Evaporation Area Research Articles

Phosphorus Speciation and Sedimentary Fluxes in Hypersaline Sediments of the Guerrero Negro Salt Evaporation Area, Baja California Sur, Mexico

In the past several decades, the techniques used to discern the different sedimentary fractions of P have been refined. This has allowed for a better understanding of P burial of the different P fractions and diagenetic reactions and, ultimately, the constraining of P residence time in the oceans. P sequential extraction was performed on eight sediment cores (between 16 and 24 cm deep) collected along a salinity gradient from the Ojo de Liebre Lagoon and the salt evaporation saltern of Guerrero Negro, Baja California Sur, Mexico in order to determine, under purely diagenetic conditions (in the absence of anthropogenic activities and biogenic sediment reworking), the fractionation and flux of P to the sediments. The majority of P was found in the authigenic fraction (37 ± 5.4% to 53 ± 8.9%), with P associated to organic matter comprising the overall smallest percentage (0.25 ± 0.43% to 21 ± 6.0%) relative to total P. The average flux of total P to the sediments for all the sites was found to be (451 ± 127) × 10−4 mol m−2 year−1, up to several orders of magnitude greater than those found in other studies. It is concluded that P is most likely transformed from P associated to organic matter to the authigenic mineral phase and that P was retained in the sediments in its mineral form rather than in reactive forms. This particular study area has the ability to retain large quantities of P in the sediments.

Sustainable desalination using solar energy

Global potable water demand is expected to grow, particularly in areas where freshwater supplies are limited. Production and supply of potable water requires significant amounts of energy, which is currently being derived from nonrenewable fossil fuels. Since energy production from fossil fuels also requires water, current practice of potable water supply powered by fossil fuel derived energy is not a sustainable approach. In this paper, a sustainable phase-change desalination process is presented that is driven solely by solar energy without any reliance on grid power. This process exploits natural gravity and barometric pressure head to maintain near vacuum conditions in an evaporation chamber. Because of the vacuum conditions, evaporation occurs at near ambient temperature, with minimal thermal energy input for phase change. This configuration enables the process to be driven by low-grade heat sources such as solar energy or waste heat streams. Results of theoretical analysis and prototype scale experimental studies conducted to evaluate and demonstrate the feasibility of operating the process using solar energy are presented. Predictions made by the theoretical model correlated well with measured performance data with r 2 > 0.94. Test results showed that, using direct solar energy alone, the system could produce up to 7.5 L/day of freshwater per m 2 of evaporator area. With the addition of a photovoltaic panel area of 6 m 2, the system could produce up to 12 L/day of freshwater per m 2 of evaporator area, at efficiencies ranging from 65% to 90%. Average specific energy need of this process is 2930 kJ/kg of freshwater, all of which can be derived from solar energy, making it a sustainable and clean process.

WAIV - Wind aided intensified evaporation for brine volume reduction and generating mineral byproducts

In this study bench pilot WAIV units (∼ 1 m2 evaporation area loaded on 0.17 m2 footprint) were operated on two different desalination brines (RO and ED) as well as on a mineral brine concentrate under arid conditions of the Negev Highlands. The evaporation rate with the WAIV unit on these feeds often gave evaporation rates per footprint that were 10-fold or greater than the pan evaporation rate obtained from the local meteorological station at Sde Boker. Desalination brines were concentrated up to 23% TDS when operating on ED concentrate. The evaporation from the WAIV unit demonstrated enrichment in the magnesium ion compared to the calcium and the sodium ion, including over a two-fold enrichment of magnesium relative to calcium as would be expected by the equilibrium solubilities of the different minerals. Despite precipitation of minerals, there is not a large buildup of deposit on the flexible evaporation surface, and this helps establish the feasibility for recovering minerals from the desalination brine by using WAIV unit. For the ED-RO hybrid desalination process which provided one of the feeds to the WAIV unit, WAIV capital costs will only be about 5.5% of the annualized desalination costs (CAPEX and OPEX).

Thermal analyses of combined utilization process of seawater by solar chimney

It is promising to simultaneously develop multiple products through the combined utilization of seawater by solar chimney technology. A small scale experimental system was set up. The collector temperature, the seawater temperature, and the temperature and humidity of the airflow under the collector were measured. Thermal network analysis of the system was carried out. The results show that the airflow is nearly saturated at the entrance of the chimney, and the mean dry-bulb and wet-bulb temperatures of the airflow have increased by 8.4 °C and 9.6 °C, respectively. The radiation heat transfer between the collector and the sky is the biggest heat loss in the system, which is up to 29.1% on average of the solar energy. However, the water evaporation heat is about 23.6% on average of the solar energy. To reduce the heat loss and enhance the water evaporation, it is necessary to reduce the emissivity and thermal conductivity of the collector and increase the evaporation areas.

