Water Evaporation Rate Research Articles

Janus Antipyretic Pastes for Efficient, Durable and Comfortable Personal Physical Cooling.

Prompt and prolonged cooling is extremely important when the body is in a fever state. Here, we proposed a concept of Janus antipyretic paste (JAP) with unique asymmetric wetting for effective and durable personal physical cooling. The prepared JAP possesses greater one-way transport capacity, and faster average water evaporation rate (∼2 times) than the original fabric. Compared to the wet cotton fabric (a reduction of ∼2.9 °C) and medical antipyretic paste (MAP) (no cooling after 5 h), the JAP achieved the best cooling effect and long cooling duration (cooling by 3.8 °C, at least 5-7 h) in practical application tests. In addition, the wearability of JAP is well validated, including its excellent breathability and good flexibility, which can maximum improve the comfort of our body. We believe the new JAP with superior cooling and comfort properties will provide promising design guidelines for the next generation of family or hospital physical cooling products.

FeOOH Quantum Dots Assembled MXene-Decorated 3D Photothermal Evaporator for Synergy Application in Solar Evaporation and Fenton Degradation.

Solar-driven water evaporation is considered as the sustainable approach to alleviate freshwater resource crisis through direct use of solar energy. However, it is still challenging to achieve the multifunctional solar evaporators equipped with both high evaporation and purification performance to handle practical complex wastewater. Here, a simple and cost-effective multifunctional 3D solar evaporator is prepared by alternately decorating the commercial sponge with FeOOH quantum dots (FQDs) supported MXene sheets composites and chitosan hydrogel coatings for enabling the solar water evaporation and organic wastewater photodegradation simultaneously. MXene composites allow the solar evaporator with excellent photothermal conversion performance, the hydrophilic chitosan hydrogel coated interconnecting skeleton structures of sponge serve as the mass transfer and water transport channels. The Fenton-catalytic FQDs anchored on the MXene sheets surface accept the photo-generated electrons of MXene sheets to induce the organic pollutant photo-Fenton degradation reaction under sunlight irradiation. The resulting evaporator possesses both excellent water evaporation rate of 2.54kg m-2h-1 and high degradation efficiency (99.24% for methylene blue), coupled with durable salt-resisting performance during long-term seawater desalination (20 wt.% NaCl). This work provides a simple and feasible strategy for designing multifunctional solar evaporators to meet the potential application scenarios in practice.

A new method to improve the thermal performance of high-level water collecting cooling tower based on the migration of vortices

This study proposes a novel annular inlet hat structure designed to address internal vortex flow within high-level water collecting cooling towers (HCTs). To investigate the effect mechanism of inlet hat, a three-dimensional numerical model for an HCT equipped with inlet hat was developed, allowing for a comprehensive analysis of the flow and temperature fields, as well as several performance parameters. The results manifest that the inlet hat strengthens the tower thermal performance by migrating the longitudinal vortices from the interior to the exterior and reducing the number of longitudinal vortices induced by crosswinds. The strengthening effect of inlet hat shows minimal variation when its width exceeds 8 m. Under the studied water flow rates, an 8-m inlet hat results in increases in air mass flow rate, water temperature drop, Merkel number, and evaporation rate by a maximum of 4.3 %, 4.2 %, 6.4 %, and 1.5 %, respectively. In terms of crosswinds, the inlet hat operates with optimal efficiency at a direction of 0° and a velocity of 13 m/s, achieving maximum increases in air mass flow rate, water temperature drop, and Merkel number of 23.3 %, 25.4 %, and 33.6 %, respectively. These findings demonstrate the feasibility and practical value of the proposed inlet hat.

