaporation rate of working fluid along the meniscus interface in a micro-order pore or slit was calculated based on the kinetic theory and the statistical rate theory to find a proper diameter of pores to cool down the heat source effectively. The results show that the smaller diameter of pores uses the pore for evaporation effectively and is preferred to achieve the smallest

  20. THE ROLE OF AQUEOUS THIN FILM EVAPORATIVE COOLING ON RATES OF ELEMENTAL MERCURY AIR-WATER EXCHANGE UNDER TEMPERATURE DISEQUILIBRIUM CONDITIONS

    EPA Science Inventory

    The technical conununity has only recently addressed the role of atmospheric temperature variations on rates of air-water vapor phase toxicant exchange. The technical literature has documented that: 1) day time rates of elemental mercury vapor phase air-water exchange can exceed ...

  1. Dynamics of evaporative colloidal patterning

    NASA Astrophysics Data System (ADS)

    Kaplan, C. Nadir; Wu, Ning; Mandre, Shreyas; Aizenberg, Joanna; Mahadevan, L.

    2015-09-01

    Drying suspensions often leave behind complex patterns of particulates, as might be seen in the coffee stains on a table. Here, we consider the dynamics of periodic band or uniform solid film formation on a vertical plate suspended partially in a drying colloidal solution. Direct observations allow us to visualize the dynamics of band and film deposition, where both are made of multiple layers of close packed particles. We further see that there is a transition between banding and filming when the colloidal concentration is varied. A minimal theory of the liquid meniscus motion along the plate reveals the dynamics of the banding and its transition to the filming as a function of the ratio of deposition and evaporation rates. We also provide a complementary multiphase model of colloids dissolved in the liquid, which couples the inhomogeneous evaporation at the evolving meniscus to the fluid and particulate flows and the transition from a dilute suspension to a porous plug. This allows us to determine the concentration dependence of the bandwidth and the deposition rate. Together, our findings allow for the control of drying-induced patterning as a function of the colloidal concentration and evaporation rate.

  2. THE FLAMMABILITY ANALYSIS AND TIME TO REACH LOWER FLAMMABILITY LIMIT CALCULATIONS ON THE WASTE EVAPORATION AT 242-A EVAPORATOR

    SciTech Connect

    HU TA

    2007-10-31

    This document describes the analysis of the waste evaporation process on the flammability behavior. The evaluation calculates the gas generation rate, time to reach 25% and 100% of the lower flammability limit (LFL), and minimum ventilation rates for the 242-A Evaporator facility during the normal evaporation process and when vacuum is lost. This analysis performs flammability calculations on the waste currently within all 28 double-shell tanks (DST) under various evaporation process conditions to provide a wide spectrum of possible flammable gas behavior. The results of this analysis are used to support flammable gas control decisions and support and upgrade to Documented Safety Analysis for the 242-A Evaporator.

  3. Saline Evaporation from Porous Media: Characteristics of Salt Precipitation and Its Effect on Evaporation

    NASA Astrophysics Data System (ADS)

    Nachshon, U.; Weisbrod, N.; Dragila, M. I.; Grader, A. S.

    2010-12-01

    Salt precipitation as subflorescence or efflorescence crust occurs during saline solutions evaporation from porous media. Non-linear synergy between evaporation and salt precipitation processes results in a complex mechanism that has yet to be quantitatively understood. Presented here is a series of experiments and a mathematical model that shed light on these processes. Experiments include: (1) long-term column evaporation experiments to quantify changes in evaporation rates due to salt precipitation; (2) long-term Hele-Shaw evaporation experiments to visualize salt precipitation at the macro scale; and (3) CT scans of evaporated porous media pre-saturated with NaI solutions to observe salt precipitation at the pore scale. Experiments were conducted for homogeneous and heterogeneous media using a number of saline solutions (NaCl, CaSO4, KCl, CuSO4 and NaI). A mathematical model was developed to explore quantitatively the physical and chemical mechanisms involved in the evaporation-salt precipitation process. The model simulated salt precipitation and it affect on evaporation. Three new stages of evaporation are introduced and defined for saline solutions: SS1, SS2 and SS3. SS1 exhibits a low and gradual decrease in evaporation rate caused by a changing osmotic potential. During SS2, evaporation rate falls precipitously a salt precipitates. SS3 is characterized by a constant, low evaporation rate. The phenomenological similarity to the classical evaporation stages of pure water, S1, S2 and S3, are only coincidental, the three saline stages correspond to entirely different mechanisms. The mathematical model was used to also quantify the diffusion coefficient through a salt crust. Heterogeneity during saline evaporation was found to strongly control the location of salt precipitation: salt precipitation occurred mainly within the fine-pore regions which act as a wick transporting water from the coarser media. Heterogeneity also permits greater saline evaporation by

  4. The Pan-STARRS Surveys

    NASA Astrophysics Data System (ADS)

    Chambers, Kenneth C.; Pan-STARRS Team

    2016-01-01

    The 4 year Pan-STARRS1 Science Mission has now completed and the final data processing and database ingest is underway. We expect to have the public release of the PS1 Survey data at approximately the time of the AAS Meeting. The full data set, including catalogs (150 Terabyte database), images (2 Petabytes), and metadata, will be available from the STScI MASTarchive. The Pan-STARRS1 Surveys include: (1) The 3pi Steradian Survey, (2) The Medium Deep survey of 10 PS1 footprints (7 sq deg each) spaced around the sky; (3) A solar system survey of the ecliptic optimized for the discovery of Near Earth Objects, (4) a Stellar Transit Survey in the galactic bulge; and (5) a time domain Survey of M31. The characteristics of the Pan-STARRS1 Surveys will be presented, including image quality, depth, cadence, and coverage. Science results span most fields of astronomy from Near Earth Objects to cosmology. The 2nd mission, the Pan-STARRS NEO Survey, is currently underway on PS1 and it will be supplemented by PS2 observations as PS2 becomes fully operational. We will also report on the status of PS2 and the prospects for future wide field surveys in the Northern Hemisphere. The Pan-STARRS1 Surveys have been made possible through contributions of the Institute for Astronomy of the University of Hawaii; the Pan-STARRS Project Office; the Max-Planck Society and its participating institutes: the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching; The Johns Hopkins University; Durham University; the University of Edinburgh; Queen's University Belfast; the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated; the National Central University of Taiwan; the Space Telescope Science Institute; the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate; the National

  5. Towards the prediction of actual evaporation from terrestrial surfaces using analytical complementary relationship

    NASA Astrophysics Data System (ADS)

    Or, Dani; Aminzadeh, Milad; Roderick, Michael L.

    2016-04-01

    Notwithstanding the centrality of potential evaporation (PE) in hydrologic and climate models, its definition and proper use remain widely debated. We propose a mechanistic, pore-based model for evaporation and energy partitioning over drying porous surfaces to define PE for a hypothetical steady-state reference surface temperature. Feedback between drying land surface and overlaying air properties is considered in the hypothetical steady-state with a vanishing sensible heat flux and diversion of available energy to evaporation. Surprisingly, the resulting steady-state PE tracks class A pan evaporation data very closely suggesting that pan evaporation occurs with negligible sensible heat flux (in agreement with summer observations). The new PE enables analytical derivation of asymmetric complementary relationship (CR) between potential and actual evaporation for a wide range of conditions in good agreement with measured actual evaporation. The derivations provide new insights into the origins of asymmetry in the CR linked to input weather data and evolution of the temperature of drying surfaces across scales. The analytical CR could offer physically-based estimates of regional scale actual evaporation during surface drying for a wide range of present and future external inputs that may resolve future energy partitioning patterns and issues related to droughts.

  6. Influence of random point defects introduced by proton irradiation on the flux creep rates and magnetic field dependence of the critical current density J c of co-evaporated GdBa2Cu3O7-δ coated conductors

    NASA Astrophysics Data System (ADS)

    Haberkorn, N.; Kim, Jeehoon; Suárez, S.; Lee, Jae-Hun; Moon, S. H.

    2015-12-01

    We report the influence of random point defects introduced by 3 MeV proton irradiation (doses of 0.5 × 1016, 1 × 1016, 2 × 1016 and 6 × 1016 cm-2) on the vortex dynamics of co-evaporated 1.3 μm thick, GdBa2Cu3O7-δ coated conductors. Our results indicate that the inclusion of additional random point defects reduces the low field and enhances the in-field critical current densities J c. The main in-field J c enhancement takes place below 40 K, which is in agreement with the expectations for pinning by random point defects. In addition, our data show a slight though clear increase in flux creep rates as a function of irradiation fluence. Maley analysis indicates that this increment can be associated with a reduction in the exponent μ characterizing the glassy behavior.

  7. Flash evaporator systems test

    NASA Technical Reports Server (NTRS)

    Dietz, J. B.

    1976-01-01

    A flash evaporator heat rejection system representative of that proposed for the space shuttle orbiter underwent extensive system testing at the NASA Johnson Space Center (JSC) to determine its operational suitability and to establish system performance/operational characteristics for use in the shuttle system. During the tests the evaporator system demonstrated its suitability to meet the shuttle requirements by: (1) efficient operation with 90 to 95% water evaporation efficiency, (2) control of outlet temperature to 40 + or - 2 F for partial heat load operation, (3) stability of control system for rapid changes in Freon inlet temperature, and (4) repeated dormant-to-active device operation without any startup procedures.

  8. Evaporative cooling in microfluidic channels

    NASA Astrophysics Data System (ADS)

    Maltezos, George; Rajagopal, Aditya; Scherer, Axel

    2006-08-01

    Evaporative cooling is an effective and energy efficient way to rapidly remove heat from a system. Specifically, evaporative cooling in microfluidic channels can provide a cost-effective solution for the cooling of electronic devices and chemical reactors. Here we present microfluidic devices fabricated by using soft-lithography techniques to form simple fluidic junctions between channels carrying refrigerant and channels carrying N2 gas. The effects of channel geometry and delivery pressure on the performance of refrigeration through vaporization of acetone, isopropyl alcohol, and ethyl ether were characterized. By varying gas inlet pressures, refrigerants, and angles of the microfluidic junctions, optimal cooling conditions were found. Refrigeration rates in excess of 40°C/s were measured, and long lasting subzero cooling in the junction could be observed.

  9. The simultaneous mass and energy evaporation (SM2E) model.

    PubMed

    Choudhary, Rehan; Klauda, Jeffery B

    2016-01-01

    In this article, the Simultaneous Mass and Energy Evaporation (SM2E) model is presented. The SM2E model is based on theoretical models for mass and energy transfer. The theoretical models systematically under or over predicted at various flow conditions: laminar, transition, and turbulent. These models were harmonized with experimental measurements to eliminate systematic under or over predictions; a total of 113 measured evaporation rates were used. The SM2E model can be used to estimate evaporation rates for pure liquids as well as liquid mixtures at laminar, transition, and turbulent flow conditions. However, due to limited availability of evaporation data, the model has so far only been tested against data for pure liquids and binary mixtures. The model can take evaporative cooling into account and when the temperature of the evaporating liquid or liquid mixture is known (e.g., isothermal evaporation), the SM2E model reduces to a mass transfer-only model. PMID:26595699

  10. Effect of nitrogen flow rate on structural, morphological and optical properties of In-rich InxAl1-xN thin films grown by plasma-assisted dual source reactive evaporation

    NASA Astrophysics Data System (ADS)

    Alizadeh, M.; Ganesh, V.; Goh, B. T.; Dee, C. F.; Mohmad, A. R.; Rahman, S. A.

    2016-08-01

    In-rich InxAl1-xN thin films were deposited on quartz substrate at various nitrogen flow rates by plasma-assisted dual source reactive evaporation technique. The elemental composition, surface morphology, structural and optical properties of the films were investigated by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Raman spectroscopy, X-ray diffraction (XRD), UV-vis spectrophotometer and photoluminescence (PL) measurements. XPS results revealed that the indium composition (x) of the InxAl1-xN films increases from 0.90 to 0.97 as the nitrogen flow rate is increased from 40 to 100 sccm, respectively. FESEM images of the surface and cross-sectional microstructure of the InxAl1-xN films showed that by increasing the N2 flow rate, the grown particles are highly agglomerated. Raman and XRD results indicated that by increasing nitrogen flow rate the In-rich InxAl1-xN films tend to turn into amorphous state. It was found that band gap energy of the films are in the range of 0.90-1.17 eV which is desirable for the application of full spectra solar cells.

  11. CAPSULE REPORT: EVAPORATION PROCESS

    EPA Science Inventory

    Evaporation has been an established technology in the metal finishing industry for many years. In this process, wastewaters containing reusable materials, such as copper, nickel, or chromium compounds are heated, producing a water vapor that is continuously removed and condensed....

  12. Trends and Patterns of Change in Temperature and Evaporation

    NASA Astrophysics Data System (ADS)

    Ragno, E.; AghaKouchak, A.

    2014-12-01

    Global mean monthly temperature has increased substantially in the past decades. On the other hand, there are contradictory reports on the response of the potential evaporation to a warming climate. In this study, ground based observations of temperature, and direct measurements of pan potential evaporation are evaluated across the United States. Furthermore, empirical simulations of the potential evaporation have been evaluated against observations. The results show that empirical (e.g., Thornthwaite method) estimates of the potential evapotranspiration show trends inconsistent with the ground-based observations. In fact, while temperature data show a significant upward trend across most of the United States, ground-based evaporation data in most locations do not exhibit a statistically significant trend. Empirical methods of potential evaporation estimation, including the Thornthwaite method, show trends similar to temperature. The primary reason is that many of the empirical approaches are dominated by temperature. Currently, empirical estimates of potential evaporation are widely used for numerous applications including water stress analysis. This indicates that using empirical estimates of potential estimation for irrigation water demand estimation and also drought assessment could lead to unrealistic results.

  13. Polarization (ellipsometric) measurements of liquid condensate deposition and evaporation rates and dew points in flowing salt/ash-containing combustion gases

    NASA Technical Reports Server (NTRS)

    Seshadri, K.; Rosner, D. E.

    1985-01-01

    An application of an optical polarization technique in a combustion environment is demonstrated by following, in real-time, growth rates of boric oxide condensate on heated platinum ribbons exposed to seeded propane-air combustion gases. The results obtained agree with the results of earlier interference measurements and also with theoretical chemical vapor deposition predictions. In comparison with the interference method, the polarization technique places less stringent requirements on surface quality, which may justify the added optical components needed for such measurements.

  14. Water repellency diminishes peatland evaporation after wildfire

    NASA Astrophysics Data System (ADS)

    Kettridge, N.; Lukenbach, M.; Hokanson, K. J.; Devito, K. J.; Petrone, R. M.; Hopkinson, C.; Waddington, J. M.

    2015-12-01

    Peatlands are a critically important global carbon reserve. There is increasing concern that such ecosystems are vulnerable to projected increases in wildfire severity under a changing climate. Severe fires may exceed peatland ecological resilience resulting in the long term degradation of this carbon store. Evaporation provides the primary mechanisms of water loss from such environments and can regulate the ecological stress in the initial years after wildfire. We examine variations in evaporation within burned peatlands after wildfire through small scale chamber and large scale remote sensing measurements. We show that near-surface water repellency limits peatland evaporation in these initial years post fire. Water repellent peat produced by the fire restricts the supply of water to the surface, reducing evaporation and providing a strong negative feedback to disturbance. This previously unidentified feedback operates at the landscape scale. High surface temperatures that result from large reductions in evaporation within water repellent peat are observed across the 60,000 ha burn scar three months after the wildfire. This large scale reduction in evaporation promotes high water table positions at a landscape scale which limits the rate of peat decomposition and supports the post fire ecohydrological recovery of the peatlands. However, severe burns are shown to exceed this negative feedback response. Deep burns at the peatland margins remove the hydrophobic layer, increasing post fire evaporation and leaving the peatland vulnerable to drying and associated ecological shifts.

  15. Measure Guideline: Evaporative Condensers

    SciTech Connect

    German, A.; Dakin, B.; Hoeschele, M.

    2012-03-01

    The purpose of this measure guideline on evaporative condensers is to provide information on a cost-effective solution for energy and demand savings in homes with cooling loads. This is a prescriptive approach that outlines selection criteria, design and installation procedures, and operation and maintenance best practices. This document has been prepared to provide a process for properly designing, installing, and maintaining evaporative condenser systems as well as understanding the benefits, costs, and tradeoffs.

  16. Mixed feed evaporator

    DOEpatents

    Vakil, Himanshu B.; Kosky, Philip G.

    1982-01-01

    In the preparation of the gaseous reactant feed to undergo a chemical reaction requiring the presence of steam, the efficiency of overall power utilization is improved by premixing the gaseous reactant feed with water and then heating to evaporate the water in the presence of the gaseous reactant feed, the heating fluid utilized being at a temperature below the boiling point of water at the pressure in the volume where the evaporation occurs.

  17. Visualization of an evaporating thin layer during the evaporation of a nanofluid droplet.

    PubMed

    Shin, Dong Hwan; Allen, Jeffrey S; Choi, Chang Kyoung; Lee, Seong Hyuk

    2015-02-01

    During the evaporation of a droplet, there exists an evaporating thin layer that is difficult to visualize because of optical restrictions. The present study visualized this thin layer by using a reflective-mode, confocal microscope that can provide improved signal-to-noise focal plane imaging over traditional optical microscopy while simultaneously serving as an interferometer when imaging thin liquid films. The spatial distribution of the evaporating thin layer thickness was determined from interferometric fringe analysis. Three distinct fringe patterns, or regions, were observed depending on the nanoparticle concentration. These regions are referred to as uniform, slow extension, and rapid extension. The formation of the three regions is closely associated with the variation of the evaporating thin layer thickness of a nanofluid droplet. The nanoparticle bank formed near the contact line region substantially affects the rate of change in the evaporating thin layer thickness that increases with the nanoparticle concentration. PMID:25586137

  18. Sheet Membrane Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  19. Evaporation of petroleum products from contaminated soils

    SciTech Connect

    Kang, S.H.; Oulman, C.S.

    1996-05-01

    Bioremediation can remove petroleum products from soil that has been contaminated by leaking underground storage tanks, but abiotic processes such as evaporation can contribute significantly to the overall removal process. The mathematical model described in this paper was developed to predict the evaporation rate of volatile liquids from petroleum-contaminated sand. The model is based on simple concepts relating to molecular diffusion embodied in the theory underlying the estimation of binary diffusivities using measurements made with an Arnold diffusion cell. The model in its simplified form indicates that the rate of evaporation for a particular volatile liquid is proportional to the square root of the product of diffusivity and partial pressure divided by the molecular weight of the liquid. This in part explains why evaporative losses from sand are so much higher for gasoline than for diesel fuel. The model also shows that the time for evaporation is directly proportional to the square of the depth dried out and inversely proportional to the vapor pressure of the volatile liquid. The model was tested using gravimetric measurements of the evaporation of n-heptane, unleaded gasoline, and diesel fuel from sand under laboratory conditions.

  20. Evaluation of polyacrylonitrile (PAN) as a binding polymer for absorbers used to treat liquid radioactive wastes

    SciTech Connect

    Sebesta, F.; John, J.; Motl, A.; Stamberg, K.

    1995-11-01

    The chemical and radiation stability of polyacrylonitrile (PAN) in the form of beads (B-PAN), similar to the beads of composite absorbers, and one selected composite absorber (ammonium molybdophosphate, the active component in PAN binder [AMP-PAN], a prospective candidate for the treatment of acidic wastes) were studied. Aqueous 1M HNO{sub 3} + 1M NaNO{sub 3}, 1M NaOH + 1M NaNO{sub 3}, and 1M NaOH were chosen as simulants of DOE acidic and alkaline wastes. In addition,radiation stability was determined indistilled water. The chemical stability of B-PAN and AMP-PAN beads was tested for a period up to one month of contact with the solution at ambient temperature. The radiation stability of the beads was checked in a radiation dose range 10{sup 3}--10{sup 6} Gy (10{sup 5}--10{sup 8} rads). In acidic solutions the stability of PAN binder was proved not to be limited by either chemical or radiation decomposition. PAN binder may thus be used for preparing composite absorbers for treatment of acid wastes from DOE facilities. The same conclusion is valid for alkaline solutions with pH up to 13. In highly alkaline solutions (concentration of NAOH higher than I M) and in the presence of NaNO{sub 3}, the stability of the tested polyacrylonitrile polymer was sufficient for applications not extending over 10 days. Cross-linking of the polymer caused by ionizing radiation was found to have a positive influence on chemical stability. This effect enables a longer period of applicability of PAN-based composite absorbers. Because of the high sorption rate achievable with PAN-based absorbers, the stability achieved is sufficient for most applications in the DOE complex. The chemical stability of binding polymer may also be further improved by testing another, more suitable type of polymer from the broad family of polyacrylonitrile polymers.

  1. Study of environmental isotope distribution in the Aswan High Dam Lake (Egypt) for estimation of evaporation of lake water and its recharge to adjacent groundwater.

    PubMed

    Aly, A I; Froehlich, K; Nada, A; Awad, M; Hamza, M; Salem, W M

    1993-03-01

    Oxygen-18 ((18)0) and deuterium isotopes were used to estimate the evaporation from the Aswan High Dam Lake and to investigate the inter-relation between the lake water and adjacent groundwater.According to stable isotopic analysis of samples taken in 1988 and 1989, the lake can be divided into two sections. In the first section extending between Abu Simbel and a point between EI-Alaki and Krosko, a remarkable vertical gradient of (18)0 and deuterium isotopic composition was observed. The second northern sector extending to the High Dam is characterised by a lower vertical isotopic gradient. In this sector in general, higher values of (18)O and deuterium contents were found at the top and lower values at the bottom. Also a strong horizontal increase of the heavy isotope content was observed. Thus, in the northern section evaporation is of dominating influence on the isotopic composition of the lake water.With the help of an evaporation pan experiment it was possible to calibrate the evaporative isotope enrichment in the lake and to facilitate a preliminary estimate of evaporative losses of lake water. The evaporation from the lake was estimated to be about 19% of the input water flow rate.The groundwater around the lake was investigated and samples from production wells and piezometers were subjected to isotopic analysis. The results indicate that recent recharge to the groundwater aquifer is limited to wells near to the lake and up to a maximum distance of about 10 km. The contribution of recent Nile water to the groundwater in these wells was estimated to range between 23 and 70%. Beyond this distance, palaeowater was observed with highly depleted deuterium and (18)0 contents, which was also confirmed by 14c dating. The age of palaeo groundwater in this area can reach values of more than 26,000 years.Recommendations are given for efficient water management of the lake water. PMID:24198080

  2. Measured performance of falling-jet flash evaporators

    NASA Astrophysics Data System (ADS)

    Green, H. J.; Olson, D. A.; Bharathan, D.; Johnson, D. H.

    1981-06-01

    The rates of heat transfer and approach to thermal equilibrium of flash evaporators operating at pressures of 2 to 4 kPa were investigated. Heat and mass transfer rates from falling jet evaporators operating in the temperature range of 18 to 30 C are measured. The initial experimental results are given and the apparatus is described.

  3. Mobile evaporator corrosion test results

    SciTech Connect

    Rozeveld, A.; Chamberlain, D.B.

    1997-05-01

    Laboratory corrosion tests were conducted on eight candidates to select a durable and cost-effective alloy for use in mobile evaporators to process radioactive waste solutions. Based on an extensive literature survey of corrosion data, three stainless steel alloys (304L, 316L, AL-6XN), four nickel-based alloys (825, 625, 690, G-30), and titanium were selected for testing. The corrosion tests included vapor phase, liquid junction (interface), liquid immersion, and crevice corrosion tests on plain and welded samples of candidate materials. Tests were conducted at 80{degrees}C for 45 days in two different test solutions: a nitric acid solution. to simulate evaporator conditions during the processing of the cesium ion-exchange eluant and a highly alkaline sodium hydroxide solution to simulate the composition of Tank 241-AW-101 during evaporation. All of the alloys exhibited excellent corrosion resistance in the alkaline test solution. Corrosion rates were very low and localized corrosion was not observed. Results from the nitric acid tests showed that only 316L stainless steel did not meet our performance criteria. The 316L welded interface and crevice specimens had rates of 22.2 mpy and 21.8 mpy, respectively, which exceeds the maximum corrosion rate of 20 mpy. The other welded samples had about the same corrosion resistance as the plain samples. None of the welded samples showed preferential weld or heat-affected zone (HAZ) attack. Vapor corrosion was negligible for all alloys. All of the alloys except 316L exhibited either {open_quotes}satisfactory{close_quotes} (2-20 mpy) or {open_quotes}excellent{close_quotes} (<2 mpy) corrosion resistance as defined by National Association of Corrosion Engineers. However, many of the alloys experienced intergranular corrosion in the nitric acid test solution, which could indicate a susceptibility to stress corrosion cracking (SCC) in this environment.

  4. An evaporation based digital microflow meter

    NASA Astrophysics Data System (ADS)

    Nie, C.; Frijns, A. J. H.; Mandamparambil, R.; Zevenbergen, M. A. G.; den Toonder, J. M. J.

    2015-11-01

    In this work, we present a digital microflow meter operating in the range 30-250 nl min-1 for water. The principle is based on determining the evaporation rate of the liquid via reading the number of wetted pore array structures in a microfluidic system, through which continuous evaporation takes place. A proof-of-principle device of the digital flow meter was designed, fabricated, and tested. The device was built on foil-based technology. In the proof-of-principle experiments, good agreement was found between set flow rates and the evaporation rates estimated from reading the number of wetted pore structures. The measurement range of the digital flow meter can be tuned and extended in a straightforward manner by changing the pore structure of the device.

  5. Considering complementary relationship of evaporation in Budyko's hydrological model

    NASA Astrophysics Data System (ADS)

    Han, Songjun; Shao, Weiwei

    2013-04-01

    In Budyko's hydrological model, actual evaporation was partitioned from precipitation as a function of the relative magnitude of precipitation and potential evaporation. In practice, both Penman equation and Priestley-Taylor equation have been used to estimate the potential evaporation with same Budyko curve, and they are not distinguished under Budyko framework. Nevertheless, according to the complementary relationship of evaporation, the definitions of Penman equation and Priestley-Taylor equation are absolutely different. When water availability is not limited, evaporation occurs at Priestley-Taylor's evaporation (Ew, referred to as wet environment evaporation). As the surface dries without changing the available energy, the actual and Penman's potential evaporation (Epen) rates depart from Ew with opposite changes in fluxes. So the question is: what is the difference of the Budyko's hydrological model with potential evaporation estimated by Penman or Priestley-Taylor equation? How to consider the complementary relationship in Budyko framework? In this study, for both long-term (multiyear) and annual values on water balances in the 29 non-humid catchments in the middle Yellow River Basin of China, the performances of Budyko's hydrological model with potential evaporation estimated by Epen and Ew were distinguished and compared. The catchments with larger value of Ep/Ew (ratio of Penman potential evaporation to Priestley-Taylor evaporation) are characterized with smaller evaporation ratios. The value of Ep/Ew can be served as another variable besides dryness index to partition actual evaporation from precipitation. With Priestley-Taylor equation as energy supply, an empirical formula for the parameter of the Budyko in terms of Ep/Ew and curve is proposed. Therefore, the complementary relationship of evaporation should be considered in the Budyko framework.

  6. Determining long and short hyporheic flow paths in Antarctic streams by comparing evaporative enrichment of D and 18O

    NASA Astrophysics Data System (ADS)

    Gooseff, M. N.; McKnight, D. M.

    2001-12-01

    In glacial meltwater streams of the Dry Valleys, Antarctica, streambeds are composed of porous alluvium, allowing the development of extensive, well-defined hyporheic zones. Stream water and subsurface water from the adjoining saturated alluvium were sampled for major ions and stable isotopes (D and 18O) in order to discritize the hyporheic zone based on variations in residence times. Subsurface water was more enriched in heavier isotopes and had higher solute content than water in the stream. Downstream surface water D and 18O enrichment rates were greater than could be accounted for by direct surface water evaporation, based on data from an evaporation pan experiment. Subsurface samples collected from wells farther from the edge of the open channel, at the upland edge of the hyporheic zone were the most enriched in D and 18O. These results suggest greater fractionation in lateral hyporheic water due to longer residence times at the edges of the hyporheic zone, and that hyporheic mixing may account for the stream water enrichment rates. Inverse modeling results using OTIS confirm the influence of exchange on stream water. These findings show that the hyporheic zones have areas of rapid stream water exchange, where "fast" biogeochemical reactions may influence water chemistry, and areas of very slow exchange in which any magnitude of chemical reaction rate may affect water chemistry.

  7. [Measurement and estimation methods and research progress of snow evaporation in forests].

    PubMed

    Li, Hui-Dong; Guan, De-Xin; Jin, Chang-Jie; Wang, An-Zhi; Yuan, Feng-Hui; Wu, Jia-Bing

    2013-12-01

    Accurate measurement and estimation of snow evaporation (sublimation) in forests is one of the important issues to the understanding of snow surface energy and water balance, and it is also an essential part of regional hydrological and climate models. This paper summarized the measurement and estimation methods of snow evaporation in forests, and made a comprehensive applicability evaluation, including mass-balance methods (snow water equivalent method, comparative measurements of snowfall and through-snowfall, snow evaporation pan, lysimeter, weighing of cut tree, weighing interception on crown, and gamma-ray attenuation technique) and micrometeorological methods (Bowen-ratio energy-balance method, Penman combination equation, aerodynamics method, surface temperature technique and eddy covariance method). Also this paper reviewed the progress of snow evaporation in different forests and its influencal factors. At last, combining the deficiency of past research, an outlook for snow evaporation rearch in forests was presented, hoping to provide a reference for related research in the future. PMID:24697085

  8. Pan-derived isotopic composition of atmospheric vapour in a Mediterranean wetland (Rhône River Delta, France).

    PubMed

    Vallet-Coulomb, Christine; Cartapanis, Olivier; Radakovitch, Olivier; Sonzogni, Corinne; Pichaud, Marc

    2010-03-01

    A continuous record of atmospheric vapour isotopic composition (delta(A)) can be derived from the isotope mass balance of a water body submitted to natural evaporation. In this paper, we present preliminary results of the application of this method to a drying evaporation pan, located in a Mediterranean wetland, during a two-month summer period. Results seem consistent with few atmospheric vapour data based on the assumption of isotopic equilibrium with precipitation, but we observed a shift between pan-derived delta(A) and the composition of vapour samples collected by cold trapping. These results suggest that further investigations are necessary to evaluate the effect of diurnal variations of atmospheric conditions on the applicability of the pan-evaporation method, and on the representative of grab atmospheric samples. We also propose a sensitivity analysis for evaluating the impact of the different measured components on delta(A) calculation, and show an improvement in the method efficiency as the pan is drying. PMID:20099185

  9. Evaporation of liquid droplets from a surface of anodized aluminum

    NASA Astrophysics Data System (ADS)

    Kuznetsov, G. V.; Feoktistov, D. V.; Orlova, E. G.

    2016-01-01

    The results of study of evaporation of water droplets and NaCl salt solution from a solid substrate made of anodized aluminum are presented in this paper. The experiment provides the parameters describing the droplet profile: contact spot diameter, contact angle, and droplet height. The specific rate of evaporation was calculated from the experimental data. The water droplets or brine droplets with concentration up to 9.1 % demonstrate evaporation with the pinning mode for the contact line. When the salt concentration in the brine is taken up to 16.7 %, the droplet spreading mode was observed. Two stages of droplet evaporation are distinguished as a function of phase transition rate.

  10. Hot air drum evaporator

    DOEpatents

    Black, Roger L.

    1981-01-01

    An evaporation system for aqueous radioactive waste uses standard 30 and 55 gallon drums. Waste solutions form cascading water sprays as they pass over a number of trays arranged in a vertical stack within a drum. Hot dry air is circulated radially of the drum through the water sprays thereby removing water vapor. The system is encased in concrete to prevent exposure to radioactivity. The use of standard 30 and 55 gallon drums permits an inexpensive compact modular design that is readily disposable, thus eliminating maintenance and radiation build-up problems encountered with conventional evaporation systems.

  11. Optimization of evaporative cooling

    NASA Astrophysics Data System (ADS)

    Sackett, C. A.; Bradley, C. C.; Hulet, R. G.

    1997-05-01

    Recent experiments have used forced evaporative cooling to produce Bose-Einstein condensation in dilute gases. The evaporative cooling process can be optimized to provide the maximum phase-space density with a specified number of atoms remaining. We show that this global optimization is approximately achieved by locally optimizing the cooling efficiency at each instant. We discuss how this method can be implemented, and present the results for our 7Li trap. The predicted behavior of the gas is found to agree well with experiment.

  12. Water repellency diminishes peatland evaporation after wildfire

    NASA Astrophysics Data System (ADS)

    Kettridge, Nick; Lukenbach, Max; Hokanson, Kelly; Devito, Kevin; Hopkinson, Chris; Petrone, Rich; Mendoza, Carl; Waddington, Mike

    2016-04-01

    Peatlands are a critically important global carbon reserve. There is increasing concern that such ecosystems are vulnerable to projected increases in wildfire severity under a changing climate. Severe fires may exceed peatland ecological resilience resulting in the long term degradation of this carbon store. Evaporation provides the primary mechanisms of water loss from such environments and can regulate the ecological stress in the initial years after wildfire. We examine variations in evaporation within burned peatlands after wildfire through small scale chamber and large scale remote sensing measurements. We show that near-surface water repellency limits peatland evaporation in these initial years post fire. Water repellent peat produced by the fire restricts the supply of water to the surface, reducing evaporation and providing a strong negative feedback to disturbance. This previously unidentified feedback operates at the landscape scale. High surface temperatures that result from large reductions in evaporation within water repellent peat are observed across the 60,000 ha burn scar three months after the wildfire. This promotes high water table positions at a landscape scale which limit the rate of peat decomposition and supports the post fire ecohydrological recovery of the peatlands. However, severe burns are shown to exceed this negative feedback response. Deep burns at the peatland margins remove the hydrophobic layer, increasing post fire evaporation and leaving the peatland vulnerable to drying and associated ecological shifts.

  13. Evaporation-induced cavitation in nanofluidic channels

    PubMed Central

    Duan, Chuanhua; Karnik, Rohit; Lu, Ming-Chang; Majumdar, Arun

    2012-01-01

    Cavitation, known as the formation of vapor bubbles when liquids are under tension, is of great interest both in condensed matter science as well as in diverse applications such as botany, hydraulic engineering, and medicine. Although widely studied in bulk and microscale-confined liquids, cavitation in the nanoscale is generally believed to be energetically unfavorable and has never been experimentally demonstrated. Here we report evaporation-induced cavitation in water-filled hydrophilic nanochannels under enormous negative pressures up to -7 MPa. As opposed to receding menisci observed in microchannel evaporation, the menisci in nanochannels are pinned at the entrance while vapor bubbles form and expand inside. Evaporation in the channels is found to be aided by advective liquid transport, which leads to an evaporation rate that is an order of magnitude higher than that governed by Fickian vapor diffusion in macro- and microscale evaporation. The vapor bubbles also exhibit unusual motion as well as translational stability and symmetry, which occur because of a balance between two competing mass fluxes driven by thermocapillarity and evaporation. Our studies expand our understanding of cavitation and provide new insights for phase-change phenomena at the nanoscale. PMID:22343530

  14. TANK 32 EVAPORATOR FEED PUMP TRANSFER ANALYSIS

    SciTech Connect

    Tamburello, D; Richard Dimenna, R; Si Lee, S

    2009-01-27

    The transfer of liquid salt solution from Tank 32 to an evaporator is to be accomplished by activating the evaporator feed pump, with the supernate surface at a minimum height of approximately 74.4 inches above the sludge layer, while simultaneously turning on the downcomer with a flow rate of 110 gpm. Previously, activation of the evaporator feed pump was an isolated event without any other components running at the same time. An analysis of the dissolved solution transfer has been performed using computational fluid dynamics (CFD) methods to determine the amount of entrained sludge solids pumped out of the tank toward the evaporator with the downcomer turned on. The analysis results shows that, for the minimum tank liquid level of 105 inches above the tank bottom (which corresponds to a liquid depth of 74.4 inches above the sludge layer), the evaporator feed pump will contain less than 0.1 wt% sludge solids in the discharge stream, which is an order of magnitude less than the 1.0 wt% undissolved solids (UDS) loading criteria to feed the evaporator. Lower liquid levels with respect to the sludge layer will result in higher amounts of sludge entrainment due to the increased plunging jet velocity from the downcomer disturbing the sludge layer.

  15. Optimized evaporation technique for leachate treatment: Small scale implementation.

    PubMed

    Benyoucef, Fatima; Makan, Abdelhadi; El Ghmari, Abderrahman; Ouatmane, Aziz

    2016-04-01

    This paper introduces an optimized evaporation technique for leachate treatment. For this purpose and in order to study the feasibility and measure the effectiveness of the forced evaporation, three cuboidal steel tubs were designed and implemented. The first control-tub was installed at the ground level to monitor natural evaporation. Similarly, the second and the third tub, models under investigation, were installed respectively at the ground level (equipped-tub 1) and out of the ground level (equipped-tub 2), and provided with special equipment to accelerate the evaporation process. The obtained results showed that the evaporation rate at the equipped-tubs was much accelerated with respect to the control-tub. It was accelerated five times in the winter period, where the evaporation rate was increased from a value of 0.37 mm/day to reach a value of 1.50 mm/day. In the summer period, the evaporation rate was accelerated more than three times and it increased from a value of 3.06 mm/day to reach a value of 10.25 mm/day. Overall, the optimized evaporation technique can be applied effectively either under electric or solar energy supply, and will accelerate the evaporation rate from three to five times whatever the season temperature. PMID:26826455

  16. Reply to the comments on "Comparison of Mann-Kendall and innovative trend method for water quality parameters of the Kizilirmak River, Turkey" by Kisi, O. and Ay, M. [J. Hydrol. 513 (2014) 362-375] and "An innovative method for trend analysis of monthly pan evaporations" by Kisi, O. [J. Hydrol. 527 (2015) 1123-1129

    NASA Astrophysics Data System (ADS)

    Kisi, Ozgur; Ay, Murat

    2016-07-01

    We thank discusser for his comments on our recent papers about application of innovative trend method (Şen, 2012) for water quality parameters (Kisi and Ay, 2014) and evaporation (Kisi, 2015) and are grateful for having the opportunity to explain and discuss the concerns raised. Illustration of the innovative Şen's trend method with some trend possibilities in the comments by discusser (in Fig. 3 in his discussion) has simple data seem to have normal distribution. However, some data may have highly skewed distribution and indicating trends in these data similar to the Figure 3 as suggested by discusser is impossible. Innovative trend analysis (Şen, 2012) of annual low flows for the duration 14-day (Q14) and 60-day (Q60) in Peterek and Dutdere stations are illustrated in Fig. 1 as an example. In Fig. 1, both half time series are sorted in ascending order. Therefore, Kisi and Ay (2014) provided "a general view" or "imaginative illustration" for the innovative Şen's trend method in Fig. 2 in their study. By this figure, general trend possibilities for any data having different distributions can be shown.