Evaporation and coverage area of pesticide droplets on hairy and waxy leaves

The fate of pesticide droplets on leaves is significantly influenced by the fine structures found on leaf surfaces. Evaporation times and the maximum coverage areas of single droplets (246, 343, 575, 762, and 886 μm) on hairy and waxy geranium leaf surfaces were determined under controlled conditions. Stereoscopic sequential images of the droplet evaporation processes were taken for five droplet sizes, three relative humidity (RH) conditions and 13 different sprays. The sprays were combinations of water, a non-ionic colloidal polymer drift retardant, an alkyl polyoxyethylene surfactant, a fungicide and three insecticides. The evaporation time and maximum coverage area of droplets were significantly changed by adding the surfactant or drift retardant to the sprays, but not by adding fungicide or insecticide. Droplet evaporation times on waxy leaves were longer than those on hairy leaves. Evaporation times increased exponentially as droplet diameter and RH increased with limited variability of regression coefficients independent of spray type and leaf surface. The maximum coverage area of droplets also increased exponentially as droplet diameter increased but it was not significantly affected by RH. On the waxy geranium leaf surfaces, the coverage area of pesticide droplets decreased throughout the evaporating process and at all RH conditions, while, on hairy leaf surfaces for the same size droplets, and at the same RH conditions, the coverage area continued to spread until evaporation was nearly completed. Given that the duration of evaporation time and the extent of the coverage area affect pesticide distribution on waxy or hairy leaves, recommendations for pesticide dosage and spray methods should be taken into account for different leaf surfaces to obtain the optimum biological effect and reduced pesticide use.

Performance of solar still with a concave wick evaporation surface

Abstract Surfaces used for evaporation and condensation phenomenon play important roles in the performance of basin type solar still. In the present study, a concave wick surface was used for evaporation, whereas four sides of a pyramid shaped still were used for condensation. Use of jute wick increased the amount of absorbed solar radiation and enhanced the evaporation surface area. A concave shaped wick surface increases the evaporation area due to the capillary effect. Results show that average distillate productivity in day time was 4.1 l/m2 and a maximum instantaneous system efficiency of 45% and average daily efficiency of 30% were recorded. The maximum hourly yield was 0.5 l/h. m2 after solar noon. An estimated cost of 1 l of distillate was 0.065 $ for the presented solar still.

Morphological variation of Aechmea distichantha (Bromeliaceae) in a Chaco forest: habitat and size‐related effects

Plants show different morphologies when growing in different habitats, but they also vary in their morphology with plant size. We examined differences in sun- and shade-grown plants of the bromeliad Aechmea distichantha with respect to relationships between plant size and variables related to plant architecture, biomass allocation and tank water dynamics. We selected vegetative plants from the understorey and from forest edges of a Chaco forest, encompassing the whole size range of this bromeliad. Plant biomass was positively correlated with most architectural variables and negatively correlated with most biomass allocation variables. Understorey plants were taller and had larger diameters, whereas sun plants had more leaves, larger sheath area, sheath biomass and sheath mass fraction. All tank water-related variables were positively correlated with plant biomass. Understorey plants had a greater projected leaf area, whereas sun plants had higher water content and evaporative area. Plasticity indices were higher for water-related than for allocation variables. In conclusion, there were architectural and biomass allocation differences between sun- and shade-grown plants along a size gradient, which, in turn, affected tank water-related variables.

Evaporation and Deposition Coverage Area of Droplets Containing Insecticides and Spray Additives on Hydrophilic, Hydrophobic, and Crabapple Leaf Surfaces

The efficiency of foliar spray applications is influenced by the evaporation and residual pattern of pesticide droplets on targets. Evaporation time and maximal coverage area of a single droplet from 246 to 886 m in size at relative humidity (RH) ranging from 30% to 90% were measured with sequential images under controlled conditions. Droplets were placed on targets inside an environmentally controlled chamber under a stereoscope and a high-definition digital camera. The spray mixtures used to form droplets included different combinations of water, a nonionic colloidal polymer drift retardant, an alkyl polyoxyethylene surfactant, and two commercially available insecticides. The droplet evaporation was investigated on crabapple leaf surfaces, and hydrophilic and hydrophobic glass slide surfaces. Adding surfactant into spray mixtures greatly increased droplet coverage area on the surfaces, while droplet evaporation time was greatly reduced. For a 343 m droplet on a crabapple leaf at 60% RH, the evaporation time decreased from 70 to 50 s and the maximal coverage area increased from 0.366 to 0.890 mm2 after the surfactant was added into the spray mixture containing water and insecticide. Adding the drift retardant into the spray mixture slightly increased the droplet evaporation time and decreased the droplet coverage area. In addition, changing the target surface from the hydrophilic slide to the hydrophobic slide greatly increased the droplet coverage area and reduced the droplet evaporation time. Increasing RH increased the droplet evaporation time greatly but did not change the coverage area. The droplet evaporation time and coverage area increased exponentially as the droplet size increased. Therefore, droplet size, surface characteristics of the target (waxy or non-waxy), RH, and chemical composition of the spray mixture (water alone, pesticide, additives) should be included as important factors that can affect the efficacy and efficiency of pesticide applications.