Turning Corn Stalk Trashes into a Photothermal Agent for Interfacial Solar Water Evaporation for Sustainable Water Purification

Biomass‐based photothermal materials have a higher photothermal conversion efficiency and contribute significantly to improved solar water evaporation systems. This work aims to transform corn stalk (CS) trash into efficient photothermal materials with centralized and less‐contact area water supply systems to achieve enhanced interfacial heat accumulation. We successfully synthesized cornstalk biochar synthesized via pyrolysis to maintain the environmental concern and is deposited onto a scalable, and cost‐effective (<1$) polyurethane foam (triangle shape, where the tip plays the wick and centralized water supply). The detailed characterizations validate the porous structure of CS biochar‐coated PU foam (CSB@PU), and enhance interfacial heat accumulation up to 47.8 °C under 1 kW m−2 solar irradiation which is endowed via thermal management of polystyrene foam (PS). This reproducible interfacial heat accumulation and sustainable evaporator bestow a water evaporation rate of up to 1.38 kg m−2 h−1, and solar‐to‐vapor conversion efficiency (84%) under one sun which is more efficient than other biomass‐derived evaporators. Inductively coupled plasma‐optical emission spectroscopy analysis validates the reductions of primary (Na+, K+, Mg2+, and Ca2+) and heavy metal ion (Fe3+, Hg2+, Cd2+, and Pb2+) concentrations in condensate, insights the potential of CSB@PU to advance the water treatment technologies.

Surface patterned polyvinyl alcohol/CNT hydrogels for sustained solar powered high concentration brine desalination and salt harvesting

Solar-driven interfacial evaporation is an attractive way to achieve water purification. However, high water evaporation rates often result in the precipitation of salt crystals on the surface of the evaporator leading to decay of the evaporation efficiency over time, which makes it difficult to balance high water evaporation rates with salt resistance. Herein, an anisotropic polyvinyl alcohol/CNT hydrogel is constructed by directional freezing and surface patterning. The polymer backbone formed by the polyvinyl alcohol chains interacts with the water clusters to reduce the evaporation enthalpy of water and the absorbed water can be released by squeezing the hydrogels due to the micron-sized vertically aligned pores. More importantly, by designing the structure of the hydrogels surface, the gas–liquid interface of the evaporators can be increased while the growth direction of the salt crystals can be controlled. As a result, the water evaporation rate can be increased from 3.26 kg m-2h−1 to 3.69 kg m-2h−1 under one sun irradiation through surface patterning. After 50 h of continuous operation in 10 wt% NaCl solution under one sun irradiation, the water evaporation rate gradually increases and a large amount of salt collection is collected, which proves its satisfactory salt resistance.

Enhanced solar-to-steam conversion efficiency using CuO-polyaniline yolk-shell structures

Herein, the low-cost copper oxide was encapsulated in the polyaniline (PANI) structure forming a yolk-shell (YS) platform which can provide a large surface area and sufficient active sites and enhance light scattering in its hollow space or voids, both of which can significantly improve the near-full usage of solar energy. The fabrication of the YS structure was assisted with a soft template (hexadecyltrimethylammonium bromide, CTAB) which the removed by the acidic etching process producing uniform voids through the composite structure. Moreover, the etching process using an acidic medium resulted in the formation of the PANI emeraldine salt which is beneficial for the salt-resistant properties of the composite. The encapsulated CuO@void@Es-PANI showed an outstanding rate of water evaporation of 1.91 kg m−2 h−1 and a corresponding high Solar-to-Steam conversion efficiency of 98.9 % under the irradiation of 1 sun compared to that of the normal mixed CuO/PANI (1.53 kg m−2 h−1 and 81.3 %). Meanwhile, the same high evaporation flux was approximately obtained after a continuous 72 h even in high saline water or contaminated seawater.

Z-scheme BiOBr/WS2 heterojunction with integrated photocatalytic degradation and photothermal water evaporation for effective dye wastewater purification

The restoration of water resources and the optimization of solar energy use are critical challenges. In this study, hydrophilic BiOBr/WS2 Z-scheme heterojunctions were prepared using a series of reactions for solar interface water evaporation and photocatalytic degradation of RhB. WS2 nanoparticles were deposited on the surface of titanium mesh using a hydrothermal method, and BiOBr nanosheets were further modified on WS2 using a successive ionic layer adsorption reaction (SILAR) method and solvothermal method. The relatively broad absorption range of WS2 in the full spectrum resulted in enhanced light absorption and improved light utilization of BiOBr/WS2. The formation of Z-scheme heterojunction between BiOBr and WS2 improved the hydrophilicity of the material, enhanced the photocatalytic degradation of organic pollutants in BiOBr/WS2 composite materials, and improved the solar interface water evaporation performance. The degradation rate of RhB by BiOBr/WS2 could reach 95.6% under one solar irradiation, and the photothermal water evaporation rate could reach 1.81 kgꞏm-2ꞏh-1. This study solved the problem of dye enrichment on solar absorber and provided a new way to construct an efficient solar interfacial water evaporation-photocatalytic system to treat dye wastewater.

