In this work, we demonstrate a 3-dimensional graphene oxide (3D GO) stalk that operates near the capillary wicking limit to achieve an evaporation flux of 34.7 kg m–2 h–1 under 1 sun conditions (1 ...kW/m2). This flux represents nearly a 100 times enhancement over a conventional solar evaporation pond. Interfacial solar evaporation traditionally uses 2D evaporators to vaporize water using sunlight, but their low evaporative water flux limits their practical applicability for desalination. Some recent studies using 3D evaporators demonstrate potential for more efficient water transfer, but the flux improvement has been marginal because of a low evaporation area index (EAI), which is defined as the ratio of the total evaporative surface area to the projected ground area. By using a 3D GO stalk with an ultrahigh EAI of 70, we achieved nearly a 20-fold enhancement over a 2D GO evaporator. The 3D GO stalk also exhibited additional advantages including omnidirectional sunlight utilization, a high evaporation flux under dark conditions from more efficient utilization of ambient heating, a dramatic increase of the evaporation rate by introducing wind, and scaling resistance in evaporating brines with a salt content of up to 17.5 wt %. This performance makes the 3D GO stalk well suited for the development of a low-cost, reduced footprint technology for zero liquid discharge in brine management applications.
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IJS, KILJ, NUK, PNG, UL, UM
Interfacial solar steam generation offers a promising and cost‐effective way for saline water desalination. However, salt accumulation and deposition on photothermal materials during saline and brine ...evaporation is detrimental to the stability and sustainability of solar evaporation. Although several antisalt strategies are developed, it is difficult to simultaneously achieve high evaporation rates (>2.0 kg m−2 h−1) and energy efficiencies. In this study, a self‐rotating photothermal evaporator with dual evaporation zones (i.e., high‐temperature and low‐temperature evaporation zones) is developed. This photothermal evaporator is sensitive to weight imbalance (<15 mg) thus is able to quickly respond to salt accumulation by rotation to refresh the evaporation surface, while the dual evaporation zones optimize the energy nexus during solar evaporation, simultaneously realizing excellent salt‐resistant performance and high evaporation rate (2.6 kg m−2 h−1), which can significantly contribute to the real‐world application of solar steam generation technology.
A dual‐zone photothermal evaporator with high sensitivity to weight imbalance is designed to solve the issue of salt accumulation on the evaporation surface during brine evaporation. The unique dual‐temperature‐zones on the evaporator surface minimize energy loss while promoting extra energy gain from surroundings. Therefore, this evaporator can simultaneously deliver a high evaporation rate (>2.0 kg m−2 h−1) and excellent salt‐resistance performance.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Evaporation is a key component of the hydrological cycle and affects regional water resources. Although the physics of evaporation is well understood, its estimation in practice remains a challenge. ...Among available methods for estimating it, the complementary principle of Bouchet has the potential to provide a practical tool for regional water resources assessment. In this study, the generalized nonlinear formulation of this principle by Brutsaert (2015) was tested against evaporation measurements from four flux stations in Australia under different climatic and vegetation conditions. The method was implemented using meteorological data and Class A pan evaporation measurements. After calibration the estimated daily evaporation values were in good agreement with flux station measurements with a mean correlation coefficient of 0.83 and a bias of 4% on average. More accurate estimates of daily evaporation were obtained when the evaporative demand or apparent potential evaporation was determined from the Penman equation instead of from pan evaporation. The obtained parameter values were found to lie well within the ranges of reported values in the literature. Advantages of the method are that only routine meteorological data are required and that it can be used to estimate long‐term evaporation trends.