  17. Waste Feed Evaporation Physical Properties Modeling

    SciTech Connect

    Daniel, W.E.

    2003-08-25

    This document describes the waste feed evaporator modeling work done in the Waste Feed Evaporation and Physical Properties Modeling test specification and in support of the Hanford River Protection Project (RPP) Waste Treatment Plant (WTP) project. A private database (ZEOLITE) was developed and used in this work in order to include the behavior of aluminosilicates such a NAS-gel in the OLI/ESP simulations, in addition to the development of the mathematical models. Mathematical models were developed that describe certain physical properties in the Hanford RPP-WTP waste feed evaporator process (FEP). In particular, models were developed for the feed stream to the first ultra-filtration step characterizing its heat capacity, thermal conductivity, and viscosity, as well as the density of the evaporator contents. The scope of the task was expanded to include the volume reduction factor across the waste feed evaporator (total evaporator feed volume/evaporator bottoms volume). All the physical properties were modeled as functions of the waste feed composition, temperature, and the high level waste recycle volumetric flow rate relative to that of the waste feed. The goal for the mathematical models was to predict the physical property to predicted simulation value. The simulation model approximating the FEP process used to develop the correlations was relatively complex, and not possible to duplicate within the scope of the bench scale evaporation experiments. Therefore, simulants were made of 13 design points (a subset of the points used in the model fits) using the compositions of the ultra-filtration feed streams as predicted by the simulation model. The chemistry and physical properties of the supernate (the modeled stream) as predicted by the simulation were compared with the analytical results of experimental simulant work as a method of validating the simulation software.

  18. Kinetic Limited Water Evaporation in Hydrophilic Nanofluidic Channels

    NASA Astrophysics Data System (ADS)

    Li, Yinxiao; Alibakhshi, Mohammad Amin; Xie, Quan; Duan, Chuanhua

    2015-11-01

    Capillary evaporation is one of the most efficient approaches for heat and mass transfer, but the interfacial resistance in capillary evaporation governed by the kinetic theory has remained poorly understood. Here we report experimental studies of the kinetic-limited water capillary evaporation in 2-D hydrophilic nanochannels. A novel hybrid nanochannel design is employed to guarantee sufficient water supply to the liquid/vapor evaporation interface and to enable precise evaporation rate measurements. We study the effects of confinement (16 ~ 105nm), temperature (20 ~ 40 °C), and relative humidity (0% ~ 60%) on the evaporation rate and the evaporation coefficient. A maximum evaporation flux of 21287 micron/s is obtained in 16-nm nanochannels at 40°C and RH =0%, which corresponds to a heat flux of 4804 W/cm°. The evaporation coefficient is found to be independent on geometrical confinement, but shows a clear dependence on temperature, decreasing from 0.55 at 20°C to 0.5 at 40 °C. These findings have implications for understanding heat and mass transport in nanofluidic devices and porous media, and shed light on further development of evaporation-based technologies for thermal management, membrane purification and lab-on-a-chip devices. The work is supported by the American Chemical Society Petroleum Research Fund (ACS PRF # 54118-DNI7) and the Faculty Startup Fund (Boston University, USA).

  19. The continuous similarity model of bulk soil-water evaporation

    NASA Technical Reports Server (NTRS)

    Clapp, R. B.

    1983-01-01

    The continuous similarity model of evaporation is described. In it, evaporation is conceptualized as a two stage process. For an initially moist soil, evaporation is first climate limited, but later it becomes soil limited. During the latter stage, the evaporation rate is termed evaporability, and mathematically it is inversely proportional to the evaporation deficit. A functional approximation of the moisture distribution within the soil column is also included in the model. The model was tested using data from four experiments conducted near Phoenix, Arizona; and there was excellent agreement between the simulated and observed evaporation. The model also predicted the time of transition to the soil limited stage reasonably well. For one of the experiments, a third stage of evaporation, when vapor diffusion predominates, was observed. The occurrence of this stage was related to the decrease in moisture at the surface of the soil. The continuous similarity model does not account for vapor flow. The results show that climate, through the potential evaporation rate, has a strong influence on the time of transition to the soil limited stage. After this transition, however, bulk evaporation is independent of climate until the effects of vapor flow within the soil predominate.

  20. A Hundred Years of Peter Pan

    ERIC Educational Resources Information Center

    Hollindale, Peter

    2005-01-01

    The centenary of the first performance of J. M. Barrie's Peter Pan was celebrated in December 2004. Taking account of the various events in Britain to mark the occasion--newspaper articles, radio and television programmes, retrospects in the original theatre--this article examines the status and popularity of Peter Pan after a hundred years. The…

  1. African Drum and Steel Pan Ensembles.

    ERIC Educational Resources Information Center

    Sunkett, Mark E.

    2000-01-01

    Discusses how to develop both African drum and steel pan ensembles providing information on teacher preparation, instrument choice, beginning the ensemble, and lesson planning. Includes additional information for the drum ensembles. Lists references and instructional materials, sources of drums and pans, and common note layout/range for steel pan…

  2. Disruption of tillage pans by slot tillage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In some areas of the central Great Plains, traditional sweep tillage for weed control has led to a root-restrictive tillage pan approximately 10 to 15 cm beneath the soil surface. Producers have shown interest in methods to disrupt this tillage pan prior to transitioning to no-till soil management. ...

  3. Peter Pan: The Text and the Myth.

    ERIC Educational Resources Information Center

    Hollindale, Peter

    1993-01-01

    Shows how the critical reception of J. M. Barrie's "Peter Pan" has varied widely since its publication. Describes the mythical qualities of the Peter Pan character and gives reasons why the story is still popular with children and why it should continue to be taught and read. (HB)

  4. Combined Evaporation and Salt Precipitation in Porous Media

    NASA Astrophysics Data System (ADS)

    Weisbrod, N.; Dragila, M. I.; Nachshon, U.; Or, D.; Shaharani, E.; Grader, A.

    2012-12-01

    The vadose zone pore water contains dissolved salts and minerals; therefore, evaporation results in high rates of salt accumulation that may change the physical and chemical properties of the porous media. Here, a series of experiments, together with a mathematical model, are presented to shed new light on these processes. Experiments included: (1) long-term column evaporation experiments to quantify changes in evaporation rates due to salt precipitation; (2) CT scans of evaporated porous media samples saturated with salt solutions, to observe salt precipitation from micro to macro scales; and (3) Infrared thermography analysis to quantify evaporation rates from porous media surfaces for homogeneous and heterogeneous conditions and constant water table, in the presence of salt precipitation. As expected, the majority of salt crystallization occurs in the upper parts of the matrix, near the evaporation front. For heterogeneous porous matrices, salt precipitation will occur mainly in the fine pore regions as preferential evaporation takes place in these locations. In addition, it was found that the precipitated NaCl salt crust diffusion coefficient for water vapor is one to two orders of magnitude lower than the vapor diffusion coefficient in free air, depending on environmental conditions and salt crystallization rates. Three new stages of evaporation were defined for saline solutions: SS1, SS2 and SS3. SS1 exhibits a low and gradual decrease in the evaporation rate due to osmotic pressure. During SS2, the evaporation rate falls progressively due to salt precipitation; SS3 is characterized by a constant low evaporation rate and determined by the diffusion rate of water vapor through the precipitated salt layer. Even though phenomenologically similar to the classical evaporation stages of pure water, these stages correspond to different mechanisms and the transition between stages can occur regardless the hydraulic conditions. As well, it was shown that matrix

  5. Structuring of polymer solutions upon solvent evaporation

    NASA Astrophysics Data System (ADS)

    Schaefer, C.; van der Schoot, P.; Michels, J. J.

    2015-02-01

    The morphology of solution-cast, phase-separated polymers becomes finer with increasing solvent evaporation rate. We address this observation theoretically for a model polymer where demixing is induced by steady solvent evaporation. In contrast to what is the case for a classical, thermal quench involving immiscible blends, the spinodal instability initially develops slowly and the associated length scale is not time invariant but decreases with time as t-1 /2. After a time lag, phase separation accelerates. Time lag and characteristic length exhibit power-law behavior as a function of the evaporation rate with exponents of -2 /3 and -1 /6 . Interestingly, at later stages the spinodal structure disappears completely while a second length scale develops. The associated structure coarsens but does not follow the usual Lifshitz-Slyozov-Wagner kinetics.

  6. Evaporation-induced self-assembled silica colloidal particle-assisted nanoporous structural evolution of poly(ethylene terephthalate) nonwoven composite separators for high-safety/high-rate lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Ran; Won, Ji-Hye; Kim, Jong Hun; Kim, Ki Jae; Lee, Sang-Young

    2012-10-01

    A facile approach to the fabrication of nanoporous structure-tuned nonwoven composite separators is demonstrated for application in high-safety/high-rate lithium-ion batteries. This strategy is based on the construction of silica (SiO2) colloidal particle-assisted nanoporous structure in a poly(ethylene terephthalate) (PET) nonwoven substrate. The nanoparticle arrangement arising from evaporation-induced self-assembly of SiO2 colloidal particles allows the evolution of the unusual nanoporous structure, i.e. well-connected interstitial voids formed between close-packed SiO2 particles adhered by styrene-butadiene rubber (SBR) binders. Meanwhile, the PET nonwoven serves as a mechanical support that contributes to suppressing thermal shrinkage of the nonwoven composite separator. The aforementioned structural novelty of the nonwoven composite separator plays a key role in providing the separator with advantageous characteristics (specifically, good electrolyte wettability, high ionic conductivity, and benign compatibility with electrodes), which leads to the better cell performance than a commercialized polyethylene (PE) separator.

  7. Dry deposition of pan to grassland vegetation

    SciTech Connect

    Doskey, P.V.; Wesely, M.L.; Cook, D.R.; Gao, W.

    1994-01-01

    Peroxyacetyl nitrate or PAN (CH{sub 3}C(O)OONO{sub 2}) is formed in the lower troposphere via photochemical reactions involving nitrogen oxides (NO{sub x}) and non-methane hydrocarbons (NMHCs). PAN has a lifetime in the free troposphere of about three months and is removed by photolysis or reaction with OH. Dry deposition will decrease its lifetime, although the few measurements that have been made indicate that this process is slow. Measurements of the uptake of PAN by alfalfa in growth chambers indicated that the dry deposition velocity (downward flux divided by concentration at a specified height) was 0.75 cm s{sup {minus}1}. Garland and Penkett measured a dry deposition velocity of 0.25 cm s{sup {minus}1} for PAN to grass and soil in a return-flow wind tunnel. Shepson et al. (1992) analyzed trends of PAN and O{sub 3} concentrations in the stable nocturnal boundary layer over mixed deciduous/coniferous forests at night, when leaf stomata were closed, and concluded that the deposition velocity for PAN was at least 0.5 cm s{sup {minus}1}. We measured the dry deposition velocity of PAN to a grassland site in the midwestern United States with a modified Bowen ratio technique. Experiments were conducted on selected days during September, October, and November of 1990. An energy balance Bowen ratio station was used to observe the differences in air temperature and water vapor content between heights of 3.0 and 0.92 m and to evaluate the surface energy balance. Air samples collected at the same two heights in Teflon {reg_sign} bags were analyzed for PAN by a gas chromatographic technique. We present an example of the variations of PAN concentrations and gradients observed during the day and compare measurements of the dry deposition velocity to expectations based on the physicochemical properties of PAN.

  8. Physiological adjustments of sand gazelles (Gazella subgutturosa) to a boom-or-bust economy: standard fasting metabolic rate, total evaporative water loss, and changes in the sizes of organs during food and water restriction.

    PubMed

    Ostrowski, Stephane; Mesochina, Pascal; Williams, Joseph B

    2006-01-01

    To test the hypothesis that desert ungulates adjust their physiology in response to long-term food and water restriction, we established three groups of sand gazelles (Gazella subgutturosa): one that was provided food and water (n = 6; CTRL) ad lib. for 4 mo, one that received ad lib. food and water for the same period but was deprived of food and water for the last 4.5 d (n = 6; EXPT(1)), and one that was exposed to 4 mo of progressive food and water restriction, an experimental regime designed to mimic conditions in a natural desert setting (n = 6; EXPT(2)). At the end of the 4-mo experiment, we measured standard fasting metabolic rate (SFMR) and total evaporative water loss (TEWL) of all sand gazelles and determined lean dry mass of organs of gazelles in CTRL and EXPT(2). Gazelles in CTRL had a mean SFMR of 2,524 +/- 194 kJ d(-1), whereas gazelles in EXPT(1) and EXPT(2) had SFMRs of 2,101+/- 232 and 1,365 +/- 182 kJ d(-1), respectively, values that differed significantly when we controlled for differences in body mass. Gazelles had TEWLs of 151.1 +/- 18.2, 138.5 +/- 17.53, and 98.4 +/- 27.2 g H(2)O d(-1) in CTRL, EXPT(1), and EXPT(2), respectively. For the latter group, mass-independent TEWL was 27.1% of the value for CTRL. We found that normally hydrated sand gazelles had a low mass-adjusted TEWL compared with other arid-zone ungulates: 13.6 g H(2)O kg(-0.898) d(-1), only 17.1% of allometric predictions, the lowest ever measured in an arid-zone ungulate. After 4 mo of progressive food and water restriction, dry lean mass of liver, heart, and muscle of gazelles in EXPT(2) was significantly less than that of these same organs in CTRL, even when we controlled for body mass decrease. Decreases in the dry lean mass of liver explained 70.4% of the variance of SFMR in food- and water-restricted gazelles. As oxygen demands decreased because of reduced organ sizes, gazelles lost less evaporative water, probably because of a decreased respiratory water loss. PMID

  9. Raman Thermometry Measurements of Free Evaporation from LiquidWater Droplets

    SciTech Connect

    Smith, Jared D.; Cappa, Christopher D.; Drisdell, Walter S.; Cohen, Ron ald C.; Saykally, Richard J.

    2006-05-22

    Recent theoretical and experimental studies of evaporation have suggested that on average, molecules in the higher-energy tail of the Boltzmann distribution are more readily transferred into the vapor during evaporation. To test these conclusions, the evaporative cooling rates of a droplet train of liquid water injected into vacuum have been studied via Raman thermometry. The resulting cooling rates are fit to an evaporative cooling model based on Knudsen's maximum rate of evaporation, in which we explicitly account for surface cooling. We have determined that the value of the evaporation coefficient ({gamma}{sub e}) of liquid water is 0.62 {+-} 0.09, confirming that a rate-limiting barrier impedes the evaporation rate. Such insight will facilitate the formulation of a microscopic mechanism for the evaporation of liquid water.

  10. Spacesuit Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Hodgson, Ed; Izenso, Mike; Chan, Weibo; Cupples, Scott

    2011-01-01

    For decades advanced spacesuit developers have pursued a regenerable, robust non-venting system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's lithium chloride Heat Pump Radiator (HPR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. The SEAR is evacuated at the onset of operations and thereafter, the water vapor absorption rate of the HPR maintains a low pressure environment for the SWME to evaporate effectively. This water vapor captured by solid LiCl in the HPR with a high enthalpy of absorption, results in sufficient temperature lift to reject most of the heat to space by radiation. After the sortie, the HPR would be heated up in a regenerator to drive off and recover the absorbed evaporant. A one-fourth scale prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The HPR was able to stably reject 60 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

  11. Early science from the Pan-STARRS1 Optical Galaxy Survey (POGS): Maps of stellar mass and star formation rate surface density obtained from distributed-computing pixel-SED fitting

    NASA Astrophysics Data System (ADS)

    Thilker, David A.; Vinsen, K.; Galaxy Properties Key Project, PS1

    2014-01-01

    To measure resolved galactic physical properties unbiased by the mask of recent star formation and dust features, we are conducting a citizen-scientist enabled nearby galaxy survey based on the unprecedented optical (g,r,i,z,y) imaging from Pan-STARRS1 (PS1). The PS1 Optical Galaxy Survey (POGS) covers 3π steradians (75% of the sky), about twice the footprint of SDSS. Whenever possible we also incorporate ancillary multi-wavelength image data from the ultraviolet (GALEX) and infrared (WISE, Spitzer) spectral regimes. For each cataloged nearby galaxy with a reliable redshift estimate of z < 0.05 - 0.1 (dependent on donated CPU power), publicly-distributed computing is being harnessed to enable pixel-by-pixel spectral energy distribution (SED) fitting, which in turn provides maps of key physical parameters such as the local stellar mass surface density, crude star formation history, and dust attenuation. With pixel SED fitting output we will then constrain parametric models of galaxy structure in a more meaningful way than ordinarily achieved. In particular, we will fit multi-component (e.g. bulge, bar, disk) galaxy models directly to the distribution of stellar mass rather than surface brightness in a single band, which is often locally biased. We will also compute non-parametric measures of morphology such as concentration, asymmetry using the POGS stellar mass and SFR surface density images. We anticipate studying how galactic substructures evolve by comparing our results with simulations and against more distant imaging surveys, some of which which will also be processed in the POGS pipeline. The reliance of our survey on citizen-scientist volunteers provides a world-wide opportunity for education. We developed an interactive interface which highlights the science being produced by each volunteer’s own CPU cycles. The POGS project has already proven popular amongst the public, attracting about 5000 volunteers with nearly 12,000 participating computers, and is

  12. Synthesis and characterization of multiwalled CNT-PAN based composite carbon nanofibers via electrospinning.

    PubMed

    Kaur, Narinder; Kumar, Vipin; Dhakate, Sanjay R

    2016-01-01

    Electrospun fibrous membranes find place in diverse applications like sensors, filters, fuel cell membranes, scaffolds for tissue engineering, organic electronics etc. The objectives of present work are to electrospun polyacrylonitrile (PAN) nanofibers and PAN-CNT nanocomposite nanofibers and convert into carbon nanofiber and carbon-CNT composite nanofiber. The work was divided into two parts, development of nanofibers and composite nanofiber. The PAN nanofibers were produced from 9 wt% PAN solution by electrospinning technique. In another case PAN-CNT composite nanofibers were developed from different concentrations of MWCNTs (1-3 wt%) in 9 wt% PAN solution by electrospinning. Both types of nanofibers were undergone through oxidation, stabilization, carbonization and graphitization. At each stage of processing of carbon and carbon-CNT composite nanofibers were characterized by SEM, AFM, TGA and XRD. It was observed that diameter of nanofiber varies with processing parameters such as applied voltage tip to collector distance, flow rate of solution and polymer concentrations etc. while in case of PAN-CNT composite nanofiber diameter decreases with increasing concentration of CNT in PAN solution. Also with stabilization, carbonization and graphitization diameter of nanofiber decreases. SEM images shows that the minimum fiber diameter in case of 3 wt% of CNT solution because as viscosity increases it reduces the phase separation of PAN and solvent and as a consequence increases in the fiber diameter. AFM images shows that surface of film is irregular which give idea about mat type orientation of fibers. XRD results show that degree of graphitization increases on increasing CNT concentration because of additional stresses exerting on the nanofiber surface in the immediate vicinity of CNTs. TGA results shows wt loss decreases as CNT concentration increases in fibers. PMID:27217998

  13. Inundation and groundwater dynamics for quantification of evaporative water loss in tropical wetlands

    NASA Astrophysics Data System (ADS)

    Schwerdtfeger, J.; Johnson, M. S.; Couto, E. G.; Amorim, R. S. S.; Sanches, L.; Campelo Júnior, J. H.; Weiler, M.

    2014-04-01

    The remoteness, complexity and heterogeneity of tropical wetlands make the characterisation of their hydrological processes challenging. In particular estimates of evaporative water loss are inherently uncertain. In view of the large influence on the local and regional climate, the quantification of evaporation is essential for the determination of the water balance of permanent and intermittent water bodies. Data for tropical wetlands are scarce where their remoteness impedes direct evaporation measurements. Seasonal inundation dynamics affect evaporation processes in tropical wetlands, which can be analysed in two stages: the first stage during the wet season and the second stage during the dry season. As yet no adequate method exists for determining second stage evaporation without soil moisture data, which are usually unavailable for the remote tropical wetlands. Our study aimed at developing a process-based model to simulate first and second stage evaporation in tropical wetlands. We selected a set of empirical potential evaporation (PET) models of varying complexity, each based on different assumptions and available datasets, and evaluated the models with pan evaporation observations in the Pantanal of South America, one of the largest tropical wetlands in the world. We used high-resolution measurements of surface and groundwater levels at different locations to determine the water available for evaporation. Actual evaporation (AET) was derived by constraining simulated PET based on available water. The model of best fit was applied to different types of water bodies with varying inundation durations and captured first and second stage evaporation. With our new model we could quantify evaporative water loss in the dry and the wet season for different locations in the Pantanal. This new spatially-explicit approach represents an improvement in our understanding of the role of evaporation in the water balance of the Pantanal. We recommend the application of this

  14. Inundation and groundwater dynamics for quantification of evaporative water loss in tropical wetlands

    NASA Astrophysics Data System (ADS)

    Schwerdtfeger, J.; Johnson, M. S.; Couto, E. G.; Amorim, R. S. S.; Sanches, L.; Campelo, J. H., Jr.; Weiler, M.

    2014-11-01

    Characterizing hydrological processes within tropical wetlands is challenging due to their remoteness, complexity and heterogeneity. In particular, estimates of evaporative water loss are inherently uncertain. In view of the large influence on the local and regional climate, the quantification of evaporation is essential for the determination of the water balance of permanent and intermittent water bodies. Data for tropical wetlands are scarce where their remoteness impedes direct evaporation measurements. Seasonal inundation dynamics affect evaporation processes in tropical wetlands, which can be analysed in two stages: the first stage during the wet season and the second stage during the dry season. As yet no adequate method exists for determining second-stage evaporation in a data-scarce environment that additionally allows for a transfer of simulated actual evaporation (AET) to other locations. Our study aimed at developing a process-based model to simulate first- and second-stage evaporation in tropical wetlands. We selected a set of empirical potential evaporation (PET) models of varying complexity, each based on different assumptions and available data sets, and evaluated the models with pan evaporation observations in the Pantanal of South America, one of the largest tropical wetlands in the world. We used high-resolution measurements of surface and groundwater levels at different locations to determine the water available for evaporation. AET was derived by constraining simulated PET based on available water. The model of best fit was applied to different types of water bodies with varying hydroperiods to capture first- and second-stage evaporation across a range of wetland types. With our new model we could quantify evaporative water loss in the dry and the wet season for different locations in the Pantanal. This new spatially explicit approach represents an improvement in our understanding of the role of evaporation in the water balance of the Pantanal

  15. Convective Evaporation Of Sprayed Liquid

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Harstad, Kenneth G.

    1987-01-01

    Theoretical model developed to analyze behavior of both dense and dilute clusters of evaporating liquid drops in gas flows. Particularly useful in search for methods of controlling evaporation, ignition, and combustion of fuel sprays.

  16. MOVES2014: Evaporative Emissions Report

    EPA Science Inventory

    Vehicle evaporative emissions are now modeled in EPA’s MOVES according to physical processes, permeation, tank vapor venting, liquid leaks, and refueling emissions. With this update, the following improvements are being incorporated into MOVES evaporative emissions methodology, a...

  17. Evaporative cooling of antiprotons for the production of trappable antihydrogen

    SciTech Connect

    Silveira, D. M.; Cesar, C. L.; Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Ashkezari, M. D.; Hayden, M. E.; Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C.; Wurtele, J. S.; Bertsche, W.; Butler, E.; Charlton, M.; Madsen, N.; Werf, D. P. van der; Friesen, T.; Hydomako, R.; and others

    2013-03-19

    We describe the implementation of evaporative cooling of charged particles in the ALPHA apparatus. Forced evaporation has been applied to cold samples of antiprotons held in Malmberg-Penning traps. Temperatures on the order of 10 K were obtained, while retaining a significant fraction of the initial number of particles. We have developed a model for the evaporation process based on simple rate equations and applied it succesfully to the experimental data. We have also observed radial re-distribution of the clouds following evaporation, explained by simple conservation laws. We discuss the relevance of this technique for the recent demonstration of magnetic trapping of antihydrogen.

  18. Evaporated VOx Thin Films

    NASA Astrophysics Data System (ADS)

    Stapinski, Tomasz; Leja, E.

    1989-03-01

    VOx thin films on glass were obtained by thermal evaporation of V205, powder. The structural investigations were carried out with the use of X-ray diffractometer. The electrical properties of the film were examined by means of temperature measurements of resistivity for the samples heat-treated in various conditions. Optical transmission and reflection spectra of VOX films of various composition showed the influence of the heat treatment.

  19. Falling film evaporator

    DOEpatents

    Bruns, Lester E.

    1976-01-01

    A falling film evaporator including a vertically oriented pipe heated exteriorly by a steam jacket and interiorly by a finned steam tube, all heating surfaces of the pipe and steam tube being formed of a material wet by water such as stainless steel, and packing within the pipe consisting of Raschig rings formed of a material that is not wet by water such as polyvinylidene fluoride.

  20. Vertical counterflow evaporative cooler

    DOEpatents

    Bourne, Richard C.; Lee, Brian Eric; Callaway, Duncan

    2005-01-25

    An evaporative heat exchanger having parallel plates that define alternating dry and wet passages. A water reservoir is located below the plates and is connected to a water distribution system. Water from the water distribution system flows through the wet passages and wets the surfaces of the plates that form the wet passages. Air flows through the dry passages, mixes with air below the plates, and flows into the wet passages before exiting through the top of the wet passages.

  1. A phylogenetic approach to total evaporative water loss in mammals.

    PubMed

    Van Sant, Matthew J; Oufiero, Christopher E; Muñoz-Garcia, Agustí; Hammond, Kimberly A; Williams, Joseph B

    2012-01-01

    Maintaining appropriate water balance is a constant challenge for terrestrial mammals, and this problem can be exacerbated in desiccating environments. It has been proposed that natural selection has provided desert-dwelling mammals physiological mechanisms to reduce rates of total evaporative water loss. In this study, we evaluated the relationship between total evaporative water loss and body mass in mammals by using a recent phylogenetic hypothesis. We compared total evaporative water loss in 80 species of arid-zone mammals to that in 56 species that inhabit mesic regions, ranging in size from 4 g to 3,500 kg, to test the hypothesis that mammals from arid environments have lower rates of total evaporative water loss than mammals from mesic environments once phylogeny is taken into account. We found that arid species had lower rates of total evaporative water loss than mesic species when using a dichotomous variable to describe habitat (arid or mesic). We also found that total evaporative water loss was negatively correlated with the average maximum and minimum environmental temperature as well as the maximum vapor pressure deficit of the environment. Annual precipitation and the variable Q (a measure of habitat aridity) were positively correlated with total evaporative water loss. These results support the hypothesis that desert-dwelling mammals have lower rates of total evaporative water loss than mesic species after controlling for body mass and evolutionary relatedness regardless of whether categorical or continuous variables are used to describe habitat. PMID:22902381

  2. An investigation of electrochemomechanical actuation of conductive Polyacrylonitrile (PAN) nanofiber composites

    NASA Astrophysics Data System (ADS)

    Gonzalez, Mark A.; Walter, Wayne W.

    2014-03-01

    A polymer-based nanofiber composite actuator designed for contractile actuation was fabricated by electrospinning, stimulated by electrolysis, and characterized by electrochemical and mechanical testing to address performance limitations and understand the activation processing effects on actuation performance. Currently, Electroactive polymers (EAPs) have provided uses in sensory and actuation technology, but have either low force output or expand rather than contract, falling short in capturing the natural kinetics and mechanics of muscle needed to provide breakthroughs in the bio-medical and robotic fields. In this study, activated Polyacrylonitrile (PAN) fibers have demonstrated biomimetic functionalities similar to the sarcomere contraction responsible for muscle function. Activated PAN has also been shown to contract and expand by electrolysis when in close vicinity to the anode and cathode, respectively. PAN nanofibers (~500 nm) especially show faster response to changes in environmental pH and improved mechanical properties compared to larger diameter fibers. Tensile testing was conducted to examine changes in mechanical properties between annealing and hydrolysis processing. Voltage driven transient effects of localized pH were examined to address pHdefined actuation thresholds of PAN fibers. Electrochemical contraction rates of the PAN/Graphite composite actuator demonstrated up to 25%/min. Strains of 58.8%, ultimate stresses up to 77.1 MPa, and moduli of 0.21 MPa were achieved with pure PAN nanofiber mats, surpassing mechanical properties of natural muscles. Further improvements, however, to contraction rates and Young's moduli were found essential to capture the function and performance of skeletal muscles appropriately.

  3. Evaporative Cooling of Antiprotons to Cryogenic Temperatures

    SciTech Connect

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Ashkezari, M. D.; Hayden, M. E.; Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C.; Wurtele, J. S.; Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A.; Madsen, N.; Werf, D. P. van der; Wilding, D.; Cesar, C. L.; Lambo, R.

    2010-07-02

    We report the application of evaporative cooling to clouds of trapped antiprotons, resulting in plasmas with measured temperature as low as 9 K. We have modeled the evaporation process for charged particles using appropriate rate equations. Good agreement between experiment and theory is observed, permitting prediction of cooling efficiency in future experiments. The technique opens up new possibilities for cooling of trapped ions and is of particular interest in antiproton physics, where a precise CPT test on trapped antihydrogen is a long-standing goal.

  4. Evaporative cooling of antiprotons to cryogenic temperatures.

    PubMed

    Andresen, G B; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A; Hydomako, R; Jonsell, S; Kurchaninov, L; Lambo, R; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wilding, D; Wurtele, J S; Yamazaki, Y

    2010-07-01

    We report the application of evaporative cooling to clouds of trapped antiprotons, resulting in plasmas with measured temperature as low as 9 K. We have modeled the evaporation process for charged particles using appropriate rate equations. Good agreement between experiment and theory is observed, permitting prediction of cooling efficiency in future experiments. The technique opens up new possibilities for cooling of trapped ions and is of particular interest in antiproton physics, where a precise CPT test on trapped antihydrogen is a long-standing goal. PMID:20867439

  5. Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; Almlie, Jay C.

    2010-01-01

    A water membrane evaporator (WME) has been conceived and tested as an alternative to the contamination-sensitive and corrosion-prone evaporators currently used for dissipating heat from space vehicles. The WME consists mainly of the following components: An outer stainless-steel screen that provides structural support for the components mentioned next; Inside and in contact with the stainless-steel screen, a hydrophobic membrane that is permeable to water vapor; Inside and in contact with the hydrophobic membrane, a hydrophilic membrane that transports the liquid feedwater to the inner surface of the hydrophobic membrane; Inside and in contact with the hydrophilic membrane, an annular array of tubes through which flows the spacecraft coolant carrying the heat to be dissipated; and An inner exclusion tube that limits the volume of feedwater in the WME. In operation, a pressurized feedwater reservoir is connected to the volume between the exclusion tube and the coolant tubes. Feedwater fills the volume, saturates the hydrophilic membrane, and is retained by the hydrophobic membrane. The outside of the WME is exposed to space vacuum. Heat from the spacecraft coolant is conducted through the tube walls and the water-saturated hydrophilic membrane to the liquid/vapor interface at the hydrophobic membrane, causing water to evaporate to space. Makeup water flows into the hydrophilic membrane through gaps between the coolant tubes.

  6. Diagnosing Evaporation of Icy Planetesimals in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Nomura, Hideko; Ishimoto, Daiki; Nagasawa, Makiko; Tanaka, Kyoko K.; Miura, Hitoshi; Nakamoto, Taishi; Tanaka, Hidekazu; Yamamoto, Tetsuo

    2015-08-01

    It is thought that eccentricities of planetesimals are excited due to gravitational interaction with protoplanets in protoplanetary disks. As a result, bow shocks are formed around the icy planetesimals and the ice is evaporated via the shock heating. Evaporation rates and orbital evolution of such planetesimals have been investigated (Tanaka et al. 2013, Nagasawa et al. 2014). In this work, we examine a possibility of diagnosing the shock heating and evaporation of icy planetesimals, using ALMA observations of lines of molecules evaporated from the planetesimals.Evaporation of ice has been studied observationally and theoretically well, for example, at a shock front of outflows associated with young stellar objects. The evaporated molecules will be destroyed via chemical reactions with other species and/or depletion on dust grains. The evaporated molecules can survive in gas-phase for around 104years in the region hotter than their evaporation temperatures, while they freeze out immediately in the cold region. As parent species evaporated from ice, saturated nitrogen- or sulphur-bearing species and organic molecules are often considered.Our calculations show that evaporated H2S is destroyed via gas-phase reactions, and SO and then SO2 are produced via chemicalreactions. The timescale of these reactions is about 104years. Therefore, H2S and SO are good tracers of shock heating and evaporation of icy planetesimals if it occurs in the region hotter than the evaporation temperatures of H2S and SO. The evaporation temperature of SO2 is higher than those of H2S and SO.Molecular lines of H2S, SO, and SO2 have not yet been detected towards protoplanetary disks by the previous radio observations. ALMA observations with high sensitivity and high spatial resolution, however, will make it possible to detect the lines of these molecules. Conditions that molecular lines of H2S and SO becomes strong enough to be detected by ALMA observations will also be discussed.

  7. Evaporation determined by the energy-budget method for Mirror Lake, New Hampshire

    USGS Publications Warehouse

    Winter, T.C.; Buso, D.C.; Rosenberry, D.O.; Likens, G.E.; Sturrock, A.M., Jr.; Mau, D.P.

    2003-01-01

    Evaporation was determined by the energy-budget method for Mirror Lake during the open water periods of 1982-1987. For all years, evaporation rates were low in spring and fall and highest during the summer. However, the times of highest evaporation rates varied during the 6 yr. Evaporation reached maximum rates in July for three of the years, in June for two of the years, and in August for one of the years. The highest evaporation rate during the 6-yr study was 0.46 cm d-1 during 27 May-4 June 1986 and 15-21 July 1987. Solar radiation and atmospheric radiation input to the lake and long-wave radiation emitted from the lake were by far the largest energy fluxes to and from the lake and had the greatest effect on evaporation rates. Energy advected to and from the lake by precipitation, surface water, and ground water had little effect on evaporation rates. In the energy-budget method, average evaporation rates are determined for energy-budget periods, which are bounded by the dates of thermal surveys of the lake. Our study compared evaporation rates calculated for short periods, usually ???1 week, with evaporation rates calculated for longer periods, usually ???2 weeks. The results indicated that the shorter periods showed more variability in evaporation rates, but seasonal patterns, with few exceptions, were similar.

  8. Evaporation of stationary alcohol layer in minichannel under air flow

    NASA Astrophysics Data System (ADS)

    Afanasyev, Ilya; Orlova, Evgenija; Feoktistov, Dmitriy

    2015-01-01

    This paper presents experimental investigation of effect of the gas flow rate moving parallel to the stationary liquid layer on the evaporation rate under the conditions of formation of a stable plane "liquid-gas" interface. The average evaporation flow rate of liquid layer (ethanol) by the gas flow (air) has been calculated using two independent methods. Obtained results have been compared with previously published data.

  9. Normal evaporation of binary alloys

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1972-01-01

    In the study of normal evaporation, it is assumed that the evaporating alloy is homogeneous, that the vapor is instantly removed, and that the alloy follows Raoult's law. The differential equation of normal evaporation relating the evaporating time to the final solute concentration is given and solved for several important special cases. Uses of the derived equations are exemplified with a Ni-Al alloy and some binary iron alloys. The accuracy of the predicted results are checked by analyses of actual experimental data on Fe-Ni and Ni-Cr alloys evaporated at 1600 C, and also on the vacuum purification of beryllium. These analyses suggest that the normal evaporation equations presented here give satisfactory results that are accurate to within an order of magnitude of the correct values, even for some highly concentrated solutions. Limited diffusion and the resultant surface solute depletion or enrichment appear important in the extension of this normal evaporation approach.

  10. STEREO Sees Comet Pan-STARRS

    NASA Video Gallery

    In early March 2013, Comet PanSTARRS became visible to the naked eye in the night sky in the Northern Hemisphere, appearing with a similar shape and brightness as a star, albeit with a trailing tai...

  11. Preparation of thin film nanofibrous composite NF membrane based on EDC/NHS modified PAN-AA nanofibrous substrate

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Wang, X.; Hsiao, B. S.

    2016-07-01

    A novel kind of thin-film nanofibrous composite (TFNC) nanofiltration (NF) membranes consisting of a polyamide (PA) barrier layer were successfully fabricated by interfacial polymerization (IFP) based on electrospun double-layer nanofibrous substrates, which have an ultrathin poly (acrylonitrile-co-acrylic acid) (PAN-AA) nanofibrous layer as top layer and a thicker polyacrylonitrile (PAN) nanofiber layer as bottom porous support layer. Immersing PAN/PAN-AA nanofibrous substrates into 1-ethyl-(3-3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) aqueous solution and piperazine (PIP) aqueous solution (0.20 wt%) sequentially for a period of time, the carboxyl groups on PAN-AA nanofibers were activated by carbodiimide and then reacted with the amide groups. The as prepared composite membrane has an integrated structure with high rejection rate (98.0%); high permeate flux (40.4 L/m2h) for MgSO4 aqueous solution (2 g/L).

  12. Infrared thermography of evaporative fluxes and dynamics of salt deposition on heterogeneous porous surfaces

    NASA Astrophysics Data System (ADS)

    Nachshon, Uri; Shahraeeni, Ebrahim; Or, Dani; Dragila, Maria; Weisbrod, Noam

    2011-12-01

    Evaporation of saline solutions from porous media, common in arid areas, involves complex interactions between mass transport, energy exchange and phase transitions. We quantified evaporation of saline solutions from heterogeneous sand columns under constant hydraulic boundary conditions to focus on effects of salt precipitation on evaporation dynamics. Mass loss measurements and infrared thermography were used to quantify evaporation rates. The latter method enables quantification of spatial and temporal variability of salt precipitation to identify its dynamic effects on evaporation. Evaporation from columns filled with texturally-contrasting sand using different salt solutions revealed preferential salt precipitation within the fine textured domains. Salt precipitation reduced evaporation rates from the fine textured regions by nearly an order of magnitude. In contrast, low evaporation rates from coarse-textured regions (due to low capillary drive) exhibited less salt precipitation and consequently less evaporation rate suppression. Experiments provided insights into two new phenomena: (1) a distinct increase in evaporation rate at the onset of evaporation; and (2) a vapor pumping mechanism related to the presence of a salt crust over semidry media. Both phenomena are related to local vapor pressure gradients established between pore water and the surface salt crust. Comparison of two salts: NaCl and NaI, which tend to precipitate above the matrix surface and within matrix pores, respectively, shows a much stronger influence of NaCl on evaporation rate suppression. This disparity reflects the limited effect of NaI precipitation on matrix resistivity for solution and vapor flows.

