Water Evaporation Research Articles

Simulation-Guided Design of Solar Steam Generator Arrays for Efficient All-Cold Evaporation under Natural Sunlight.

Solar-powered interfacial evaporation has emerged as a promising, sustainable technology for clean water production with its minimal carbon footprint. Currently, extensive research efforts focus on enhancing solar evaporation rates and broadening the applicability of three-dimensional (3D) interfacial steam generators (SGs). For large-scale water production, individual 3D SGs must be integrated into system-level SG arrays for deployment in portable devices or solar distillation plants. Therefore, the SG array's configuration plays an even more critical role in boosting solar evaporation. From a methodological perspective, the development of numerical simulation and evaluation methods to predict the solar evaporation of SG arrays is an emerging research frontier. Nonetheless, the complex energy-water-solute interactions within SG arrays remain largely underexplored. Herein, 3D SGs and their integrated SG arrays are developed. The temperature, relative humidity, airflow, and air particle distributions throughout individual SGs and SG arrays are simulated, guiding the optimization of SG structures and the arrangement of SG arrays. By promoting cold evaporation, 8-Fin SG achieves the highest water evaporation rate of over 2.3 kg m-2 h-1 under 1 sun, with a further increase to 4.8 kg m-2 h-1 under a moderate airflow, positioning it among the best-performing solar-powered SGs. The circular array configuration of nine 8-Fin SGs (12 cm spacing) enables sustained "all-cold evaporation" in each unit, where continuous energy harvesting from both ambient air and bulk water drives an exceptional evaporation rate of 5.9 kg m-2 h-1 of the SG array under natural sunlight. We present an integrated approach combining numerical simulation with experimental studies of SG and their arrays, inspiring a new paradigm for advancing SG arrays toward system-level applications.

Water-Stable Al3Ni4 Polynuclear Heterometallic Compound for Near-Infrared Photothermal Conversion.

In this paper, a polynuclear heterometallic compound (H3O)[Al3Ni4(OH)6(MBA-NO2)6(H2O)6] (Al3Ni4, H2MBA-NO2 = 2-hydroxy-3-methoxy-5-nitrobenzoic acid) with a seven-star disk metal core has been synthesized by the solvothermal method. Al3Ni4 has good stability in water and several organic solvents, and its solid powder shows a good photothermal effect under 980 nm laser irradiation, and the temperature can reach 138.8 °C within 100 s under 1.0 W cm-2 power irradiation. Considering its good photothermal effect, water evaporation of Al3Ni4 was measured. It can be further used as a photothermal material in seawater evaporation.

Saline Soil Management and Improvement Protection Strategies Based on Sustainable Agricultural Development Goals

The shortage of water resources, the serious harm of soil salinization and the large loss of nitrogen caused by excessive application of nitrogen fertilizer are the main factors restricting the sustainable development of agriculture in irrigation areas. Based on this factor, saline irrigation area needs to find a soil improvement method that can keep water and restrain salt, increase fertilizer and increase production under the condition of reducing the amount of nitrogen fertilizer application, which is of great practical significance for promoting the development of saline soil improvement technology and high and stable grain yield. In this paper, the physical and chemical properties, temporal and spatial dynamic distribution of water, fertilizer and salt content, sunflower yield and water and nitrogen use efficiency of saline soil in Hetao irrigation area were studied by means of field experiment and numerical analysis, and the improvement mechanism and water, fertilizer and salt regulation effects of different soil amendments on saline soil in irrigation area were revealed. The results showed that the biochar treatment group significantly reduced soil pH and conductivity, effectively inhibited salt accumulation in the soil, and increased soil organic matter content and nutrient content such as total nitrogen, available phosphorus and available potassium. The porous structure of biochar enhances the soil’s water retention capacity and reduces soil water evaporation. The combination of carbon and nitrogen application treatment not only reduced nitrogen loss but also prevented salt from moving to the soil surface, further optimizing the soil environment. In terms of crop growth and yield, the group treated with carbon nitrogen combined application showed the best growth performance of sunflowers, with rapid plant height growth, lush leaves, and the highest leaf area index. The overall growth momentum was stronger than other treatment groups.

Fabrication of photothermal carbon nanodot materials coated with luffa evaporation structure for solar energy water evaporation

Solar water evaporation is considered one of the most sustainable and environmentally friendly technologies. To achieve good evaporation performance, a combination of materials with good photothermal conversion efficiency and good evaporation structure is required. In this study, we used carbon nanodots as a photothermal material made that synthesis by hydrothermal of urea and citric acid. At the same time, luffa possessing advantages such as good water transport and easy attachment of carbon nanodots was chosen as the evaporation structure. The results showed that carbon nanodots material had an average size of less than 5 nm and a good absorption range in the wavelength of 200-800 nm. The absorption range of the material has expanded to the near-infrared region (NIR region), increasing the ability to absorb sunlight and convert it into heat energy, subsequently, improving the evaporation efficiency. The carbon nanodots/ luffa composite structure showed a high evaporation rate of 1.25 kg.m-2h -1 under 1 sun irradiation (1 kW.m-2).