Key Points
The generalized nonlinear complementary relationship is accurate in predicting daily evaporation from routine meteorological data
The apparent potential evaporation required in the method can be estimated from Class A evaporation pan or from the Penman equation
The optimized model parameter values are fairly conservative and well within the range of reported values in the literature
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Solar‐driven evaporation is a promising way of using abundant solar energy for desalinating polluted water or seawater, which addresses the challenge of global fresh water scarcity. ...Cost‐effectiveness and durability are key factors for practical solar‐driven evaporation technology. The present cutting‐edge techniques mostly rely on costly and complex fabricated nanomaterials, such as metallic nanoparticles, nanotubes, nanoporous hydrogels, graphene, and graphene derivatives. Herein, a black nylon fiber (BNF) flocking board with a vertically aligned array prepared via a convenient electrostatic flocking technique is reported, presenting an extremely high solar absorbance (99.6%), a water self‐supply capability, and a unique salt self‐dissolution capability for seawater desalination. Through a carefully designed 3D structure, a plug‐in‐type BNF flocking board steam generator realizes a high evaporation rate of 2.09 kg m−2 h−1 under 1 kW m−2 solar illumination, well beyond its corresponding upper limit of 1.50 kg m−2 h−1 (assuming 100% solar energy is being used for evaporation latent heat). With the advantages of high‐efficiency fabrication, cost‐effectiveness, high evaporation rate, and high endurance in seawater desalination, this 3D design provides a new strategy to build up an economic, sustainable, and rapid solar‐driven steam generation system.
Black nylon fiber (BNF) flocking board with a vertically aligned array is prepared via a convenient electrostatic flocking technique. Through a carefully designed 3D structure, simultaneously a combination of high solar absorbance and wicking capillary, a plug‐in‐type BNF flocking board solar‐driven evaporation generator realizes a high evaporation rate of 2.09 kg m−2 h−1 under 1 kW m−2 solar illumination.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Over the past decades, changing climate has exerted pronounced influences on the cryo‐hydrological environment on the Tibetan Plateau. One major manifestation is the widespread lake expansions over ...Tibetan endorheic basins. The enlarged lake water surface areas are expected to significantly alter land‐atmosphere water fluxes, which in return may pose feedbacks to the climate system and hydrological processes. The goal of this study is to investigate the potential influences of the recent lake expansions on amplifying the evaporation flux over the basins of inner Tibetan Plateau (ITP). We detected that the ITP lakes have experienced a net inundation increase of 4,542.3 km2 during 2000–2015, about 95.6% of which was contributed by lakes larger than 1 km2. We further estimated the land and water evaporations based on multi‐source, available actual evapotranspiration (ETa) and potential evapotranspiration data sets, and in situ evaporation records. The differences between land ETa and lake water evaporation were employed to represent the evaporation alternation over newly inundated basin (named “land‐to‐lake” hereafter) areas. The land ETa was estimated based on the average of three commonly used gridded data sets while the over‐lake evaporation was calculated by the empirical correction of potential evaporation estimates by spatial interpolation of pan evaporation. A conservative estimate using the pan coefficient of 0.6 indicates that the newly inundated lake area may have led to a potential evaporation increase of 3.08 ± 1.08 Gt/year on the ITP. The increased evaporation flux is close to half of the recent annual growth rate of lake water storage in the ITP. Despite unneglectable uncertainties, our estimates initiate an important assessment of how the recent lake expansion across the ITP has influenced the local land‐atmosphere interactions and the water cycle. Accounting this evaporation amplification is crucial to reduce the uncertainty in estimating basin‐scale water budgets and projecting the regional water balance.
Spatial pattern of evaporated water budget over the newly inundated lake area across the ITP basins.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Open water evaporation, which often consumes a large fraction of annual storage (especially in arid and semi‐arid regions), is a controlling variable for modern water resource management. Developing ...a daily reservoir evaporation data set is necessary for reservoir operations to consider the influence of evaporation in a timely manner. However, over the past few decades, the quantification of reservoir evaporation has primarily relied on monthly Class A pan evaporation observations, which might lead to largely biased estimations because they do not incorporate the effects of heat storage and fetch. In this study, we developed a general Daily Lake Evaporation Model (DLEM) based on Penman's equation combined with daily atmospheric reanalysis data sets, to improve the validity and frequency of reservoir evaporation monitoring. Compared with daily evaporation estimates from eddy covariance systems, the DLEM showed good quality and reliability, with R2 values ranging from 0.50 to 0.73 and RMSE values ranging from 1.13 to 1.97 mm day−1 in four different sites. By applying DLEM to all 188 major reservoirs in Texas, we generated a long‐term data set of (1 January 1981–31 December 2021) daily evaporation rates. The results reveal a clear geographic distribution and strong seasonality of evaporation throughout Texas, where the mean evaporation rate is highest during July, with 6.85 mm day−1. Trend analysis indicates that the annual average evaporation rate has significantly increased since 1981 at a rate of 0.076 mm day−1 decade−1. This study provides sufficient data support for water resource operations and management, and regional water planning.