  13. Monthly evaporation forecasting using artificial neural networks and support vector machines

    NASA Astrophysics Data System (ADS)

    Tezel, Gulay; Buyukyildiz, Meral

    2016-04-01

    Evaporation is one of the most important components of the hydrological cycle, but is relatively difficult to estimate, due to its complexity, as it can be influenced by numerous factors. Estimation of evaporation is important for the design of reservoirs, especially in arid and semi-arid areas. Artificial neural network methods and support vector machines (SVM) are frequently utilized to estimate evaporation and other hydrological variables. In this study, usability of artificial neural networks (ANNs) (multilayer perceptron (MLP) and radial basis function network (RBFN)) and ɛ-support vector regression (SVR) artificial intelligence methods was investigated to estimate monthly pan evaporation. For this aim, temperature, relative humidity, wind speed, and precipitation data for the period 1972 to 2005 from Beysehir meteorology station were used as input variables while pan evaporation values were used as output. The Romanenko and Meyer method was also considered for the comparison. The results were compared with observed class A pan evaporation data. In MLP method, four different training algorithms, gradient descent with momentum and adaptive learning rule backpropagation (GDX), Levenberg-Marquardt (LVM), scaled conjugate gradient (SCG), and resilient backpropagation (RBP), were used. Also, ɛ-SVR model was used as SVR model. The models were designed via 10-fold cross-validation (CV); algorithm performance was assessed via mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R 2). According to the performance criteria, the ANN algorithms and ɛ-SVR had similar results. The ANNs and ɛ-SVR methods were found to perform better than the Romanenko and Meyer methods. Consequently, the best performance using the test data was obtained using SCG(4,2,2,1) with R 2 = 0.905.

  14. Intensification of evaporation processes using surfactants

    NASA Astrophysics Data System (ADS)

    Sharifullin, V. N.; Sharifullin, A. V.

    2015-06-01

    The effect of a group of low molecular surfactants on the evaporation rate during nucleate boiling of water is investigated. It is found that the vaporization rate and heat flux from the heater increase by 4-8% in an electric boiler with surfactants. The analysis of the process based on the model of the phase contact surface restoration made it possible to formulate the mechanism of the effect of considered surfactants.

  15. 3 CFR 8651 - Proclamation 8651 of April 8, 2011. Pan American Day and Pan American Week, 2011

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 3 The President 1 2012-01-01 2012-01-01 false Proclamation 8651 of April 8, 2011. Pan American Day and Pan American Week, 2011 8651 Proclamation 8651 Presidential Documents Proclamations Proclamation 8651 of April 8, 2011 Proc. 8651 Pan American Day and Pan American Week, 2011By the President of...

  16. 3 CFR 8798 - Proclamation 8798 of April 9, 2012. Pan American Day and Pan American Week, 2012

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 3 The President 1 2013-01-01 2013-01-01 false Proclamation 8798 of April 9, 2012. Pan American Day and Pan American Week, 2012 8798 Proclamation 8798 Presidential Documents Proclamations Proclamation 8798 of April 9, 2012 Proc. 8798 Pan American Day and Pan American Week, 2012By the President of...

  17. 3 CFR 8957 - Proclamation 8957 of April 12, 2013. Pan American Day and Pan American Week, 2013

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 3 The President 1 2014-01-01 2014-01-01 false Proclamation 8957 of April 12, 2013. Pan American Day and Pan American Week, 2013 8957 Proclamation 8957 Presidential Documents Proclamations Proclamation 8957 of April 12, 2013 Proc. 8957 Pan American Day and Pan American Week, 2013By the President...

  18. Structural basis for Pan3 binding to Pan2 and its function in mRNA recruitment and deadenylation

    PubMed Central

    Wolf, Jana; Valkov, Eugene; Allen, Mark D; Meineke, Birthe; Gordiyenko, Yuliya; McLaughlin, Stephen H; Olsen, Tayla M; Robinson, Carol V; Bycroft, Mark; Stewart, Murray; Passmore, Lori A

    2014-01-01

    The conserved eukaryotic Pan2–Pan3 deadenylation complex shortens cytoplasmic mRNA 3′ polyA tails to regulate mRNA stability. Although the exonuclease activity resides in Pan2, efficient deadenylation requires Pan3. The mechanistic role of Pan3 is unclear. Here, we show that Pan3 binds RNA directly both through its pseudokinase/C-terminal domain and via an N-terminal zinc finger that binds polyA RNA specifically. In contrast, isolated Pan2 is unable to bind RNA. Pan3 binds to the region of Pan2 that links its N-terminal WD40 domain to the C-terminal part that contains the exonuclease, with a 2:1 stoichiometry. The crystal structure of the Pan2 linker region bound to a Pan3 homodimer shows how the unusual structural asymmetry of the Pan3 dimer is used to form an extensive high-affinity interaction. This binding allows Pan3 to supply Pan2 with substrate polyA RNA, facilitating efficient mRNA deadenylation by the intact Pan2–Pan3 complex. PMID:24872509

  19. 3 CFR 8495 - Proclamation 8495 of April 9, 2010. Pan American Day and Pan American Week, 2010

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 3 The President 1 2011-01-01 2011-01-01 false Proclamation 8495 of April 9, 2010. Pan American Day and Pan American Week, 2010 8495 Proclamation 8495 Presidential Documents Proclamations Proclamation 8495 of April 9, 2010 Proc. 8495 Pan American Day and Pan American Week, 2010By the President of the United States of America A Proclamation...

  20. A stochastic assessment of climate change impacts on precipitation and potential evaporation in Alberta

    NASA Astrophysics Data System (ADS)

    Vashchyshyn, I.; Wheater, H. S.; Chun, K.

    2012-12-01

    In many climate change investigations, changes in precipitation are projected under various scenarios; however, changes in evaporation have received relatively less attention. For irrigation and water resources management, the difference between potential evaporation and precipitation can provide better quantification of local water availability and drought conditions. Therefore, projecting joint variations in precipitation and potential evaporation can provide better information for climate change adaptation. A stochastic approach based on a Generalised Linear Model (GLM) framework is proposed to study these together at a station scale. Eight stations in Alberta are selected for which historical pan evaporation records and up-to-date meteorological information are available. Results show that potential evaporation estimated from Global Circulation Models directly can be unreliable. The evaporation ensemble simulated by the GLM approach can represent observed evaporation more realistically and provide better uncertainty quantification. If only simulated precipitation is considered, the projected drought conditions in the 2080s are likely to be less severe than that in the 2000s. However, the projected difference between precipitation and evaporation (water deficit) shows that the future drought conditions may be higher or lower, varying between the stations. Implications of the results and further development of the proposed approach to address spatial dependence between stations are also discussed.

  1. Pan-information Location Map

    NASA Astrophysics Data System (ADS)

    Zhu, X. Y.; Guo, W.; Huang, L.; Hu, T.; Gao, W. X.

    2013-11-01

    A huge amount of information, including geographic, environmental, socio-economic, personal and social network information, has been generated from diverse sources. Most of this information exists separately and is disorderly even if some of it is about the same person, feature, phenomenon or event. Users generally need to collect related information from different sources and then utilize them in applications. An automatic mechanism, therefore, for establishing a connection between potentially-related information will profoundly expand the usefulness of this huge body of information. A connection tie is semantic location describing semantically concepts and attributes of locations as well as relationships between locations, since 80% of information contains some kind of geographic reference but not all of geographic reference has explicit geographic coordinates. Semantic location is an orthogonal form of location representation which can be represented as domain ontology or UML format. Semantic location associates various kinds of information about a same object to provide timely information services according to users' demands, habits, preferences and applications. Based on this idea, a Pan-Information Location Map (PILM) is proposed as a new-style 4D map to associates semantic location-based information dynamically to organize and consolidate the locality and characteristics of corresponding features and events, and delivers on-demand information with a User-Adaptive Smart Display (UASD).

  2. Kepler Planets: A Tale of Evaporation

    NASA Astrophysics Data System (ADS)

    Owen, James E.; Wu, Yanqin

    2013-10-01

    Inspired by the Kepler mission's planet discoveries, we consider the thermal contraction of planets close to their parent star, under the influence of evaporation. The mass-loss rates are based on hydrodynamic models of evaporation that include both X-ray and EUV irradiation. We find that only low mass planets with hydrogen envelopes are significantly affected by evaporation, with evaporation being able to remove massive hydrogen envelopes inward of ~0.1 AU for Neptune-mass objects, while evaporation is negligible for Jupiter-mass objects. Moreover, most of the evaporation occurs in the first 100 Myr of stars' lives when they are more chromospherically active. We construct a theoretical population of planets with varying core masses, envelope masses, orbital separations, and stellar spectral types, and compare this population with the sizes and densities measured for low-mass planets, both in the Kepler mission and from radial velocity surveys. This exercise leads us to conclude that evaporation is the driving force of evolution for close-in Kepler planets. In fact, some 50% of the Kepler planet candidates may have been significantly eroded. Evaporation explains two striking correlations observed in these objects: a lack of large radius/low density planets close to the stars and a possible bimodal distribution in planet sizes with a deficit of planets around 2 R ⊕. Planets that have experienced high X-ray exposures are generally smaller than this size, and those with lower X-ray exposures are typically larger. A bimodal planet size distribution is naturally predicted by the evaporation model, where, depending on their X-ray exposure, close-in planets can either hold on to hydrogen envelopes ~0.5%-1% in mass or be stripped entirely. To quantitatively reproduce the observed features, we argue that not only do low-mass Kepler planets need to be made of rocky cores surrounded with hydrogen envelopes, but few of them should have initial masses above 20 M ⊕ and the

  3. KEPLER PLANETS: A TALE OF EVAPORATION

    SciTech Connect

    Owen, James E.; Wu, Yanqin E-mail: wu@astro.utoronto.ca

    2013-10-01

    Inspired by the Kepler mission's planet discoveries, we consider the thermal contraction of planets close to their parent star, under the influence of evaporation. The mass-loss rates are based on hydrodynamic models of evaporation that include both X-ray and EUV irradiation. We find that only low mass planets with hydrogen envelopes are significantly affected by evaporation, with evaporation being able to remove massive hydrogen envelopes inward of ∼0.1 AU for Neptune-mass objects, while evaporation is negligible for Jupiter-mass objects. Moreover, most of the evaporation occurs in the first 100 Myr of stars' lives when they are more chromospherically active. We construct a theoretical population of planets with varying core masses, envelope masses, orbital separations, and stellar spectral types, and compare this population with the sizes and densities measured for low-mass planets, both in the Kepler mission and from radial velocity surveys. This exercise leads us to conclude that evaporation is the driving force of evolution for close-in Kepler planets. In fact, some 50% of the Kepler planet candidates may have been significantly eroded. Evaporation explains two striking correlations observed in these objects: a lack of large radius/low density planets close to the stars and a possible bimodal distribution in planet sizes with a deficit of planets around 2 R{sub ⊕}. Planets that have experienced high X-ray exposures are generally smaller than this size, and those with lower X-ray exposures are typically larger. A bimodal planet size distribution is naturally predicted by the evaporation model, where, depending on their X-ray exposure, close-in planets can either hold on to hydrogen envelopes ∼0.5%-1% in mass or be stripped entirely. To quantitatively reproduce the observed features, we argue that not only do low-mass Kepler planets need to be made of rocky cores surrounded with hydrogen envelopes, but few of them should have initial masses above 20 M

  4. The Pan-STARRS discovery machine

    NASA Astrophysics Data System (ADS)

    Chambers, Kenneth C.

    2014-11-01

    The Pan-STARRS System has proven to be a remarkable machine for discovery. The PS1 Science Mission has drawn to a close, and the second Pan-STARRS survey, optimized for NEO's has begun. PS2 is in the commissioning stages and will eventually support NEO discovery as well. The performance of the PS1 system, sky coverage, cadence, and data quality of the Pan-STARRS1 Surveys will be presented as well as progress in reprocessing of the data taken to date and the plans for the public release of all Pan-STARRS1 data products in the spring of 2015. Science results related to planetary studies and the dust will be presented. The Pan-STARRS1 Surveys (PS1) have been made possible through contributions of the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation under Grant No. AST-1238877, the University of Maryland, and Eotvos Lorand University (ELTE).

  5. An electronic pan/tilt/zoom camera system

    NASA Technical Reports Server (NTRS)

    Zimmermann, Steve; Martin, H. Lee

    1991-01-01

    A camera system for omnidirectional image viewing applications that provides pan, tilt, zoom, and rotational orientation within a hemispherical field of view (FOV) using no moving parts was developed. The imaging device is based on the effect that from a fisheye lens, which produces a circular image of an entire hemispherical FOV, can be mathematically corrected using high speed electronic circuitry. An incoming fisheye image from any image acquisition source is captured in memory of the device, a transformation is performed for the viewing region of interest and viewing direction, and a corrected image is output as a video image signal for viewing, recording, or analysis. As a result, this device can accomplish the functions of pan, tilt, rotation, and zoom throughout a hemispherical FOV without the need for any mechanical mechanisms. A programmable transformation processor provides flexible control over viewing situations. Multiple images, each with different image magnifications and pan tilt rotation parameters, can be obtained from a single camera. The image transformation device can provide corrected images at frame rates compatible with RS-170 standard video equipment.

  6. Method of evaporation

    NASA Technical Reports Server (NTRS)

    Dufresne, Eugene R.

    1987-01-01

    Liquids, such as juices, milk, molten metal and the like are concentrated by forming uniformly-sized, small droplets in a precision droplet forming assembly and deploying the droplets in free fall downwardly as a central column within an evacuated column with cool walls. A portion of the solvent evaporates. The vapor flows to the wall, condenses, and usually flows down the wall as a film to condensate collector and drain. The vertical column of freely falling droplets enters the splash guard. The condensate can be collected, sent to other towers or recycled.

  7. Determining the Inception and Magnitude of Subsurface Evaporation

    NASA Astrophysics Data System (ADS)

    Deol, P. K.; Heitman, J.; Amoozegar, A.; Clayton Field Study Team

    2011-12-01

    Evaporation from an initially wet soil occurs at the soil surface but further drying of surface soil with time results in the formation of a dry surface layer. At this stage, the evaporation front moves from the surface to the subsurface. This phenomenon occurs in a highly dynamic near-surface zone making it very challenging to know the location/depth of the evaporation front and to quantify the subsurface evaporation rate. Recent studies show that subsurface evaporation can be measured using a sensible heat balance approach by accounting for the latent heat flux originating below soil surface which is not taken into account in the traditional surface energy balance equation. The soil sensible energy balance approach has been successfully tested against mass balance for estimating evaporation under steady-state controlled lab conditions, as well as to a limited extent in the field. Limitations of the approach for field conditions include inability of instrumentation to quantify evaporation during the initial shift between surface and subsurface evaporation (i.e. when evaporation occurs at depths shallower than approximately 3 mm). The objectives of this study are to 1) find indicators of the change in the location of the evaporation front from surface to subsurface, and 2) test the sensible heat balance approach for quantifying evaporation from the inception of the subsurface evaporation zone. Recently introduced multi-needle heat pulse probes were used to make continuous soil temperature and thermal property measurements in the near-surface zone at the mm scale in a bare surface soil. Preliminary results from this investigation will be presented.

  8. Convective flows in evaporating sessile droplets.

    PubMed

    Barmi, Meysam R; Meinhart, Carl D

    2014-03-01

    The evaporation rate and internal convective flows of a sessile droplet with a pinned contact line were formulated and investigated numerically. We developed and analyzed a unified numerical model that includes the effects of temperature, droplet volume, and contact angle on evaporation rate and internal flows. The temperature gradient on the air/liquid interface causes an internal flow due to Marangoni stress, which provides good convective mixing within the droplet, depending upon Marangoni number. As the droplet volume decreases, the thermal gradient becomes smaller and the Marangoni flow becomes negligible. Simultaneously, as the droplet height decreases, evaporation-induced flow creates a large jet-like flow radially toward the contact line. For a droplet containing suspended particles, this jet-like convective flow carries particles toward the contact line and deposits them on the surface, forming the so-called "coffee ring stain". In addition, we reported a simple polynomial correlation for dimensionless evaporation time as a function of initial contact angle of the pinned sessile droplet which agrees well with the previous experimental and numerical results. PMID:24512008

  9. Evaporation of Liquid Hydrocarbon Mixtures on Titan

    NASA Astrophysics Data System (ADS)

    Luspay-Kuti, Adrienn; Chevrier, V. F.; Rivera-Valentin, E. G.; Singh, S.; Roe, L. A.; Wagner, A.

    2013-10-01

    Besides Earth, Titan is the only other known planetary body with proven stable liquids on its surface. The hydrological cycle of these liquid hydrocarbon mixtures is critical in understanding Titan’s atmosphere and surface features. Evaporation of liquid surface bodies has been indirectly observed as shoreline changes from measurements by Cassini ISS and RADAR (Hayes et al. 2011, Icarus 211, 655-671; Turtle et al. 2011, Science 18, 1414-1417.), but the long seasons of Saturn strongly limit the time span of these observations and their validity over the course of an entire Titan year. Using a novel Titan simulation chamber, the evaporation rate of liquid methane and dissolved nitrogen mixture under Titan surface conditions was derived (Luspay-Kuti et al. 2012, GRL 39, L23203), which is especially applicable to low latitude transient liquids. Polar lakes, though, are expected to be composed of a variety of hydrocarbons, primarily a mixture of ethane and methane (e.g. Cordier et al. 2009, ApJL 707, L128-L131). Here we performed laboratory simulations of ethane-methane mixtures with varying mole fraction under conditions suitable for the polar regions of Titan. We will discuss results specifically addressing the evaporation behavior as the solution becomes increasingly ethane dominated, providing quantitative values for the evaporation rate at every step. These laboratory results are relevant to polar lakes, such as Ontario Lacus, and can shed light on their stability.

  10. The Pan-STARRS search for Near Earth Objects

    NASA Astrophysics Data System (ADS)

    Wainscoat, Richard J.; Chambers, Kenneth; Lilly, Eva; Weryk, Robert; Chastel, Serge; Denneau, Larry; Micheli, Marco

    2015-11-01

    The two Pan-STARRS telescopes, located on Haleakala, Hawaii, are 1.8-meter diameter telescopes equipped with 1.4 Gigapixel cameras that deliver 7 square degree fields of view. The first telescope, Pan-STARRS1 (PS1), has been conducting a survey for Near-Earth Objects. The second telescope, Pan-STARRS2 (PS2) is nearing completion. The telescope was commissioned using an incomplete focal plane with only 18 good detectors (60 required). The camera is presently being upgraded, and will be operated from October 2015 with 60 detectors (some engineering grade). A final upgrade to the camera in early 2016 will make the telescope fully operational.The two telescopes survey much of the sky accessible from Haleakala multiple times each lunation. The area surveyed ranges from +90 degrees in the north down to -47.5 degrees declination in the south. The “sweet spots” close to the Sun have been productive in discovery of large objects.The PS1 survey is becoming more mature and productive, having discovered more than half of all NEOs in 2015 to date, and more than 60% of the larger NEOs and PHAs discovered in 2015. Both PS1 and PS2 deliver excellent astrometry and photometry. PS1 continues to discover a significant number of large (> 1km) NEOs. PS1 has become the leading discover of comets, discovering more than half of the new comets in both 2014 and 2015.In good weather conditions, the discovery rate of NEO candidates by PS1 overwhelms the external NEO followup resources. particularly for fainter NEOs. As a result, we needed to repeat fields to recover NEO candidates. As PS2 matures, with a complete focal plane, and when the G96 camera upgrade is complete, the combination of these three telescopes will facilitate a higher NEO discovery rate, a better census of the NEOs in the sky, and better orbits for NEOs. This will in turn lead to a better understanding of the size and orbit distribution of NEOs. The Pan-STARRS NEO survey is also likely to discover asteroids suitable for

  11. Evaporation Dynamics of Moss and Bare Soil in Boreal Forests

    NASA Astrophysics Data System (ADS)

    Dempster, S.; Young, J. M.; Barron, C. G.; Bolton, W. R.

    2013-12-01

    Evaporation dynamics of mosses is a critical process in boreal and arctic systems and represents a key uncertainty in hydrology and climate models. At this point, moss evaporation is not well quantified at the plot or landscape scale. Relative to bare soil or litter evaporation, moss evaporation can be challenging to predict because the water flux is not isolated to the moss surface. Evaporation can originate from nearly 10 cm below the surface. Some mosses can wick moisture from even deeper than 10 cm, which subsequently evaporates. The goal of this study was to use field measurements to quantify the moss evaporation dynamics in a coniferous forest relative to bare ground or litter evaporation dynamics in a deciduous forest in Interior Alaska. Measurements were made in two ecosystem types within the boreal forest of Interior Alaska: a deciduous forest devoid of moss and a coniferous forest with a thick moss layer. A small clear chamber was attached to a LiCor 840 infrared gas analyzer in a closed loop system with a low flow rate. Water fluxes were measured for ~ 90 seconds on each plot in dry and wet soil and moss conditions. Additional measurements included: soil temperature, soil moisture, air temperature, barometric pressure, dew point, relative humidity, and wind speed. Thermal infrared images were also captured in congruence with water flux measurements to determine skin temperature. We found that the moss evaporation rate was over 100% greater than the soil evaporation rate (0.057 g/min vs. 0.024 g/min), and evaporation rates in both systems were most strongly driven by relative humidity and surface temperature. Surface temperature was lower at the birch site than the black spruce site because trees shade the surface beneath the birch. High fluxes associated with high water content were sustained for a longer period of time over the mosses compared to the bare soil. The thermal IR data showed that skin temperature lagged the evaporation flux, such that the

  12. An evaporation model of colloidal suspension droplets

    NASA Astrophysics Data System (ADS)

    Sartori, Silvana; Li\\ Nán, Amable; Lasheras, Juan C.

    2009-11-01

    Colloidal suspensions of polymers in water or other solvents are widely used in the pharmaceutical industry to coat tablets with different agents. These allow controlling the rate at which the drug is delivered, taste or physical appearance. The coating is performed by simultaneously spraying and drying the tablets with the colloidal suspension at moderately high temperatures. The spreading of the coating on the pills surface depends on the droplet Webber and Reynolds numbers, angle of impact, but more importantly on the rheological properties of the drop. We present a model for the evaporation of a colloidal suspension droplet in a hot air environment with temperatures substantially lower than the boiling temperature of the carrier fluid. As the liquid vaporizes from the surface, a compacting front advances into the droplet faster than the liquid surface regresses, forming a shell of a porous medium where the particles reach their maximum packing density. While the surface regresses, the evaporation rate is determined by both the rate at which heat is transported to the droplet surface and the rate at which liquid vapor is diffused away from it. This regime continues until the compacting front reaches the center of the droplet, at which point the evaporation rate is drastically reduced.

  13. Atmospheric convective transport contribution to evaporative sessile droplets

    NASA Astrophysics Data System (ADS)

    Carle, Florian; Semenov, Sergey; Medale, Marc; Brutin, David

    2014-11-01

    The scientific community struggles with the creation of an accurate quantitative description of sessile droplet evaporation flux rate. The classically used description considers evaporation as a quasi-steady process controlled by the diffusion of vapor into the air, and the whole system is assumed to be isothermal at the ambient temperature. However, when two types of fluids (alcohols and alkanes) are let to evaporate on heated substrates while a side view camera measures their evaporation flux rate, droplets tend to see their evaporation flux rate underestimated by this model mostly due to convection. This experimental study aims to understand how atmospheric convective transport in the vapor phase influences evaporation in order to developed an empirical model that describes with accuracy the evaporation flux rate. The Rayleigh number is used to analyze the contribution of natural convection and an empirical model is developed combining diffusive and convective transport for each type of fluid. The influence of the molecular chain length (and the increasing number of carbon atoms) is also being discussed.

  14. Lunar PanCam: Adapting ExoMars PanCam for the ESA Lunar Lander

    NASA Astrophysics Data System (ADS)

    Coates, A. J.; Griffiths, A. D.; Leff, C. E.; Schmitz, N.; Barnes, D. P.; Josset, J.-L.; Hancock, B. K.; Cousins, C. R.; Jaumann, R.; Crawford, I. A.; Paar, G.; Bauer, A.; the PanCam Team

    2012-12-01

    A scientific camera system would provide valuable geological context from the surface for lunar lander missions. Here, we describe the PanCam instrument from the ESA ExoMars rover and its possible adaptation for the proposed ESA lunar lander. The scientific objectives of the ESA ExoMars rover are designed to answer several key questions in the search for life on Mars. The ExoMars PanCam instrument will set the geological and morphological context for that mission. We describe the PanCam scientific objectives in geology, and atmospheric science, and 3D vision objectives. We also describe the design of PanCam, which includes a stereo pair of Wide Angle Cameras (WACs), each of which has a filter wheel, and a High Resolution Camera for close up investigations. The cameras are housed in an optical bench (OB) and electrical interface is provided via the PanCam Interface Unit (PIU). Additional hardware items include a PanCam Calibration Target (PCT). We also briefly discuss some PanCam testing during field trials. In addition, we examine how such a 'Lunar PanCam' could be adapted for use on the Lunar surface on the proposed ESA lunar lander.

  15. 76 FR 20831 - Pan American Day and Pan American Week, 2011

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-13

    ... From the Federal Register Online via the Government Publishing Office #0; #0; #0; Presidential Documents #0; #0; #0;#0;Federal Register / Vol. 76, No. 71 / Wednesday, April 13, 2011 / Presidential Documents#0;#0; ] Proclamation 8651 of April 8, 2011 Pan American Day and Pan American Week, 2011 By the President of the United States of America A...

  16. 75 FR 19181 - Pan American Day and Pan American Week, 2010

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-14

    ... the two hundred and thirty-fourth. (Presidential Sig.) [FR Doc. 2010-8672 Filed 4-13-10; 8:45 am... Documents#0;#0; #0; #0;Title 3-- #0;The President ] Proclamation 8495 of April 9, 2010 Pan American Day and Pan American Week, 2010 By the President of the United States of America A Proclamation More than...

  17. Control of solvent evaporation in hen egg white lysozyme crystallization

    NASA Technical Reports Server (NTRS)

    Wilson, L. J.; Suddath, F. L.

    1992-01-01

    An investigation of the role of solvent evaporation in tetragonal lysozyme crystallization was preformed with a device that employs N2(g) to control the evaporation of solvent from a micro-volume crystallization hanging drop. The number of crystals was found to vary with the rate at which the final supersaturation level was achieved. It was found that the more rapid the approach to supersaturation the larger the number of crystals. Accordingly, the crystals reached a smaller terminal size. Elongation of the (110) face parallel to the four-fold axis was observed with the slower evaporation rates.

  18. Representative shuttle evaporative heat sink

    NASA Technical Reports Server (NTRS)

    Hixon, C. W.

    1978-01-01

    The design, fabrication, and testing of a representative shuttle evaporative heat sink (RSEHS) system which vaporizes an expendable fluid to provide cooling for the shuttle heat transport fluid loop is reported. The optimized RSEHS minimum weight design meets or exceeds the shuttle flash evaporator system requirements. A cold trap which cryo-pumps flash evaporator exhaust water from the CSD vacuum chamber test facility to prevent water contamination of the chamber pumping equipment is also described.

  19. Evaporative precooling unit

    SciTech Connect

    Rogers, A.R.

    1988-03-15

    In combination with a refrigeration unit, an evaporative heat exchange unit for precooling an air stream traveling toward and over the condensing coil of the refrigeration unit is described. The heat exchange unit includes: (a) a frame, (b) a porous heat transfer pad mounted in the frame; (c) nozzle means carried on the frame for directing a spray mist forwardly of the heat transfer pad, the spray mist emitted from the nozzle means initially traveling in a direction of travel such that the mist will not contact the porous heat transfer pad; (d) means mounted on the frame for causing the turbulent intermixing of the air stream with the spray mist prior to the air stream passing through the porous heat transfer pad; and (e) means for controlling the quantity of water emitted by the nozzle means such that substantially all of the spray mist is intermixed with the air stream prior to the air stream passing through the heat transfer pad.

  20. Pan-STARRS Moving Object Processing System

    NASA Astrophysics Data System (ADS)

    Jedicke, R.; Denneau, L.; Grav, T.; Heasley, J.; Kubica, Jeremy; Pan-STARRS Team

    2005-12-01

    The Institute for Astronomy at the University of Hawaii is developing a large optical astronomical surveying system - the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). The Moving Object Processing System (MOPS) client of the Pan-STARRS image processing pipeline is developing software to automatically discover and identify >90% of near-Earth objects (NEOs) 300m in diameter and >80% of other classes of asteroids and comets. In developing its software, MOPS has created a synthetic solar system model (SSM) with over 10 million objects whose distributions of orbital characteristics matches those expected for objects that Pan-STARRS will observe. MOPS verifies its correct operation by simulating the survey and subsequent discovery of synthetically generated objects. MOPS also employs novel techniques in handling the computationally difficult problem of linking large numbers of unknown asteroids in a field of detections. We will describe the creation and verification of the Pan-STARRS MOPS SSM, demonstrate synthetic detections and observations by the MOPS, describe the MOPS asteroid linking techniques, describe accuracy and throughput of the entire MOPS system, and provide predictions regarding the numbers and kinds of objects, including as yet undiscovered "extreme objects", that the MOPS expects to find over its 10-year lifetime. Pan-STARRS is funded under a grant from the U.S. Air Force.

  1. Evaporation and skin penetration characteristics of mosquito repellent formulations

    SciTech Connect

    Reifenrath, W.G.; Hawkins, G.S.; Kurtz, M.S.

    1989-03-01

    Formulations of the mosquito repellent N,N-diethyl-3-methylbenzamide (deet) in combination with a variety of additives were developed to control repellent evaporation and percutaneous penetration. Deet was also formulated with the repellent dimethyl phthalate to study the interaction of the two compounds on the skin. The evaporation and penetration processes were evaluated on whole and split-thickness pig skin using radiolabeled repellents with an in vitro apparatus. Under essentially still air and air flow conditions, one of the deet formulations resulted in significantly reduced total evaporation and percutaneous penetration of deet as compared to unformulated repellent. When deet and dimethyl phthalate were combined, neither repellent affected the total amount of evaporation and penetration of the other compound. However, initial percutaneous penetration and evaporation rates were slightly less and decayed less rapidly than when both chemicals were tested separately at the same dose. These results indicated a degree of competition of the two compounds for the same avenues of loss.

  2. Evaporative cooling of the dipolar hydroxyl radical.

    PubMed

    Stuhl, Benjamin K; Hummon, Matthew T; Yeo, Mark; Quéméner, Goulven; Bohn, John L; Ye, Jun

    2012-12-20

    Atomic physics was revolutionized by the development of forced evaporative cooling, which led directly to the observation of Bose-Einstein condensation, quantum-degenerate Fermi gases and ultracold optical lattice simulations of condensed-matter phenomena. More recently, substantial progress has been made in the production of cold molecular gases. Their permanent electric dipole moment is expected to generate systems with varied and controllable phases, dynamics and chemistry. However, although advances have been made in both direct cooling and cold-association techniques, evaporative cooling has not been achieved so far. This is due to unfavourable ratios of elastic to inelastic scattering and impractically slow thermalization rates in the available trapped species. Here we report the observation of microwave-forced evaporative cooling of neutral hydroxyl (OH(•)) molecules loaded from a Stark-decelerated beam into an extremely high-gradient magnetic quadrupole trap. We demonstrate cooling by at least one order of magnitude in temperature, and a corresponding increase in phase-space density by three orders of magnitude, limited only by the low-temperature sensitivity of our spectroscopic thermometry technique. With evaporative cooling and a sufficiently large initial population, much colder temperatures are possible; even a quantum-degenerate gas of this dipolar radical (or anything else it can sympathetically cool) may be within reach. PMID:23257881

  3. Spacesuit Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Hodgson, Ed; Izenson, Mike; Chan, Weibo; Bue, Grant C.

    2012-01-01

    For decades advanced spacesuit developers have pursued a regenerable, robust nonventing system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s Lithium Chloride Absorber Radiator (LCAR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. This water vapor is then captured by solid LiCl in the LCAR with a high enthalpy of absorption, resulting in sufficient temperature lift to reject heat to space by radiation. After the sortie, the LCAR would be heated up and dried in a regenerator to drive off and recover the absorbed evaporant. A engineering development prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The LCAR was able to stably reject 75 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

  4. Thermal modeling of flow in the San Diego Aqueduct, California, and its relation to evaporation

    USGS Publications Warehouse

    Jobson, Harvey E.

    1980-01-01

    The thermal balance of the 26-kilometer long concrete-lined San Diego Aqueduct, a canal in southern California, was studied to determine the coefficients in a Dalton type evaporation formula. Meteorologic and hydraulic variables, as well as water temperature, were monitored continuously for a 1-year period. A thermal model was calibrated by use of data obtained during a 28-day period to determine the coefficients which best described the thermal balance of the canal. The coefficients applicable to the San Diego Aqueduct are similar to those commonly obtained from lake evaporation studies except that a greater evaporation at low windspeeds is indicated. The model was verified by use of data obtained during 113 days which did not include the calibration data. These data verified that the derived wind function realistically represents the canal evaporation. An annual evaporation of 2.08 meters was computed which is about 91 percent of the amount of water evaporated annually from nearby class A evaporation pans. (Kosco-USGS)

  5. Droplet evaporation on heated hydrophobic and superhydrophobic surfaces.

    PubMed

    Dash, Susmita; Garimella, Suresh V

    2014-04-01

    The evaporation characteristics of sessile water droplets on smooth hydrophobic and structured superhydrophobic heated surfaces are experimentally investigated. Droplets placed on the hierarchical superhydrophobic surface subtend a very high contact angle (∼160°) and demonstrate low roll-off angle (∼1°), while the hydrophobic substrate supports corresponding values of 120° and ∼10°. The substrates are heated to different constant temperatures in the range of 40-60 °C, which causes the droplet to evaporate much faster than in the case of natural evaporation without heating. The geometric parameters of the droplet, such as contact angle, contact radius, and volume evolution over time, are experimentally tracked. The droplets are observed to evaporate primarily in a constant-contact-angle mode where the contact line slides along the surface. The measurements are compared with predictions from a model based on diffusion of vapor into the ambient that assumes isothermal conditions. This vapor-diffusion-only model captures the qualitative evaporation characteristics on both test substrates, but reasonable quantitative agreement is achieved only for the hydrophobic surface. The superhydrophobic surface demonstrates significant deviation between the measured evaporation rate and that obtained using the vapor-diffusion-only model, with the difference being amplified as the substrate temperature is increased. A simple model considering thermal diffusion through the droplet is used to highlight the important role of evaporative cooling at the droplet interface in determining the droplet evaporation characteristics on superhydrophobic surfaces. PMID:24827255

  6. Multilayer composite material and method for evaporative cooling

    NASA Technical Reports Server (NTRS)

    Buckley, Theresa M. (Inventor)

    2002-01-01

    A multilayer composite material and method for evaporative cooling of a person employs an evaporative cooling liquid that changes phase from a liquid to a gaseous state to absorb thermal energy. The evaporative cooling liquid is absorbed into a superabsorbent material enclosed within the multilayer composite material. The multilayer composite material has a high percentage of the evaporative cooling liquid in the matrix. The cooling effect can be sustained for an extended period of time because of the high percentage of phase change liquid that can be absorbed into the superabsorbent. Such a composite can be used for cooling febrile patients by evaporative cooling as the evaporative cooling liquid in the matrix changes from a liquid to a gaseous state to absorb thermal energy. The composite can be made with a perforated barrier material around the outside to regulate the evaporation rate of the phase change liquid. Alternatively, the composite can be made with an imperveous barrier material or semipermeable membrane on one side to prevent the liquid from contacting the person's skin. The evaporative cooling liquid in the matrix can be recharged by soaking the material in the liquid. The multilayer composite material can be fashioned into blankets, garments and other articles.

  7. Small Scale Evaporation Kinetics of a Binary Fluid Mixture

    NASA Astrophysics Data System (ADS)

    Basdeo, Carl; Ye, Dezhuang; Kalonia, Devendra; Fan, Tai-Hsi; Mechanical Engineering Team; Pharmaceutical Sciences Collaboration

    2013-03-01

    Evaporation induces a concentrating effect in liquid mixtures. The transient process has significant influence on the dynamic behaviors of a complex fluid. To simultaneously investigate the fluid properties and small-scale evaporation kinetics during the transient process, the quartz crystal microbalance is applied to a binary mixture droplet of light alcohols including both a single volatile component (a fast evaporation followed by a slow evaporation) and a mixture of two volatile components with comparable evaporation rates. The density and viscosity stratification are evaluated by the shear wave, and the evaporation kinetics is measured by the resonant signature of the acoustic p-wave. The evaporation flux can be precisely determined by the resonant frequency spikes and the complex impedance. To predict the concentration field, the moving interface, and the precision evaporation kinetics of the mixture, a multiphase model is developed to interpret the complex impedance signals based on the underlying mass and momentum transport phenomena. The experimental method and theoretical model are developed for better characterizing and understanding of the drying process involving liquid mixtures of protein pharmaceuticals.

  8. Vacuum flash evaporated polymer composites

    DOEpatents

    Affinito, John D.; Gross, Mark E.

    1997-01-01

    A method for fabrication of polymer composite layers in a vacuum is disclosed. More specifically, the method of dissolving salts in a monomer solution, vacuum flash evaporating the solution, condensing the flash evaporated solution as a liquid film, and forming the condensed liquid film into a polymer composite layer on a substrate is disclosed.

  9. Vacuum flash evaporated polymer composites

    DOEpatents

    Affinito, J.D.; Gross, M.E.

    1997-10-28

    A method for fabrication of polymer composite layers in a vacuum is disclosed. More specifically, the method of dissolving salts in a monomer solution, vacuum flash evaporating the solution, condensing the flash evaporated solution as a liquid film, and forming the condensed liquid film into a polymer composite layer on a substrate is disclosed.

  10. Experimental Investigation of Microstructured Evaporators

    NASA Astrophysics Data System (ADS)

    Wibel, W.; Westermann, S.; Maikowske, S.; Brandner, J. J.

    2012-11-01

    Microfluidic devices have become more and more popular over the last decades [1]. Cooling is a topic where microstructures offer significant advantages compared to conventional techniques due the much higher possible surface to volume ratios and short heat transfer lengths. By evaporating of a fluid in microchannels, compact, fast and powerful cooling devices become possible [2]. Experimental results for different designs of microstructured evaporators are presented here. They have been obtained either using water as evaporating coolant or the refrigerant R134a (Tetrafluoroethane). A new microstructured evaporator design consisting of bended microchannels instead of straight channels for a better performance is shown and compared to previous results [2] for the evaporation of R134a in straight microchannels.

  11. Molecular Mechanism of Water Evaporation

    NASA Astrophysics Data System (ADS)

    Nagata, Yuki; Usui, Kota; Bonn, Mischa

    2015-12-01

    Evaporation is the process by which water changes from a liquid to a gas or vapor, and is a key step in Earth's water cycle. At the molecular level, evaporation requires breaking at least one very strong intermolecular bond between two water molecules at the interface. Despite the importance of this process the molecular mechanism by which an evaporating water molecule gains sufficient energy to escape from the surface has remained elusive. Here, we show, using molecular dynamics simulations at the water-air interface with polarizable classical force field models, that the high kinetic energy of the evaporated water molecule is enabled by a well-timed making and breaking of hydrogen bonds involving at least three water molecules at the interface, the recoil of which allows one of the molecules to escape. The evaporation of water is thus enabled by concerted, ultrafast hydrogen-bond dynamics of interfacial water, and follows one specific molecular pathway.