Decoupling of Bonding Strength and Water Retention in Aqueous Wood Adhesive Inspired by Plant Cell.

Aqueous wood adhesives with both water retention and strong bonding strength are essential for wood industrial applications. However, the enhanced water retention of adhesive often suffers from low water resistance and bonding strength due to its increased hydrophilicity. Inspired by the water retention and mechanical support in plant cell, we develop a multifunctional biomass soybean meal (SM) adhesive by combining the rigid internal boron-nitrogen coordinated boronic esters structure for reinforcement with the flexible zwitterionic polymer for water retention. Such a design provides good dry (2.03 MPa) and wet shear (1.14 MPa) strengths and demonstrates durable adhesion in various harsh environments for up to 80 days. The adhesive exhibits the anticipated water retention property, extending the plywood shaping manufacturing time to 60 min due to the ability of the water-retaining polymer to convert free water into a bound state and suppress water evaporation. Additionally, the adhesive demonstrates a 10-fold increase in mildew resistance compared with the SM adhesive and exhibits good flame retardancy. This study presents a versatile and efficient approach for developing durable, water-retaining, and sustainable aqueous adhesives for various bonding techniques and shaping materials.

Integrating stable radical hydrogen-bonded organic frameworks with silver nanoparticles for highly efficient solar-driven water evaporation

Integrating stable radical hydrogen-bonded organic frameworks with silver nanoparticles for highly efficient solar-driven water evaporation

Bandgap Engineering on UiO-66 Metal-Organic Framework Derivatives for Solar-Driven Seawater Desalination.

The growing scarcity of freshwater, driven by climate change and pollution, necessitates the development of efficient and sustainable desalination technologies. Solar-powered interfacial water evaporation has emerged as a promising solution; however, its practical implementation is hindered bythe limited availability of efficient and stable photothermal materials. Herein, a bandgap engineering strategy via linker modification to enhance the photothermal conversion capability of metal-organic frameworks (MOFs) is reported toward efficient solar-driven desalination. By systematically introducing functional groups with varying electron-donating and electron-withdrawing abilities, the energy bandgap of UiO-66-X (X = ─F, ─H, ─OH, ─NH2, ─(NH2)2) is finely tuned. Density functional theory (DFT) calculationsand femtosecond transient absorption (fs-TA) spectroscopy reveal that stronger electron-donating functional groups narrow the bandgap of the MOFs, thereby improving their photothermal conversion efficiency. The optimized UiO-66-(NH2)2 material reaches a peak surface temperature of 58.7°C when exposed to simulated sunlight at ≈1 kW·m-2 with a photothermal conversion efficiency of 86.50% and an evaporation rate of 2.34 kg·m-2·h-1 with an evaporation efficiency of 97.40%. This study presents a novel approach for fine-tuning the bandgap in photothermal materials, offering a pathway toward advanced solar desalination technologies to address the global water scarcity crisis.

Temperature-triggered inflatable hydrogel muscles with snap-through instability for untethered robots

Pneumatic artificial muscles have been widely used in the field of robotics because of their large output force and fast actuation, however, the accompanying bulky compressors and pumps limit their miniaturized applications. Despite current untethered pneumatic artificial muscles can be driven by adjusting the internal pressure, it is challenging to structurally mimic natural muscles with high water content. Here, we propose untethered pneumatic artificial muscles comprising a hydrogel actuator with snap-through instability and an air storage chamber. These hydrogel actuators can realize the conversion from hydrophobic association of octyl acrylate moieties to host-guest interaction between β-cyclodextrin and octyl acrylate under thermal stimuli, leading to the decrease of their moduli. The inflated hydrogel actuators exhibit rapid actuation with a radial expansion speed of 200% s−1, which are powered by snap-through instability, thermal expansion of the gas inside the hydrogel actuator, and evaporation of water on its internal surface. With the pneumatic artificial muscles miniaturized, we demonstrate diving and rolling robots, exemplifying bionic robots able to adapt to and modify the environment. We expect that the design of hydrogel actuator in miniaturized pneumatic artificial muscles will facilitate rapid locomotion for future bionic robotic platforms.