Bioinspired Photothermal Metal-Organic Framework Cocrystal with Ultra-Fast Water Transporting Channels for Solar-Driven Interfacial Water Evaporation.

Herein, a bioinspired metal-organic framework (MOF) cocrystal produced from the co-assembly of a MOF [Ni3(hexaiminobenzene)2, Ni3(HIB)2] and p-chloranils (CHLs) is reported. Because of the 2D conjugation nature and the formation of persistent anion radicals, this cocrystal shows an excellent photothermal property, and is further used as an absorber in solar-driven interfacial water evaporation. The solar-driven interfacial water evaporation rate (4.04 kg m-2 h-1) is among the best compared with those of previously reported photothermal materials. Molecular dynamics simulation results suggested that the rotating of the CHL molecules relative to the MOF planes tuned the pore size to enable the ultra-fast water transporting, and thus ultra-high water transporting rates (1.11 × 1011 and 3.21 × 1011 H2O s-1 channel-1 at 298.2 and 323.0 K, respectively) for layered cocrystal structures, that are much higher than that of aquaporins (≈1.1 × 1010 H2O s-1 channel-1 at 298.2 K), are observed. The superior solar-driven water evaporation performance is thus attributed to the synergistic effect of the ultra-fast water transporting pores together with the excellent photothermal property of the cocrystal. This research provided a biomimetic strategy of rational design and production of charge transfer cocrystals to modulate their pores and photothermal properties for solar-driven interfacial water evaporation.

Towards Sustainable Energy Solutions: Evaluating the Impact of Floating PV Systems in Reducing Water Evaporation and Enhancing Energy Production in Northern Cyprus

Floating photovoltaic systems (FPVSs) are gaining popularity, especially in countries with high population density and abundant solar energy resources. FPVSs provide a variety of advantages, particularly in situations where land is limited. Therefore, the main objective of the study is to evaluate the solar energy potential and investigate the techno-economic perspective of FPVSs at 15 water reservoirs in Northern Cyprus for the first time. Due to the solar radiation variations, solar power generation is uncertain; therefore, precise characterization is required to manage the grid effectively. In this paper, four distribution functions (Johnson SB, pert, Phased Bi-Weibull, and Kumaraswamy) are newly introduced to analyze the characteristics of solar irradiation, expressed by global horizontal irradiation (GHI), at the selected sites. These distribution functions are compared with common distribution functions to assess their suitability. The results demonstrated that the proposed distribution functions, with the exception of Phased Bi-Weibull, outperform the common distribution regarding fitting GHI distribution. Moreover, this work aims to evaluate the effects of floating photovoltaic systems on water evaporation rates at 15 reservoirs. To this aim, five methods were used to estimate the rate of water evaporation based on weather data. Different scenarios of covering the reservoir’s surface with an FPVS were studied and discussed. The findings showed that annual savings at 100% coverage can reach 6.21 × 105 m3 compared to 0 m3 without PV panels. Finally, technical and economic assessment of FPVSs with various scales, floating assemblies, and PV technologies was conducted to determine the optimal system. The results revealed that a floating structure (North orientation-tilt 6°) and bifacial panels produced the maximum performance for the proposed FPVSs at the selected sites. Consequently, it is observed that the percentage of reduction in electricity production from fossil fuel can be varied from 10.19% to 47.21% at 75% FPV occupancy.