  12. An evaporation model of multicomponent solution drops

    NASA Astrophysics Data System (ADS)

    Sartori, Silvana; Liñán, Amable; Lasheras, Juan C.

    2010-11-01

    Solutions of polymers are widely used in the pharmaceutical industry as tablets coatings. These allow controlling the rate at which the drug is delivered, taste or appearance. The coating is performed by spraying and drying the tablets at moderate temperatures. The wetting of the coating solution on the pill's surface depends on the droplet Webber and Re numbers, angle of impact and on the rheological properties of the droplet. We present a model for the evaporation of multicomponent solutions droplets in a hot air environment with temperatures substantially lower than the boiling temperature of the solvent. As the liquid vaporizes from the surface the fluid in the drop increases in concentration, until reaching its saturation point. After saturation, precipitation occurs uniformly within the drop. As the surface regresses, a compacting front formed by the precipitate at its maximum packing density advances into the drop, while the solute continues precipitating uniformly. This porous shell grows fast due to the double effect of surface regression and precipitation. The evaporation rate is determined by the rates at which heat is transported to the droplet surface and at which liquid vapor diffuses away from it. When the drop is fully compacted, the evaporation is drastically reduced.

  13. Processing Petabytes for Pan-STARRS

    NASA Astrophysics Data System (ADS)

    Price, Paul A.; Magnier, E. A.; Hoblitt, J.; Pan-STARRS Team

    2007-05-01

    The Pan-STARRS Image Processing Pipeline is responsible for the calibration and characterization of the images flowing from the newly commissioned Pan-STARRS 1 Telescope. Every 40 sec, a 1.4 billion pixel exposure requires standard detrend operations, source identification and photometry, astrometry, warping to a sky tesselation, subtraction against a template and photometry of variable sources. To meet this challenge, we have designed a flexible pipeline, able to reduce single-CCD cameras as well as the behemoth mosaic cameras. We describe the design and current status of our pipeline, including performance on actual PS1 images.

  14. Analysis of the effects of evaporative cooling on the evaporation of liquid droplets using a combined field approach.

    PubMed

    Xu, Xuefeng; Ma, Liran

    2015-01-01

    During liquid evaporation, the equations for the vapor concentration in the atmosphere and for the temperature in the liquid are coupled and must be solved in an iterative manner. In the present paper, a combined field approach which unifies the coupled fields into one single hybrid field and thus makes the iteration unnecessary is proposed. By using this approach, the influences of the evaporative cooling on the evaporation of pinned sessile droplets are investigated, and its predictions are found in good agreement with the previous theoretical and experimental results. A dimensionless number Ec which can evaluate the strength of the evaporative cooling is then introduced, and the results show that both the evaporation flux along the droplet surface and the total evaporation rate of the droplet decrease as the evaporative cooling number Ec increases. For drying droplets, there exists a critical value EcCrit below which the evaporative cooling effect can be neglected and above which the significance of the effect increases dramatically. The present work may also have more general applications to coupled field problems in which all the fields have the same governing equation. PMID:25721987

  15. The evaporative function of cockroach hygroreceptors.

    PubMed

    Tichy, Harald; Kallina, Wolfgang

    2013-01-01

    Insect hygroreceptors associate as antagonistic pairs of a moist cell and a dry cell together with a cold cell in small cuticular sensilla on the antennae. The mechanisms by which the atmospheric humidity stimulates the hygroreceptive cells remain elusive. Three models for humidity transduction have been proposed in which hygroreceptors operate either as mechanical hygrometers, evaporation detectors or psychrometers. Mechanical hygrometers are assumed to respond to the relative humidity, evaporation detectors to the saturation deficit and psychrometers to the temperature depression (the difference between wet-bulb and dry-bulb temperatures). The models refer to different ways of expressing humidity. This also means, however, that at different temperatures these different types of hygroreceptors indicate very different humidity conditions. The present study tested the adequacy of the three models on the cockroach's moist and dry cells by determining whether the specific predictions about the temperature-dependence of the humidity responses are indeed observed. While in previous studies stimulation consisted of rapid step-like humidity changes, here we changed humidity slowly and continuously up and down in a sinusoidal fashion. The low rates of change made it possible to measure instantaneous humidity values based on UV-absorption and to assign these values to the hygroreceptive sensillum. The moist cell fitted neither the mechanical hygrometer nor the evaporation detector model: the temperature dependence of its humidity responses could not be attributed to relative humidity or to saturation deficit, respectively. The psychrometer model, however, was verified by the close relationships of the moist cell's response with the wet-bulb temperature and the dry cell's response with the dry-bulb temperature. Thus, the hygroreceptors respond to evaporation and the resulting cooling due to the wetness or dryness of the air. The drier the ambient air (absolutely) and the

  16. The Evaporative Function of Cockroach Hygroreceptors

    PubMed Central

    Tichy, Harald; Kallina, Wolfgang

    2013-01-01

    Insect hygroreceptors associate as antagonistic pairs of a moist cell and a dry cell together with a cold cell in small cuticular sensilla on the antennae. The mechanisms by which the atmospheric humidity stimulates the hygroreceptive cells remain elusive. Three models for humidity transduction have been proposed in which hygroreceptors operate either as mechanical hygrometers, evaporation detectors or psychrometers. Mechanical hygrometers are assumed to respond to the relative humidity, evaporation detectors to the saturation deficit and psychrometers to the temperature depression (the difference between wet-bulb and dry-bulb temperatures). The models refer to different ways of expressing humidity. This also means, however, that at different temperatures these different types of hygroreceptors indicate very different humidity conditions. The present study tested the adequacy of the three models on the cockroach’s moist and dry cells by determining whether the specific predictions about the temperature-dependence of the humidity responses are indeed observed. While in previous studies stimulation consisted of rapid step-like humidity changes, here we changed humidity slowly and continuously up and down in a sinusoidal fashion. The low rates of change made it possible to measure instantaneous humidity values based on UV-absorption and to assign these values to the hygroreceptive sensillum. The moist cell fitted neither the mechanical hygrometer nor the evaporation detector model: the temperature dependence of its humidity responses could not be attributed to relative humidity or to saturation deficit, respectively. The psychrometer model, however, was verified by the close relationships of the moist cell’s response with the wet-bulb temperature and the dry cell’s response with the dry-bulb temperature. Thus, the hygroreceptors respond to evaporation and the resulting cooling due to the wetness or dryness of the air. The drier the ambient air (absolutely) and

  17. Evaporation and instabilities of microscopic capillary bridges

    PubMed Central

    Maeda, Nobuo; Israelachvili, Jacob N.; Kohonen, Mika M.

    2003-01-01

    The formation and disappearance of liquid bridges between two surfaces can occur either through equilibrium or nonequilibrium processes. In the first instance, the bridge molecules are in thermodynamic equilibrium with the surrounding vapor medium. In the second, chemical potential gradients result in material transfer; mechanical instabilities, because of van der Waals force jumps on approach or a Rayleigh instability on rapid separation, may trigger irreversible film coalescence or bridge snapping. We have studied the growth and disappearance mechanisms of laterally microscopic liquid bridges of three hydrocarbon liquids in slit-like pores. At rapid slit-opening rates, the bridges rupture by means of a mechanical instability described by the Young–Laplace equation. Noncontinuum but apparently reversible behavior is observed when a bridge is held at nanoscopic surface separations H close to the thermodynamic equilibrium Kelvin length, 2rKcosθ, where rK is the Kelvin radius and θ is the contact angle. During the course of slow evaporation (at H > 2rKcosθ) and subsequent regrowth by capillary condensation (at H < 2rKcosθ), the refractive index of the bridge may vary continuously and reversibly between that of the bulk liquid and vapor. The evaporation process becomes irreversible only at the very final stage of evaporation, when the refractive index of the fluid attains virtually that of the vapor. Measured refractive index profiles and the time-dependence of evaporating neck diameters also seem to differ from predictions based on a continuum picture of bridge evaporation far from the critical point. We discuss these findings in terms of the probable density profiles in evolving liquid bridges. PMID:12538868

  18. The desorptivity model of bulk soil-water evaporation

    NASA Technical Reports Server (NTRS)

    Clapp, R. B.

    1983-01-01

    Available models of bulk evaporation from a bare-surfaced soil are difficult to apply to field conditions where evaporation is complicated by two main factors: rate-limiting climatic conditions and redistribution of soil moisture following infiltration. Both factors are included in the "desorptivity model', wherein the evaporation rate during the second stage (the soil-limiting stage) of evaporation is related to the desorptivity parameter, A. Analytical approximations for A are presented. The approximations are independent of the surface soil moisture. However, calculations using the approximations indicate that both soil texture and soil moisture content at depth significantly affect A. Because the moisture content at depth decreases in time during redistribution, it follows that the A parameter also changes with time. Consequently, a method to calculate a representative value of A was developed. When applied to field data, the desorptivity model estimated cumulative evaporation well. The model is easy to calculate, but its usefulness is limited because it requires an independent estimate of the time of transition between the first and second stages of evaporation. The model shows that bulk evaporation after the transition to the second stage is largely independent of climatic conditions.

  19. Lake evaporation estimates in tropical Africa (Lake Ziway, Ethiopia)

    NASA Astrophysics Data System (ADS)

    Vallet-Coulomb, Christine; Legesse, Dagnachew; Gasse, Françoise; Travi, Yves; Chernet, Tesfaye

    2001-05-01

    Estimates of evaporation from an open shallow lake in tropical Africa (Lake Ziway, Main Ethiopian Rift) are made by using monthly hydrometeorological data available for the past three decades. On the one hand, annual average estimates are inferred from three climatic approaches, which can be applied in areas with limited meteorological data. The lake energy balance yields an evaporation rate of 1780 mm yr -1, assuming a Bowen ratio of 0.15 (that of Lake Victoria). The Penman method gives an annual evaporation rate of 1870 mm. The complementary relationship lake evaporation model (CRLE) applied on monthly averaged values of air temperature, air humidity and sunshine duration gives 1730 mm yr -1. The sensitivity of each method to changes in input variables is analyzed in order to test the stability of the resulting estimates. This helps discuss uncertainties and possible inter-annual variations of the evaporation rate. On the other hand, the monthly lake level records together with precipitation and river discharge data between 1969 and 1990, allow us to estimate the water balance, providing an annual rate of 1937 mm for the combined evaporation and groundwater losses. The chloride budget is used to discriminate the groundwater from the evaporation loss. It gives us an annual evaporation rate of 1740 mm and a corresponding groundwater loss of 200 mm yr -1. The groundwater loss estimate is of the same order of magnitude as the surface outflow, but the associated error in the former is significant because the result is sensitive to the poorly known chloride content of river inflows. Our results can be used to forecast the impact of increased water consumption in the basin.

  20. Rapid Evaporation of microbubbles

    NASA Astrophysics Data System (ADS)

    Gautam, Jitendra; Esmaeeli, Asghar

    2008-11-01

    When a liquid is heated to a temperature far above its boiling point, it evaporates abruptly. Boiling of liquid at high temperatures can be explosive and destructive, and poses a potential hazard for a host of industrial processes. Explosive boiling may occur if a cold and volatile liquid is brought into contact with a hot and non-volatile liquid, or if a liquid is superheated or depressurized rapidly. Such possibilities are realized, for example, in the depressurization of low boiling point liquefied natural gas (LNG) in the pipelines or storage tanks as a result of a leak. While boiling of highly heated liquids can be destructive at macroscale, the (nearly) instantaneous pace of the process and the release of large amount of kinetic energy make the phenomena extremely attractive at microscale where it is possible to utilize the released energy to derive micromechanical systems. For instance, there is currently a growing interest in micro-explosion of liquid for generation of micro bubbles for actuation purposes. The aim of the current study is to gain a fundamental understanding of the subject using direct numerical simulations. In particular, we seek to investigate the boundary between stable and unstable nucleus growth in terms of the degree of liquid superheat and to compare the dynamics of unstable and stable growth.

  1. Evaporation from groundwater discharge playas, Estancia Basin, central New Mexico

    USGS Publications Warehouse

    Menking, Kirsten M.; Anderson, Roger Y.; Brunsell, Nathaniel A.; Allen, Bruce D.; Ellwein, Amy L.; Loveland, Thomas A.; Hostetler, Steven W.

    2000-01-01

    Bowen ratio meteorological stations have been deployed to measure rates of evaporation from groundwater discharge playas and from an adjacent vegetated bench in the Estancia Basin, in central New Mexico. The playas are remnants of late Pleistocene pluvial Lake Estancia and are discharge areas for groundwater originating as precipitation in the adjacent Manzano Mts. They also accumulate water during local precipitation events. Evaporation is calculated from measured values of net radiation, soil heat flux, atmospheric temperature, and relative humidity. Evaporation rates are strongly dependent on the presence or absence of standing water in the playas, with rates increasing more than 600% after individual rainstorms. Evaporation at site E-12, in the southeastern part of the playa Complex, measured 74 cm over a yearlong period from mid-1997 through mid-1998. This value compares favorably to earlier estimates from northern Estancia playas, but is nearly three times greater than evaporation at a similar playa in western Utah. Differences in geographical position, salt crust composition, and physical properties may explain some of the difference in evaporation rates in these two geographic regions.

  2. Externally Induced Evaporation of Young Stellar Disks in Orion

    NASA Technical Reports Server (NTRS)

    Johnstone, D.; Hollenbach, D.; Shu, F.

    1996-01-01

    In this paper we propose a model for the evaporation of disks around young low-mass stars by external sources of high energy photons. Two evaporation techniques are possible. Lyman continuum radiation can ionize hydrogen at the disk surface powering a steady thermal ionized disk-wind, or FUV radiation can heat the disk through photo-electric grain processes powering a slower thermal neutral disk-wind. Applying these two models to the evaporating objects in the Trapezium produces a satisfactory solution to both the mass-loss rate and size of the ionized envelopes.

  3. Effect of meibomian lipid layer on evaporation of tears

    NASA Astrophysics Data System (ADS)

    Miano, F.; Calcara, M.; Giuliano, F.; Millar, T. J.; Enea, V.

    2004-07-01

    The outer interface of a tear film was studied with the aid of a model system able to investigate the interfacial phenomena derived from the spreading of an insoluble lipid multilayer onto a tear-like aqueous fluid. The interactions of such a layer with proteins dissolved in the aqueous phase beneath were also investigated. Emphasis was given to evaporation phenomena because the increased rate of tear evaporation in humans is often related to a number of ocular dysfunctions. The model tear was studied as a pendant drop that permitted a functional evaluation of the effect of lipids and proteins upon the evaporation of water from the tear film.

  4. Development of Ground and Remotely Based Evaporation Measurements at the Salar de Atacama, Northern Chile

    NASA Astrophysics Data System (ADS)

    Kampf, S. K.; Tyler, S. W.; Menz, S. F.; Muñoz, J. F.; Astete, C. O.

    2001-12-01

    Evaporation represents an important component of the water budget in desert playa lakes, and accurate spatial and temporal assessment of evaporation rates has the potential to greatly improve the accuracy of hydrologic models in such environments. To this end, evaporation at the Salar de Atacama, a large playa in the Atacama Desert of northern Chile, has been examined at a variety of spatial and temporal scales. Previous investigators have measured evaporation from the Salar using lysimeters and Bowen Ratio stations and have found that actual evaporation rates in much of the playa are extremely low (<10 mm yr-1), in spite of shallow groundwater. Lake-scale evaporation can, however, be difficult to determine based solely on such point measurements, as evaporation rates may vary spatially as a function of water depth, crust type and vegetation. In this study, eddy correlation techniques have been used to validate and expand the database of evaporation rates on the playa surface. These evaporation rates in conjunction with measurements of meteorological parameters and other components of the land surface energy balance allow determination of evaporation rates using remotely sensed images. Thermal and visible near infrared bands from the Advanced Spaceborne Thermal Emission and Radiation radiometer (ASTER) on Terra I are being used to determine ground surface temperature, emissivity and albedo, values which are implemented into a numerical energy balance model to extrapolate evaporation rates over the entire playa surface. Preliminary results of evaporation and energy budget measurements taken during the first field campaign at the Salar are presented along with an assessment of the ability of ASTER imagery to provide accurate measurements of evaporation rates in playa environments.

  5. Student-Centered Designs of Pan-African Literature Courses

    ERIC Educational Resources Information Center

    M'Baye, Babacar

    2010-01-01

    A student-centered teaching methodology is an essential ingredient of a successful Pan-African literary course. In this article, the author defines Pan-Africanism and how to go about designing a Pan-African literature course. The author combines reading assignments with journals, film presentations, and lectures in a productive learning…

  6. Rotatable prism for pan and tilt

    NASA Technical Reports Server (NTRS)

    Ball, W. B.

    1980-01-01

    Compact, inexpensive, motor-driven prisms change field of view of TV camera. Camera and prism rotate about lens axis to produce pan effect. Rotating prism around axis parallel to lens produces tilt. Size of drive unit and required clearance are little more than size of camera.

  7. The PAN-DA data acquisition system

    SciTech Connect

    Petravick, D.; Berg, D.; Berman, E.; Bernett, M.; Constanta-Fanourakis, P.; Dorries, T.; Haire, M.; Kaczar, K; MacKinnon, B.; Moore, C.; Nicinski, T.; Oleynik, G.; Pordes, R.; Sergey, G.; Votava, M.; White, V.

    1989-05-01

    The Online and Data Acquisition software groups at Fermi National Accelerator Laboratory have extended the VAXONLINE data acquisition package to include a VME based data path. The resulting environment, PAN-DA, provides a high throughput for logging, filtering, formatting and selecting events. 10 refs., 1 fig.

  8. Imitation in Neonatal Chimpanzees ("Pan Troglodytes")

    ERIC Educational Resources Information Center

    Myowa-Yamakoshi, Masako; Tomonaga, Masaki; Tanaka, Masayuki; Matsuzawa, Tetsuro

    2004-01-01

    This paper provides evidence for imitative abilities in neonatal chimpanzees ("Pan troglodytes"), our closest relatives. Two chimpanzees were reared from birth by their biological mothers. At less than 7 days of age the chimpanzees could discriminate between, and imitate, human facial gestures (tongue protrusion and mouth opening). By the time…

  9. Trends in evaporation and surface cooling in the Mississippi River basin

    USGS Publications Warehouse

    Milly, P.C.D.; Dunne, K.A.

    2001-01-01

    A synthesis of available data for the Mississippi River basin (area 3 ?? 106 km2) reveals an upward trend in evaporation during recent decades, driven primarily by increases in precipitation and secondarily by human water use. A cloud-related decrease in surface net radiation appears to have accompanied the precipitation trend. Resultant evaporative and radiative cooling of the land and lower atmosphere quantitatively explains downward trends in observed pan evaporation. These cooling tendencies also reconcile the observed regional atmospheric cooling with the anticipated regional "greenhouse warming." If recent high levels of precipitation (which correlate with the North Atlantic Oscillation) are mainly caused by an internal climatic fluctuation, an eventual return to normal precipitation could reveal heretofore-unrealized warming in the basin. If, instead, they are caused by some unidentified forcing that will continue to grow in the future, then continued intensification of water cycling and suppression of warming in the basin could result.

  10. Corrosion study of simulated evaporator components

    SciTech Connect

    Schreiber, S.B.; Dunn, S.L.

    1989-07-01

    At the Los Alamos Plutonium Facility, ion exchange effluents and precipitation filtrates containing discardable levels of transuranic elements are concentrated using a thermosiphon evaporator before cement fixation for waste disposal. Because of changing process feed streams and scrap recovery requirements, trace amounts of free chloride ions (Cl/sup /minus//) are being introduced into the stainless steel (SS) evaporator, potentially increasing corrosion rates and thereby reducing its useful life. This study was performed to determine the effects of Cl/sup /minus// in simulated evaporator feed solutions that contain significant amounts of ferric ions (Fe/sup 3+/) in nitric acid (HNO/sub 3/). A simulated environment was produced by heating 316 SS cans that contained various tests solutions. The surface was monitored for signs of pitting or stress cracking, and vessel weight loss was measured on a daily basis to establish a rough corrosion rate. The final conclusion is that the nitric acid solution provides enough free nitrate ions (NO/sub 3//sup /minus//) to maintain minimal corrosion in a dilute ferric chloride environment. 3 refs., 5 figs., 10 tabs.

  11. Dense spray evaporation as a mixing process

    NASA Astrophysics Data System (ADS)

    de Rivas, A.; Villermaux, E.

    2016-05-01

    We explore the processes by which a dense set of small liquid droplets (a spray) evaporates in a dry, stirred gas phase. A dense spray of micron-sized liquid (water or ethanol) droplets is formed in air by a pneumatic atomizer in a closed chamber. The spray is conveyed in ambient air as a plume whose extension depends on the relative humidity of the diluting medium. Standard shear instabilities develop at the plume edge, forming the stretched lamellar structures familiar with passive scalars. Unlike passive scalars however, these lamellae vanish in a finite time, because individual droplets evaporate at their border in contact with the dry environment. Experiments demonstrate that the lifetime of an individual droplet embedded in a lamellae is much larger than expected from the usual d2 law describing the fate of a single drop evaporating in a quiescent environment. By analogy with the way mixing times are understood from the convection-diffusion equation for passive scalars, we show that the lifetime of a spray lamellae stretched at a constant rate γ is tv=1/γ ln(1/+ϕ ϕ ) , where ϕ is a parameter that incorporates the thermodynamic and diffusional properties of the vapor in the diluting phase. The case of time-dependent stretching rates is examined too. A dense spray behaves almost as a (nonconserved) passive scalar.

  12. Evaporative cooling of flare plasma

    NASA Technical Reports Server (NTRS)

    Antiochos, S. K.; Sturrock, P. A.

    1976-01-01

    A one-dimensional loop model for the evaporative cooling of the coronal flare plasma was investigated. Conductive losses dominated radiative cooling, and the evaporative velocities were small compared to the sound speed. The profile and evolution of the temperature were calculated. The model was in agreement with soft X-ray observations on the evolution of flare temperatures and emission measures. The effect of evaporation was to greatly reduce the conductive heat flux into the chromosphere and to enhance the EUV emission from the coronal flare plasma.

  13. Evaporative cooling of flare plasma

    NASA Technical Reports Server (NTRS)

    Antiochos, S. K.; Sturrock, P. A.

    1978-01-01

    We investigate a one-dimensional loop model for the evaporative cooling of the coronal flare plasma. The important assumptions are that conductive losses dominate radiative cooling and that the evaporative velocities are small compared with the sound speed. We calculate the profile and evolution of the temperature and verify the accuracy of our assumptions for plasma parameters typical of flare regions. The model is in agreement with soft X-ray observations on the evolution of flare temperatures and emission measures. The effect of evaporation is to greatly reduce the conductive heat flux into the chromosphere and to enhance the EUV emission from the coronal flare plasma.

  14. Estimating evaporative vapor generation from automobiles based on parking activities.

    PubMed

    Dong, Xinyi; Tschantz, Michael; Fu, Joshua S

    2015-07-01

    A new approach is proposed to quantify the evaporative vapor generation based on real parking activity data. As compared to the existing methods, two improvements are applied in this new approach to reduce the uncertainties: First, evaporative vapor generation from diurnal parking events is usually calculated based on estimated average parking duration for the whole fleet, while in this study, vapor generation rate is calculated based on parking activities distribution. Second, rather than using the daily temperature gradient, this study uses hourly temperature observations to derive the hourly incremental vapor generation rates. The parking distribution and hourly incremental vapor generation rates are then adopted with Wade-Reddy's equation to estimate the weighted average evaporative generation. We find that hourly incremental rates can better describe the temporal variations of vapor generation, and the weighted vapor generation rate is 5-8% less than calculation without considering parking activity. PMID:25818089

  15. Investigation of evaporate deposits in the “Great Ear” area of Lop Nor salt plain, Xinjiang Province, China

    NASA Astrophysics Data System (ADS)

    Ma, L.; Li, B.; Jiang, P.; Lowenstein, T. K.; Zhong, J.; Sheng, J.; Wu, H.

    2009-12-01

    In arid regions of the world, salt pans are common features occupying the lowest areas of closed interior basin. The Lop Nor salt plain is located at the east end of the Tarim Basin, Xinjiang Province, China. Widespread Holocene salt deposits were known to cover thousands of square kilometers and up to hundreds of meters thick. However, the salt pans in the central-eastern sector of the Lop Nor salt plain is unusually represented by successive concentric black-and-white rings that closely resembled a big human ear in satellite images. The total area of the “Great Ear” is approximately 5,500 km2, and the internal morphology is considered essentially flat with an elevation of 800 m. A series of detailed field investigations on the “Great Ear” salt pans involved describing evaporates and surface morphologies, measuring chemical compositions, and groundwater depths. The deposits show clear lateral variations in salt content, water content, evaporate mineralogy, as well as the microrelief of salt crust in the “Great Ear” area. Spatially, spectral imaging variation corresponds to color variation in the “Great Ear”, which suggests surface moist conditions of a salt pan: dark-toned areas are wet and the bright-toned areas are dry. In the wet zone, capillary fringing of groundwater brines control the precipitation of evaporites and microrelief genesis. The salt pans are marked by pressure-ridge and well-developed hexagonal honeycomb polygons structures, where the microrelief of salt crust ranges from 30 to 80 cm. In the dry salt pans zone, groundwater discharge was not observed on the surface and the salt crust is characterized by low relief, low salinity, a lack of efflorescences crusts, and significant amounts of detrital sediments. This zone shows bright-tone in the satellite images due to higher reflectance of dry salt-encrusted pans surface. Though, the sediment beneath the surface typically is saturated with concentrated brines and displacive

  16. Production of stable tellurium evaporated targets

    NASA Astrophysics Data System (ADS)

    Greene, John P.; Palumbo, Annalia; Tan, Wanpeng; Görres, Joachim; Wiescher, Michael C.

    2008-06-01

    Due to the low melting point of tellurium metal, self-supporting Te targets degrade quickly when exposed to particle beams. This situation is greatly improved if the tellurium material is evaporated onto C foil backings. Elastic scattering in target and backing layers broadens the Te peak, making measurements difficult, while too little material reduces the reaction rate. Therefore, it is necessary to optimize the target thickness. Evaporated metallic and oxide Te targets were prepared at Argonne National Laboratory by vacuum deposition from a resistively heated source boat. The stability of the targets was then tested by exposing them to a varying intensity alpha beam with an energy range from 17 to 27 MeV using the FN Tandem Van de Graaff accelerator at the University of Notre Dame. Optimal target thicknesses and beam currents were then obtained for p-process experiments. A description of the apparatus and production method will be presented.

  17. Thermoelectric integrated membrane evaporation water recovery technology

    NASA Technical Reports Server (NTRS)

    Roebelen, G. J., Jr.; Winkler, H. E.; Dehner, G. F.

    1982-01-01

    The recently developed Thermoelectric Integrated Membrane Evaporation Subsystem (TIMES) offers a highly competitive approach to water recovery from waste fluids for future on-orbit stations such as the Space Operations Center. Low power, compactness and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber membrane evaporator with a thermoelectric heat pump. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than pumps and an accumulator, thus solving problems inherent in other reclamation subsystem designs. In an extensive test program, over 850 hours of operation were accumulated during which time high quality product water was recovered from both urine and wash water at an average steady state production rate of 2.2 pounds per hour.

  18. Influence of surface wettability on transport mechanisms governing water droplet evaporation.

    PubMed

    Pan, Zhenhai; Weibel, Justin A; Garimella, Suresh V

    2014-08-19

    Prediction and manipulation of the evaporation of small droplets is a fundamental problem with importance in a variety of microfluidic, microfabrication, and biomedical applications. A vapor-diffusion-based model has been widely employed to predict the interfacial evaporation rate; however, its scope of applicability is limited due to incorporation of a number of simplifying assumptions of the physical behavior. Two key transport mechanisms besides vapor diffusion-evaporative cooling and natural convection in the surrounding gas-are investigated here as a function of the substrate wettability using an augmented droplet evaporation model. Three regimes are distinguished by the instantaneous contact angle (CA). In Regime I (CA ≲ 60°), the flat droplet shape results in a small thermal resistance between the liquid-vapor interface and substrate, which mitigates the effect of evaporative cooling; upward gas-phase natural convection enhances evaporation. In Regime II (60 ≲ CA ≲ 90°), evaporative cooling at the interface suppresses evaporation with increasing contact angle and counterbalances the gas-phase convection enhancement. Because effects of the evaporative cooling and gas-phase convection mechanisms largely neutralize each other, the vapor-diffusion-based model can predict the overall evaporation rates in this regime. In Regime III (CA ≳ 90°), evaporative cooling suppresses the evaporation rate significantly and reverses entirely the direction of natural convection induced by vapor concentration gradients in the gas phase. Delineation of these counteracting mechanisms reconciles previous debate (founded on single-surface experiments or models that consider only a subset of the governing transport mechanisms) regarding the applicability of the classic vapor-diffusion model. The vapor diffusion-based model cannot predict the local evaporation flux along the interface for high contact angle (CA ≥ 90°) when evaporative cooling is strong and the

  19. CHEMISTRY IN EVAPORATING ICES-UNEXPLORED TERRITORY

    SciTech Connect

    Cecchi-Pestellini, Cesare; Rawlings, Jonathan M. C.; Viti, Serena; Williams, David A. E-mail: jcr@star.ucl.ac.u E-mail: daw@star.ucl.ac.u

    2010-12-20

    We suggest that three-body chemistry may occur in warm high-density gas evaporating in transient co-desorption events on interstellar ices. Using a highly idealized computational model we explore the chemical conversion from simple species of the ice to more complex species containing several heavy atoms, as a function of density and of adopted three-body rate coefficients. We predict that there is a wide range of densities and rate coefficients in which a significant chemical conversion may occur. We discuss the implications of this idea for the astrochemistry of hot cores.

  20. Modeling evaporation from spent nuclear fuel storage pools: A diffusion approach

    NASA Astrophysics Data System (ADS)

    Hugo, Bruce Robert

    Accurate prediction of evaporative losses from light water reactor nuclear power plant (NPP) spent fuel storage pools (SFPs) is important for activities ranging from sizing of water makeup systems during NPP design to predicting the time available to supply emergency makeup water following severe accidents. Existing correlations for predicting evaporation from water surfaces are only optimized for conditions typical of swimming pools. This new approach modeling evaporation as a diffusion process has yielded an evaporation rate model that provided a better fit of published high temperature evaporation data and measurements from two SFPs than other published evaporation correlations. Insights from treating evaporation as a diffusion process include correcting for the effects of air flow and solutes on evaporation rate. An accurate modeling of the effects of air flow on evaporation rate is required to explain the observed temperature data from the Fukushima Daiichi Unit 4 SFP during the 2011 loss of cooling event; the diffusion model of evaporation provides a significantly better fit to this data than existing evaporation models.

  1. Pan-Planets: Searching for hot Jupiters around cool dwarfs

    NASA Astrophysics Data System (ADS)

    Obermeier, C.; Koppenhoefer, J.; Saglia, R. P.; Henning, Th.; Bender, R.; Kodric, M.; Deacon, N.; Riffeser, A.; Burgett, W.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Metcalfe, N.; Price, P. A.; Sweeney, W.; Wainscoat, R. J.; Waters, C.

    2016-03-01

    The Pan-Planets survey observed an area of 42 sq deg. in the galactic disk for about 165 h. The main scientific goal of the project is the detection of transiting planets around M dwarfs. We establish an efficient procedure for determining the stellar parameters Teff and log g of all sources using a method based on SED fitting, utilizing a three-dimensional dust map and proper motion information. In this way we identify more than 60 000 M dwarfs, which is by far the largest sample of low-mass stars observed in a transit survey to date. We present several planet candidates around M dwarfs and hotter stars that are currently being followed up. Using Monte Carlo simulations we calculate the detection efficiency of the Pan-Planets survey for different stellar and planetary populations. We expect to find 3.0+3.3-1.6 hot Jupiters around F, G, and K dwarfs with periods lower than 10 days based on the planet occurrence rates derived in previous surveys. For M dwarfs, the percentage of stars with a hot Jupiter is under debate. Theoretical models expect a lower occurrence rate than for larger main sequence stars. However, radial velocity surveys find upper limits of about 1% due to their small sample, while the Kepler survey finds a occurrence rate that we estimate to be at least 0.17b(+0.67-0.04) %, making it even higher than the determined fraction from OGLE-III for F, G and K stellar types, 0.14 (+0.15-0.076) %. With the large sample size of Pan-Planets, we are able to determine an occurrence rate of 0.11 (+0.37-0.02) % in case one of our candidates turns out to be a real detection. If, however, none of our candidates turn out to be true planets, we are able to put an upper limit of 0.34% with a 95% confidence on the hot Jupiter occurrence rate of M dwarfs. This limit is a significant improvement over previous estimates where the lowest limit published so far is 1.1% found in the WFCAM Transit Survey. Therefore we cannot yet confirm the theoretical prediction of a lower

  2. Coupling dynamic blow down and pool evaporation model for LNG.

    PubMed

    Woodward, John L

    2007-02-20

    Treating the dynamic effects of accidental discharges of liquefied natural gas (LNG) is important for realistic predictions of pool radius. Two phenomena have important influence on pool spread dynamics, time-varying discharge (blow down) and pool ignition. Time-varying discharge occurs because a punctured LNG tanker or storage tank drains with a decreasing liquid head and decreasing head-space pressure. Pool ignition increases the evaporation rate of a pool and consequently decreases the ultimate pool area. This paper describes an approach to treat these phenomena in a dynamic pool evaporation model. The pool evaporation model developed here has two separate regimes. Early in the spill, momentum forces dominate and the pool spreads independently of pool evaporation rate and the corresponding heat transfer rate. After the average pool depth drops below a minimum value, momentum forces are largely dissipated and the thin edges of the pool completely evaporate, so pool area is established by the heat transfer rate. The maximum extent of a burning pool is predicted to be significantly less than that of an unignited pool because the duration of the first regime is reduced by higher heat transfer rates. The maximum extent of an LNG pool is predicted to be larger upon accounting for blow down compared with using a constant average discharge rate. However, the maximum pool extent occurs only momentarily before retreating. PMID:17184912

  3. Experimental simulations of CH4 evaporation on Titan

    NASA Astrophysics Data System (ADS)

    Luspay-Kuti, A.; Chevrier, V. F.; Wasiak, F. C.; Roe, L. A.; Welivitiya, W. D. D. P.; Cornet, T.; Singh, S.; Rivera-Valentin, E. G.

    2012-12-01

    We present the first experimental results on the evaporation of liquid CH4 under simulated Titan surface conditions similar to those observed at the Huygens landing site. An average evaporation rate of (3.1 ± 0.6) × 10-4 kg s-1 m-2 at 94 K and 1.5 bar was measured. While our results are generally higher than previous models based on energy balance, they show an excellent match with a theoretical mass transfer approach. Indeed, we find that evaporation in the Titan environmental chamber is predominantly diffusion driven and affected by the buoyancy of lighter CH4 in the heavier N2 atmosphere. After correcting for the difference in gravity of Earth and Titan, the resulting evaporation rate is (1.6 ± 0.3) × 10-4 kg s-1m-2 (or 1.13 ± 0.3 mm hr-1). Using our experimental evaporation rates, we determine that the low-latitude storm recently observed by Cassini ISS would have resulted in a maximum evaporated mass of (5.4 ± 1.2) × 1010 kg of CH4 equivalent to a 2.4 ± 0.5 m thick layer over 80 days. Based on our results, a sufficient amount of CH4 can accumulate in the otherwise arid equatorial regions to produce transient ponds and liquid flows.

  4. Evaporative cooling: effective latent heat of evaporation in relation to evaporation distance from the skin.

    PubMed

    Havenith, George; Bröde, Peter; den Hartog, Emiel; Kuklane, Kalev; Holmer, Ingvar; Rossi, Rene M; Richards, Mark; Farnworth, Brian; Wang, Xiaoxin

    2013-03-15

    Calculation of evaporative heat loss is essential to heat balance calculations. Despite recognition that the value for latent heat of evaporation, used in these calculations, may not always reflect the real cooling benefit to the body, only limited quantitative data on this is available, which has found little use in recent literature. In this experiment a thermal manikin, (MTNW, Seattle, WA) was used to determine the effective cooling power of moisture evaporation. The manikin measures both heat loss and mass loss independently, allowing a direct calculation of an effective latent heat of evaporation (λeff). The location of the evaporation was varied: from the skin or from the underwear or from the outerwear. Outerwear of different permeabilities was used, and different numbers of layers were used. Tests took place in 20°C, 0.5 m/s at different humidities and were performed both dry and with a wet layer, allowing the breakdown of heat loss in dry and evaporative components. For evaporation from the skin, λeff is close to the theoretical value (2,430 J/g) but starts to drop when more clothing is worn, e.g., by 11% for underwear and permeable coverall. When evaporation is from the underwear, λeff reduction is 28% wearing a permeable outer. When evaporation is from the outermost layer only, the reduction exceeds 62% (no base layer), increasing toward 80% with more layers between skin and wet outerwear. In semi- and impermeable outerwear, the added effect of condensation in the clothing opposes this effect. A general formula for the calculation of λeff was developed. PMID:23329814

  5. Explosive evaporation in solar flares

    NASA Technical Reports Server (NTRS)

    Fisher, George H.

    1987-01-01

    This paper develops a simple analytical model for the phenomenon of 'explosive evaporation' driven by nonthermal electron heating in solar flares. The model relates the electron energy flux and spectrum, plus details of the preflare atmosphere, to the time scale for explosive evaporation to occur, the maximum pressure and temperature to be reached, rough estimates for the UV pulse emission flux and duration, and the evolution of the blueshifted component of the soft X-ray lines. An expression is given for the time scale for buildup to maximum pressures and the onset of rapid motion of the explosively evaporating plasma. This evaporation can excite a rapid response of UV line and continuum emission. The emission lines formed in the plasma approach a given emissivity-weighted blueshift speed.

  6. Dual manifold heat pipe evaporator

    DOEpatents

    Adkins, Douglas R.; Rawlinson, K. Scott

    1994-01-01

    An improved evaporator section for a dual manifold heat pipe. Both the upper and lower manifolds can have surfaces exposed to the heat source which evaporate the working fluid. The tubes in the tube bank between the manifolds have openings in their lower extensions into the lower manifold to provide for the transport of evaporated working fluid from the lower manifold into the tubes and from there on into the upper manifold and on to the condenser portion of the heat pipe. A wick structure lining the inner walls of the evaporator tubes extends into both the upper and lower manifolds. At least some of the tubes also have overflow tubes contained within them to carry condensed working fluid from the upper manifold to pass to the lower without spilling down the inside walls of the tubes.

  7. Dual manifold heat pipe evaporator

    DOEpatents

    Adkins, D.R.; Rawlinson, K.S.