Determining historic (1950 - 2000) average precipitation and temperature for Pakistan by using climate downscaling technique

There is an immense hydropower potential in Pakistan. To utilize those resources effectively, it’s compulsory to know about climate history that helps in hydropower project feasibility. For that, there is an assessment required of a specific site from a hydrology perspective i.e. water level or evaporation rate, where spatial data regarding different parameters such as precipitation and temperature is compulsory. Based on this, a climate downscaling technique is used in this paper that requires the input time series data sets of temperature and precipitation, based on 30 arc seconds and 0.5˚ resolution. A downscaled dataset has been generated by using time series input data sets of the Global Precipitation Climatology Centre (GPCC) and Climate Research Unit (CRU) that are of 0.5˚ resolution. Along with such low-resolution datasets, a 30˚ high-resolution time series data sets of WorldClim are also used for temperature and precipitation. A downscaled historical (1950 - 2000) gridded data of precipitation and temperature for Pakistan is generated through the statistical climate downscaling technique to interpolate the coarse resolution data into fine spatial resolution data with the help of Piecewise Cubic Hermite Interpolation Polynomial (PCHIP) interpolation scheme. These downscaled historical precipitation and temperature data in ASCII format are programmed in MATLAB, defining the boundary region of Pakistan to calculate their average annual, seasonal, and monthly temperature and precipitation values. The average annual, seasonal, and monthly precipitation and temperature historical data are plotted for Pakistan using a spreadsheet generated in MATLAB. Such plotted data can be used in the prediction of water stream flow rate and evaporation rate by using hydrology models in the future that help in assessing the hydropower of the Pakistan before commencement of the hydro projects.

Advances in Stored-Product Pest Management: Combined Effects of Diatomaceous Earths with Botanicals, Insecticides, Entomopathogenic/Plant Pathogenic Fungi, and Silica Gel

Diatomaceous earth (DE) consists of fossilized remnants of diatoms, which are marine or freshwater unicellular algae. Most DEs originate from fossilized sedimentary layers of diatoms deposited in water bodies during the Eocene and Miocene periods, much more than 20 million years ago. Processed DE, a soft, chalky powder, is widely used as an insecticide due to the highly absorptive and abrasive nature of its particles. As an insecticide, DE removes the wax coating of the insect epicuticle, the primary barrier against water loss. This results in water evaporation, leading to desiccation and death of the targeted insects. This review emphasizes the co-treatment of DEs with biological agents that have insecticidal properties (e.g., essential oils, plant powders, silica gel, and species/isolates of fungi), reducing the quantities used in single-application treatments and suggesting paths for the sustainable management of insects damaging stored products.

Electricity Generation From Ambient Water Evaporation in the Absence of Sunlight via PVA‐Based Porous Hydrogels

AbstractIn the current era where electronics and technologies are getting smaller in size, off‐grid and battery‐free features are getting increasingly sought after. This motivates innovation in ambient energy harvesting from light, heat, and mechanical sources. Among these technologies, hydrovoltaics has emerged as a promising source of electricity by harvesting energy from ubiquitous water evaporation. However, the power densities of hydrovoltaics are so far limited to the order of hundreds of mW cm⁻2. In this work, a porous polyvinyl alcohol (PVA) hydrogel in combination with a thermoelectric generator (TEG) is devised to directly capture energy from water evaporation. It is found that under moderate environmental conditions with relative humidity (RH) of 40%, temperature of 26 °C, and mild wind speed of 2.8 m s−1, a temperature gradient (ΔTTEG) of ≈2 °C is established across the TEG. This gives rise to 1.71 mW of power output, which is equivalent to 1.02 W m−2 power density. This is more than 3 fold higher than traditional hydrovoltaics. This work opens a pathway for further investigation into scavenging electricity from water evaporation.

Friction Behavior and Microscopic Mechanism of Hydrogels in an Open‐Air Environment

AbstractHydrogels composed of a solvent‐saturated, cross‐linked polymer network exhibit unique interfacial rheology and ultralow friction, making them valuable in biomedical applications. Despite their widespread use in open‐air environments, the lubrication behaviors of hydrogels under these conditions remain poorly understood. Here, the microscopic mechanisms underlying the friction characteristics of hydrogels through a combination of experiments, theoretical analyses, and molecular dynamics simulations is explored. It is found that water evaporation from the hydrogel surface reduces the hydrodynamic layer thickness and increases surface viscosity, leading to a gradual rise in friction. On the other hand, optimizing pore size and water mobility within the hydrogel enhances water transport from the interior to the surface, mitigating evaporation and enabling consistently low friction. It is also explored how soaking time, water affinity, and applied normal load influence hydrogel lubrication. The findings elucidate the microscopic mechanisms governing the friction behaviors of hydrogels and provide guidelines for designing hydrogel systems with sustained exceptional lubrication properties in open‐air applications.