Efficiency of Optimized Fabrication Process for Light-absorbing Membranes from Sewage Sludge Applied in Solar-driven Steam Generation Systems

Solar-driven evaporation systems have been studied to provide clean water, especially for islandic areas. Carbon materials made from sludge in domestic wastewater treatment plants have been studied to produce light-absorbing membranes in solar-to-steam (STS) systems. However, the technical limitation of this method is that the water evaporation rate is still low. In this study, the process of manufacturing light-absorbing membranes was optimized to simplify the process while increasing the water evaporation rate and testing the application of converting seawater into fresh water. The optimal evaporation rate was 2.65 kg.m-2.h-1, higher than the system using vacuum drying membranes (1.88 kg.m-2.h-1) under 0.6 kW/m2 illumination conditions. When illuminated, the surface temperature of the TN_0.1 light-absorbing membrane reached 36.5°C, meaning 2.5°C higher than that of the reference membrane (without carbon material). The results of analyzing some anion and cation indicators in the harvested water showed that the fabricated STS systems could be applied well to convert seawater into fresh water for domestic use. Especially, the treatment efficiencies for , , , reach 99.87%, 94.35%, 99.5%, 99.98%, and 99.44%, respectively.

Perylene diimide-derived supramolecules-modified graphene sponge as a high-efficiency solar steam generator

Generating steam using solar energy appears to be an effective approach to obtaining clean water, especially from salty water and wastewater, since the sun is a natural and constant source. Compared to many methods, studies in solar steam generation have accelerated due to being highly efficient, sustainable, and low-cost. Graphene sponges (GrSs), possessing structural flexibility and effective photothermal activity, are widely used for this purpose. However, the hydrophobic character of these materials limits their effectiveness in solar steam generators. At this point, we prepared perylene diimide-derived supramolecules (PDI) modified three-dimensional (3D) gradient hydrophobic GrS (PDI/GGrS) as the highly efficient solar thermal converter for the generation of clean water. PDI allowed us to achieve perfect absorption of broad-band sunlight and GGrS facilitated water transport through channels of sponge structure. As a result, PDI/GGrS has achieved a high water evaporation rate of 3.5 kg h−1 m−2 with a superior solar thermal conversion efficiency of up to 90 %. This study can provide new possibilities for harvesting solar energy by producing clean water from seawater, wastewater, and even acidic/alkali solutions.

Remote sensing insights into water allocation and evaporation challenges in the Hirmand River Basin, after the operation of Kamal Khan Dam

Study RegionThe Hirmand River Basin is a vital transboundary river system, that originates in Afghanistan’s Hindu Kush Mountains and flows into the Sistan Depression, and encompassing the Chah Nimeh Reservoirs in Iran and the Godzareh Depression in Afghanistan. Study FocusThe Kamal Khan Dam, constructed on the Hirmand River in Afghanistan, has significantly altered the downstream water direction and distribution between the Chah Nimeh Reservoirs and Godzareh Depression. Utilizing remote sensing techniques, particularly Landsat 8 satellite imagery and the FAO 56 PM as a evaporation retrieval method, the research focuses on evaluating changes in water allocation and evaporation rates in these regions over the past decade. New Hydrological Insights for the RegionThe findings reveal that after operation of the Kamal Khan Dam, water allocation to the Chah Nimeh Reservoirs has drastically decreased, leading to a 54 % reduction in their average area from 2020–2023 compared to the previous years. Conversely, the Godzareh Depression, now receiving the redirected water, has experienced significantly higher evaporation rates, contributing to substantial water losses. These changes underscore the critical need for effective water management strategies to address the escalating water scarcity and hydrological imbalances in this arid region.

Fabrication of Micro/Nanostructured Copper Fibers by Vibration Cutting for Felt-Based Freshwater Purification

Freshwater purification from wasted water and seawater is crucial in addressing the global problem of water scarcity. Porous fiber felt with a micro/nanostructure emerges as an efficient approach for water purification; however, its production usually relies on chemical postprocessing to create micro/nano structures on the fiber surface, which might pollute the environment. This study proposed an ecofriendly method to produce micro/nanostructured copper fiber felt without chemical treatment. First, a new transverse-feeding vibration cutting is proposed to fabricate micro/nanostructured fibers with controllable structure characteristics. Through the sintering of the structured fibers without postprocessing, the fiber felt can be produced in an ecofriendly way and exhibit special wettability and excellent photothermal properties. Felt-based freshwater purification, including oil–water separation and solar-driven seawater desalination, can be realized effectively. Results show an oil–water separation efficiency of > 90% and a high evaporation rate of water of > 1.08 kg m−2 h−1 at 73 mW cm−2 are achieved, demonstrating the application prospect of the produced fiber felt.