Water consumption of an evaporative cooling systemin the midwest (2009)

Water meters were installed on the evaporative cooling system of a long, low-profile, cross-ventilated dairy in the upper Midwest. The evaporative pad along the west side measured 10 by 350 ft. The water usage per unit surface area of the evaporative pad was 0.29 gallons/hour per square foot of evaporative pad surface area. The total daily water usage per stall averaged 13 gallons with a maximum of 22.7 gallons. Results from this study indicate that peak hourly water usage may be as much as 3 times the average values. The evaporative pad efficiency was 65% between noon and 0800 hours and 79% between midnight and 0400 hours.; Dairy Day, 2009, Kansas State University, Manhattan, KS, 2009; Dairy Research, 2009 is known as Dairy Day, 2009

Fine structure and chemical analysis of the metathoracic scent gland secretion in Graphosoma lineatum (Linnaeus, 1758) (Heteroptera, Pentatomidae)

Morphology and ultrastructure of metathoracic scent glands (MTGs) of Graphosoma lineatum (Heteroptera, Pentatomidae) were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Extracts of the volatile fraction of the MTG secretion from males and females were subjected to initial analysis. One pair of the MTG is composed of a reservoir and a pair of lateral glands connected to the reservoir with a duct. MTGs are open in between the meso- and metacoxae, on evaporation areas with a mushroom-like structure. Reservoir walls embody two types of cells, type I and type II, respectively. Cells of type I have numerous organelles, while type II cells have only been found in a certain area of the reservoir wall. They have large secretory ducts lined by a cuticular intima layer. The lateral glands connected to reservoir have two further types of cells. Lateral glands are lined by type A secretory cells and secretory duct is found in their cytoplasm. Type B cells are poor in organelles and are smaller than type A cells. Coupled gas chromatography-mass spectrometry examinations revealed that both in males and females of G. lineatum MTGs 14 chemical compounds occur, among which only 10 are common. These secretions indicate information such as defensive and pheromonal activities, other functions could be attributed to the secretion of the MTG of G. lineatum by comparison with other closely related bug species. In the analyses of MTGs of females of G. lineatum, n-octadecanoic acid was observed at the most and n-undecane was determined at lowest level, while males of G. lineatum n-tridecane was determined at the highest level; and ( E)-2-hexenyl acetate has been observed at the lowest. To cite this article: D. Durak, Y. Kalender, C. R. Biologies 332 (2009).

Mathematical simulation of the evaporation in operation area of a bubble evaporator

Simulation of evaporation in operation area of an evaporator is considered. We obtained a formalized model of this process and optimum conditions of an engineering system on the basis on the analysis.

Mathematical model development for a new solar desalination system (SDS)

Supply of adequate quantities of fresh potable water is one of the most serious problems confronting human especially when we know that one third of the world population are suffering from water shortage and it is expected to reach two thirds in the near future. Therefore, desalination, as a non-conventional water resource, has become one of the most interesting alternative water sources to partially face the fresh water shortage in the near future. The objective of this study is to obtain a general mathematical model for a newly developed solar still that uses parabolic reflector-tube absorber desalination technology. A computer program has been developed to simulate the still operation and to solve the governing heat and mass transfer action, which occurs during the operation. The program will then be used to study the still production in different cases. The study revealed that increasing the solar intensity, ambient temperature, efficiency of reflector material, reflector aperture area, and evaporation area increases the unit productivity. On the other hand, increasing wind velocity, saline water depth, condenser emissivity, and condenser thickness have a small effect on the productivity.