Mechanical property variation mechanisms of granite subjected to real‐time high temperatures and subsequent cooling treatment

AbstractDuring geothermal resource exploitation, the potential deterioration of mechanical properties in high‐temperature granite subjected to cooling poses a significant safety concern. To address this, the present study investigates the coupled thermo‐mechanical behavior of granite during heating and cooling through a combination of laboratory tests and finite difference method analysis. Initial investigations involve X‐ray diffraction, thermal expansion test, thermogravimetric analysis, and uniaxial compression test. Results show the significant variations of granite properties under different thermal conditions, attributed to temperature gradients, water evaporation, and mineral phase transitions. Subsequently, a model considering temperature‐dependent parameters and real‐time cooling rates was employed to simulate linear heating and nonlinear cooling processes. Simulation results indicate that the thermal cracking predominantly occurs during the heating stage, with tensile failure as the primary mode. Additionally, a faster real‐time cooling rate at higher temperatures intensifies the thermal cracking behavior in granite. This study effectively elucidates the thermo‐mechanical coupling behavior of granite during heating and cooling processes, providing insights into the mechanisms of mechanical property changes with rising or decreasing temperatures.

Water Balance and Evaporation for Two Intermittent Estuarine Lakes

The management of small intermittently open or closed estuaries (ICOLLs) requires the prediction of lake water levels and the probability of breaching of the entrance barrier in real time, seasonally, and long term. The water balance is a key tool that in turn requires prediction of the open water evaporation. The drivers of the water balance of two ICOLLs on the south-east coast of Australia were studied: The two ICOLLs, Durras Lake and Lake Wollumboola, have very different morphologies: Durras Lake is a drowned stream valley with a largely steep, forested catchment, while Lake Wollumboola is a back-dune lagoon ICOLL with a wider, shallow water body. For these small estuaries, hydrologic and geomorphic data are generally limited or unavailable; hence, methods were developed to use data routinely available, primarily from government agencies, without using regionally averaged or “text book” parameter values. For both lakes, evaporation was shown to be on average larger than either of the inflows from the catchment or from the direct rainfall on the lakes; thus, evaporation must be reliably predicted for use in the water balance. The calculated evaporation agreed with widely used but data-intensive formulas. For each ICOLL a robust linear correlation of lake evaporation with the incident solar radiation accounted for 94% of the variance in the evaporation. The seasonal variation of evaporation fitted a cosine curve, again accounting for 94% of the variance of the evaporation. Validation of the water balances using the evaporation-solar correlation and a derived runoff coefficient provided a close match with the historical record. On most days, the water loss from the lakes by evaporation was larger than the sum of the inflows from catchment runoff and direct rainfall on the lakes. Storms of duration 1–3 days rapidly increased the water storages and the lake levels, potentially leading to breaching of the entrance barrier. This fluctuating balance drives the intermittent behaviour of these ICOLLs and emphasises the importance of accurately assessing the lake evaporation.

Three‐Phase Emulsion Derived Solar‐Thermal Reduced Graphene Oxide/Octadecane Phase‐Change Foam for Salt‐Resistant Day‐Night Water Evaporation

AbstractA solar‐thermal reduced graphene oxide/octadecane (RGO/oct) phase‐change foam is fabricated by the interfacial assembly of an air‐in‐oil‐in‐water three‐phase emulsion and subsequent chemical reduction of graphene oxide (GO) for day‐night evaporation and desalination. The GO sheets assemble at the water‐oct interfaces in the presence of an amphiphilic alkyl glycoside while air pores are generated inside the hydrophobic oct component under stirring, leading to GO/oct/air microspheres. During subsequent molding, the GO is chemically reduced with ascorbic acid, and the resultant RGO/oct/air microspheres with closed pores constitute the solar‐thermal RGO/oct phase‐change foam. The air pores suppress heat conduction to bulk water, while the phase‐change oct prevents heat loss to the environment, hence enhancing the heat localization capability of the RGO/oct foam. The foam exhibits a high evaporation rate of 4.29 kg m−2 h−1 under 1‐sun irradiation. Interestingly, oct can release latent heat in the absence of solar light irradiation, enabling water evaporation at nighttime with an evaporation rate of 2.30 kg m−2 h−1. The overlap molding of the microspheres allows the rearrangement of salt concentration gradients, exhibiting satisfactory salt resistance of the foam during the stable evaporation of brine with 25 wt.% of NaCl for 10 h.