    1994-01-04

    An improved evaporator section is described for a dual manifold heat pipe. Both the upper and lower manifolds can have surfaces exposed to the heat source which evaporate the working fluid. The tubes in the tube bank between the manifolds have openings in their lower extensions into the lower manifold to provide for the transport of evaporated working fluid from the lower manifold into the tubes and from there on into the upper manifold and on to the condenser portion of the heat pipe. A wick structure lining the inner walls of the evaporator tubes extends into both the upper and lower manifolds. At least some of the tubes also have overflow tubes contained within them to carry condensed working fluid from the upper manifold to pass to the lower without spilling down the inside walls of the tubes. 1 figure.

  8. Horst Meyer and Quantum Evaporation

    NASA Astrophysics Data System (ADS)

    Balibar, S.

    2016-06-01

    With their 1963 article in Cryogenics Horst Meyer and his collaborators triggered intense research activity on the evaporation of superfluid helium. Discussing this subject with him in 1975 was enlightening. Fifty years later, the analogy between the photoelectric effect and the evaporation of superfluid helium in the low temperature limit is not yet clear, although remarkable progress has been made in its observation and its understanding. This special issue of the Journal of Low Temperature Physics is an opportunity to recall the history of quantum evaporation, and to express my gratitude to Horst Meyer. It describes quickly most of the experimental and theoretical works which have been published on quantum evaporation during the last 50 years, but it is not a comprehensive review of this fascinating subject.

  9. Evaporation Tower With Prill Nozzles

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.

    1984-01-01

    Tower more efficient than conventional evaporation equipment. Liquids such as milk and fruit juice concentrated by passing them through tiny nozzle to form droplets, then allowing droplets to fall through evacuated tower with cooled walls.

  10. Estimation of evaporative loss based on the stable isotope composition of water using Hydrocalculator

    NASA Astrophysics Data System (ADS)

    Skrzypek, Grzegorz; Mydłowski, Adam; Dogramaci, Shawan; Hedley, Paul; Gibson, John J.; Grierson, Pauline F.

    2015-04-01

    Accurate quantification of evaporative losses to the atmosphere from surface water bodies is essential for calibration and validation of hydrological models, particularly in remote arid and semi-arid regions, where intermittent rivers are generally minimally gauged. Analyses of the stable hydrogen and oxygen isotope composition of water can be used to estimate evaporative losses from individual pools in such regions in the absence of instrumental data but calculations can be complex, especially in highly variable systems. In this study, we reviewed and combined the most recent equations required for estimation of evaporative losses based on the revised Craig-Gordon model. The updated procedure is presented step-by-step, increasing ease of replication of all calculations. The main constraints and sources of uncertainties in the model were also evaluated. Based on this procedure we have designed a new software, Hydrocalculator, that allows quick and robust estimation of evaporative losses based on isotopic composition of water. The software was validated against measures of field pan evaporation under arid conditions in northwest Australia as well as published data from other regions. We found that the major factor contributing to the overall uncertainty in evaporative loss calculations using this method is uncertainty in estimation of the isotope composition of ambient air moisture.

  11. An investigation on the estimation of evaporation by combining artificial neural network and dynamic factor analysis

    NASA Astrophysics Data System (ADS)

    Sun, W.; Chiang, Y.; Chang, F.

    2010-12-01

    Evaporation is a substantial factor in hydrological circle, moreover a significant reference to the management of both water resources and agricultural irrigation. In general, evaporation can be directly measured by evaporation pan. As for its estimation, the accuracy of traditional empirical equation is not very precise. Therefore, in this study the Dynamic Factor Analysis (DFA) is first applied to investigating the interaction and the tendency of each gauging station. Additionally, the analysis can effectively establish the common trend at each gauging station by evaluating the corresponding AIC (Akaike Information Criterion) values. Furthermore, the meteorological factors such as relative humidity and temperature are also conducted to identify the explanatory variables which have higher relation to evaporation. These variables are further used as inputs to the Back-Propagation Neural Network (BPNN) and are expected to provide meaningful information for successfully estimating evaporation. The applicability and reliability of the BPNN was demonstrated by comparing its performance with that of empirical formula. Keywords: Evaporation, Dynamic Factor Analysis, Artificial Neural Network.

  12. Marangoni instability induced convection in an evaporating liquid droplet

    NASA Technical Reports Server (NTRS)

    Chai, An-Ti; Rashidnia, N.; Arpaci, V. S.

    1992-01-01

    The processes occurring when a liquid drop undergoes evaporation are described. When a liquid drop undergoes evaporation, its surface temperature decreases. If the droplet is free floating in a microgravity environment, the heat transfer process inside the droplet is initially condition controlled. As the process continues, a radial temperature gradient builds up at the free surface until the critical Marangoni number is exceeded. Then the onset of instability induces thermocapillary convective flows, which in turn speed up the evaporation. The convective flows will subside when the interior of the droplet reaches a certain equilibrium temperature, and the process will return to the diffusion controlled mode. Both preliminary modeling and recent laboratory data have confirmed that Marangoni instability induced convection can and does occur in the droplet evaporation process. Mathematical models representing Marangoni instability in an evaporating liquid drop are presented. An ideal space experiment to study and characterize the onset of Marangoni instability in an evaporating liquid droplet and to establish the effect of Marangoni instability induced convection on the droplet evaporation rate is outlined and the need for conducting such experiments in space is highlighted. However, before an opportunity to conduct experiments in space arises, ground based experiments have to be conducted to study feasibility issues and proof of concept. A ground based experiment of this type is outlined.

  13. A shortcut for designing evaporators

    SciTech Connect

    Durand, M.I.A.A.

    1996-01-01

    Multiple-effect evaporation is commonly used in chemical process plants to minimize energy consumption and cooling water. In this system, several evaporators are connected by piping so that vapor passes from one effect to the next in series. Thus, the heat supplied to the first evaporator is used to vaporize water in the first effect; this vapor, in turn, passes to the next effect, until, finally, the heat in the vapor supplied to the last effect passes on to the condenser. The net result of this arrangement is the multiple reuse of heat, and a marked increase in the economic of the evaporation system. In addition to savings in steam use, there is also a saving in condenser cooling water as the number of effects increases. On the other hand, an increase in the number of effects represents an increase in capital costs since more heat transfer area is required in the evaporator system. Thus, the choice of the proper--that is, optimum--number of effects is dictated by an economic balance between the savings in steam and cooling water versus that of the additional investment costs. The paper describes the basic equations and an economic analysis of evaporator systems, and illustrates the method with an example.

  14. PAN/PS elctrospun fibers for oil spill cleanup

    NASA Astrophysics Data System (ADS)

    Ying, Qiao; Lili, Zhao; Haixiang, Sun; Peng, Li

    2014-08-01

    A high-capacity oil sorbent was fabricated by electrospinning using PS/PAN blend. Morphology, contact angle and oil adsorption of PAN/PS fiber and PP nonwoven fabric were studied. It was found that the PAN/PS fiber had a smaller diameter than PP, and the maximum sorption capacities of the PAN/PS sorbent for pump oil, peanut oil, diesel, and gasoline were 194.85, 131.7, 66.75, and 43.38 g/g, which were far higher than those of PP. The sorbent PS/PAN fiber showed a contact angle of water144.32° and diesel oil 0°. The sorption kinetics of PAN/PS and PP sorbent were also investigated. Compared with the commercial PP fabric, the PAN/PS fiber seems to have the ability to be used in oil-spill cleanup application.

  15. DWPF Recycle Evaporator Simulant Tests

    SciTech Connect

    Stone, M

    2005-04-05

    Testing was performed to determine the feasibility and processing characteristics of an evaporation process to reduce the volume of the recycle stream from the Defense Waste Processing Facility (DWPF). The concentrated recycle would be returned to DWPF while the overhead condensate would be transferred to the Effluent Treatment Plant. Various blends of evaporator feed were tested using simulants developed from characterization of actual recycle streams from DWPF and input from DWPF-Engineering. The simulated feed was evaporated in laboratory scale apparatus to target a 30X volume reduction. Condensate and concentrate samples from each run were analyzed and the process characteristics (foaming, scaling, etc) were visually monitored during each run. The following conclusions were made from the testing: Concentration of the ''typical'' recycle stream in DWPF by 30X was feasible. The addition of DWTT recycle streams to the typical recycle stream raises the solids content of the evaporator feed considerably and lowers the amount of concentration that can be achieved. Foaming was noted during all evaporation tests and must be addressed prior to operation of the full-scale evaporator. Tests were conducted that identified Dow Corning 2210 as an antifoam candidate that warrants further evaluation. The condensate has the potential to exceed the ETP WAC for mercury, silicon, and TOC. Controlling the amount of equipment decontamination recycle in the evaporator blend would help meet the TOC limits. The evaporator condensate will be saturated with mercury and elemental mercury will collect in the evaporator condensate collection vessel. No scaling on heating surfaces was noted during the tests, but splatter onto the walls of the evaporation vessels led to a buildup of solids. These solids were difficult to remove with 2M nitric acid. Precipitation of solids was not noted during the testing. Some of the aluminum present in the recycle streams was converted from gibbsite to

  16. Evaporation Kinetics of Laboratory Generated Secondary Organic Aerosols at Elevated Relative Humidity

    SciTech Connect

    Wilson, Jacqueline M.; Imre, D.; Beranek, Josef; Shrivastava, ManishKumar B.; Zelenyuk, Alla

    2015-01-06

    Secondary organic aerosols (SOA) dominate atmospheric organic aerosols that affect climate, air quality, and health. Recent studies indicate that, contrary to previously held assumptions, at low relative humidity (RH) these particles are semi-solid and evaporate orders of magnitude slower than expected. Elevated relative humidity has the potential to affect significantly formation, properties, and atmospheric evolution of SOA particles. Here we present a study of the effect of RH on the room-temperature evaporation kinetics of SOA particles formed by ozonolysis of α-pinene and limonene. Experiments were carried out on SOA particles generated, evaporated, and aged at 0%, 50% and 90% RH. We find that in all cases evaporation begins with a relatively fast phase, during which 30% to 70% of the particle mass evaporates in 2 hours, followed by a much slower evaporation rate. Evaporation kinetics at 0% and 50% RH are nearly the same, while at 90% RH a slightly larger fraction evaporates. In all cases, aging the particles prior to inducing evaporation reduces the evaporative losses, with aging at elevated RH leading to more significant effect. In all cases, SOA evaporation is nearly size-independent, providing direct evidence that oligomers play a crucial role in determining the evaporation kinetics.

  17. Stick-Jump (SJ) Evaporation of Strongly Pinned Nanoliter Volume Sessile Water Droplets on Quick Drying, Micropatterned Surfaces.

    PubMed

    Debuisson, Damien; Merlen, Alain; Senez, Vincent; Arscott, Steve

    2016-03-22

    We present an experimental study of stick-jump (SJ) evaporation of strongly pinned nanoliter volume sessile water droplets drying on micropatterned surfaces. The evaporation is studied on surfaces composed of photolithographically micropatterned negative photoresist (SU-8). The micropatterning of the SU-8 enables circular, smooth, trough-like features to be formed which causes a very strong pinning of the three phase (liquid-vapor-solid) contact line of an evaporating droplet. This is ideal for studying SJ evaporation as it contains sequential constant contact radius (CCR) evaporation phases during droplet evaporation. The evaporation was studied in nonconfined conditions, and forced convection was not used. Micropatterned concentric circles were defined having an initial radius of 1000 μm decreasing by a spacing ranging from 500 to 50 μm. The droplet evaporates, successively pinning and depinning from circle to circle. For each pinning radius, the droplet contact angle and volume are observed to decrease quasi-linearly with time. The experimental average evaporation rates were found to decrease with decreasing pining radii. In contrast, the experimental average evaporation flux is found to increase with decreasing droplet radii. The data also demonstrate the influence of the initial contact angle on evaporation rate and flux. The data indicate that the total evaporation time of a droplet depends on the specific micropattern spacing and that the total evaporation time on micropatterned surfaces is always less than on flat, homogeneous surfaces. Although the surface patterning is observed to have little effect on the average droplet flux-indicating that the underlying evaporation physics is not significantly changed by the patterning-the total evaporation time is considerably modified by patterning, up to a factor or almost 2 compared to evaporation on a flat, homogeneous surface. The closely spaced concentric circle pinning maintains a large droplet radius and

  18. Transient Marangoni convection in hanging evaporating drops

    NASA Astrophysics Data System (ADS)

    Savino, R.; Fico, S.

    2004-10-01

    A combined experimental and numerical analysis has been carried out to study Marangoni effects during the evaporation of droplets. The experiments are performed with pendant drops of silicone oils (with different viscosities) and hydrocarbons. The temperature of the disk sustaining the drop is rapidly increased or decreased in order to study transient heating or cooling processes. The velocity field in the droplet is evaluated monitoring the motion of tracers in the meridian plane, using a laser sheet illumination system and a video camera. Surface temperature distributions of the drops are detected by infrared thermocamera. The numerical model is based on axisymmetric Navier-Stokes equations, taking into account the presence of Marangoni shear stresses and evaporative cooling at the liquid-air interface. Marangoni flows cause a larger, more uniform surface temperature, increasing heat transfer from disk to droplet, as well as evaporation rate. When Marangoni effects are negligible, larger surface temperature differences occur along the drop surface and heat transfer is relatively small. The role of Marangoni and buoyancy flows in silicone oils with different viscosities and hydrocarbons is discussed and correlations are presented between experimental and numerical results.

  19. Evaporated Lithium Surface Coatings in NSTX

    SciTech Connect

    Kugel, H. W.; Mansfield, D.; Maingi, R.; Bel, M. G.; Bell, R. E.; Allain, J. P.; Gates, D.; Gerhardt, S.; Kaita, R.; Kallman, J.; Kaye, S.; LeBlanc, B.; Majeski, R.; Menard, J.; Mueller, D.; Ono, M.

    2009-04-09

    Two lithium evaporators were used to evaporate more than 100 g of lithium on to the NSTX lower divertor region. Prior to each discharge, the evaporators were withdrawn behind shutters, where they also remained during the subsequent HeGDC applied for periods up to 9.5 min. After the HeGDC, the shutters were opened and the LITERs were reinserted to deposit lithium on the lower divertor target for 10 min, at rates of 10-70 mg/min, prior to the next discharge. The major improvements in plasma performance from these lithium depositions include: 1) plasma density reduction as a result of lithium deposition; 2) suppression of ELMs; 3) improvement of energy confinement in a low-triangularity shape; 4) improvement in plasma performance for standard, high-triangularity discharges; 5) reduction of the required HeGDC time between discharges; 6) increased pedestal electron and ion temperature; 7) reduced SOL plasma density; and 8) reduced edge neutral density.

  20. Structural and evaporative evolutions in desiccating sessile drops of blood

    NASA Astrophysics Data System (ADS)

    Sobac, B.; Brutin, D.

    2011-07-01

    We report an experimental investigation of the drying of a deposited drop of whole blood. Flow motion, adhesion, gelation, and fracturation all occur during the evaporation of this complex matter, leading to a final typical pattern. Two distinct regimes of evaporation are highlighted: the first is driven by convection, diffusion, and gelation in a liquid phase, whereas the second, with a much slower rate of evaporation, is characterized by the mass transport of the liquid left over in the gellified biocomponent matter. A diffusion model of the drying process allows a prediction of the transition between these two regimes of evaporation. Moreover, the formation of cracks and other events occurring during the drying are examined and shown to be driven by critical solid mass concentrations.

  1. Desiccant Enhanced Evaporative Air Conditioning: Parametric Analysis and Design; Preprint

    SciTech Connect

    Woods, J.; Kozubal, E.

    2012-10-01

    This paper presents a parametric analysis using a numerical model of a new concept in desiccant and evaporative air conditioning. The concept consists of two stages: a liquid desiccant dehumidifier and a dew-point evaporative cooler. Each stage consists of stacked air channel pairs separated by a plastic sheet. In the first stage, a liquid desiccant film removes moisture from the process (supply-side) air through a membrane. An evaporatively-cooled exhaust airstream on the other side of the plastic sheet cools the desiccant. The second-stage indirect evaporative cooler sensibly cools the dried process air. We analyze the tradeoff between device size and energy efficiency. This tradeoff depends strongly on process air channel thicknesses, the ratio of first-stage to second-stage area, and the second-stage exhaust air flow rate. A sensitivity analysis reiterates the importance of the process air boundary layers and suggests a need for increasing airside heat and mass transfer enhancements.

  2. Evaporative Emission Model (EVAP 3. 0) (for microcomputers). Software

    SciTech Connect

    Not Available

    1993-02-01

    The potential role of automotive evaporative emissions in the formation of photochemical smog has underscored the need for an accurate evaluation of real-world motor vehicle evaporative emission rates. Two general categories of information are needed to predict evaporative emissions for vehicles in actual use. The first category defines the environment that a vehicle experiences in the real world. This includes conditions such as driving pattern, ambient temperature, refueling behavior, and gasoline Reid vapor pressure (RVP). The second category describes how the vehicle responds to these conditions. This includes weathering of the fuel in the fuel tank and how evaporative emissions vary as a function of RVP, ambient temperature, and fuel tank level.

  3. EVAPORATION OF ICY PLANETESIMALS DUE TO BOW SHOCKS

    SciTech Connect

    Tanaka, Kyoko K.; Yamamoto, Tetsuo; Tanaka, Hidekazu; Miura, Hitoshi; Nagasawa, Makiko; Nakamoto, Taishi

    2013-02-20

    We present the novel concept of evaporation of planetesimals as a result of bow shocks associated with planetesimals orbiting with supersonic velocities relative to the gas in a protoplanetary disk. We evaluate the evaporation rates of the planetesimals based on a simple model describing planetesimal heating and evaporation by the bow shock. We find that icy planetesimals with radius {approx}>100 km evaporate efficiently even outside the snow line in the stage of planetary oligarchic growth, where strong bow shocks are produced by gravitational perturbations from protoplanets. The obtained results suggest that the formation of gas giant planets is suppressed owing to insufficient accretion of icy planetesimals onto the protoplanet within the {approx}<5 AU disk region.

  4. Microdroplet evaporation with a forced pinned contact line.

    PubMed

    Gleason, Kevin; Putnam, Shawn A

    2014-09-01

    Experimental and numerical investigations of water microdroplet evaporation on heated, laser patterned polymer substrates are reported. The study is focused on both (i) controlling a droplet's contact line dynamics during evaporation to identifying how the contact line influences evaporative heat transfer and (ii) validating numerical simulations with experimental data. Droplets are formed on the polymer surface using a bottom-up methodology, where a computer-controlled syringe pump feeds water through a 200 μm diameter fluid channel within the heated polymer substrate. This methodology facilitates precise control of the droplet's growth rate, size, and inlet temperature. In addition to this microchannel supply line, the substrate surfaces are laser patterned with a moatlike trench around the fluid-channel outlet, adding additional control of the droplet's contact line motion, area, and contact angle. In comparison to evaporation on a nonpatterned polymer surface, the laser patterned trench increases contact line pinning time by ∼60% of the droplet's lifetime. Numerical simulations of diffusion controlled evaporation are compared the experimental data with a pinned contact line. These diffusion based simulations consistently over predict the droplet's evaporation rate. In efforts to improve this model, a temperature distribution along the droplet's liquid-vapor interface is imposed to account for the concentration distribution of saturated vapor along the interface, which yields improved predictions within 2-4% of the experimental data throughout the droplet's lifetime on heated substrates. PMID:25102248

  5. Tear evaporation from the ocular surface.

    PubMed

    Tsubota, K; Yamada, M

    1992-09-01

    A simple method was developed to measure tear evaporation. A sensor was inserted into a chamber covering the eye. The humidity inside each chamber then was measured every 10 sec for 2 min with both eyes either closed or open but allowing normal blinking. The difference between these conditions represented evaporation from the ocular surface. Using this method, the tear evaporation rate at 40% ambient humidity (TEROS 40) was calculated. The average TEROS 40 in normal subjects (n = 43) was 15.6 +/- 3.8 x 10(-7) g/sec. It was 9.5 +/- 5.6 x 10(-7) g/sec in patients with dry eye symptoms (n = 72, P less than 0.001). The insertion of lacrimal collagen implants in one group of such patients (n = 10) increased the TEROS 40 from 10.2 +/- 5.5 x 10(-7) g/sec to 18.2 +/- 4.8 x 10(-7) g/sec (P less than 0.01). The instillation of eye drops increased the TEROS 40 significantly in patients with dry eye symptoms for at least 1 min (n = 10, P less than 0.01); a continued effect depended on the type of eye drop. Increased TEROS 40 still was observed 5 min after instillation of viscous eye drops (0.1% and 0.3% sodium hyaluronic acid); the TEROS 40 returned to original levels within 5 min after instillation of artificial tears of normal viscosity with or without 0.05% sodium hyaluronate. In all cases, TEROS 40 returned to original levels within 10 min. This was a quick reliable method for measuring tear evaporation from the ocular surface, and it can be applied to evaluate tear dynamics and subclassifications of dry eyes. PMID:1526744

  6. The interaction of evaporative and convective instabilities

    NASA Astrophysics Data System (ADS)

    Ozen, O.

    Evaporative convection arises in a variety of natural and industrial processes, such as drying of lakebeds, heat pipe technology and dry-eye syndrome. The phenomenon of evaporative convection leads to an interfacial instability where an erstwhile flat surface becomes undulated as a control variable, such as temperature drop, exceeds a critical value. This instability has been investigated by others assuming that the vapor phase is infinitely deep and passive, i.e. vapor fluid dynamics has been ignored. However, when we look at some engineering processes, such as distillation columns, heat pipes and drying technologies where phase change takes place we might imagine that the assumption of an infinitely deep vapor layer or at least that of a passive vapor is inappropriate. Previous work on convection in bilayer systems with no phase-change suggests that active vapor layers play a major role in determining the stability of an interface. Hence, for the case of convection with phase-change, we will address this issue and try to answer the question whether the infinitely deep and passive vapor layer is a valid assumption. We have also investigated, theoretically, the gravity and surface tension gradient-driven instabilities occurring during the evaporation of a liquid into its own vapor taking into account the fluid dynamics of both phases and the finiteness of the domains of each phase, i.e. the liquid and its vapor are assumed to be confined between two horizontal plates, and different heating arrangements are applied. The effects of fluid layer depths, the evaporation rate and the temperature gradient applied across the fluids on the stability of the interface are studied. The modes of the flow pattern are determined for each scenario. The physics of the instability are explained and a comparison is made with the results of similar, yet physically different problems.

  7. BRDF of Salt Pan Regolith Samples

    NASA Technical Reports Server (NTRS)

    Georgiev, Georgi T.; Gatebe, Charles K.; Butler, James J.; King, Michael D.

    2008-01-01

    Laboratory Bi-directional Reflectance Distribution Function (BRDF) measurements of salt pan regolith samples are presented in this study in an effort to understand the role of spatial and spectral variability of the natural biome. The samples were obtained from Etosha Pan, Namibia (19.20 deg S, 15.93 deg E, alt. 1100 m). It is shown how the BRDF depends on the measurement geometry - incident and scatter angles and on the sample particle sizes. As a demonstration of the application of the results, airborne BRDF measurements acquires with NASA's Cloud Absorption Radiometer (CAR) over the same general site where the regolith samples were collected are compared with the laboratory results. Good agreement between laboratory measured and field measured BRDF is reported.

  8. Characteristic lengths affecting evaporative drying of porous media.

    PubMed

    Lehmann, Peter; Assouline, Shmuel; Or, Dani

    2008-05-01

    Evaporation from porous media involves mass and energy transport including phase change, vapor diffusion, and liquid flow, resulting in complex displacement patterns affecting drying rates. Force balance considering media properties yields characteristic lengths affecting the transition in the evaporation rate from a liquid-flow-based first stage limited only by vapor exchange with air to a second stage controlled by vapor diffusion through the medium. The characteristic lengths determine the extent of the hydraulically connected region between the receding drying front and evaporating surface (film region) and the onset of flow rate limitations through this film region. Water is displaced from large pores at the receding drying front to supply evaporation from hydraulically connected finer pores at the surface. Liquid flow is driven by a capillary pressure gradient spanned by the width of the pore size distribution and is sustained as long as the capillary gradient remains larger than gravitational forces and viscous dissipation. The maximum extent of the film region sustaining liquid flow is determined by a characteristic length L_{C} combining the gravity characteristic length L_{G} and viscous dissipation characteristic length L_{V} . We used two sands with particle sizes 0.1-0.5 mm ("fine") and 0.3-0.9 mm ("coarse") to measure the evaporation from columns of different lengths under various atmospheric evaporative demands. The value of L_{G} determined from capillary pressure-saturation relationships was 90 mm for the coarse sand and 140 mm for the fine sand. A significant decrease in drying rate occurred when the drying front reached the predicted L_{G} value (viscous dissipation was negligibly small in sand and L_{C} approximately L_{G} ). The approach enables a prediction of the duration of first-stage evaporation with the highest water losses from soil to the atmosphere. PMID:18643163

  9. Constraints in calculations of evaporative losses in arid climates using the stable isotope composition of water

    NASA Astrophysics Data System (ADS)

    Skrzypek, G.; Mydlowski, A.; Dogramaci, S.; Hedley, P.; Gibson, J. J.; Grierson, P. F.

    2014-12-01

    Accurate quantification of evaporative losses to the atmosphere from surface water bodies is essential for calibration and validation of hydrological models, particularly in remote arid and semi-arid regions, where rivers and lakes are generally minimally gauged. In this study, we reviewed and combined the most recent equations for estimation of evaporative losses based on the revised Craig-Gordon model. We designed new software, called Hydrocalculator, which allows quick and robust estimation of evaporative losses based on the isotopic composition of water. We validated Hydrocalculator by testing the range of uncertainty in the estimation of evaporative losses in arid climates by cross-validating a simplified stable isotope model with field pan evaporation experiments. The use of standardized pans (1.2 m diameter, volume 300 dm3) in hot and dry climates (temperature 29°C and relative humidity between 19 and 26%) allowed simulation of fast evaporation from shallow water bodies. Several factors may contribute to the uncertainty in the evaporative loss calculations. The analytical uncertainty in the determination of the stable isotope composition of water may contribute to ~0.6% for δ18O and ~1.4% for δ2H. The model is less sensitive to uncertainty in climatic variables and an uncertainty of 1°C in air temperature will result only in the ~0.1% uncertainty in δ18O and δ2H. However, uncertainty in relative humidity of 10% will result in an uncertainty in the final outcome of 0.4% (δ18O) and 1.0% (δ2H). Significantly higher uncertainty in evaporative loss estimation is thus associated with uncertainty in ambient air moisture estimation or analysis. An error of 20‰ in δ2H and 5.0‰ in δ18O will result in a maximum difference of 2.4% (δ2H) and 1.7% (δ18O) in the final calculations. Hydrocalculator can thus provide accurate, rapid and cost-effective insight into the water balance of surface water pools. We used the new software to determine the origin of

  10. Evaporation of volatile organic compounds from human skin in vitro.

    PubMed

    Gajjar, Rachna M; Miller, Matthew A; Kasting, Gerald B

    2013-08-01

    The specific evaporation rates of 21 volatile organic compounds (VOCs) from either human skin or a glass substrate mounted in modified Franz diffusion cells were determined gravimetrically. The diffusion cells were positioned either on a laboratory bench top or in a controlled position in a fume hood, simulating indoor and outdoor environments, respectively. A data set of 54 observations (34 skin and 20 glass) was assembled and subjected to a correlation analysis employing 5 evaporative mass transfer relationships drawn from the literature. Models developed by Nielsen et al. (Prediction of isothermal evaporation rates of pure volatile organic compounds in occupational environments: a theoretical approach based on laminar boundary layer theory. Ann Occup Hyg 1995;39:497-511.) and the U.S. Environmental Protection Agency (Peress, Estimate evaporative losses from spills. Chem Eng Prog 2003; April: 32-34.) were found to be the most effective at correlating observed and calculated evaporation rates under the various conditions. The U.S. EPA model was selected for further use based on its simplicity. This is a turbulent flow model based only on vapor pressure and molecular weight of the VOC and the effective air flow rate u. Optimum values of u for the two laboratory environments studied were 0.23 m s(-1) (bench top) and 0.92 m s(-1) (fume hood). PMID:23609116

  11. Effects of Evaporation/Condensation on Spreading and Contact Angle of a Volatile Liquid Drop

    NASA Technical Reports Server (NTRS)

    Zhang, Nengli; Chao, David F.; Singh, Bhim S. (Technical Monitor)

    2000-01-01

    Effects of evaporation/condensation on spreading and contact angle were experimentally studied. A sessile drop of R-113 was tested at different vapor environments to determine the effects of evaporation/condensation on the evolution of contact diameter and contact angle of the drop. Condensation on the drop surface occurs at both the saturated and a nonsaturated vapor environments and promotes the spreading. When the drop is placed in the saturated vapor environment it tends to completely wetting and spreads rapidly. In a nonsaturated vapor environment, the evolution of the sessile drop is divided three stages: condensation-spreading stage, evaporation-retracting stage and rapid contracting stage. In the first stage the drop behaves as in the saturated environment. In the evaporation -retracting stage, the competition between spreading and evaporation of the drop determines the evolution characteristics of the contact diameter and the contact angle. A lower evaporation rate struggles against the spreading power to turn the drop from spreading to retracting with a continuous increase of the contact angle. The drop placed in open air has a much higher evaporation rate. The strong evaporation suppresses the spreading and accelerates the retraction of the drop with a linear decrease of the contact diameter. The contraction of the evaporating drops is gradually accelerated when the contact diameter decreases to 3 min and less till drying up, though the evaporation rate is gradually slowing down.

  12. Evaporation of pure liquid sessile and spherical suspended drops: a review.

    PubMed

    Erbil, H Yildirim

    2012-01-15

    A sessile drop is an isolated drop which has been deposited on a solid substrate where the wetted area is limited by a contact line and characterized by contact angle, contact radius and drop height. Diffusion-controlled evaporation of a sessile drop in an ambient gas is an important topic of interest because it plays a crucial role in many scientific applications such as controlling the deposition of particles on solid surfaces, in ink-jet printing, spraying of pesticides, micro/nano material fabrication, thin film coatings, biochemical assays, drop wise cooling, deposition of DNA/RNA micro-arrays, and manufacture of novel optical and electronic materials in the last decades. This paper presents a review of the published articles for a period of approximately 120 years related to the evaporation of both sessile drops and nearly spherical droplets suspended from thin fibers. After presenting a brief history of the subject, we discuss the basic theory comprising evaporation of micrometer and millimeter sized spherical drops, self cooling on the drop surface and evaporation rate of sessile drops on solids. The effects of drop cooling, resultant lateral evaporative flux and Marangoni flows on evaporation rate are also discussed. This review also has some special topics such as drop evaporation on superhydrophobic surfaces, determination of the receding contact angle from drop evaporation, substrate thermal conductivity effect on drop evaporation and the rate evaporation of water in liquid marbles. PMID:22277832

  13. Modelling sub-daily evaporation from a small reservoir.

    NASA Astrophysics Data System (ADS)

    McGloin, Ryan; McGowan, Hamish; McJannet, David; Burn, Stewart

    2013-04-01

    . Prairie, J. J. Cole, C. M. Duarte, L. J. Tranvik, R. G. Striegl, W. H. McDowell, P. Kortelainen, N. F. Caraco, J. M. Melack and J. J. Middelburg (2006), The global abundance and size distribution of lakes, ponds, and impoundments, Limnology and Oceanography, 51, 2388-2397. Granger, R.J. and N. Hedstrom (2011), Modelling hourly rates of evaporation from small lakes, Hydrological and Earth System Sciences, 15, doi:10.5194/hess-15-267-2011. Imberger, J. and J.C. Patterson (1981), Dynamic Reservoir Simulation Model - DYRESM: 5, In: Transport Models for Inland and Coastal Waters. H.B. Fischer (Ed.). Academic Press, New York, 310-361.

  14. Modeling of two-layer liquid-gas flow with account for evaporation

    NASA Astrophysics Data System (ADS)

    Goncharova, O. N.; Rezanova, E. V.; Lyulin, Yu. V.; Kabov, O. A.

    2015-09-01

    Two-layer gas-liquid flows and evaporation intensity at the interface were studied. The influence of gas flow rate, longitudinal gradient of temperature, the Soret effect on the nature of flow and transfer processes was demonstrated. Experimental and theoretical results were compared; they show dependence of evaporation at the interface on gas flow rates.

  15. The impact of humidity on evaporative cooling in small desert birds exposed to high air temperatures.

    PubMed

    Gerson, Alexander R; Smith, Eric Krabbe; Smit, Ben; McKechnie, Andrew E; Wolf, Blair O

    2014-01-01

    Environmental temperatures that exceed body temperature (Tb) force endothermic animals to rely solely on evaporative cooling to dissipate heat. However, evaporative heat dissipation can be drastically reduced by environmental humidity, imposing a thermoregulatory challenge. The goal of this study was to investigate the effects of humidity on the thermoregulation of desert birds and to compare the sensitivity of cutaneous and respiratory evaporation to reduced vapor density gradients. Rates of evaporative water loss, metabolic rate, and Tb were measured in birds exposed to humidities ranging from ∼2 to 30 g H2O m(-3) (0%-100% relative humidity at 30°C) at air temperatures between 44° and 56°C. In sociable weavers, a species that dissipates heat primarily through panting, rates of evaporative water loss were inhibited by as much as 36% by high humidity at 48°C, and these birds showed a high degree of hyperthermia. At lower temperatures (40°-44°C), evaporative water loss was largely unaffected by humidity in this species. In Namaqua doves, which primarily use cutaneous evaporation, increasing humidity reduced rates of evaporative water loss, but overall rates of water loss were lower than those observed in sociable weavers. Our data suggest that cutaneous evaporation is more efficient than panting, requiring less water to maintain Tb at a given temperature, but panting appears less sensitive to humidity over the air temperature range investigated here. PMID:25461643

  16. Control methods and systems for indirect evaporative coolers

    SciTech Connect

    Woods, Jason; Kozubal, Erik

    2015-09-22

    A control method for operating an indirect evaporative cooler to control temperature and humidity. The method includes operating an airflow control device to provide supply air at a flow rate to a liquid desiccant dehumidifier. The supply air flows through the dehumidifier and an indirect evaporative cooler prior to exiting an outlet into a space. The method includes operating a pump to provide liquid desiccant to the liquid desiccant dehumidifier and sensing a temperature of an airstream at the outlet of the indirect evaporative cooler. The method includes comparing the temperature of the airstream at the outlet to a setpoint temperature at the outlet and controlling the pump to set the flow rate of the liquid desiccant. The method includes sensing space temperature, comparing the space temperature with a setpoint temperature, and controlling the airflow control device to set the flow rate of the supply air based on the comparison.

  17. Removal of aluminium from aqueous solutions using PAN-based adsorbents: characterisation, kinetics, equilibrium and thermodynamic studies.

    PubMed

    Aly, Zaynab; Graulet, Adrien; Scales, Nicholas; Hanley, Tracey

    2014-03-01

    Economic adsorbents in bead form were fabricated and utilised for the adsorption of Al(3+) from aqueous solutions. Polyacrylonitrile (PAN) beads, PAN powder and the thermally treated PAN beads (250 °C/48 h/Ar and 600 °C/48 h/Ar-H2) were characterised using different techniques including Fourier transform infrared spectroscopy, X-ray diffraction, specific surface analysis (Brunauer-Emmett-Teller), thermogravimetric analysis as well as scanning electron microscopy. Effects of pH, contact time, kinetics and adsorption isotherms at different temperatures were investigated in batch mode experiments. Aluminium kinetic data best fit the Lagergren pseudo-second-order adsorption model indicating a one-step, surface-only, adsorption process with chemisorption being the rate limiting step. Equilibrium adsorption data followed a Langmuir adsorption model with fairly low monolayer adsorption capacities suitable for freshwater clean-up only. Various constants including thermodynamic constants were evaluated from the experimental results obtained at 20, 40 and 60 °C. Positive values of ΔH° indicated that the adsorption of Al(3+) onto all three adsorbents was endothermic with less energy input required for PAN powder compared to PAN beads and low-temperature thermally treated PAN. Negative ΔG° values indicated that the aluminium adsorption process was spontaneous for all adsorbents examined. PMID:24297464

  18. A model of the biogeographical journey from Proto-pan to Pan paniscus.

    PubMed

    Myers Thompson, Jo A

    2003-04-01

    Pan paniscus is unique in the group of African apes because of its range south of the Congo River. Examination of the bio-geographical journey of the genus Pan to the species P. paniscus is important when discussing the evolution of African apes. This paper is a review of the paleo-geographic events, the zoogeography, and faunal sorting which influenced P. paniscus divergence from the Proto-pan ancestor within the recent Miocene through Pliocene Epochs, approximately 10-2 MYA. Finally, by elucidating modern day evidence of food plant forms in the southern periphery exploited by P. paniscus in the forest/savanna mosaic habitat, we are able to conclude with those extrinsic events that most influenced the occurrence and distribution of P. paniscus. PMID:12687485

  19. Tubular sublimatory evaporator heat sink

    NASA Technical Reports Server (NTRS)

    Webbon, B. W. (Inventor)

    1977-01-01

    An evaporative refrigerator or cooler comprising a bundle of spaced, porous walled tubes closed at one of their ends and vented to a vacuum at the other end is disclosed. The tube bundle is surrounded by a water jacket having a hot water inlet distribution manifold and a cooled water outlet through a plenum chamber. Hot water is pumped into the jacket to circulate around the tubes, and when this water meets the vacuum existing inside the tubes, it evaporates thereby cooling the water in the jacket. If cooling proceeds to the point where water penetrating or surrounding all or part of the tubes freezes, operation continues with local sublimation of the ice on the tubes while the circulating water attempts to melt the ice. Both sublimation and evaporation may take place simultaneously in different regions of the device.

  20. Evaporation duct communication: Test Plan

    NASA Astrophysics Data System (ADS)

    Anderson, K. D.

    1991-02-01

    The Evaporation Duct Communication (EDCOM) project is an effort to provide an alternative ship-to-ship communications channel using the natural environment. A microwave communication link can be used on an over-the-water, over-the-horizon path through the evaporation duct. This report shows how a microwave communication link, operating at a range separation of more than twice the line-of-sight range, can be constructed. This link can achieve about 80-percent availability at a transmission frequency of 14.5 GHz and can be constructed using off-the-shelf RF equipment. Operation of this link will provide the first set of measurements of channel capacity that can be critically dependent on the existence of an oceanic evaporation duct. Construction of this link presents a unique opportunity to study and evaluate an alternative communications channel that can be used to alleviate naval battlegroup communications load.