Green conversion of waste polyester into few-layer graphene for interfacial solar-driven evaporation and hydroelectric electricity generation

The coupling of solar-driven interfacial evaporation with hydrovoltaic technology is emerged as a hopeful approach to alleviate energy crisis and freshwater shortage. However, constructing low-cost evaporators with high-performance freshwater and electricity co-generation and unveiling the co-generation mechanism remain a grand challenge. Herein, we report the green transformation of waste poly(ε-caprolactone) into graphene through a salt-assisted carbonization strategy and build a flexible bi-functional graphene-based evaporator for freshwater and electricity co-generation. The graphene exhibits a typical wrinkled structure with curved edges and is composed of 7–8 discontinuous layers with rich oxygen-containing groups. The graphene-based evaporator exhibits excellent sunlight absorption (98%), photo-to-thermal conversion property, good water transport ability, low water evaporation enthalpy, and low thermal conductivity of 0.06 W m−1 K−1. The evaporator not only exhibits a notable water evaporation rate (2.92 kg m−2 h−1), but also achieves the maximum output voltage of 310 mV, surpassing many previously reported evaporators/generators. The result of molecular dynamics simulation proves the diffusion difference between H+ and OH− in water and graphene, which eventually leads to the voltage generation. Not only will this work help to improve the upcycling of waste plastics and achieve carbon neutrality, but it will also open an avenue for co-generation of freshwater and electricity.

A perspective view of salt crystallization from solution in porous media: morphology, mechanism, and salt efflorescence.

Salt efflorescence is one of the major hazards to cultural heritages, masonries, and highways etc. It is now generally accepted that damages caused by salt efflorescence are mainly due to continuous cycles of salt crystallization/dissolution or hydration/dehydration in confined spaces. The position where salt efflorescence occurs and its type are closely related to the degree of damages caused by salt efflorescence. It is known that water is the key environmental factor determining the salt crystallization position. But influence of the correlation between water supply and evaporation on the position of salt crystallization is still not clearly understood. In this work, a set of experiments are designed to investigate salt efflorescence in porous matrix. It is found that the types and positions of salt efflorescence have little to do with nucleation, but are mainly governed by crystal growth, which is controlled by the rates of water evaporation, water and salt supply, capillary forces and surface properties of the porous matrices.

Enhanced solar interfacial evaporation through lignin-polyaniline composite coatings on Balsa wood substrates

Solar interfacial evaporation employing wood-derived substrates is increasingly acknowledged as a viable desalination and wastewater treatment technique. This study presents an optimized method that enhances the efficiency of solar interfacial evaporation by applying a coating of lignin-polyaniline composites (EHL-PANI) onto balsa wood substrates. Initial assessments involved comparing evaporators made from various kinds of wood, identifying balsa wood-based photothermal evaporators as the most effective, with an evaporation rate of 1.63 kg·m−2·h−1 and an efficiency of 72.7 %. Photothermal properties were further improved through the chemical oxidation of enzymatic hydrolysis lignin (EHL) with polyaniline, producing a composite with notably high dispersion stability and uniform particle distribution. This modification resulted in reduced particle size and enhanced stability of the polyaniline, which is crucial for boosting photothermal activity. Additionally, the EHL-PANI composites demonstrated exceptional light absorption, exceeding 95 %, and significant photothermal conversion efficiency across a broad wavelength range, attributable to polyaniline's broadband light absorption characteristics. A prototype evaporator, featuring the EHL-PANI coated on a balsa wood substrate, was constructed to assess performance, achieving a water evaporation rate of 2.10 kg·m−2·h−1 and an efficiency of 80.7 % under solar illumination of 1 kW·m−2.

Bifunctional Photothermal Evaporator Based on an MXene/Fe-MOF Collaborative Effect toward Efficient Solar Steam Generation and Simultaneous VOC Removal.