The Utility of Satellite Snow Depth Observations for Downscaling Hydrologic Variables Over the Indus Basin Mountain Ranges

Abstract Accurate, high resolution, and continuous estimates of snow characteristics and related hydrologic variables are critical to understanding freshwater availability in regions where snowmelt dominates the hydrologic cycle. However, such estimates are difficult to obtain, especially in mountainous regions. Recent advances in data assimilation and radar satellite technologies can be leveraged to produce snow depth estimates in these data sparse regions. In paired synthetic and real-data experiments, we use a particle batch smoother to assimilate Sentinel-1 satellite snow depth observations into a coarse resolution land surface model. We produce continuous, downscaled estimates of snow depth, snow covered fraction, snow water equivalent, precipitation, runoff, and evaporation over the Indus Basin in High Mountain Asia (HMA). In the synthetic experiment, data assimilation reduces the initial open loop root mean square error (RMSE) for snow depth and snow water equivalent (SWE) estimates by ~50% and decreases the bias in other model variables. We show that assimilating only a single peak snow depth satellite observation improves snow depth and SWE estimates by reducing bias and RMSE by 40% or more. In the real-data experiment, assimilating all available Sentinel-1 snow depth observations reduces bias in snow disappearance date by over 30 days and improves the temporal evolution, spatial representation, and magnitude of SWE. Ultimately, we demonstrate that downscaling model variables through a data assimilation update step reduces model errors and improves the spatial representation of peak snow.

The Influence of Intermittent Localized Corrosion on the Mechanical Properties of Steel Rebars

Steel rebars are conventionally used in combination with concrete in buildings and civil engineering structures. A main degradation issue of these composite systems is the localized corrosion of the steel rebars. This fact promotes a scaling of the concrete surface and an aggressive localized attack of the rebars, until a cross-section reduction and detrimental static consequences. In this concern, steel rebars were immersed in a 3.5 % weight NaCl solution. A set of rebars were subjected to continuous immersion in the solution, whereas another set to a cyclic exposure consisting of immersion and drying at 25oC, 50oC and 100oC. The cyclic exposure and the temperature influenced the corrosion speed. A different extent of localized deterioration was detected. Some surface corrosion features barely affected the tensile properties of the rebar. Only at a later corrosion stage, the morphological features of the degradation contributed to a lowering of the mechanical properties, especially the tensile strength. The load-extension response of reinforcement during the tension tests did not directly correlate with the rust grade and the visual degradation aspect. An increase in the temperature and the water evaporation enhanced the presence of pits until 50oC. Corrosion pits were also seen, if the exposition to the solution was done in an intermittent rapid and cyclic mode, along the corroded bars. The corrosion features tend to affect the stress-strain response in tension of the rebars.

Surface Oxygen Vacancy Engineering for Enhanced Volatile Organic Compounds Removal in Solar-Interfacial Water Evaporation.

Solar-interfacial water-vapor conversion has emerged as a promising method for clean water production, particularly in water-scarce regions, but a major challenge is the volatile organic compounds (VOCs) along with water vapor, leading to polluted condensed water. This study introduces a novel design strategy that leverages surface oxygen vacancies (OVs) in photocatalysts to maximize both oxygen (O2) utilization from the air and photocarrier efficiency at the air-water interface, building upon previous research that demonstrated that oxygen concentration at the interface can be significantly higher than that in bulk water. By enhancing oxygen adsorption and facilitating charge carrier separation, OVs significantly improve reactive oxygen species (ROS, including ·O2- and ·OH) generation and overall photocatalytic activity. As a demonstration, the surface OVs-engineered BiOCl-based photocatalytic solar interfacial evaporator demonstrated a 3.41-fold increase in VOC (phenol) removal efficiency compared to a conventional system, achieving over 99.6% VOC removal in condensed water and maintaining a high water vapor generation flux of 1.90 kg/m2/h. This innovative design was further validated using ZnO-based photocatalysts, demonstrating the broad applicability of OV-engineering in interfacial systems. By fully utilizing both the high oxygen content at the air-water interface and improving photocarrier dynamics, this approach represents a significant advancement in photocatalytic water treatment technologies, offering a scalable and highly efficient solution for VOC removal and clean water production.

Numerical Investigation on Heat Transfer Performance and Bubble Characteristics of Rectangular Channels under Different Low-Pressures

Numerical Investigation on Heat Transfer Performance and Bubble Characteristics of Rectangular Channels under Different Low-Pressures

Numerical and experimental study of water-gas transport laws in the cathode channel of proton-exchange membrane fuel cell

Numerical and experimental study of water-gas transport laws in the cathode channel of proton-exchange membrane fuel cell