  1. A theoretical study of the spheroidal droplet evaporation in forced convection

    NASA Astrophysics Data System (ADS)

    Li, Jie; Zhang, Jian

    2014-11-01

    In many applications, the shape of a droplet may be assumed to be an oblate spheroid. A theoretical study is conducted on the evaporation of an oblate spheroidal droplet under forced convection conditions. Closed-form analytical expressions of the mass evaporation rate for an oblate spheroid are derived, in the regime of controlled mass-transfer and heat-transfer, respectively. The variation of droplet size during the evaporation process is presented in the regime of shrinking dynamic model. Comparing with the droplets having the same surface area, an increase in the aspect ratio enhances the mass evaporation rate and prolongs the burnout time.

  2. Pan Eurasian Experiment (PEEX): a new research initiative focused on the Northern Pan-Eurasian Region

    NASA Astrophysics Data System (ADS)

    Petäjä, Tuukka; Lappalainen, Hanna; Zaytseva, Nina; Shvidenko, Anatoli; Kujansuu, Joni; Kerminen, Veli-Matti; Viisanen, Yrjö; Kotlyakov, Vladimir; Kasimov, Nikolai; Bondur, Valery; Matvienko, Gennadi; Zilitinkevich, Sergej; Kulmala, Markku

    2014-05-01

    The increasing human activities are changing the environment and the humanity is we are pushing the safe boundaries of the globe. It is of utmost importance to gauge with a comprehensive research program on the current status of the environment, particularly in the most vulnerable locations. Pan-Eurasian Experiment (PEEX) is a new multidisciplinary research approach aiming at resolving the major uncertainties in the Earth system science and global sustainability questions in the Arctic and boreal Pan-Eurasian regions. The PEEX program aims (i) to understand the Earth system and the influence of environmental and societal changes in pristine and industrialized Pan-Eurasian environments, (ii) to establish and sustain long-term, continuous and comprehensive ground-based airborne and seaborne research infrastructures, and to utilize satellite data and multi-scale model frameworks, (iii) to contribute to regional climate scenarios in the northern Pan-Eurasia and determine the relevant factors and interactions influencing human and societal wellbeing (iv) to promote the dissemination of PEEX scientific results and strategies in scientific and stake-holder communities and policy making, (v) to educate the next generation of multidisciplinary global change experts and scientists, and (vi) to increase the public awareness of climate change impacts in the Pan-Eurasian region. The development of PEEX research infrastructure will be one of the first activities of PEEX. PEEX will find synergies with the major European land-atmosphere observation infrastructures such as ICOS a research infrastructure to decipher the greenhouse gas balance of Europe and adjacent regions, ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network-project), and ANAEE (The experimentation in terrestrial ecosystem research) networks and with the flag ship stations like the SMEARs (Station for Measuring Ecosystem-Atmosphere Relations) when design, re-organizing and networking existing

  3. Development of a more efficient maple syrup evaporator. Final report

    SciTech Connect

    Parsons, D.

    1982-11-30

    The goal of this project was to retrofit a traditional wood-fired maple syrup evaporator to make more efficient use of the wood fuel. A sap preheater was constructed that used waste heat from the steam to preheat the incoming sap. The preheater was tested on the evaporator and 8% more water was processed. There were some problems that will be discussed in the body of the report. A sap pan with fins incorporated into the bottom (described in the 1st and 2nd quarterly reports) was built but was not tested because the fins could not be properly sealed at the ends. Put more simply, it leaked. The bulk of time and energy was spent designing, building, and installing the forced draft and heat exchanger system (refer to 3rd quarterly report). A squirrel cage blower forced fresh air through twelve pipes that were arranged in the stack to the firebox and a draft inducer was mounted on top of the stack. With this arrangement plus the preheater 27% more water was processed than the original rig with the same amount of wood.

  4. Evaporation kinetics of laboratory-generated secondary organic aerosols at elevated relative humidity.

    PubMed

    Wilson, Jacqueline; Imre, Dan; Beránek, Josef; Shrivastava, Manish; Zelenyuk, Alla

    2015-01-01

    Secondary organic aerosols (SOA) dominate atmospheric organic aerosols that affect climate, air quality, and health. Recent studies indicate that, contrary to previously held assumptions, at low relative humidity (RH) these particles are semisolid and evaporate orders of magnitude slower than expected. Elevated relative humidity has the potential to affect significantly formation, properties, and atmospheric evolution of SOA particles. Here we present a study of the effect of RH on the room-temperature evaporation kinetics of SOA particles formed by ozonolysis of α-pinene and limonene. Experiments were carried out on α-pinene SOA particles generated, evaporated, and aged at <5%, 50 and 90% RH, and on limonene SOA particles at <5% and 90% RH. We find that in all cases evaporation begins with a relatively fast phase, during which 30-70% of the particle mass evaporates in 2 h, followed by a much slower evaporation rate. Evaporation kinetics at <5% and 50% RH are nearly the same, while at 90% RH a slightly larger fraction evaporates. In all cases, aging the particles prior to inducing evaporation reduces the evaporative losses; with aging at elevated RH leading to a more significant effect. In all cases, the observed SOA evaporation is nearly size-independent. PMID:25494490

  5. Evaporation of primordial black holes

    NASA Astrophysics Data System (ADS)

    Hawking, S. W.

    The usual explanation of the isotropy of the universe is that inflation would have smoothed out any inhomogeneities. However, if the universe was initially fractal or in a foam like state, an overall inflation would have left it in the same state. I suggest that the universe did indeed begin with a tangled web of wormholes connecting pairs of black holes but that the inflationary expansion was unstable: wormholes that are slightly smaller correspond to black holes that are hotter than the cosmological background and evaporate away. This picture is supported by calculations with Raphael Bousso of the evaporation of primordial black holes in the s-wave and large N approximations.

  6. Improving the conceptualization of the evaporation flux in conceptual rainfall-runoff models by using remotely sensed catchment scale evaporation estimates.

    NASA Astrophysics Data System (ADS)

    Aalbers, Emma; Coenders-Gerrits, Miriam; Savenije, Hubert

    2014-05-01

    If we look at how evaporation is modelled in commonly used lumped conceptual rainfall-runoff models, the static nature of the conceptualization is striking. In this conceptualization the evaporation flux usually is linearly related to the relative soil moisture content until a certain threshold is reached, after which evaporation takes place at the potential rate. The potential evaporation is a function of meteorological parameters, sometimes it includes a surface resistance term or a scaling factor to account for different land use types in the catchment. Vegetation specific variables and the dynamics associated with the seasons (e.g. phenology, effects of soil temperature) are generally not explicitly taken into account. This means that the dynamic character of evaporation in these lumped rainfall-runoff models is only expressed by the dynamics in water availability - i.e. a function of precipitation (model input) and the partitioning of water - and a form of available energy for vaporization. Moreover, the modeled evaporation flux is the aggregated flux over the entire catchment. How can spatial variability in the temporal dynamics be expressed in these models? In other words, to what extent does the modeled evaporation flux represent the 'real' evaporation integrated over the entire catchment? Since temporally continuous evaporation observations are not available at the scale of the catchment this cannot be tested straightforwardly. What is available is a range of remote sensing techniques for upscaling point measurements of evaporation to the catchment scale or to estimate evaporation from thermal images. In this research catchment scale evaporation estimates from the SEBS algorithm combined with optical remote sensing data are explored. This provides snapshots of the spatial variability of evaporation throughout the year, which can be used to determine homogeneous functional areas within the catchment with comparable temporal dynamics in evaporation. With

  7. Evaporation Mechanism of Cu from Liquid Fe Containing C and S

    NASA Astrophysics Data System (ADS)

    Jung, Sung-Hoon; Kang, Youn-Bae

    2016-08-01

    A number of liquid-gas experiments were carried out in order to elucidate evaporation mechanism of Cu from liquid Fe containing C and S. Rate of Cu evaporation in liquid Fe droplets at 1873 K (1600 °C) was determined using electromagnetic levitation equipment. Evaporation rate of the Cu under various conditions (flow rate of gas mixtures, initial C, and S concentrations) was examined. It was found from a series of kinetic analyses of the experimental data that Cu evaporates in forms of Cu(g) and CuS(g). As was reported for the Sn evaporation from liquid iron (Jung et al. Met. Mater. Trans. 46B, 250-258, 2014), S plays two roles for the evaporation of Cu: accelerating the rate by forming CuS(g) and decelerating the rate by blocking evaporation sites. As a result of these combinatorial effects, the evaporation of Cu is decelerated at low S content, but is accelerated at high S content. Based on the elucidated mechanism, an evaporation model equation for Cu was developed in the present study, which takes into account (1) evaporation of Cu in the two forms (Cu(g) and CuS(g)), (2) surface blocking by S using ideal Langmuir adsorption, and (3) effect of C. The obtained rate constant of a reaction Cu i + S i = CuS i (g), k CuS R , is 1.37 × 10-9 m4 mol-1 s-1, and the residual rate constant, k CuS r , is 4.11 × 10-10 m4 mol-1 s-1 at 1873 K (1600 °C). Both of them were found to be one order lower than those for Sn evaporation.

  8. Hollow-cathode evaporators

    SciTech Connect

    Saenko, V.A.; Kravatskii, V.A.; Veremeichenko, G.N.; Vladimirov, A.I.

    1985-08-01

    This paper describes devices for producing plasma from the vapor of a solid substance under vacuum and depositing films from the plasma. The plasma is produced by a discharge between a hollow cathode crucible and an anode, which are placed in a magnetic field longitudinal in relation to the vapor flow. The basic parameters are: film deposition rate 1-70 nm/sec, consumption of working substance 1-30 mg/sec, ionization factor for the working substance in the flow 1-10%, ion-current density at the substrate 0.1-10 mA/cm/sup 2/. Films of Cu, Au, Ag, Cr, and A1 have been made with parameters better than those of films deposited without ionization.

  9. Evaporation control research, 1959-60

    USGS Publications Warehouse

    U.S. Geological Survey

    1963-01-01

    Two hundred and forty-five dispersions of long-chain alkanols were formulated by using various emulsifiers and alkanols. The dispensing and spreading ability of each of these formulations was tested. The most promising emulsifier that could be used with any of the alkanols was glyceryl monostearate (self-emulsifying). However, the concentration of the alkanol in the dispersion form varied somewhat: with the length of the carbon chain. A maximum concentration of 16 percent was obtained using the longer chain alkanols in the dispersion form without losing any of the properties of a fluid. Nine field tests were undertaken on small stock tanks. The retardant materials used in these tests were dodecanol, hexadecanol, and octadecanol. These materials were applied in either liquid or dispersion form. Four types of dispensing equipment were tested. The first type used a pressure system which sprayed a liquid onto the surface of the water. An anemometer and wind-controlled vane, operated by an electrical system, determined the length End frequency of application. The second type was similar to the first except that gravity was utilized to force the liquid onto the surface. The third type. used a drip system with rates of about 10 drops per minute. The fourth type used a gravity feed and a wind-controlled valve which allowed the dispersion material to flow onto the surface of the water when the wind was in the proper direction. In the field tests, the best reduction in evaporation was obtained using octadecanol in dispersion form and dispensed with the wind-controlled valve and gravity feed system. The maximum reduction in evaporation for a 2-week period was 27 percent. However, the economics of suppressing evaporation from stock tanks is questionable because of the short travel time across the tank by the film. There are still many problems unsolved. Some of these can be resolved in the laboratory whereas others can be resolved only in the field. Some of the more serious

  10. Evaporation of drops on two parallel fibers: influence of the liquid morphology and fiber elasticity.

    PubMed

    Duprat, Camille; Bick, Alison D; Warren, Patrick B; Stone, Howard A

    2013-06-25

    We investigate experimentally the evaporation of liquid accumulated on a pair of parallel fibers, rigid or flexible. The liquid wetting the fibers can adopt two distinct morphologies: a compact drop shape, whose evaporation dynamics is similar to that of an isolated aerosol droplet, or a long liquid column of constant cross-section, whose evaporation dynamics depends upon the aspect ratio of the column. We thus find that the evaporation rate is constant for drops, while it increases strongly for columns as the interfiber distance decreases, and we propose a model to explain this behavior. When the fibers are flexible, the transition from drops to columns can be induced by the deformation of the fibers because of the capillary forces applied by the drop. Thus, we find that the evaporation rate increases with increasing flexibility. Furthermore, complex morphology transitions occur upon drying, which results in spreading of the drop as it evaporates. PMID:23705986

  11. Wind increases "evaporative demand" but reduces plant water requirements

    NASA Astrophysics Data System (ADS)

    Schymanski, S. J.; Or, D.

    2015-12-01

    Transpiration is commonly conceptualised as a fraction of some potential rate, determined by stomatal or canopy resistance. Therefore, so-called "atmospheric evaporative demand" or "potential evaporation" is generally used alongside with precipitation and soil moisture to characterise the environmental conditions that affect plant water use. An increase in potential evaporation (e.g. due to climate change) is generally believed to cause increased transpiration and/or vegetation water stress, aggravating drought effects. In the present study, we investigated the question whether potential evaporation constitutes a meaningful reference for transpiration and compared sensitivity of potential evaporation and leaf transpiration to atmospheric forcing. Based on modelling results and supporting experimental evidence, we conclude that stomatal resistance cannot be parameterised as a factor relating transpiration to potential evaporation, as the ratio between transpiration and potential evaporation not only varies with stomatal resistance, but also with wind speed, air temperature, irradiance and relative humidity. Furthermore, the effect of wind speed in particular implies increase in potential evaporation, which is commonly interpreted as increased "water stress", but at the same time can reduce leaf transpiration, implying a decrease in water demand at the leaf scale. In fact, in a range of field measurements, we found that water use efficiency (WUE, carbon uptake per water transpired) commonly increases with increasing wind speed, enabling plants to conserve water during photosynthesis. We estimate that the observed global decrease in terrestrial near-surface wind speeds could have reduced WUE at a magnitude similar to the increase in WUE attributed to global rise in atmospheric carbon dioxide concentrations. We conclude that trends in wind speed and atmospheric carbon dioxide concentrations have to be considered explicitly for the estimation of drought effects on

  12. 22. RW Meyer Sugar Mill: 18761889. Sorghum Pan. Manufactured by ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. RW Meyer Sugar Mill: 1876-1889. Sorghum Pan. Manufactured by John Nott & Co., Honolulu, Hawaii, 1878. View: Historical view, 1934, T.T. Waterman Collection, Hawaiian Sugar Planters' Association, Oahu, Hawaii. View looking toward east end of sorghum pan and interior of east end of the boiling house. Walls and final compartment of the sorghum pan are still intact. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

  13. Detection and Behavior of Pan Wakes in Saturn's A Ring

    NASA Technical Reports Server (NTRS)

    Horn, L. J.; Showalter, M. R.; Russell, C. T.

    1996-01-01

    Six previously unseen Pan wakes are found interior and exterior to the Encke gap in Saturn's A ring, one in the Voyager 2 photopolarimeter (PPS) stellar occultation data and five in the Voyager 1 radio science (RSS) Earth occultation data. Pan orbits at the center of the Encke gap and maintains it...The detection of Pan wakes at longitudes greater than 360(deg) demonstrates that wakes persist for much longer than originally hypothesized and may interact with one another.

  14. Ozone export from East Asia: The role of PAN

    NASA Astrophysics Data System (ADS)

    Jiang, Zhe; Worden, John R.; Payne, Vivienne H.; Zhu, Liye; Fischer, Emily; Walker, Thomas; Jones, Dylan B. A.

    2016-06-01

    Peroxyacetyl nitrate (PAN) is an important ozone (O3) precursor. The lifetime of PAN is approximately 1 month in the free troposphere, and this allows O3 production to occur in pollution plumes at intercontinental distances from its source. In this study we use the Goddard Earth Observing System (GEOS)-Chem global chemical transport model, new satellite measurements of PAN from the Aura Tropospheric Emission Spectrometer (TES), and data from the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign over North America, to study the role of natural and anthropogenic Asian emissions on free tropospheric (900-400 hPa) PAN distributions and subsequent O3 production. Using the ARCTAS data with GEOS-Chem, we show that while GEOS-Chem is unbiased with respect to the aircraft data, TES version 7 PAN data are biased high for regions with surface temperatures colder than 285 K. However, GEOS-Chem and TES measurements provide a consistent representation (within 15% difference) of PAN abundance over East Asia. Because of the good agreement between model and observations, we use the GEOS-Chem model to evaluate the sources of PAN precursors and the effect of free tropospheric PAN on the export of O3 from Asia to North America. The GEOS-Chem model results show that the largest contributors to free tropospheric PAN over Asia and the northern Pacific are anthropogenic and soil NOx emissions. Biomass burning emissions have important contributions to free tropospheric PAN over northern Pacific (25% in April), while the contribution from lightning over northern Pacific is significant in July (40%). Strong springtime transport in April results in more export of free tropospheric PAN and O3 from East Asian emissions. This free tropospheric PAN contributes about 35% to the abundance of free tropospheric O3 over western North America in spring and 25% in summer.

  15. Theoretical and testing performance of an innovative indirect evaporative chiller

    SciTech Connect

    Jiang, Yi; Xie, Xiaoyun

    2010-12-15

    An indirect evaporative chiller is a device used to produce chilled water at a temperature between the wet bulb temperature and dew point of the outdoor air, which can be used in building HVAC systems. This article presents a theoretical analysis and practical performance of an innovative indirect evaporative chiller. First, the process of the indirect evaporative chiller is introduced; then, the matching characteristics of the process are presented and analyzed. It can be shown that the process that produces cold water by using dry air is a nearly-reversible process, so the ideal produced chilled water temperature of the indirect evaporative chiller can be set close to the dew point temperature of the chiller's inlet air. After the indirect evaporative chiller was designed, simulations were done to analyze the output water temperature, the cooling efficiency relative to the inlet dew point temperature, and the COP that the chiller can performance. The first installation of the indirect evaporative chiller of this kind has been run for 5 years in a building in the city of Shihezi. The tested output water temperature of the chiller is around 14-20 C, which is just in between of the outdoor wet bulb temperature and dew point. The tested COP{sub r,s} of the developed indirect evaporative chiller reaches 9.1. Compared with ordinary air conditioning systems, the indirect evaporative chiller can save more than 40% in energy consumption due to the fact that the only energy consumed is from pumps and fans. An added bonus is that the indirect evaporative chiller uses no CFCs that pollute to the aerosphere. The tested internal parameters, such as the water-air flow rate ratio and heat transfer area for each heat transfer process inside the chiller, were analyzed and compared with designed values. The tested indoor air conditions, with a room temperature of 23-27 C and relative humidity of 50-70%, proved that the developed practical indirect evaporative chiller successfully

  16. Global sources and significance of peroxyacetyl nitrate (PAN)

    NASA Astrophysics Data System (ADS)

    Fischer, E. V.; Jacob, D. J.; Yantosca, R. M.; Payer, M.

    2012-12-01

    Peroxyacetyl nitrate (PAN), formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs) serves as a thermally unstable reservoir for nitrogen oxide radicals (NO and NO2, collectively termed NOx). PAN permits NOx to impact the global distribution of the two most important atmospheric oxidants, ozone (O3) and the OH radical. PAN is also a critical channel through which climate-driven changes to the biosphere will affect atmospheric composition, notably through biogenic NMVOC emissions and fires. We use a 3-D chemical transport model (GEOS-Chem) constrained by a global suite of observations to evaluate the sources and significance of PAN. We quantify individual NMVOC and NOX contributions to PAN formation, and we identify where PAN has a significant impact on remote O3, OH and nitrogen deposition. We find that a simulation with improved budgets for key NMVOCs (ethane, acetaldehyde, ethanol, acetone and select aromatic species) is able to reproduce the main features of the global PAN distribution. We also show that the treatment of PAN formation in fires plays an important role in determining the global impact of this PAN source. The contributions of acetaldehyde, acetone and methylglyoxal to PAN formation reflect the sources and lifetimes of these immediate precursors. Acetaldehyde, which is emitted directly from biogenic sources and formed via hydrocarbon oxidation, is the most important peroxyacetyl radical precursor globally. Methylglyoxal, an oxidation product of both isoprene and aromatic species, is responsible for about a third of peroxyactyl radical formation in the lower troposphere. Isoprene oxidation products, other than methylglyoxal, are also significant for the global PAN budget. With updated (lower) photolysis yields, acetone is less important for PAN formation than previously thought. It is responsible for less peroxyactyl radical formation globally than each of the other immediate precursors below 200 hPa. Lightning

  17. Forced-Flow Evaporative Cooler

    NASA Technical Reports Server (NTRS)

    Ellis, Wilbert E.; Niggemann, Richard E.

    1987-01-01

    Evaporative cooler absorbs heat efficiently under unusual gravitational conditions by using centrifugal force and vapor vortexes to maintain good thermal contact between heat-transfer surface and vaporizable coolant. System useful for cooling electronic or other equipment under low gravity encountered in spacecraft or under multiple-gravity conditions frequently experienced in high-performance airplanes.

  18. Simulation of a refrigerant evaporator

    NASA Astrophysics Data System (ADS)

    Vandermeer, Jakob Stefanus

    A computer model for the design and optimization of the compressor refrigeration cycle especially with respect to dynamic behavior was developed. A steady state version was also developed. The model describing the refrigerant is divided into the evaporation and superheating regions. A mechanism based on empirics corrects the model for the influence of transportation times in the evaporation region. The mass balance of the refrigerant in the superheat region is regarded as quasi-static, because of the small mass of the vapor. The energy balance accounts for a distributed model and is represented by the steady state solution of the partial differential equation which describes this area for the steady conditions. A correction for the dynamical effects was added to this solution, for all influencing parameters, according to the analytical dynamic solution for the case of the evaporation temperature as input parameter. The expansion device model was worked out for the usual type of device in combination with a dry evaporator, the thermostatic expansion valve. Validation tests are described.

  19. Micromachined evaporators for AMTEC cells

    SciTech Connect

    Izenson, M.G.; Crowley, C.J.

    1996-12-31

    To achieve high cell efficiency and reliability, the capillary pumping system for Alkali Metal Thermal to Electric Conversion (AMTEC) must have three key characteristics: (1) very small pores to achieve a high capillary pumping head, (2) high permeability for the flow of liquid sodium to minimize internal losses, and (3) be made from a material that is exceptionally stable at high temperatures in a sodium environment. The authors have developed micromachining techniques to manufacture high performance evaporators for AMTEC cells. The evaporators have been fabricated from stainless steel, molybdenum, and a niobium alloy (Nb-1Zr). The regular, micromachined structure leads to very high capillary pumping head with high permeability for liquid flow. Data from tests performed with common fluids at room temperature characterize the capillary pumping head and permeability of these structures. Three micromachined evaporators have been built into AMTEC cells and operated at temperatures up to 1,100 K. Results from these tests confirm the excellent pumping capabilities of the micromachined evaporators.

  20. Membrane evaporator/sublimator investigation

    NASA Technical Reports Server (NTRS)

    Elam, J.; Ruder, J.; Strumpf, H.

    1974-01-01

    Data are presented on a new evaporator/sublimator concept using a hollow fiber membrane unit with a high permeability to liquid water. The aim of the program was to obtain a more reliable, lightweight and simpler Extra Vehicular Life Support System (EVLSS) cooling concept than is currently being used.

  1. Evaporation estimation of rift valley lakes: comparison of models.

    PubMed

    Melesse, Assefa M; Abtew, Wossenu; Dessalegne, Tibebe

    2009-01-01

    Evapotranspiration (ET) accounts for a substantial amount of the water flux in the arid and semi-arid regions of the World. Accurate estimation of ET has been a challenge for hydrologists, mainly because of the spatiotemporal variability of the environmental and physical parameters governing the latent heat flux. In addition, most available ET models depend on intensive meteorological information for ET estimation. Such data are not available at the desired spatial and temporal scales in less developed and remote parts of the world. This limitation has necessitated the development of simple models that are less data intensive and provide ET estimates with acceptable level of accuracy. Remote sensing approach can also be applied to large areas where meteorological data are not available and field scale data collection is costly, time consuming and difficult. In areas like the Rift Valley regions of Ethiopia, the applicability of the Simple Method (Abtew Method) of lake evaporation estimation and surface energy balance approach using remote sensing was studied. The Simple Method and a remote sensing-based lake evaporation estimates were compared to the Penman, Energy balance, Pan, Radiation and Complementary Relationship Lake Evaporation (CRLE) methods applied in the region. Results indicate a good correspondence of the models outputs to that of the above methods. Comparison of the 1986 and 2000 monthly lake ET from the Landsat images to the Simple and Penman Methods show that the remote sensing and surface energy balance approach is promising for large scale applications to understand the spatial variation of the latent heat flux. PMID:22303142

  2. Token transfers among great apes (Gorilla gorilla, Pongo pygmaeus, Pan paniscus, and Pan troglodytes): species differences, gestural requests, and reciprocal exchange.

    PubMed

    Pelé, Marie; Dufour, Valérie; Thierry, Bernard; Call, Josep

    2009-11-01

    Great apes appear to be the nonhuman primates most capable of recognizing trading opportunities and engaging in transfers of commodities with conspecifics. Spontaneous exchange of goods between them has not yet been reported. We tested gorillas (Gorilla gorilla), orangutans (Pongo pygmaeus), bonobos (Pan paniscus), and chimpanzees (Pan troglodytes) in a token-exchange task involving two conspecifics and a human experimenter. Tested in pairs, subjects had to exchange tokens with a partner to obtain food from the experimenter. We observed 4, 5, 264, and 328 transfers of tokens in gorillas, chimpanzees, orangutans, and bonobos, respectively. Most gifts were indirect in gorillas, chimpanzees, and bonobos, whereas most were direct in orangutans. The analysis showed no evidence of calculated reciprocity in interactions. A main finding of the study was the high rate of repeated gifts and begging gestures recorded in orangutans. This raises the question of the meaning of pointing in great apes and their ability to understand the communicative intent of others. PMID:19929106

  3. Correlations for Saturation Efficiency of Evaporative Cooling Pads

    NASA Astrophysics Data System (ADS)

    Jain, J. K.; Hindoliya, D. A.

    2014-01-01

    This paper presents some experimental investigations to obtain correlations for saturation efficiency of evaporative cooling pads. Two commonly used materials namely aspen and khus fibers along with new materials namely coconut fibers and palash fibers were tested in a laboratory using suitably fabricated test setup. Simple mathematical correlations have been developed for calculating saturation efficiency of evaporating cooling pads which can be used to predict their performance at any desired mass flow rate. Performances of four different pad materials were also compared using developed correlations. An attempt was made to test two new materials (i.e. fibers of palash wood and coconut) to check their suitability as wetted media for evaporative cooling pads. It was found that Palash wood fibers offered highest saturation efficiency compared to that of other existing materials such as aspen and khus fibers at different mass flow rate of air.

  4. Indirect evaporative cooler with condensation of primary airflow

    SciTech Connect

    Vollebregt, H.J.M.; Jong, T. de

    1994-12-31

    In this paper a new application for indirect evaporative cooling is introduced. This cooling principle may be used to cool and dehumidify closed greenhouses. A prototype indirect evaporative cooler with a crossflow configuration was built and its performance was determined in an experimental facility. During tests under Dutch design conditions of the greenhouse and outside air, the plate temperature was less than the dew point of the greenhouse air, so condensation occurred. The rates of sensible and latent heat transferred from the greenhouse air by the prototype cooler were determined. Also, the influence of greenhouse and outside air conditions and airflow rates in the cooler on the enthalpy efficiency was studied. Although the amount of condensation in the prototype indirect evaporative cooler was large, the resulting climate in a closed greenhouse may be more humid than that in a conventional one.

  5. Evaporation from weighing precipitation gauges: impacts on automated gauge measurements and quality assurance methods

    NASA Astrophysics Data System (ADS)

    Leeper, R. D.; Kochendorfer, J.

    2015-06-01

    Evaporation from a precipitation gauge can cause errors in the amount of measured precipitation. For automated weighing-bucket gauges, the World Meteorological Organization (WMO) suggests the use of evaporative suppressants and frequent observations to limit these biases. However, the use of evaporation suppressants is not always feasible due to environmental hazards and the added cost of maintenance, transport, and disposal of the gauge additive. In addition, research has suggested that evaporation prior to precipitation may affect precipitation measurements from auto-recording gauges operating at sub-hourly frequencies. For further evaluation, a field campaign was conducted to monitor evaporation and its impacts on the quality of precipitation measurements from gauges used at U.S. Climate Reference Network (USCRN) stations. Two Geonor gauges were collocated, with one gauge using an evaporative suppressant (referred to as Geonor-NonEvap) and the other with no suppressant (referred to as Geonor-Evap) to evaluate evaporative losses and evaporation biases on precipitation measurements. From June to August, evaporative losses from the Geonor-Evap gauge exceeded accumulated precipitation, with an average loss of 0.12 mm h-1. The impact of evaporation on precipitation measurements was sensitive to the choice of calculation method. In general, the pairwise method that utilized a longer time series to smooth out sensor noise was more sensitive to gauge evaporation (-4.6% bias with respect to control) than the weighted-average method that calculated depth change over a smaller window (<+1% bias). These results indicate that while climate and gauge design affect gauge evaporation rates, computational methods also influence the magnitude of evaporation biases on precipitation measurements. This study can be used to advance quality insurance (QA) techniques used in other automated networks to mitigate the impact of evaporation biases on precipitation measurements.

  6. NWCF Evaporator Tank System 2001 Offgas Emissions Inventory

    SciTech Connect

    Boardman, R.D.; Lamb, K.M.; Matejka, L.A.; Nenni, J.A.

    2002-02-27

    An offgas emissions inventory and liquid stream characterization of the Idaho New Waste Calcining Facility (NWCF) Evaporator Tank System (ETS), formerly known as the High Level Liquid Waste Evaporator (HLLWE), has been completed. The emissions rates of volatile and semi-volatile organic compounds, multiple metals, particulate, and hydrochloric acid were measured in accordance with an approved Quality Assurance Project Plan (QAPjP) and Test Plan that invoked U.S. Environmental Protection Agency (EPA) standard sample collection and analysis procedures. Offgas samples were collected during the start up and at the end of evaporator batches when it was hypothesized the emissions would be at peak rates. Corresponding collection of samples from the evaporator feed overhead condensate, and bottoms was made at approximately the same time as the emissions inventory to support material balance determinations for the evaporator process. The data indicate that organic compound emissions are slightly higher at the beginning of the batch while metals emissions, including mercury, are slightly higher at the end of the evaporator batch. The maximum emissions concentrations are low for all constituents of primary concern. Mercury emissions were less than 5 ppbv, while the sum of HCl and Cl2 emissions was less than 1 ppmv. The sum of all organic emissions also was less than 1 ppmv. The estimated hazardous quotient (HQ) for the evaporator was 6.2e-6 as compared to 0.25 for the EPA target criteria. The cancer risk was 1.3e-10 compared to an EPA target of le-5.

  7. NWCF Evaporator Tank System 2001 Offgas Emissions Inventory

    SciTech Connect

    Boardman, Richard Doin; Lamb, Kenneth Mitchel; Matejka, Leon Anthony; Nenni, Joseph A

    2002-02-01

    An offgas emissions inventory and liquid stream characterization of the Idaho New Waste Calcining Facility (NWCF) Evaporator Tank System (ETS), formerly known as the High Level Liquid Waste Evaporator (HLLWE), has been completed. The emissions rates of volatile and semi-volatile organic compounds, multiple metals, particulate, and hydrochloric acid were measured in accordance with an approved Quality Assurance Project Plan (QAPjP) and Test Plan that invoked U.S. Environmental Protection Agency (EPA) standard sample collection and analysis procedures. Offgas samples were collected during the start up and at the end of evaporator batches when it was hypothesized the emissions would be at peak rates. Corresponding collection of samples from the evaporator feed overhead condensate, and bottoms was made at approximately the same time as the emissions inventory to support material balance determinations for the evaporator process. The data indicate that organic compound emissions are slightly higher at the beginning of the batch while metals emissions, including mercury, are slightly higher at the end of the evaporator batch. The maximum emissions concentrations are low for all constituents of primary concern. Mercury emissions were less than 5 ppbv, while the sum of HCl and Cl2 emissions was less than 1 ppmv. The sum of all organic emissions also was less than 1 ppmv. The estimated hazardous quotient (HQ) for the evaporator was 6.2e-6 as compared to 0.25 for the EPA target criteria. The cancer risk was 1.3e-10 compared to an EPA target of le-5.

  8. Slow-blue PanSTARRS transients

    NASA Astrophysics Data System (ADS)

    MacLeod, Chelsea L.; Bruce, Alastair; Lawrence, Andy; Ward, Martin; Collinson, James; Elvis, Martin; Gezari, Suvi; Smartt, Steven; Smith, Ken; Wright, Darryl; Fraser, Morgan

    2015-01-01

    Photometric and spectroscopic monitoring of 50 blue, nuclear "transients" in PanSTARRS-1 has revealed different types of extremely variable AGN. The majority show a gradual brightening by ~2 mag from the SDSS observation a decade ago and may represent a new class of AGN microlensed by foreground galaxies. Spectra from the William Herschel Telescope identify these as z~1 AGN with atypical spectroscopic properties. We present an analysis of their photometric and spectroscopic variability in an effort to constrain the detailed structure of the source AGN.

  9. Studbook of Pan paniscus Schwarz, 1929.

    PubMed

    Guzen, A

    1975-01-01

    On the basis of information provided by various zoos who have, or used to have, Pan paniscus in their collections, as well as information in the International Zoo Yearbook or in the literature, an approximate outline has been given of our knowledge of this animal since the description given in 1929 by Schwarz. The status of species is preferred to that of subspecies. The question whether the bonobo should be regarded as a true dwarf form is considered. It is, however, emphasized that the majority of researchers - and for different reasons - consider the species to be the primate closest to man. PMID:1163394

  10. Insights into the Maize Pan-Genome and Pan-Transcriptome[W][OPEN

    PubMed Central

    Hirsch, Candice N.; Foerster, Jillian M.; Johnson, James M.; Sekhon, Rajandeep S.; Muttoni, German; Vaillancourt, Brieanne; Peñagaricano, Francisco; Lindquist, Erika; Pedraza, Mary Ann; Barry, Kerrie; de Leon, Natalia; Kaeppler, Shawn M.; Buell, C. Robin

    2014-01-01

    Genomes at the species level are dynamic, with genes present in every individual (core) and genes in a subset of individuals (dispensable) that collectively constitute the pan-genome. Using transcriptome sequencing of seedling RNA from 503 maize (Zea mays) inbred lines to characterize the maize pan-genome, we identified 8681 representative transcript assemblies (RTAs) with 16.4% expressed in all lines and 82.7% expressed in subsets of the lines. Interestingly, with linkage disequilibrium mapping, 76.7% of the RTAs with at least one single nucleotide polymorphism (SNP) could be mapped to a single genetic position, distributed primarily throughout the nonpericentromeric portion of the genome. Stepwise iterative clustering of RTAs suggests, within the context of the genotypes used in this study, that the maize genome is restricted and further sampling of seedling RNA within this germplasm base will result in minimal discovery. Genome-wide association studies based on SNPs and transcript abundance in the pan-genome revealed loci associated with the timing of the juvenile-to-adult vegetative and vegetative-to-reproductive developmental transitions, two traits important for fitness and adaptation. This study revealed the dynamic nature of the maize pan-genome and demonstrated that a substantial portion of variation may lie outside the single reference genome for a species. PMID:24488960

  11. Summertime distributions of peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN) in Beijing: Understanding the sources and major sink of PAN

    NASA Astrophysics Data System (ADS)

    Zhang, Gen; Mu, Yujing; Zhou, Lingxi; Zhang, Chenglong; Zhang, Yuanyuan; Liu, Junfeng; Fang, Shuangxi; Yao, Bo

    2015-02-01

    Peroxyacetyl nitrate (PAN), a major secondary pollutant in the atmosphere, has received much concern for its particular importance in atmospheric chemistry and adverse effects on human and plants. Atmospheric PAN and PPN were measured by using a gas chromatograph equipped with electron capture detector (GC-ECD) from June to September 2010, and the source and major sink for PAN were firstly studied in Beijing. The distinct diurnal variations of PAN and PPN with maximum in the afternoon were observed, and the mean and maximum values were 2.61 ± 2.57 ppbv (N = 839) and 12.5 ppbv for PAN and 0.52 ± 0.38 ppbv (N = 152) and 2.16 ppbv for PPN during the measuring period, respectively. Good correlation (R = 0.85) between PAN and PPN with a slope (ΔPPN/ΔPAN) of 0.134 indicated that anthropogenic volatile organic compounds (AVOCs) dominated the photochemical formation of PANs in Beijing. Further, we found acetaldehyde was the predominant carbonyl precursor of PAN with the contribution of 59.7% to the total peroxyacetyl (PA) radical. Methyl glyoxal, methacrolein, acetone, methyl vinyl ketone, and biacetyl contributed 7.1%, 8.8%, 19.7%, 3.4%, and 1.3% to total PA radical, respectively. Anti-correlation between PAN concentrations and the NO/NO2 ratios was found during the whole investigating period. In addition, the amount of PAN lost by thermal decomposition (TPAN) accounted for remarkable fractions of PAN observed under high temperature during both daytime and nighttime.

  12. Water addition, evaporation and water holding capacity of poultry litter.

    PubMed

    Dunlop, Mark W; Blackall, Patrick J; Stuetz, Richard M

    2015-12-15

    Litter moisture content has been related to ammonia, dust and odour emissions as well as bird health and welfare. Improved understanding of the water holding properties of poultry litter as well as water additions to litter and evaporation from litter will contribute to improved litter moisture management during the meat chicken grow-out. The purpose of this paper is to demonstrate how management and environmental conditions over the course of a grow-out affect the volume of water A) applied to litter, B) able to be stored in litter, and C) evaporated from litter on a daily basis. The same unit of measurement has been used to enable direct comparison-litres of water per square metre of poultry shed floor area, L/m(2), assuming a litter depth of 5cm. An equation was developed to estimate the amount of water added to litter from bird excretion and drinking spillage, which are sources of regular water application to the litter. Using this equation showed that water applied to litter from these sources changes over the course of a grow-out, and can be as much as 3.2L/m(2)/day. Over a 56day grow-out, the total quantity of water added to the litter was estimated to be 104L/m(2). Litter porosity, water holding capacity and water evaporation rates from litter were measured experimentally. Litter porosity decreased and water holding capacity increased over the course of a grow-out due to manure addition. Water evaporation rates at 25°C and 50% relative humidity ranged from 0.5 to 10L/m(2)/day. Evaporation rates increased with litter moisture content and air speed. Maintaining dry litter at the peak of a grow-out is likely to be challenging because evaporation rates from dry litter may be insufficient to remove the quantity of water added to the litter on a daily basis. PMID:26367067

  13. Evaporation from Lake Mead, Arizona and Nevada, 1997-99

    USGS Publications Warehouse

    Westenburg, Craig L.; DeMeo, Guy A.; Tanko, Daron J.