Key Points
A general Daily Lake Evaporation Model (DLEM) is developed on modified‐Penman evaporation and compared with in situ eddy covariance measurements
A first long‐term (40+ years) regional scale daily reservoir evaporation data set is generated for 188 major reservoirs in Texas (US)
While shortwave radiation affects the long‐term spatial distribution and trends, high wind speed is likely to cause daily extremes
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
ZnOaSnO2 branchastem nanostructures were realized on a basis of a two-step process. In step 1, SnO2-stem nanowires were synthesized. In step 2, ZnO-branch nanowires were successfully grown on the ...SnO2-stem nanowires through a simple evaporation technique. We have pre-deposited thin Au layers on the surface of SnO2 nanowire stems and subsequently evaporated Zn powders on the nanowires. The ZnO branches, which sprouted from the SnO2 stems, had diameters in a range of 30a35ANBnm. As-synthesized branches were of single crystalline hexagonal ZnO structures. Since the branch tips were comprised of Au-containing nanoparticles, the Au-catalyzed vapor-liquid-solid growth mechanism was more likely to control the growth process of the ZnO branches. To test a potential use of ZnOaSnO2 branchastem nanostructures in chemical gas sensors, their sensing performances with respect to NO2 gas were investigated, showing the promising potential in chemical gas sensors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Groundwater resources in some parts of the lower section of Shire River valley, Malawi, are not useable for rural domestic water supply due to high salinity. In this study, a combined assessment of ...isotopic ( super(87)Sr/ super(86)Sr, delta super(18)O and delta super(2)H) and major ion composition was conducted in order to identify the hydro-geochemical evolution of the groundwater and thereby the causes of salinity. Three major end-members (representing fresh- and saline groundwater, and evaporated recharge) were identified based on major ion and isotopic composition. The saline groundwater is inferred to result from dissolution of evaporitic salts (halite) and the fresh groundwater shows influence of silicate weathering. Conservative mixing models show that brackish groundwater samples result from a three component mixture comprising the identified end-members. Hence their salinity is interpreted to result from mixing of fresh groundwater with evaporated recharge and saline groundwater. On the other hand, the groundwater with low TDS, found at some distance from areas of high salinity, is influenced by mixing of evaporated recharge and fresh groundwater only. Close to the Shire marshes, where there is shallow groundwater, composition of stable isotopes of water indicates that evaporation may also be an important factor.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Publications from the literature were gathered concerning the evaporation of liquids and presented the most significant results. The phenomenon of evaporation is influenced by the gas and liquid ...conditions: the gas pressure above the liquid surface, its material properties, temperature, humidity, characteristic velocity and turbulence coefficient of the flow; and the material properties of the liquid, its surface temperature, the convective flow and the size of liquid surface open to the environment. The phenomenon of evaporation can be categorized based on various factors, such as gas convection, the type and direction of driving forces, and the gas and liquid conditions affecting evaporation, the equation governing the evaporation rate or the type of evaporation. Each categorization method has its advantages and disadvantages, and these methods were introduced. The correlations that are suitable for the determination of evaporation rate have been collected from the literature and presented in a table together with their range of validity. We collected 32 correlations for evaporation under natural convection, 7 correlations for evaporation under mixed convection, and 116 correlations for evaporation under forced convection. In addition, different application examples were given for each evaporation category, and publications were presented in which the equations included in the N-S-S, M-S-S and F-S-S evaporation cases were examined.
•Theoretical background of evaporation.•Evaporation categorization methods.•Effect of gas and liquid conditions on evaporation rate.•Equations for determining evaporation rate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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