Numerical study of PV/T-SAHP system

In order to utilize solar energy effectively and to achieve a higher electrical efficiency by limiting the operating temperature of the photovoltaic (PV) panel, a novel photovoltaic/thermal solar-assisted heat pump (PV/T-SAHP) system was proposed and constructed. The hybrid solar system generates electricity and thermal energy simultaneously. A distributed parameters model of the PV/T-SAHP system was developed and applied to analyze the system dynamic performance in terms of PV action, photothermal action and Rankine cycle processes. The simulation results indicated that the coefficient of performance (COP) of the proposed PV/T-SAHP can be much better than that of the conventional heat pump. Both PV-efficiency and photothermic efficiency have been improved considerably. The results also showed that the performance of this PV/T-SAHP system was strongly influenced by the evaporator area, tube pitch and tilt angle of the PV/T evaporator, which are the key factors in PV/T-SAHP system optimization and PV/T evaporator design.

Visualization and performance measurement of operating mesh-wicked heat pipes

This work presents visualization of the evaporation/boiling process and thermal measurements of operating horizontal transparent heat pipes. The heat pipes consisted of a two-layered copper mesh wick consisting of 100 and/or 200 mesh screens, a glass tube and water as the working fluid. Experimental results indicated that nucleate boiling was prompted for a wick having a fine 200-mesh bottom layer. When the fluid charge approximately equaled the pore volume in the wick, the water–vapor interface receded into more curved menisci with increasing heat load Q. Thus, larger capillary forces and evaporation areas were attained to meet the increasing need of liquid supply and evaporation rate at the water–vapor interface. At Q = 40 and 45 W, the water film became less than 100 μm and the nucleate boiling observed at lower heat loads disappeared. Optimal thermal characteristics with smallest thermal resistances across the evaporator and lowest overall temperature distributions were found for such a wick/charge combination. Under a smaller charge, partial dry-out was observed in the evaporator. Under a larger charge, liquid recession with increasing heat load was limited and bubbles grew and burst violently at high heat loads. The effects of different wicks and fluid charges on the evaporation/boiling characteristics were discussed.

Gradient pore size distributions in porous silicon oxycarbide materials

Hybrid materials have been obtained using a given concentration of tetraethylorthosilicate (TEOS) and polydimethylsiloxane (PDMS). Different size and shape monolithic samples have been achieved by using containers of both different evaporation areas and heights. The hybrid materials have been pyrolyzed under nitrogen atmosphere to yield porous silicon oxycarbide glasses, consisting of interconnected spherical particles and a continuous open-pore channel. The texture of the glasses shows a gradient particle size distribution (PtSD) from the top (2.88 μm) to the bottom (7.83 μm) of the samples. This gradient in the particle size leads also to a gradient distribution of porosities in the oxycarbide glasses. Thus, pore sizes increases from 6 μm at the top evaporation face to 13 μm at the bottom of the samples, and porosities in the corresponding regions decrease from 77% to 63%, respectively. The gradient distribution has been assigned to a gradient concentration of PDMS in the hybrid preceramic material as determined by the elemental analysis. The carbon concentration (free and covalently bonded carbon) in the hybrid materials increases with the sample thickness or height. However, the lower concentration of PDMS molecules found at the bottom of the hybrid samples leads, after pyrolysis, to higher values of retained carbon and pore sizes in the SiOC glasses. An interesting finding is that the gradient PDMS distribution also provokes a gradient nanodomain size of the segregated free carbon as a form of graphite, typical in SiOC glasses.

Area changes of Lake Qinghai in the latest 20 years based on remote sensing study

采用NOAA/AVHRR资料,对青海湖湖面进行水体判识,并利用线性混合模式对混合象元进行处理,定量估算了近20年青海湖湖水面积并分析了变化趋势,表明近20年青海湖湖水面积在不断减小,每年减少约4km²,并且青海湖干涸部分主要在其北部.进一步采用主成分分析和回归分析方法对青海湖地区降水、气温和蒸发量做了初步气候分析,表明青海湖地区降水减少、气温升高、蒸发量增加是青海湖湖水面积逐年减少的主要原因.;The water areas of Lake Qinghai in the past twenty years have been identified using NOAA/AVHRR satellite data. Theresults show that the area of Lake Qinghai has been decreased in these years, and the area of decreasing is mainly in the north of LakeQinghai. To find out the climate elements which affect the area of Lake Qinghai, precipitation, temperature and evaporation in theregion of Lake Qinghai are analyzed. The results show that increasing in temperature and evaporation, and the decreasing inprecipitation are the main reasons for the decreasing in the area of Lake Qinghai.