    2006-01-01

    Lake Mead is one of a series of large Colorado River reservoirs operated and maintained by the Bureau of Reclamation. The Colorado River system of reservoirs and diversions is an important source of water for millions of people in seven Western States and Mexico. The U.S. Geological Survey, in cooperation with the Bureau of Reclamation, conducted a study from 1997 to 1999 to estimate evaporation from Lake Mead. For this study, micrometeorological and hydrologic data were collected continually from instrumented platforms deployed at four locations on the lake, open-water areas of Boulder Basin, Virgin Basin, and Overton Arm and a protected cove in Boulder Basin. Data collected at the platforms were used to estimate Lake Mead evaporation by solving an energy-budget equation. The average annual evaporation rate at open-water stations from January 1998 to December 1999 was 7.5 feet. Because the spatial variation of monthly and annual evaporation rates was minimal for the open-water stations, a single open-water station in Boulder Basin would provide data that are adequate to estimate evaporation from Lake Mead.

  14. Instability of evaporation fronts in the interstellar medium

    SciTech Connect

    Kim, Jeong-Gyu; Kim, Woong-Tae E-mail: wkim@astro.snu.ac.kr

    2013-12-10

    The neutral component of the interstellar medium is segregated into the cold neutral medium (CNM) and warm neutral medium (WNM) as a result of thermal instability. It was found that a plane-parallel CNM-WNM evaporation interface, across which the CNM undergoes thermal expansion, is linearly unstable to corrugational disturbances, in complete analogy with the Darrieus-Landau instability (DLI) of terrestrial flames. We perform a full linear stability analysis as well as nonlinear hydrodynamic simulations of the DLI of such evaporation fronts in the presence of thermal conduction. We find that the DLI is suppressed at short length scales by conduction. The length and time scales of the fastest growing mode are inversely proportional to the evaporation flow speed of the CNM and its square, respectively. In the nonlinear stage, the DLI saturates to a steady state where the front deforms to a finger-like shape protruding toward the WNM, without generating turbulence. The evaporation rate at nonlinear saturation is larger than the initial plane-parallel value by a factor of ∼2.4 when the equilibrium thermal pressure is 1800 k {sub B} cm{sup –3} K. The degrees of front deformation and evaporation-rate enhancement at nonlinear saturation are determined primarily by the density ratio between the CNM and WNM. We demonstrate that the Field length in the thermally unstable medium should be resolved by at least four grid points to obtain reliable numerical outcomes involving thermal instability.

  15. Evaporative cooling of speleothem drip water.

    PubMed

    Cuthbert, M O; Rau, G C; Andersen, M S; Roshan, H; Rutlidge, H; Marjo, C E; Markowska, M; Jex, C N; Graham, P W; Mariethoz, G; Acworth, R I; Baker, A

    2014-01-01

    This study describes the first use of concurrent high-precision temperature and drip rate monitoring to explore what controls the temperature of speleothem forming drip water. Two contrasting sites, one with fast transient and one with slow constant dripping, in a temperate semi-arid location (Wellington, NSW, Australia), exhibit drip water temperatures which deviate significantly from the cave air temperature. We confirm the hypothesis that evaporative cooling is the dominant, but so far unattributed, control causing significant disequilibrium between drip water and host rock/air temperatures. The amount of cooling is dependent on the drip rate, relative humidity and ventilation. Our results have implications for the interpretation of temperature-sensitive, speleothem climate proxies such as δ(18)O, cave microecology and the use of heat as a tracer in karst. Understanding the processes controlling the temperature of speleothem-forming cave drip waters is vital for assessing the reliability of such deposits as archives of climate change. PMID:24895139

  16. Evaporative cooling of speleothem drip water

    PubMed Central

    Cuthbert, M. O.; Rau, G. C.; Andersen, M. S.; Roshan, H.; Rutlidge, H.; Marjo, C. E.; Markowska, M.; Jex, C. N.; Graham, P. W.; Mariethoz, G.; Acworth, R. I.; Baker, A.

    2014-01-01

    This study describes the first use of concurrent high-precision temperature and drip rate monitoring to explore what controls the temperature of speleothem forming drip water. Two contrasting sites, one with fast transient and one with slow constant dripping, in a temperate semi-arid location (Wellington, NSW, Australia), exhibit drip water temperatures which deviate significantly from the cave air temperature. We confirm the hypothesis that evaporative cooling is the dominant, but so far unattributed, control causing significant disequilibrium between drip water and host rock/air temperatures. The amount of cooling is dependent on the drip rate, relative humidity and ventilation. Our results have implications for the interpretation of temperature-sensitive, speleothem climate proxies such as δ18O, cave microecology and the use of heat as a tracer in karst. Understanding the processes controlling the temperature of speleothem-forming cave drip waters is vital for assessing the reliability of such deposits as archives of climate change. PMID:24895139

  17. Isotopic Compositions of Evaporative Fluxes

    NASA Astrophysics Data System (ADS)

    Feng, X.; Lauder, A. M.; Kopec, B. G.; Dade, W. B.; Virginia, R. A.; Posmentier, E. S.

    2013-12-01

    The isotopic fluxes of evaporation from a water surface are typically computed using a one-dimensional model, originally conceptualized by Craig and Gordon (1965) and further developed and adapted to different natural settings (such as transpiration, open surface evaporation, etc.) by various investigators. These models have two distinguishing characteristics. First, there exists a laminar layer where molecular diffusion away from the water-air interface causes kinetic isotopic fractionation. The magnitude of this fractionation is controlled by the diffusion/transport coefficient of each vapor isotopologue in air and their concentration gradients, the latter being controlled by relative humidity, isotopic ratios of ambient air, and turbulent conditions (such as wind and surface roughness). Second, the horizontal variations are ignored. In particular, the effect of horizontal advection on isotopic variations in the ambient air is not considered. The research reported here addresses the effects of relinquishing the simplifying assumptions in both of these areas. We developed a model, in which the simplification of a purely laminar layer is dropped. Instead, we express the vertical transport coefficient as the sum of the molecular diffusivity, that differs for each water isotopologue, and the turbulent diffusivity that increases linearly with height but does not vary among water isotopologues. With this model, the kinetic isotopic effect reduces with height in the vicinity of the water surface, and the net isotopic fractionation through the boundary layer can be integrated. The advantage of this conceptualization is that the magnitude of kinetic isotopic fractionation can be assessed directly with changing environmental conditions, such as humidity and wind speed, rather than approximated by discontinuous empirical functions of the environmental conditions, as in the conventional models mentioned above. To address the effect of lateral heterogeneity, we expanded the

  18. Pan-European catalogue of flood events

    NASA Astrophysics Data System (ADS)

    Parajka, Juraj; Mangini, Walter; Viglione, Alberto; Hundecha, Yeshewatesfa; Ceola, Serena

    2016-04-01

    There have been numerous extreme flood events observed in Europe in the past years. One of the way to improve our understanding about causing flood generation mechanisms is to analyse spatial and temporal variability of a large number of flood events. The aim of this study is to present a pan-European catalogue of flood events developed within the SWITCH-ON EU Project. The flood events are identified from daily discharge observations at 1315 stations listed in Global Runoff Data Centre database. The average length of discharge time-series for selected stations is 54 years. For each event, basin boundary and additional hydrological and weather characteristics are extracted. Hydrological characteristics are extracted from the pan-European HYPE model simulations. Precipitation, together with the corresponding proportions of rainfall and snowfall, snowmelt, and evapotranspiration are computed as total amounts between the event start date and event peak date. Soil moisture, soil moisture deficit, and basin accumulated snow water equivalent are computed for the event start date. Weather characteristics are derived from the weather circulation pattern catalogue developed within COST 733 Project. The results are generated in an open data access and tools framework which allows reproduction and extension of results to other regions. More information about the analysis and project are available at: http://www.water-switch-on.eu/lab.html.

  19. Quantifying Evaporation in a Permeable Pavement System

    EPA Science Inventory

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. Th...

  20. Ratosa playa lake in southern Spain. Karst pan or compound sink?

    PubMed

    Rodríguez-Rodríguez, Miguel; Martos-Rosillo, Sergio; Pedrera, Antonio; Benavente-Herrera, José

    2015-04-01

    In Andalusia (Spain), there are more than 45 semiarid playa lakes protected as natural reserves and related to karstic outcrops. Some of them are located over regional karstic aquifers and have internal drainage networks with sporadic surface outlets, such as sinkholes (compound sinks), but the majority of such playas have no internal drainage systems, so the only water output is evaporation (karst pans). Karst pans are perched and disconnected from the groundwater system. The fact that the Ratosa playa lake is partially located over a karstic Sierra, as well as other hydromorphological observations, it is suggested that the system could be of a compound type, but a detailed hydrogeological analysis showed that the playa is disconnected from the aquifer, so it is in fact a karst pan. Once the hydrological functioning had been established, a monthly water balance for a 10-year period (1998-2008), enabled us to reproduce the evolution of the water level of the playa lake. Estimations of runoff were carried out by a soil water estimate for a water holding capacity in the soil of 191 mm. Results show a good correlation (>90%) after calibration with the time series of water level in the lake for the same period confirming geological observations. Our results highlight that this water body is extremely vulnerable to hydrological alterations of its watershed caused by human activities, particularly those related to land-use change for agriculture. For this reason, we propose a new protection zone, based on hydrological knowledge, instead of the present Peripheral Area of Protection. PMID:25810083

  1. Numerical prediction of pressure fluctuations in a prototype pump turbine base on PANS methods

    NASA Astrophysics Data System (ADS)

    Liu, J. T.; Li, Y.; Gao, Y.; Hu, Q.; Wu, Y. L.

    2016-05-01

    Unsteady flow and pressure fluctuations within a prototypel pump turbine are numerically studied using a nonlinear Partial Averaged Navier Stokes (PANS) model. Pump turbine operating at different conditions with guide vanes opening angle 6° is simulated. Results revealed that the predictions of performance and relative peak-to-peak amplitude by PANS approach agree well with the experimental data. The amplitude of the pressure fluctuation in the vaneless space at turbine mode on a “S” curve increases with the decrease of the flow rate, and it has maximum value when it runs close to runaway line at turbine braking mode. The amplitude of the pressure fluctuation in the vaneless space at turbine braking mode on a “S” curve decreases with the reduce of the flow rate. The above high pressure fluctuations should be avoided during the design of pump turbines especially those operating at high-head condition.

  2. Biogeomorphically driven salt pan formation in Sarcocornia-dominated salt-marshes

    NASA Astrophysics Data System (ADS)

    Escapa, Mauricio; Perillo, Gerardo M. E.; Iribarne, Oscar

    2015-01-01

    Salt-marshes are under increasing threat, particularly from sea-level rise and increased wave action associated with climate change. The development and stability of these valuable habitats largely depend on complex interactions between biotic and abiotic processes operating at different scales. Also, interactions between biotic and abiotic processes drive internal morphological change in salt-marshes. In this paper we used a biogeomorphological approach to assess the impact of biological activities and interactions on salt pan formation in Sarcocornia-dominated salt marshes. Salt pans represent a key physiographic feature of salt-marshes and recent studies hypothesized that biogeomorphic processes could be related to salt pan formation in SW Atlantic salt-marshes. The glasswort Sarcocornia perennis is one of the dominant plants in the salt-marshes of the Bahía Blanca Estuary (Argentina) where they form patches up to 8 m in diameter. These salt-marshes are also inhabited in great densities by the burrowing crab Neohelice (Chasmagnathus) granulata whose bioturbation rates are among the highest reported for salt-marshes worldwide. A set of biological interactions between N. granulata and S. perennis appears to be responsible for salt pan development in these areas which has not been described elsewhere. The main objective of this work was to determine the ecological interactions occurring between plants and crabs that lead to salt pan formation by using field-based sampling and manipulative experiments. Our results showed that S. perennis facilitated crab colonization of the salt-marsh by buffering otherwise stressful physical conditions (e.g., temperature, desiccation). Crabs preferred to construct burrows underneath plants and, once they reach high densities (up to 40 burrows m- 2), the sediment reworking caused plant die-off in the central area of patches. At this state, the patches lose elevation and become depressed due to the continuous bioturbation by crabs

  3. Experimental investigation of liquid drop evaporation on a heated solid surface

    NASA Astrophysics Data System (ADS)

    Semenov, A. A.; Feoktistov, D. V.; Zaitsev, D. V.; Kuznetsov, G. V.; Kabov, O. A.

    2015-11-01

    Evaporation of a water drop was studied experimentally at a temperature difference between the solid surface and surrounding atmosphere from 30 to 60 °C. The studies were performed on the substrates with micro- and nanocoatings with different wettability. The features of evaporation were studied for the pinned, partially pinned, and depinned three-phase contact line (solid-liquid-gas interface). It is shown that with a decrease in the water drop volume, the specific evaporation rate (mass flow per unit of surface area) increases, particularly at the last stage of evaporation.

  4. A study of diamond laminated surfaces in evaporative spray cooling

    NASA Astrophysics Data System (ADS)

    Sehmbey, M. S.; Pais, M. R.; Chow, L. C.

    This effort is directed towards studying the performance of diamond laminated surfaces under conditions of evaporative spray cooling of high-heat-flux electronic components. The experimental results presented illustrate the robustness of the surface, as well as its heat transfer characteristics, wettability and roughness. Exceptional heat flux rates of over 1100 W/sq cm were obtained within superheats of 40 C.

  5. Probing light dark matter via evaporation from the Sun

    NASA Astrophysics Data System (ADS)

    Kouvaris, Chris

    2015-10-01

    Dark matter particles can be captured by the Sun with rates that depend on the dark matter mass and the DM-nucleon cross section. However, for masses below ˜3.3 GeV , the captured dark matter particles evaporate, leading to an equilibrium where the rate of captured particles is equal to the rate of evaporating ones. Unlike dark matter particles from the halo, the evaporating dark matter particles have velocities that are not limited to values below the escape velocity of the Galaxy. Despite the fact that high velocities are exponentially suppressed, I demonstrate here that current underground detectors have the possibility to probe/constrain low dark matter parameter space by (not)-observing the high energy tail of the evaporating dark matter particles from the Sun. I also show that the functional form of the differential rate of counts with respect to the recoil energy in Earth-based detectors can identify precisely the mass and the cross section of the dark matter particle in this case.

  6. Atmospheric peroxyacetyl nitrate (PAN): a global budget and source attribution

    NASA Astrophysics Data System (ADS)

    Fischer, E. V.; Jacob, D. J.; Yantosca, R. M.; Sulprizio, M. P.; Millet, D. B.; Mao, J.; Paulot, F.; Singh, H. B.; Roiger, A.-E.; Ries, L.; Talbot, R. W.; Dzepina, K.; Pandey Deolal, S.

    2013-10-01

    Peroxyacetyl nitrate (PAN) formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs), is the principal tropospheric reservoir for nitrogen oxide radicals (NOx = NO + NO2). PAN enables the transport and release of NOx to the remote troposphere with major implications for the global distributions of ozone and OH, the main tropospheric oxidants. Simulation of PAN is a challenge for global models because of the dependence of PAN on vertical transport as well as complex and uncertain NMVOC sources and chemistry. Here we use an improved representation of NMVOCs in a global 3-D chemical transport model (GEOS-Chem) and show that it can simulate PAN observations from aircraft campaigns worldwide. The immediate carbonyl precursors for PAN formation include acetaldehyde (44% of the global source), methylglyoxal (30%), acetone (7%), and a suite of other isoprene and terpene oxidation products (19%). A diversity of NMVOC emissions is responsible for PAN formation globally including isoprene (37%) and alkanes (14%). Anthropogenic sources are dominant in the extratropical Northern Hemisphere outside the growing season. Open fires appear to play little role except at high northern latitudes in spring, although results are very sensitive to plume chemistry and plume rise. Lightning NOx is the dominant contributor to the observed PAN maximum in the free troposphere over the South Atlantic.

  7. Atmospheric peroxyacetyl nitrate (PAN): a global budget and source attribution

    NASA Astrophysics Data System (ADS)

    Fischer, E. V.; Jacob, D. J.; Yantosca, R. M.; Sulprizio, M. P.; Millet, D. B.; Mao, J.; Paulot, F.; Singh, H. B.; Roiger, A.; Ries, L.; Talbot, R. W.; Dzepina, K.; Pandey Deolal, S.

    2014-03-01

    Peroxyacetyl nitrate (PAN) formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs) is the principal tropospheric reservoir for nitrogen oxide radicals (NOx = NO + NO2). PAN enables the transport and release of NOx to the remote troposphere with major implications for the global distributions of ozone and OH, the main tropospheric oxidants. Simulation of PAN is a challenge for global models because of the dependence of PAN on vertical transport as well as complex and uncertain NMVOC sources and chemistry. Here we use an improved representation of NMVOCs in a global 3-D chemical transport model (GEOS-Chem) and show that it can simulate PAN observations from aircraft campaigns worldwide. The immediate carbonyl precursors for PAN formation include acetaldehyde (44% of the global source), methylglyoxal (30%), acetone (7%), and a suite of other isoprene and terpene oxidation products (19%). A diversity of NMVOC emissions is responsible for PAN formation globally including isoprene (37%) and alkanes (14%). Anthropogenic sources are dominant in the extratropical Northern Hemisphere outside the growing season. Open fires appear to play little role except at high northern latitudes in spring, although results are very sensitive to plume chemistry and plume rise. Lightning NOx is the dominant contributor to the observed PAN maximum in the free troposphere over the South Atlantic.

  8. Solar still versus solar evaporator: A comparative study between their thermal behaviors

    SciTech Connect

    Sartori, E.

    1996-12-31

    This paper presents a theoretical comparison between the thermal behavior of a basin type solar still and that from a solar evaporator. The analyses are twofold: (a) comparing the system temperatures and the heat and mass transfer rates in the transient mode; (b) obtaining parametric representations from both systems using their heat and mass transfer equations. Such comparisons had never been done before. It is shown, among other things, that the evaporation in solar stills is much less than that in open evaporation despite the higher water temperatures in the former system. This is also true even when the water temperature of both systems is the same. It is also observed that the distillation and evaporation rates increase with the increasing water temperature and temperature difference. For relatively high water temperatures of each system the evaporative fraction is equivalent to more than 50% of the corresponding total heat transfer rate. 32 refs., 15 figs.

  9. Kinetics of Evaporation of Pinned Nanofluid Volatile Droplets at Subatmospheric Pressures.

    PubMed

    Orejon, Daniel; Shanahan, Martin E R; Takata, Yasuyuki; Sefiane, Khellil

    2016-06-14

    We examine the effects of nanoparticle addition at low concentration on the evaporation kinetics of droplets in the constant radius mode. The evaporative behavior of deionized water and Al2O3 nanoparticle laden water on an aluminum substrate was observed at atmospheric and at different subatmospheric pressures. The two fluids exhibit the same evaporative behavior, independent of the droplet volume or the subatmospheric pressure. Moreover, the linear relationship between evaporation rate and droplet radius, initially proposed by Picknett and Bexon nearly four decades ago for droplets evaporating in the constant radius mode, is satisfied for both liquids. In addition, we have established a unified correlation solely function of fluid properties that extends this relationship to any subatmospheric pressure and fluid tested. We conclude that the addition of a small quantity of nanoparticles to the base fluid does not modify the kinetics of evaporation for pinned volatile droplets. PMID:27218303

  10. 21 CFR 131.130 - Evaporated milk.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Evaporated milk. 131.130 Section 131.130 Food and... CONSUMPTION MILK AND CREAM Requirements for Specific Standardized Milk and Cream § 131.130 Evaporated milk. (a) Description. Evaporated milk is the liquid food obtained by partial removal of water only from milk....

  11. Iodine retention during evaporative volume reduction

    DOEpatents

    Godbee, H.W.; Cathers, G.I.; Blanco, R.E.

    1975-11-18

    An improved method for retaining radioactive iodine in aqueous waste solutions during volume reduction is disclosed. The method applies to evaporative volume reduction processes whereby the decontaminated (evaporated) water can be returned safely to the environment. The method generally comprises isotopically diluting the waste solution with a nonradioactive iodide and maintaining the solution at a high pH during evaporation.

  12. SEWAGE DISPOSAL BY EVAPORATION-TRANSPIRATION

    EPA Science Inventory

    One of the methods for on-site disposal of wastewater from individual homes is by evaporation. Two types of evaporative disposal systems have been investigated in this study; evapo-transpiration (ET) beds and mechanical evaporation units. Twenty nine test lysimeters of 0.22 cubic...

  13. Does groundwater enhance evaporative cooling?

    NASA Astrophysics Data System (ADS)

    Rouholahnejad, E.

    2015-12-01

    Evaporation is a key process in land-climate interactions, not only because it directly regulates the hydrological cycle, but also because it contributes to the Earth's energy balance. Due to its feedbacks on large-scale water processes and its impact on the dynamics of the atmosphere, it has been considered as a driver of droughts and heatwaves1-3. While evaporation from ocean surfaces is likely to increase with rising temperatures, it is unclear whether evapotranspiration from land surfaces could similarly increase, due to possible limitations imposed by soil moisture and vegetation physiology4. Observations suggest that groundwater (hereafter GW) has an important role in hydrological budgets and soil moisture variability in many regions, supplying moisture for evapotranspiration during dry seasons5, 6. Although modeling studies suggest that GW is often close enough to the surface to interact with the atmosphere7, 8, the soil water storage is often underestimated by land surface models. This is most likely due to neglecting the lateral movement of water from topographically higher altitudes to valley bottoms and its convergence close to the land surface, as well as the upward movement of water in the capillary fringe.The focus of this study is to understand where and when GW may significantly enhance the availability of soil water for evapotranspiration. We also quantified the potential contribution of GW to evapotranspiration in the areas where GW is a major supply. We used the global network of eddy covariance observations9 (FLUXNET) along with global modeled GW depth10 and GLEAM ET model estimates11 to address the current gap in modelling ET due to neglecting GW supply. Having identified areas where GW is tightly coupled with the atmosphere through evaporation processes, the study provides the basis to examine the "air conditioning effect" of GW and test the idea if GW enhances evaporation to the extent that leads to a cooler temperatures and wetter climates.

  14. Evaporation by mechanical vapor recompression

    NASA Astrophysics Data System (ADS)

    Iverson, C. H.; Coury, G. E.

    1980-04-01

    Progress in the development of a study of the application of the technologies of mechanical vapor recompression and falling film evaporation as applied to the beet sugar industry is reported. Progress is reported in the following areas: technical literature search; report on visit to European factories using these technologies; energy balance studies of factories offered by the industry as candidates for the demonstration plants; and report on energy balance studies and the recommendations as to the site for the demonstration plant.

  15. Dynamics of Soil Water Evaporation during Soil Drying: Laboratory Experiment and Numerical Analysis

    PubMed Central

    Han, Jiangbo; Zhou, Zhifang

    2013-01-01

    Laboratory and numerical experiments were conducted to investigate the evolution of soil water evaporation during a continuous drying event. Simulated soil water contents and temperatures by the calibrated model well reproduced measured values at different depths. Results show that the evaporative drying process could be divided into three stages, beginning with a relatively high evaporation rate during stage 1, followed by a lower rate during transient stage and stage 2, and finally maintaining a very low and constant rate during stage 3. The condensation zone was located immediately below the evaporation zone in the profile. Both peaks of evaporation and condensation rate increased rapidly during stage 1 and transition stage, decreased during stage 2, and maintained constant during stage 3. The width of evaporation zone kept a continuous increase during stages 1 and 2 and maintained a nearly constant value of 0.68 cm during stage 3. When the evaporation zone totally moved into the subsurface, a dry surface layer (DSL) formed above the evaporation zone at the end of stage 2. The width of DSL also presented a continuous increase during stage 2 and kept a constant value of 0.71 cm during stage 3. PMID:24489492

  16. Comparison of evaporation computation methods, Pretty Lake, Lagrange County, northeastern Indiana

    USGS Publications Warehouse

    Ficke, John F.

    1972-01-01

    The different methods, although poor, agree that evaporation when there is ice cover is generally small (less than 0.1 cm day" 1 ), but the evaporation rates during the few days just before freezeup or just after ice breakup are significant

  17. Dynamics of soil water evaporation during soil drying: laboratory experiment and numerical analysis.

    PubMed

    Han, Jiangbo; Zhou, Zhifang

    2013-01-01

    Laboratory and numerical experiments were conducted to investigate the evolution of soil water evaporation during a continuous drying event. Simulated soil water contents and temperatures by the calibrated model well reproduced measured values at different depths. Results show that the evaporative drying process could be divided into three stages, beginning with a relatively high evaporation rate during stage 1, followed by a lower rate during transient stage and stage 2, and finally maintaining a very low and constant rate during stage 3. The condensation zone was located immediately below the evaporation zone in the profile. Both peaks of evaporation and condensation rate increased rapidly during stage 1 and transition stage, decreased during stage 2, and maintained constant during stage 3. The width of evaporation zone kept a continuous increase during stages 1 and 2 and maintained a nearly constant value of 0.68 cm during stage 3. When the evaporation zone totally moved into the subsurface, a dry surface layer (DSL) formed above the evaporation zone at the end of stage 2. The width of DSL also presented a continuous increase during stage 2 and kept a constant value of 0.71 cm during stage 3. PMID:24489492

  18. Aerogel Materials by Evaporative Drying: Potential for Space Applications

    NASA Technical Reports Server (NTRS)

    Plawsky, Joel L.

    1999-01-01

    Aerogel wafers were made using an evaporative drying procedure. The main steps were sol formulation, gelation, aging, capping, and drying. Of these, the most critical step was drying. Both the rate of evaporation and temperature of the system must be controlled for best results. Aerogel materials should be benchmarked against more traditional foams and current systems may have to be redesigned to make best use of aerogel strengths. Finally, the flexibility of this procedure lends itself to producing aerogel materials for many uses other than insulation. Such uses may include catalysis, sensing, and composite materials.

  19. Evaporation and condensation at a liquid surface. II. Methanol

    NASA Astrophysics Data System (ADS)

    Matsumoto, Mitsuhiro; Yasuoka, Kenji; Kataoka, Yosuke

    1994-11-01

    The rates of evaporation and condensation of methanol under the vapor-liquid equilibrium condition at the temperature of 300 and 350 K are investigated with a molecular dynamics computer simulation. Compared with the argon system (reported in part I), the ratio of self-reflection is similar (˜10%), but the ratio of molecule exchange is several times larger than the argon, which suggests that the conventional assumption of condensation as a unimolecular process completely fails for associating fluids. The resulting total condensation coefficient is 20%-25%, and has a quantitative agreement with a recent experiment. The temperature dependence of the evaporation-condensation behavior is not significant.

  20. Clogging of Manifolds with Evaporatively Frozen Propellants. Part 2; Analysis

    NASA Technical Reports Server (NTRS)

    Simmon, J. A.; Gift, R. D.; Spurlock, J. M.

    1966-01-01

    The mechanisms of evaporative freezing of leaking propellant and the creation of flow stoppages within injector manifolds is discussed. A quantitative analysis of the conditions, including the existence of minimum and maximum leak rates, for the accumulation of evaporatively frozen propellant is presented. Clogging of the injector manifolds of the Apollo SPS and the Gemini OAMS engines by the freezing of leaking propellant is predicted and the seriousness of the consequences are discussed. Based on the analysis a realistic evaluation of selected techniques to eliminate flow stoppages by frozen propellant is made.

  1. Nonmagnetic impellers improve evaporative cooling

    SciTech Connect

    Hausman, T. )

    1993-03-01

    This article describes how nonmagnetic impeller flow sensors help improve efficiency of open evaporative cooling water systems. Open evaporative cooling water systems provide economical heat sinks with efficient reuse of water. However, their water loss through evaporation, though minimal, results in an increased concentration of dissolved and suspended impurities in the remaining water. To deconcentrate the water and minimize impurities, the system water is bled off and replaced with fresh makeup water. Bleedoff helps, but to maintain efficient operation and protect the system from water-related catastrophes, various chemical treatments are required for the control of corrosion, deposition, and biological growth. Efficient addition of makeup water and chemical additives can be achieved by a system design employing multiple data points, using flow sensors having high reproducibility for good trend data. In such a system, nonmagnetic flow sensors provide 1% accuracy and excellent reproducibility. In addition, their low initial cost and long service life mean that they can be used cost effectively at multiple data collection points to eliminate approximations.

  2. Influence of Oil on Refrigerant Evaporator Performance

    NASA Astrophysics Data System (ADS)

    Jong-Soo, Kim; Nagata, Katsuya; Katsuta, Masafumi; Tomosugi, Hiroyuki; Kikuchi, Kouichiro; Horichi, Toshiaki

    To explore the quantitative effect of the lubrication oil on the thermal and hydraulic evaporator performance, the detailed structure of two-phase refrigerant (R11) and lubrication oil (Suniso 5GS) flow has been investigated. Experiment has been performed using a transparent tube 20mm in inner diameter and 2600mm in total length as main test section, which was heated by surrounding hot water bath. This water bath also functioned as the visual observation section of the transition of two-phase flow pattern. Oil mass concentration was controlled initially, and circulated into the system. The void fraction at the main test section was measured by direct volume measurement using so-called "Quick Closing Valve" method. Since the effect of oil on the transition of two-phase flow pattern is emphasized at the low flow rate, operation was made at relatively low mass velocity, 50 and 100 kg/m2·s, five different oil concentrations were taken. Throughout the experiment, the evaporation pressure was kept at 105 kPa. In general, when contamination of the lubrication oil happened, the void fraction was decreasing due to the change of viscosity and surface tension and the occurence of the foaming. To correlate the void fraction as function of quality, Zivi's expression was modified to include the effect of oil concentration. The agreement between the data and this proposed correlation was favorable. Finally, to take into account the effect of lubrication oil, the new flow pattern diagram was proposed.

  3. Multispectral remote sensing contribution to land surface evaporation

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.

    1990-01-01

    The global water cycle is perhaps the most important of all the biogeochemical cycles and evaporation, which is a significant component of the water cycle, is also linked with the energy and carbon cycles. Long-term evaporation over large areas has generally been computed as the difference of precipitation and river runoff. Analysis of short-term evaporation rate and its spatial pattern, however, is extremely complex, and multispectral remotely sensed data could aid in such analysis. Multispectral data considered here are visible and near-infrared reflectances, infrared surface temperature and the 37 GHz brightness temperatures. These observations are found to be not totally independent of each other. A few of their relationships are established and discussed considering physically-based models.

  4. Fundamental study of evaporation model in micron pore

    NASA Astrophysics Data System (ADS)

    Oinuma, Ryoji

    As the demand for high performance small electronic devices has increased, heat removal from these devices for space use is approaching critical limits. A heat pipe is a promising device to enhance the heat removal performance due to the phase change phenomena for space thermal management system. Even though a heat pipe has a big potential to remove the thermal energy from a high heat flux source, the heat removal performance of heat pipes cannot be predicted well since the first principle of evaporation has not been established. The purpose of this study is to establish a method to apply the evaporation model based on the statistical rate theory for engineering application including vapor-liquid-structure intermolecular effect. The evaporation model is applied to the heat pipe performance analysis through a pressure balance and an energy balance in the loop heat pipe.

  5. Variation of Phreatic Evaporation of Bare Soil and Integration Application in Water Allocation in Shule Basin

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Huang, P.; Gong, G.

    2011-12-01

    Phreatic evaporation is a key element in regional water balance, but it is hardly measured directly. Recently the development of some new technologies brings new dawn to phreatic evaporation measurement, such as eddy covariance, remote sensing ET and so on. But the new technologies have no ability to connect to groundwater yet. Conventional groundwater balance equipment was set up in Shule basin in northwestern China, with located E97°01', N45°13' , altitude 1520m, annual average precipitation 61.8mm and annual evaporation 2600mm (pan 20cm). The experiment field contains 45 lysimeters (65cm diameter). 11 different water table depths are set in the lysimeters, which are 0.5m, 0.75m, 1.0m, 1.25m, 1.5m, 2.0m, 2.5m, 3.0m, 4.0m, 5.0m and 6.0m. The water table in the lysimeter is controlled by Marriott Bottle System. The evaporation and percolation is measured for three different soil types (silt sandy soil, loam soil and clay soil) in the 11 different water table depths. Based on the data from 2006 to 2010, the influences of atmosphere evaporation capacity, phreatic water depth and soil textures are analyzed. Empirical formulae for estimating phreatic evaporation are regressed. The fitting precision of the different formulae are evaluated. The results show that, fitting effect of common empirical formulae is good in Shule river basin. For the different soil types, fitting effect of silt soil is the best, while that of clay soil is relatively low. At last, formulae fitted in other areas and phreatic evaporation tests are summarized. The reasons of difference of fitted coefficients lie in three aspects: the range of depth of groundwater, choice of the value of water evaporation, method to optimize coefficients. Physical meaning of the coefficients in empirical formulae is analyzed. The features, fitting effect and notes in application of formulae are evaluated. The results are applied in water requirement calculation of ecological conservation Dunhuang Xihu Nature

  6. Numerical simulation of dip-coating in the evaporative regime.

    PubMed

    Dey, Mohar; Doumenc, Frédéric; Guerrier, Béatrice

    2016-02-01

    A hydrodynamic model is used for numerical simulations of a polymer solution in a dip-coating-like experiment. We focus on the regime of small capillary numbers where the liquid flow is driven by evaporation, in contrast to the well-known Landau-Levich regime dominated by viscous forces. Lubrication approximation is used to describe the flow in the liquid phase. Evaporation in stagnant air is considered (diffusion-limited evaporation), which results in a coupling between liquid and gas phases. Self-patterning due to the solutal Marangoni effect is observed for some ranges of the control parameters. We first investigate the effect of evaporation rate on the deposit morphology. Then the role of the spatial variations in the evaporative flux on the wavelength and mean thickness of the dried deposit is ascertained, by comparing the 2D and 1D diffusion models for the gas phase. Finally, for the very low substrate velocities, we discuss the relative importance of diffusive and advective components of the polymer flux, and consequences on the choice of the boundary conditions. PMID:26920522

  7. Influence of electron evaporative cooling on ultracold plasma expansion

    SciTech Connect

    Wilson, Truman; Chen, Wei-Ting; Roberts, Jacob

    2013-07-15

    The expansion of ultracold neutral plasmas (UCP) is driven primarily by the thermal pressure of the electron component and is therefore sensitive to the electron temperature. For typical UCP spatial extents, evaporative cooling has a significant influence on the UCP expansion rate at lower densities (less than 10{sup 8}/cm{sup 3}). We studied the effect of electron evaporation in this density range. Owing to the low density, the effects of three-body recombination were negligible. We modeled the expansion by taking into account the change in electron temperature owing to evaporation as well as adiabatic expansion and found good agreement with our data. We also developed a simple model for initial evaporation over a range of ultracold plasma densities, sizes, and electron temperatures to determine over what parameter range electron evaporation is expected to have a significant effect. We also report on a signal calibration technique, which relates the signal at our detector to the total number of ions and electrons in the ultracold plasma.

  8. Evaporation as the transport mechanism of metals in arid regions.

    PubMed

    Lima, Ana T; Safar, Zeinab; Loch, J P Gustav

    2014-09-01

    Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust. PMID:24997976

  9. Membrane-Based Water Evaporator for a Space Suit

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; McCann, Charles J.; O'Connell, Mary K.; Andrea, Scott

    2004-01-01

    A membrane-based water evaporator has been developed that is intended to serve as a heat-rejection device for a space suit. This evaporator would replace the current sublimator that is sensitive to contamination of its feedwater. The design of the membrane-based evaporator takes advantage of recent advances in hydrophobic micropore membranes to provide robust heat rejection with much less sensitivity to contamination. The low contamination sensitivity allows use of the heat transport loop as feedwater, eliminating the need for the separate feedwater system used for the sublimator. A cross section of the evaporator is shown in the accompanying figure. The space-suit cooling loop water flows into a distribution plenum, through a narrow annulus lined on both sides with a hydrophobic membrane, into an exit plenum, and returns to the space suit. Two perforated metal tubes encase the membranes and provide structural strength. Evaporation at the membrane inner surface dissipates the waste heat from the space suit. The water vapor passes through the membrane, into a steam duct and is vented to the vacuum environment through a back-pressure valve. The back-pressure setting can be adjusted to regulate the heat-rejection rate and the water outlet temperature.

  10. Harnessing Nanoparticles to Control Evaporation at Liquid-Vapor Interfaces

    NASA Astrophysics Data System (ADS)

    Yong, Xin

    2015-11-01

    It is well known that nanoparticles with appropriate size and surface chemistry adsorb to liquid-vapor interfaces and consequently modify the mechanical properties of the interfaces. However, little has been explored about the effect of nanoparticles on the heat transfer occurring at the interfaces. Using many-body dissipative particle dynamics (MDPD), we model an evaporating interface with adsorbed nanoparticles. Homogeneous and amphiphilic Janus nanoparticles, which contain hydrophobic and hydrophobic surface regions, are considered in this study. We measure the variation in the evaporation rates of the interface by gradually increasing particle loading until a hexagonal-close-packed monolayer is achieved. We explore the effect of surface chemistry and surface composition of the particles and demonstrate that evaporation can be readily adjusted by tuning the interaction parameters and amphiphilic ratio. Importantly, we observe that the evaporation suppression by adsorbed nanoparticles occurs only when the ambient vapor pressure is low. This study provides a fundamental understanding of the phase transition in multiphase interfacial systems and opens up new routes to additional control over evaporating interfaces.

  11. Numerical Study of a Hydrodynamic Instability Driven by Evaporation

    NASA Astrophysics Data System (ADS)

    Hernandez-Zapata, Sergio; Romo-Cruz, Julio Cesar Ruben; Lopez-Sanchez, Erick Javier; Ruiz-Chavarria, Gerardo

    2013-11-01

    The study of hydrodynamic instabilities in liquid layers produced by evaporation has several applications on industry and technology. In this work we study numerically the conditions under which a liquid layer becomes unstable when evaporation in the vapor-liquid interphase is present. The evaporation process follows the Hertz-Knudsen law (the evaporation rate is proportional to the difference between the saturated vapor pressure at the liquid layer temperature and the vapor partial pressure in the environment). Additionally to the usual boundary conditions on solid walls (for example, the non-slip condition for the velocity), we analyze the boundary conditions in the vapor-liquid interphase where the momentum and energy balances have to be taken into account and where the evaporation plays a crucial role. To solve this problem the linear theory of stability is used; that is, a small perturbation around the basic solution is applied (flow at rest and a temperature stationary field). The equations are solved using the Chebyshev pseudo-spectral method. The results are compared with the more usual Rayleigh-Bénard and Marangoni mechanisms as well as with some experiments carried out by our team. Authors acknowledge DGAPA-UNAM by support under project IN116312, ``Vorticidad y Ondas no lineales en fluidos.''

  12. Flash evaporation from turbulent water jets

    NASA Astrophysics Data System (ADS)

    Bharathan, D.; Penney, T.

    1983-02-01

    Results of an experimental investigation of flash evaporation from turbulent planar and axisymmetric water jets are reported. In the range of jet thicknesses tested, for planar jets, due to shattering, evaporation is found to be nearly independent of the jet thickness. Evaporation from the planar jets was found to be dependent on the initial level of turbulence in the water supply manifold. An approximate analysis to model the evaporation process based on the physical phenomena and experimental observations is outlined. Comparisons between the experimental data and analytical predictions of the liquid temperature variation along the jet are included. Use of screens in the water jet are shown to be effective for enhancing evaporation.