Physically Based Coupled Model for Simulating 1D Surface–2D Subsurface Flow and Plant Water Uptake in Irrigation Furrows. I: Model Development

Physically based modeling of the interacting water flow during a furrow irrigation season can contribute to both a sustainable irrigation management and an improvement of the furrow irrigation efficiency. This paper presents a process based seasonal furrow irrigation model which describes the interacting one-dimensional surface — two-dimensional subsurface flow and crop growth during a whole growing period. The irrigation advance model presented in a previous study is extended to all hydraulic phases of an irrigation event. It is based on an analytical solution of the zero-inertia surface flow equations and is iteratively coupled with the two-dimensional subsurface flow model HYDRUS-2. A conceptual crop growth model calculates daily evaporation, transpiration and leaf area index. The crop model and HYDRUS-2 are coupled via its common boundaries, namely (1) by the flux across the soil-atmosphere interface; and (2) by the flux from the root zone, which is associated with the plant water uptake. We assume the water stress is the only environmental factor reducing crop development and hence final crop yield. The model performance is evaluated with field experimental data in the companion paper, Part II: Model Test and Evaluation (Wohling and Mailhol 2007).

Fine Structure and Chemical Analysis of the Metathoracic Scent Gland of Eurygaster maura (Linnaeus, 1758) (Heteroptera: Scutelleridae)

The morphology and ultrastructure of the metathoracic scent glands (MTG) of Eurygaster maura were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Also, extracts of the volatile fraction of the MTG secretion from males and females were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). In SEM investigations, MTG are composed of a reservoir and a pair of lateral glands connected to the reservoir by a duct. MTG are open in between the meso- and the metacoxae. These areas, called evaporation areas, are composed of mushroom-like elements. In TEM investigations, the reservoir walls contained two types of cells. Generally, a reservoir is lined by a single layer of epithelial cells, type I cells, which have numerous organelles. Type II cells are found only in a certain area of the reservoir wall. These cells have large secretory ducts lined by a cuticular intima layer. The lateral glands are lined by secretory cells and a secretory duct found in their cytoplasm. Nuclei of secretory cells are closed to the basal region of the cells and circular-shaped. In GC-MS investigations, the MTG exhibited a typical scutellerid composition. In general, (E)-2-hexanal, (E)-2-hexenyl acetate, n-tridecane, n-hexanoic acid, octadecanoic acid, and n-dodecane compounds were present, while diisooctyl acetate and 14-Beta-H-Pregna were detected only in the male extracts of Eurygaster maura.

MORPHOLOGY AND CHEMICAL ANALYSIS OF THE METATHORACIC SCENT GLANDS OF COREUS MARGINATUS (LINNAEUS, 1758) (HETEROPTERA: COREIDAE) FROM TURKEY

The morphology of the metathoracic scent glands of Coreus marginatus (Linnaeus, 1758) (Heteroptera: Coreidae) was studied by scanning electron microscopy. The metathoracic scent glands are composed of a reservoir and a pair of lateral glands that connect to the reservoir through a duct. The metathoracic scent glands open to the surface through paired ostioles located between the 2nd and 3rd coxae in evaporation areas with a mushroom-like structure. Extracts of the volatile fraction from male and female metathoracic gland secretions were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). Thirteen and sixteen compounds were detected in males and females, respectively. Most of the chemical compounds are qualitatively similar on each male and female but they differ in their quantity. In the analyses of metathoracic scent glands of females of C. marginatus, n-hexenoic acid (22.46%) was determined at the most and 14-Beta-H-Pregna (0.12%) was determined at the least in all samples. In males, octadecanoic acid (57.78%) was determined at the most and n-hexyl acetate (0.06%) was determined at the least in all samples.

Design parameters and preliminary experimental investigation of an indirect vertical solar still

Obtaining water is one of the major occupations of rural peoples in the desert of Algeria. In some zones of desert, the available water is too salty for humans to consume without serious consequences. The only reliable source is groundwater accessible through foggara or the well. The introduction of solar distillation in arid areas of Algeria promises to enhance the quality of life and to improve health standards. An indirect vertical solar still consisting of a flat plate collector, an evaporation chamber and condensation chamber, forms a compact unit. The principle of operation of such a still, the main design parameters and the results of solar still preliminary performance tests are presented in this paper. The present discussion is restricted to the design parameters and preliminary performance testing of the solar still with a nominal flat plate collecting area of 0.942 m 2 and an evaporation area of 0.869 m 2, utilizing solar energy as source of heat. The daily productivity of the solar still during winter period, December 2005 to January 2006, varied from 0.863 to 1.323 l/m 2.d, when the solar radiation intensity was in the range 19.15–26.08 MJ/m 2, under daily ambient temperature that varied from 10.68 to 15.19°C, maximum hourly efficiency ranged from 47.69 to 57.85%.