  13. Evaporator Development for an Evaporative Heat Pipe System

    NASA Technical Reports Server (NTRS)

    Peters, Leigh C.

    2004-01-01

    As fossil fuel resources continue to deplete, research for alternate power sources continues to develop. One of these alternate technologies is fuel cells. They are a practical fuel source able to provide significant amounts of power for applications from laptops to automobiles and their only byproduct is water. However, although this technology is over a century old and NASA has been working with it since the early 1960 s there is still room for improvement. The research I am involved in at NASA's Glenn Research Center is focusing on what is called a regenerative fuel cell system. The unique characteristic of this type of system is that it used an outside power source to create electrolysis of the water it produces and it then reuses the hydrogen and oxygen to continue producing power. The advantage of this type of system is that, for example, on space missions it can use solar power to recharge its gas supplies between periods when the object being orbited blocks out the sun. This particular system however is far from completion. This is because of the many components that are required to make up a fuel cell that need to be tested individually. The specific part of the system that is being worked on this summer of 2004 is the cooling system. The fuel cell stack, that is the part that actually creates the power, also produces a lot of heat. When not properly cooled, it has been known to cause fires which, needless to say are not conducive to the type of power that is trying to be created. In order to cool the fuel cell stack in this system we are developing a heat pipe cooling system. One of the main components of a heat pipe cooling system is what is known as the evaporator, and that is what happens to be the part of the system we are developing this summer. In most heat pipe systems the evaporator is a tube in which the working fluid is cooled and then re-circulated through the system to absorb more heat energy from the fuel cell stack. For this system, instead

  14. The nanofibrous PAN-PANi scaffold as an efficient substrate for skeletal muscle differentiation using satellite cells.

    PubMed

    Hosseinzadeh, Simzar; Mahmoudifard, Matin; Mohamadyar-Toupkanlou, Farzaneh; Dodel, Masomeh; Hajarizadeh, Atena; Adabi, Mahdi; Soleimani, Masoud

    2016-07-01

    Among polymers, polyaniline (PANi) has been introduced as a good candidate for muscle regeneration due to high conductivity and also biocompatibility. Herein, for the first time, we report the use of electrospun nanofibrous membrane of PAN-PANi as efficient scaffold for muscle regeneration. The prepared PAN-PANi electrospun nanofibrous membrane was characterized by scanning electron microscopy (SEM), Attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) and tensile examination. The softer scaffolds of non-composite electrospun nanofibrous PAN govern a higher rate of cell growth in spite of lower differentiation value. On the other hand, PAN-PANi electrospun nanofibrous membrane exposed high cell proliferation and also differentiation value. Thank to the conductive property and higher Young's modulus of composite type due to the employment of PANi, satellite cells were induced into more matured form as analyzed by Real-Time PCR. On the other hand, grafting of composite nanofibrous electrospun scaffold with gelatin increased the surface stiffness directing satellite cells into lower cell proliferation and highest value of differentiation. Our results for first time showed the significant role of combination between conductivity, mechanical property and surface modification of PAN-PANi electrospun nanofibers and provid new insights into most biocompatible scaffolds for muscle tissue engineering. The schematic figure conveys the effective combination of conductive and surface stiffness on muscle tissue engineering. PMID:27086138

  15. Characterising the distribution and morphology of creeks and pans on salt marshes in England and Wales using Google Earth

    NASA Astrophysics Data System (ADS)

    Goudie, Alice

    2013-09-01

    By using Google Earth images and simple morphometric analyses, pan and creek characteristics of salt marshes across England and Wales have been mapped and related to key environmental variables, including tidal range, sea level change, coastal configuration, sediment type and erosion state. Pan density was found to be higher on the west coast or where there is a moderate tidal range and low sea level change. Pan density is also higher on back barrier and drowned valley marshes and when creek density is low. Maximum pan size is partly controlled by pan density. Creek density and sinuosity showed great variability between areas with marshes in the south having a higher creek density. Creek density is related to tidal prism and marshes undergoing high rates of sea level change usually have higher creek densities. Marshes with an upstream configuration (embayment, drowned valley and back barrier) have lower creek densities due to a lower tidal prism. Sediment type also plays a role with lower creek densities found on coarser sediment types. Creek sinuosity seems to be largely controlled by tidal range with higher sinuosities on meso- or macro-tidal marshes. This large-scale, Google Earth-based, analysis of the distribution and likely environmental controls on salt marsh morphometry illustrates the utility of Digital Globes as sources of freely-available, high resolution imagery for geomorphological research.

  16. Clinical Evaluation of Youth with Pediatric Acute-Onset Neuropsychiatric Syndrome (PANS): Recommendations from the 2013 PANS Consensus Conference

    PubMed Central

    Frankovich, Jennifer; Cooperstock, Michael; Cunningham, Madeleine W.; Latimer, M. Elizabeth; Murphy, Tanya K.; Pasternack, Mark; Thienemann, Margo; Williams, Kyle; Walter, Jolan; Swedo, Susan E.

    2015-01-01

    Abstract On May 23 and 24, 2013, the First PANS Consensus Conference was convened at Stanford University, calling together a geographically diverse group of clinicians and researchers from complementary fields of pediatrics: General and developmental pediatrics, infectious diseases, immunology, rheumatology, neurology, and child psychiatry. Participants were academicians with clinical and research interests in pediatric autoimmune neuropsychiatric disorder associated with streptococcus (PANDAS) in youth, and the larger category of pediatric acute-onset neuropsychiatric syndrome (PANS). The goals were to clarify the diagnostic boundaries of PANS, to develop systematic strategies for evaluation of suspected PANS cases, and to set forth the most urgently needed studies in this field. Presented here is a consensus statement proposing recommendations for the diagnostic evaluation of youth presenting with PANS. PMID:25325534

  17. Evaporative cooling and water balance during flight in birds.

    PubMed

    Torre-Bueno, J R

    1978-08-01

    The rate of evaporative cooling was calculated from the rate of mass loss in starlings (Sturnus vulgaris) during 90 min flights in a wind-tunnel. Evaporative heat loss ranged from 5% of the metabolic rate at -5 degrees C to 19% of the metabolic rate at 29 degrees C. Radiation and convection accounted for the balance of the heat loss. On average, starlings dehydrated during flights at all temperatures above 7 degrees C. The comparison of these results with data from field studies, which indicate that long-distance migrants do not dehydrate, suggests that migrants may maintain water balance by ascending to colder air in which convection carries off most of the heat produced. PMID:702042

  18. Public Release of Pan-STARRS Data

    NASA Astrophysics Data System (ADS)

    Flewelling, Heather; Consortium, panstarrs

    2015-08-01

    Pan-STARRS 1 is a 1.8 meter survey telescope, located on Haleakala, Hawaii, with a 1.4 Gigapixel camera, a 7 square degree field of view, and 5 filters (g,r,i,z,y). The public release of data, which is available to everyone, consists of 4 years of data taken between May 2010 and April 2014. Two of the surveys available in the public release are the 3pi survey and the Medium Deep (MD) survey. The 3pi survey has roughly 60 epochs (12 per filter) covering 3/4 of the sky and everything north of -30 degrees declination. The MD survey consists of 10 fields, observed in a couple of filters each night, usually 8 exposures per filter per field, for about 4000 epochs per MD field. The available data product are accessed through the “Postage Stamp Server” and through the Published Science Products Subsystem (PSPS), both of these are available through the Pan-STARRS Science Interface (PSI). The Postage Stamp Server provides images and catalogs for different stages of processing on single exposures, stack images, difference images, and forced photometry. The PSPS is a SQLServer database that can be queried via script or web interface, with a database for each MD field and a large database for the 3pi survey. This database has relative photometry and astrometry and object associations, making it easy to do searches across the entire sky as well as tools to generate lightcurves of individual objects as a function of time.

  19. Heterochrony and geometric morphometrics: a comparison of cranial growth in Pan paniscus versus Pan troglodytes.

    PubMed

    Mitteroecker, Philipp; Gunz, Philipp; Bookstein, Fred L

    2005-01-01

    Heterochrony, the classic framework in which to study ontogeny and phylogeny, in essence relies on a univariate concept of shape. Though principal component (PC) plots of multivariate shape data seem to resemble classical bivariate allometric plots, the language of heterochrony cannot be translated directly into general multivariate methodology. We simulate idealized multivariate ontogenetic trajectories and explore their appearance in PC plots of shape space and size-shape space. Only if the trajectories of two related species lie along exactly the same path in shape space can the classic terminology of heterochrony apply and pure dissociation of size change against shape change be detected. Regional heterochrony--the variation of apparent heterochrony by region--implies a dissociation of local growth fields and cannot be identified in an overall PC analysis. We exemplify a geometric morphometric approach to these issues using adult and subadult crania of 48 Pan paniscus and 47 Pan troglodytes specimens. On each specimen, we digitized 47 landmarks and 144 semilandmarks on facial curves and the external neurocranial surface. We reject the hypothesis of global heterochrony in the cranium of Pan as well as regional heterochrony for the lower face, the upper face, and the neurocranium. PMID:15876197

  20. Brief communication: dental development timing in captive Pan paniscus with comparisons to Pan troglodytes.

    PubMed

    Bolter, Debra R; Zihlman, Adrienne L

    2011-08-01

    Dental eruption provides markers of growth and is one component of a chimpanzee's physical development. Dental markers help characterize transitions between life stages, e.g., infant to juvenile. Most of what we know about the timing of development in chimpanzees derives from Pan troglodytes. Much less is known about the sister species, Pan paniscus, with few in captivity and a restricted wild range in central Africa. Here we report on the dental eruption timing for female captive P. paniscus (n = 5) from the Milwaukee and San Diego Zoos whose ages are known and range from birth to age 8.54 years. Some observations were recorded in zoo records on the gingiva during life; others were made at death on the gingiva and on the skeleton. At birth, P. paniscus infants have no teeth emerged. By 0.83 years, all but the deciduous second molars (dm(2) ) (when both upper and lower dentitions are referenced collectively, no super or subscript notation is used) and canines (dc) are emerged. For permanent teeth, results show a sequence polymorphism for an early P4 eruption, not previously described for P. paniscus. Comparisons between P. paniscus and P. troglodytes document absolute timing differences of emergence in upper second incisors (I(2) ), and upper and lower canines (C) and third molars (M3). The genus Pan encompasses variability in growth not previously recognized. These preliminary data suggest that physical growth in captive P. paniscus may be accelerated, a general pattern found in captive P. troglodytes. PMID:21541924

  1. Integrating variations in the soil chloride profile and evaporativity for in-situ estimation of evaporation in arid zones: an application in south-eastern Morocco

    NASA Astrophysics Data System (ADS)

    Bouhlassa, Saïdati; Ammary, Bouchaib; Paré, Samuel; Safsaf, Naima

    2016-06-01

    In arid regions, knowledge of the evaporation rate from the water table is essential for appropriate management of scarce resources and to prevent land degradation. Soil chloride profiles in the unsaturated zone of a bare soil in an arid area of south-eastern Morocco were used to assess the evaporation flux, using chloride inventories in conjunction with evaporative demand. Moisture fluxes were calculated from measured chloride concentrations on the basis of a steady-state flow model. The chloride profiles displayed large variations in concentrations and had (1) low chloride concentrations near the soil surface, (2) maximum chloride concentrations at depths of 11-14 cm beneath the soil surface, respectively in July and February, and (3) gradually decreasing chloride concentrations while depth increased below these peaks. Evaporative demands were found to be inversely proportional to the depth of evaporation fronts and proportional to evaporation fluxes. In addition, the evaporation along the profiles seems to be controlled by the soil composition and texture. The investigation of chloride profiles in February and July enabled the determination of a value for annual evaporation (˜30 mm), which is in good agreement with the value estimated by the Allison-Barnes type model (˜32 mm).

  2. Effect of soil type patterns on the variability of bare soil evaporation within a field: comparison of eddy covariance measurements with potential and actual evaporation calculations

    NASA Astrophysics Data System (ADS)

    Vanderborght, J.; Graf, A.; Steenpass, C.; Scharnagl, B.; Prolingheuer, N.; Herbst, M.; Vereecken, H.

    2009-12-01

    Bare soil evaporation was measured with the eddy-covariance method at the Selhausen field site. The site has a distinct gradient in soil texture with a considerably higher stone content at the upper part of the field. Because of this gradient, a spatial variation in evaporation fluxes in the field is expected. Because of the higher stone content at the upper part of the field, it is expected that the water that is stored in the soil surface layer and can be evaporated at a maximal evaporation rate, which is determined by the energy that is available for evaporation, is considerable smaller in the upper than in the lower part of the field. We investigated whether this hypothesis is supported by eddy covariance (EC) measurements of the evaporation fluxes at the field site. The EC measurements were combined with a footprint model that predicts the location of the soil surface that contributes to the measured evaporation flux. In this way, evaporation measurements of the two parts of the field site could be distinguished. However, since only one EC station was available, simultaneous evaporation measurements for the two field parts were not available. As a consequence, the datasets of measurements had to be interpreted and put into context of the meteorological and soil hydrological conditions. The potential evapotranspiration was calculated using the FAO method (Allen et al., 1998) to represent the meteorological conditions whereas a simple soil evaporation model (Boesten and Stroosnijder, 1986) was used to represent the influence of the precipitation and soil hydrological conditions on the actual evaporation rate. Since different soil parameters were required to describe the evaporation measurements for the upper and lower part of the plot, our starting hypothesis that more water is evaporated in the lower part of the field could be confirmed. Allen, R. G., L. S. Pereira, D. Raes, and M. Smith (1998), Crop evapotranspiration: Guidelines for computing crop water

  3. Indirect evaporative coolers with enhanced heat transfer

    SciTech Connect

    Kozubal, Eric; Woods, Jason; Judkoff, Ron

    2015-09-22

    A separator plate assembly for use in an indirect evaporative cooler (IEC) with an air-to-air heat exchanger. The assembly includes a separator plate with a first surface defining a dry channel and a second surface defining a wet channel. The assembly includes heat transfer enhancements provided on the first surface for increasing heat transfer rates. The heat transfer enhancements may include slit fins with bodies extending outward from the first surface of separator plate or may take other forms including vortex generators, offset strip fins, and wavy fins. In slit fin implementations, the separator plate has holes proximate to each of the slit fins, and the separator plate assembly may include a sealing layer applied to the second surface of the separator plate to block air flow through the holes. The sealing layer can be a thickness of adhesive, and a layer of wicking material is applied to the adhesive.

  4. Steam Oxidation and Chromia Evaporation in Ultra-Supercritical Steam Boilers and Turbines

    SciTech Connect

    Gordon H. Holcomb

    2009-01-01

    U.S. Department of Energy’s goals include power generation from coal at 60% efficiency, which requires steam conditions of up to 760 °C and 340 atm, so-called ultra-supercritical (USC) conditions. Evaporation of protective chromia scales is expected to be a primary corrosion mechanism. A methodology to calculate Cr evaporation rates from chromia scales was developed and combined with Cr diffusion calculations within the alloy (with a constant flux of Cr leaving the alloy from evaporation) to predict Cr concentration profiles and to predict the time until breakaway oxidation. At the highest temperatures and pressures, the time until breakaway oxidation was predicted to be quite short for the turbine blade, and of concern within the steam pipe and the higher temperature portions of the superheater tube. Alloy additions such as Ti may allow for a reduction in evaporation rate with time, mitigating the deleterious effects of chromia evaporation.

  5. Putting the "vap" into evaporation

    NASA Astrophysics Data System (ADS)

    Shuttleworth, W. J.

    2007-01-01

    In the spirit of the Special Issue of HESS to which it contributes, this paper documents the origin and development of the science of natural evaporation from land surfaces over the last 30-35 years, since the symposium A View from the Watershed was held to commemorate the opening of the new Institute of Hydrology (IH) building in 1973. Important subsequent technical progress includes the ability to measure routinely the diurnal cycle of near-surface meteorological variables using automatic weather stations, and of surface energy and momentum exchanges using automated implementations of the Bowen Ratio/Energy Budget technique and the Eddy Correlation technique, along with the capability to estimate the "fetch" for which these measurements apply. These improvements have been complemented by new methods to measure the separate components of evaporation, including: the interception process using randomly relocated below-canopy gauges, transpiration fluxes from individual leaves/shoots using porometers and from plants/plant components using stem-flow gauges and soil evaporation using micro-lysimeters and soil moisture depletion methods. In recent years progress has been made in making theory-based area-average estimates of evaporation using scintillometers, and model-based area-average estimates by assembling many streams of relevant data into Land Data Assimilation Systems. Theoretical progress has been made in extending near-surface turbulence theory to accommodate the effect of the "excess" boundary layer resistance to leaf-to-air transfer of energy and mass fluxes relative to that for momentum, and to allow for observed shortcoming in stability factors in the transition layer immediately above vegetation. Controversy regarding the relative merits of multi-layer model and "big leaf" representations of whole-canopy exchanges has been resolved in favour of the latter approach. Important gaps in the theory of canopy-atmosphere interactions have been filled, including

  6. Evaporative oxidation treatability test report

    SciTech Connect

    1995-04-01

    In 1992, Congress passed the Federal Facilities Compliance Act that requires the U.S. Department of Energy (DOE) to treat and dispose of its mixed waste in accordance with the Resource Conservation and Recovery Act (RCRA) land disposal restrictions (LDRs). In response to the need for mixed-waste treatment capacity where available off-site commercial treatment facilities do not exist or cannot be used, the DOE Albuquerque Operations Office (DOE-AL) organized a Treatment Selection Team to match mixed wastes with treatment options and develop a strategy for treatment of its mixed wastes. DOE-AL manages operations at nine sites with mixed-waste inventories. The Treatment Selection Team determined a need to develop mobile treatment capacity to treat wastes at the sites where the wastes are generated. Treatment processes used for mixed waste not only must address the hazardous component (i.e., meet LDRs) but also must contain the radioactive component in a form that allows final disposal while protecting workers, the public, and the environment. On the basis of recommendations of the Treatment Selection Team, DOE-AL assigned projects to the sites to bring mixed-waste treatment capacity on-line. The three technologies assigned to the DOE Grand Junction Projects Office (GJPO) are evaporative oxidation, thermal desorption, and treated wastewater evaporation. Rust Geotech, the DOE-GJPO prime contractor, was assigned to design and fabricate mobile treatment units (MTUs) for these three technologies and to deliver the MTUs to selected DOE-AL sites. To conduct treatability tests at the GJPO, Rust leased a pilot-scale evaporative oxidation unit from the Clemson Technical Center (CTC), Anderson, South Carolina. The purpose of this report is to document the findings and results of tests performed using this equipment.

  7. The STM4195 Gene Product (PanS) Transports Coenzyme A Precursors in Salmonella enterica

    PubMed Central

    Ernst, Dustin C.

    2015-01-01

    ABSTRACT Coenzyme A (CoA) is a ubiquitous coenzyme involved in fundamental metabolic processes. CoA is synthesized from pantothenic acid by a pathway that is largely conserved among bacteria and eukaryotes and consists of five enzymatic steps. While higher organisms, including humans, must scavenge pantothenate from the environment, most bacteria and plants are capable of de novo pantothenate biosynthesis. In Salmonella enterica, precursors to pantothenate can be salvaged, but subsequent intermediates are not transported due to their phosphorylated state, and thus the pathway from pantothenate to CoA is considered essential. Genetic analyses identified the STM4195 gene product of Salmonella enterica serovar Typhimurium as a transporter of pantothenate precursors, ketopantoate and pantoate and, to a lesser extent, pantothenate. Further results indicated that STM4195 transports a product of CoA degradation that serves as a precursor to CoA and enters the biosynthetic pathway between PanC and CoaBC (dfp). The relevant CoA derivative is distinguishable from pantothenate, pantetheine, and pantethine and has spectral properties indicating the adenine moiety of CoA is intact. Taken together, the results presented here provide evidence of a transport mechanism for the uptake of ketopantoate, pantoate, and pantothenate and demonstrate a role for STM4195 in the salvage of a CoA derivative of unknown structure. The STM4195 gene is renamed panS to reflect participation in pantothenate salvage that was uncovered herein. IMPORTANCE This manuscript describes a transporter for two pantothenate precursors in addition to the existence and transport of a salvageable coenzyme A (CoA) derivative. Specifically, these studies defined a function for an STM protein in S. enterica that was distinct from the annotated role and led to its designation as PanS (pantothenate salvage). The presence of a salvageable CoA derivative and a transporter for it suggests the possibility that this

  8. Pan-Nitinol Occluder and Special Delivery Device for Closure of Patent Ductus Arteriosus

    PubMed Central

    Jiang, Hai-bin; Bai, Yuan; Zong, Gang-jun; Han, Lin; Li, Wei-ping; Lu, Yang; Qin, Yong-wen; Zhao, Xian-xian

    2013-01-01

    The aim of this study was to evaluate a new type of occluder for patent ductus arteriosus. Patent ductus arteriosus was established in a canine model by anastomosing a length of autologous jugular vein to the descending aorta and the left pulmonary artery in an end-to-side fashion. Transcatheter closure of each patent ductus arteriosus was performed on 10 dogs, which were then monitored for as long as 6 months with aortography, echocardiography, and histologic evaluation. Transcatheter closure with use of the novel pan-nitinol device was successful in all canine models. Postoperative echocardiography showed that the location and shape of the occluders were normal, without any residual shunting. Further histologic evaluation confirmed that the occluder surface was completely endothelialized 3 months after implantation. Transcatheter patent ductus arteriosus closure with the pan-nitinol occluder can be performed safely and successfully in a canine model and shows good biological compatibility and low mortality rates. PMID:23466429

  9. Organic Evaporator steam valve failure

    SciTech Connect

    Jacobs, R. A.

    1992-09-29

    DWPF Technical has requested an analysis of the capacity of the organic Evaporator (OE) condenser (OEC) be performed to determine its capability in the case where the OE steam flow control valve fails open. Calculations of the OE boilup and the OEC heat transfer coefficient indicate the OEC will have more than enough capacity to remove the heat at maximum OE boilup. In fact, the Salt Cell Vent Condenser (SCVC) should also have sufficient capacity to handle the maximum OE boilup. Therefore it would require simultaneous loss of OEC and/or SCVC condensing capacity for the steam valve failure to cause high benzene in the Process Vessel Vent System (PVVS).

  10. Cloacal evaporation: an important and previously undescribed mechanism for avian thermoregulation.

    PubMed

    Hoffman, Ty C M; Walsberg, Glenn E; DeNardo, Dale F

    2007-03-01

    We present the first experimental evidence that a bird is capable of evaporating enough water from the cloaca to be important for thermoregulation. We measured rates of evaporation occurring from the mouth, the skin, and the cloaca of Inca doves Columbina inca Lesson and Eurasian quail Coturnix coturnix Linnaeus. Inca doves showed no significant increase in cutaneous evaporation in response to curtailment of buccopharyngeal evaporation. Cloacal evaporation in doves was negligible at ambient temperatures of 30 degrees , 35 degrees and 40 degrees C. However, at 42 degrees C, the apportionment of total evaporation in doves was 53.4% cutaneous, 25.4% buccopharyngeal and 21.2% cloacal, with cloacal evaporation shedding, on average, 150 mW of heat. In contrast, the evaporative apportionment in quail at 32 degrees C (the highest ambient temperature tolerated by this species) was 58.2% cutaneous, 35.4% buccopharyngeal and 6.4% cloacal. These results suggest that, for some birds, cloacal evaporation can be controlled and could serve as an important emergency tactic for thermoregulation at high ambient temperatures. PMID:17297135

  11. On the role of physiochemical properties on evaporation behavior of DISI biofuel sprays

    NASA Astrophysics Data System (ADS)

    Knorsch, Tobias; Heldmann, Markus; Zigan, Lars; Wensing, Michael; Leipertz, Alfred

    2013-06-01

    Biofuels and alternative fuels are increasingly being blended to conventional gasoline fuel to reduce the overall CO2 emissions. The effect on NOx and soot formation is still unclear as the atomization and evaporation of gasoline with biocomponents differ depending on fuel specific physiochemical properties. This work focuses on describing the biofuel evaporation behavior of gasoline sprays at homogeneous charge (early injection timing) and stratified-charge conditions (late injection timing mode) used in modern direct injection spark ignition engines (DISI). A spray plume of a 6-hole solenoid injector is analyzed in terms of liquid spray propagation, and local droplet sizes studied in an injection chamber. Depending on the operating conditions, different physiochemical properties are found to dominate the atomization and evaporation processes: For low and moderate ambient temperature and pressure, high-boiling point components show a strong influence on the spray droplet size distribution. However, at elevated temperature and pressure, the evaporation behavior changes completely. Due to a high degree of evaporation, the evaporation cooling effect dominates the local droplet sizes. Fuel mixtures owing a larger heat of vaporization show larger droplet sizes—even if these fuels have a lower boiling point. Depending on the local evaporation behavior, the different remaining droplet momentum in the spray controls the air entrainment and the subsequent progress of evaporation and mixing. Overall, it can be stated that the heat of vaporization is a dominating physiochemical property for the droplet evaporation rate at high-level supercharged conditions.

  12. Chemical evolution of multicomponent aerosol particles during evaporation

    NASA Astrophysics Data System (ADS)

    Zardini, Alessandro; Riipinen, Ilona; Pagels, Joakim; Eriksson, Axel; Worsnop, Douglas; Switieckli, Erik; Kulmala, Markku; Bilde, Merete

    2010-05-01

    Atmospheric aerosol particles have an important but not well quantified effect on climate and human health. Despite the efforts made in the last decades, the formation and evolution of aerosol particles in the atmosphere is still not fully understood. The uncertainty is partly due to the complex chemical composition of the particles which comprise inorganic and organic compounds. Many organics (like dicarboxylic acids) can be present both in the gas and in the condensed phase due to their low vapor pressure. Clearly, an understanding of this partition is crucial to address any other issue in atmospheric physics and chemistry. Moreover, many organics are water soluble, and their influence on the properties of aqueous solution droplets is still poorly characterized. The solid and sub-cooled liquid state vapor pressures of some organic compounds have been previously determined by measuring the evaporation rate of single-compound crystals [1-3] or binary aqueous droplets [4-6]. In this work, we deploy the HTDMA technique (Hygroscopicity Tandem Differential Mobility Analyzer) coupled with a 3.5m laminar flow-tube and an Aerosol Mass Spectrometer (AMS) for determining the chemical evolution during evaporation of ternary droplets made of one dicarboxylic acid (succinic acid, commonly found in atmospheric samples) and one inorganic compound (sodium chloride or ammonium sulfate) in different mixing ratios, in equilibrium with water vapor at a fixed relative humidity. In addition, we investigate the evaporation of multicomponent droplets and crystals made of three organic species (dicarboxylic acids and sugars), of which one or two are semi-volatile. 1. Bilde M. and Pandis, S.N.: Evaporation Rates and Vapor Pressures of Individual Aerosol Species Formed in the Atmospheric Oxidation of alpha- and beta-Pinene. Environmental Science and Technology, 35, 2001. 2. Bilde M., et al.: Even-Odd Alternation of Evaporation Rates and Vapor Pressures of C3-C9 Dicarboxylic Acid Aerosols

  13. End-evaporation kinetics in living-polymer systems

    NASA Astrophysics Data System (ADS)

    Marques, C. M.; Turner, M. S.; Cates, M. E.

    1993-11-01

    We study theoretically the process of ``end-evaporation'' in living polymer systems, such as wormlike surfactant micelles. End-evaporation occurs when single monomers either break away from, or join onto, a chain end, the rates being described by the (mean-field) rate constants k and k', respectively. Thus the chains can exchange material with one-another via a bath of free monomers. The relaxation of a system of living polymers after a small temperature jump (T-jump) is studied theoretically. The effect of a T-jump is to prepare the system with the wrong mean chain length, which relaxes to its equilibrium value L¯ by end-evaporation. It is found that the number of free monomers in the system relaxes almost completely in a time of order 1/kL¯, while the weight-average chain length, which is the quantity measured in light scattering experiments, relaxes on a time scale τD=4L¯2/k, which is three powers of L¯ longer. We also predict that the stress relaxation after a step strain is dominated by end-evaporation whenever τD≲τrep, where τrep is the reptation (disengagement) time for a chain of length L¯. In this case the stress relaxation is found to be ``stretched exponential'' for times smaller than τD and single exponential for longer times.

  14. Phase 2 report on the evaluation of polyacrylonitrile (PAN) as a binding polymer for absorbers used to treat liquid radioactive wastes

    SciTech Connect

    Sebesta, F.; John, J.; Motl, A.

    1996-05-01

    The performance of PAN-based composite absorbers was evaluated in dynamic experiments at flow rates ranging from 25--100 bed volumes (BV) per hour. Composite absorbers with active components of ammonium molybdophosphate (AMP) PAN and K-Co ferrocyanide (KCoFC) PAN were used for separating Cs from a 1 M HNO{sub 3} + 1 M NaNO{sub 3} + 2 {times} 10{sup {minus}5} M CsCl acidic simulant solution. KCoFC-PAN and two other FC-based composite absorbers were tested for separating Cs from alkaline simulant solutions containing 0.01 M to 1 M NaOH and 1 M NaNO{sub 3} + x {times} 10{sup {minus}4} M CsCl. The efficiency of the Cs sorption on the AMP-PAN absorber from acidic simulant solutions was negatively influenced by the dissolution of the AMP active component. At flow rates of 50 BV/hr, the decontamination factor of about 10{sup 3} could be maintained for treatment of 380 BV of the feed. With the KCoFC-PAN absorber, the decontamination factor of about 10{sup 3} could be maintained for a feed volume as great as 1,800 BV. In alkaline simulant solutions, significant decomposition of the active components was observed, and the best performance was exhibited by the KCoFC-PAN absorber. Introductory experiments confirmed that Cs may be washed out of the composite absorbers. Regeneration of both absorbers for repetitive use was also found to be possible. The main result of the study is that PAN was proven to be a versatile polymer capable of forming porous composite absorbers with a large number of primary absorbers. The composite absorbers proved to be capable of withstanding the harsh acidic and alkaline conditions and significant radiation doses that may be expected in the treatment of US DOE wastes. A field demonstration is proposed as a follow-on activity.

  15. Experimental and theoretical investigations of falling film evaporation

    NASA Astrophysics Data System (ADS)

    Pehlivan, Hüseyin; Özdemir, Mustafa

    2012-06-01

    In this study, a mathematical model was developed for falling film evaporation in vacuum using heat transfer relations. An experimental device was designed. experimental set-up which was used was equipped with a triangular weir distribution device and it had the ability to record data up to 3 m. Experiments were performed in a single-effect process with sucrose-water solution varying from 3 to 20% concentration rate of sucrose and we used a vertical tube evaporator with the dimensions of laboratory scale. The model that was developed considers convection, shear stress, viscosity and conjugate heat transfer while most of the previous works ignored these factors. The main factors influencing the heat transfer mechanism performance of the unit were investigated and analyzed. We concluded that the experimental studies are verified by the developed model. Furthermore, it was also concluded that, the heat transfer is affected by the mass flow rate, sucrose concentration rate in solution, film thickness and pressure.

  16. Hydrodynamic Instabilities Produced by Evaporation

    NASA Astrophysics Data System (ADS)

    Romo-Cruz, Julio Cesar Ruben; Hernandez-Zapata, Sergio; Ruiz-Chavarria, Gerardo

    2012-11-01

    When a liquid layer (alcohol in the present work) is in an environment where its relative humidity is less than 100 percent evaporation appears. When RH is above a certain threshold the liquid is at rest. If RH decreases below this threshold the flow becomes unstable, and hydrodynamic cells develop. The aim of this work is to understand the formation of those cells and its main features. Firstly, we investigate how the cell size depends on the layer width. We also study how temperature depends on the vertical coordinate when the cells are present. An inverse temperature gradient is found, that is, the bottom of liquid layer is colder than the free surface. This shows that the intuitive idea that the cells are due to a direct temperature gradient, following a Marangoni-like process, does not work. We propose the hypothesis that the evaporation produce a pressure gradient that is responsible of the cell development. On the other hand, using a Schlieren technique we study the topography of the free surface when cells are present. Finally the alcohol vapor layer adjacent to the liquid surface is explored using scattering experiments, giving some insight on the plausibility of the hypothesis described previously. Authors acknowledge support by DGAPA-UNAM under project IN116312 ``Vorticidad y ondas no lineales en fluidos.''

  17. Testing of the Multi-Fluid Evaporator Engineering Development Unit

    NASA Technical Reports Server (NTRS)

    Quinn, Gregory; O'Connor, Ed; Riga, Ken; Anderson, Molly; Westheimer, David

    2007-01-01

    Hamilton Sundstrand is under contract with the NASA Johnson Space Center to develop a scalable, evaporative heat rejection system called the Multi-Fluid Evaporator (MFE). It is being designed to support the Orion Crew Module and to support future Constellation missions. The MFE would be used from Earth sea level conditions to the vacuum of space. The current Shuttle configuration utilizes an ammonia boiler and flash evaporator system to achieve cooling at all altitudes. The MFE system combines both functions into a single compact package with significant weight reduction and improved freeze-up protection. The heat exchanger core is designed so that radial flow of the evaporant provides increasing surface area to keep the back pressure low. The multiple layer construction of the core allows for efficient scale up to the desired heat rejection rate. The full scale MFE prototype will be constructed with four core sections that, combined with a novel control scheme, manage the risk of freezing the heat exchanger cores. A sub-scale MFE engineering development unit (EDU) has been built, and is identical to one of the four sections of a full scale prototype. The EDU has completed testing at Hamilton Sundstrand. The overall test objective was to determine the thermal performance of the EDU. The first set of tests simulated how each of the four sections of the prototype would perform by varying the chamber pressure, evaporant flow rate, coolant flow rate and coolant temperature. A second set of tests was conducted with an outlet steam header in place to verify that the outlet steam orifices prevent freeze-up in the core while also allowing the desired thermal turn-down ratio. This paper discusses the EDU tests and results.

  18. Assessment of the Multi-Fluid Evaporator Technology

    NASA Astrophysics Data System (ADS)

    Quinn, Gregory; O'Connor, Edward

    2008-01-01

    Hamilton Sundstrand has developed a scalable evaporative heat rejection system called the Multi-Fluid Evaporator (MFE). It was designed to support the Orion Crew Module and to support future Constellation missions. The MFE would be used as a heat sink from Earth sea level conditions to the vacuum of space. The current shuttle configuration utilizes an ammonia boiler and water based flash evaporator system to achieve cooling at all altitudes. This system combines both functions into a single compact package with improved freeze-up protection. The heat exchanger core is designed so that radial flow of the evaporant provides increasing surface area to keep the back pressure low. The multiple layer construction of the core allows for efficient scale up to the desired heat rejection rate. A full-scale system uses multiple core sections that, combined with a novel control scheme, manage the risk of freezing the heat exchanger cores. A single-core MFE engineering development unit (EDU) was built in 2006, followed by a full scale, four-core prototype in 2007. The EDU underwent extensive thermal testing while the prototype was being built. Lessons learned from the EDU were incorporated into the prototype and proven out in check-out testing. The EDU and prototype testing proved out the MFE's ability to passively control back-pressure, avoid unwanted icing, tolerate icing if it should occur, provide a three-to-one turn down ratio in heat load and scale up efficiently. Some issues with these first designs of the MFE have limited its ability to reject heat without liquid evaporant carry-over. However, they are due to the implementation of the design rather than the fundamentals of the technology. This paper discusses the background, development and present state of the Multi-Fluid Evaporator technology and concludes with efforts underway to advance the state-of-the-art.

  19. Out-of-tank evaporator demonstration. Final report

    SciTech Connect

    Lucero, A.J.; Jennings, H.L.; VanEssen, D.C.

    1998-02-01

    The project reported here was conducted to demonstrate a skid-mounted, subatmospheric evaporator to concentrate liquid low-level waste (LLLW) stored in underground tanks at Oak Ridge National Laboratory (ORNL). This waste is similar to wastes stored at Hanford and Savannah River. A single-stage subatmospheric evaporator rated to produce 90 gallons of distillate per hour was procured from Delta Thermal, Inc., of Pensacola, Florida, and installed in an existing building. During the 8-day demonstration, 22,000 gal of LLLW was concentrated by 25% with the evaporator system. Decontamination factors achieved averaged 5 x 10{sup 6} (i.e., the distillate contained five million times less Cesium 137 than the feed). Evaporator performance substantially exceeded design requirements and expectations based on bench-scale surrogate test data. Out-of tank evaporator demonstration operations successfully addressed the feasibility of hands-on maintenance. Demonstration activities indicate that: (1) skid-mounted, mobile equipment is a viable alternative for the treatment of ORNL LLLW, and (2) hands-on maintenance and decontamination for movement to another site is achievable. Cost analysis show that 10% of the demonstration costs will be immediately recovered by elimination of solidification and disposal costs. The entire cost of the demonstration can be recovered by processing the inventory of Melton Valley Storage Tank waste and/or sluice water prior to solidifications. An additional savings of approximately $200,000 per year can be obtained by processing newly generated waste through the system. The results indicate that this type of evaporator system should be considered for application across the DOE complex. 25 refs., 11 figs., 2 tabs.

  20. Evaporation from Lake Mead, Nevada and Arizona, March 2010 through February 2012

    USGS Publications Warehouse

    Moreo, Michael T.; Swancar, Amy

    2013-01-01

    Evaporation from Lake Mead was measured using the eddy-covariance method for the 2-year period starting March 2010 and ending February 2012. When corrected for energy imbalances, annual eddy-covariance evaporation was 2,074 and 1,881 millimeters (81.65 and 74.07 inches), within the range of previous estimates. There was a 9-percent decrease in the evaporation rate and a 10-percent increase in the lake surface area during the second year of the study compared to the first. These offsetting factors resulted in a nearly identical 720 million cubic meters (584,000 acre feet) evaporation volume for both years. Monthly evaporation rates were best correlated with wind speed, vapor pressure difference, and atmospheric stability. Differences between individual monthly evaporation and mean monthly evaporation were as much as 20 percent. Net radiation provided most of the energy available for evaporative processes; however, advected heat from the Colorado River was an important energy source during the second year of the study. Peak evaporation lagged peak net radiation by 2 months because a larger proportion of the net radiation that reaches the lake goes to heating up the water column during the spring and summer months. As most of this stored energy is released, higher evaporation rates are sustained during fall months even though net radiation declines. The release of stored heat also fueled nighttime evaporation, which accounted for 37 percent of total evaporation. The annual energy-balance ratio was 0.90 on average and varied only 0.01 between the 2 years, thus implying that 90 percent of estimated available energy was accounted for by turbulent energy measured using the eddy-covariance method. More than 90 percent of the turbulent-flux source area represented the open-water surface, and 94 percent of 30-minute turbulent-flux measurements originated from wind directions where the fetch ranged from 2,000 to 16,000 meters. Evaporation uncertainties were estimated to be 5