Solar-driven interfacial water evaporation has become one of the most promising approaches to effectively harvesting freshwater, yet the fabrication of high-performance and multifunctional solar interfacial evaporators (SIEs) still remains a huge challenge to date. In this study, a multifunctional MXene and Fe-MOF@cellulose acetate/polyvinylpyrrolidone (MXM@CP) SIE was prepared via a facile "electrospinning and suction filtration deposition" coupling strategy. Thanks to the incorporation of MXene, MXM@CP displayed excellent photothermal conversion performance. Together with the fast water transport channel provided by the porous cellulose acetate electrospinning substrate, a remarkable solar-driven water evaporation property was achieved for MXM@CP, showing a higher water evaporation rate of 1.1 kg m-2 h-1 under one sun irradiation. Moreover, the resultant composite film also exhibited excellent Fenton catalytic activity to effectively degrade volatile organic compounds (VOCs) due to the synergistic effect of the MXene and Fe-based MOF (Fe-MOF). Particularly, a relatively higher degradation rate of 82.8% was acquired for the resulting evaporator toward the benzene contaminant. These results provide new insights into the construction of high-performance and multifunctional SIEs toward clean freshwater collection from the VOC-contaminated water system.

Portable self-powered electrochemical aptasensor for ultrasensitive and real-time detection of microcystin-RR based on hydrovoltaic-photothermal coupling effect

Coupling different energy harvesting technologies to obtain an excellent output signal is essential for the development of high-performance self-powered electrochemical sensors. Herein, a novel hydrovoltaic-photothermal coupling self-powered electrochemical aptasensing platform was designed for sensitive detection of microcystin (MC-RR) with a digital multimeter as a direct visual readout strategy. The straightforward ultrasonic method was employed to synthesize polyaniline (PANI) and bismuth oxybromide (BiOBr) nanosheets, which were then integrated as active components in a hydrovoltaic device. The unique layer structure of two-dimensional (2D) nanomaterials BiOBr can create flexible interlayer spaces to accommodate various ions and water molecules, which was beneficial to construct evaporation-driven channels. Meanwhile, the exceptional photothermal characteristics of polyaniline could accelerate the water evaporation rate, consequently boosting the migration speed of charge carriers and increasing output signal. Moreover, a digital multimeter was connected to the constructed sensor for real-time displaying the output signal. With the assistance of aptamer, a novel self-powered electrochemical aptasensing platform was constructed for sensitive detection of MC-RR. Under optimum conditions, the output signal of the hydrovoltaic-photothermal coupling cell was linearly related to the logarithm of MC-RR concentration in the range of 1 fM to 1 nM with a detection limit of 0.31 fM (S/N = 3). Furthermore, this sensor also exhibited many advantages such as high selectivity, good repeatability and portability. Such novel strategy not only offers a completely new general approach to construct high-performance self-powered devices for the detection of MC-RR, but also provides a new strategy for advancing the miniaturization and field application of self-powered electrochemical sensors.

Combustion synthesis of TiO2/C composites for enhanced photocatalytic H2O2 production and solar steam evaporation efficiency

In this work, a simple combustion method was proposed for the controllable synthesis of TiO2/C composites, which can achieve both the efficient solar water evaporation at the interface and photocatalytic H2O2 production. Structural and morphological characteristic indicated the co-existence of carbon quantum dots and amorphous carbon, which were well distributed on the surface of the TiO2. TiO2/C composites displayed the enhanced visible light absorption and the rapid separation of photogenerated electron-hole pairs. TiO2/C-10 exhibited an excellent photocatalytic H2O2 production activity of 3068.46 μmol/g/h under simulated solar irradiation. Besides, its water evaporation rate reach up to 5.81 kg·m−2·h−1 under the simulated solar irradiation.

Controlled airflow fluctuations for improved performance of mist cooling systems: Enhanced evaporation and thermal comfort

Rising global temperatures and resulting heat stress on people necessitate sustainable outdoor cooling solutions. Mist cooling offers promise, and this work proposes a novel approach: incorporating fluctuating airflows into misting systems. We hypothesize that mist-cooled fluctuating airflows could provide more efficient outdoor cooling for people, for two reasons: 1) Increased turbulence and mixing promoting higher water evaporation rates; 2) dynamic airflow leveraging transient thermal perception for improved comfort.Wind tunnel experiments and numerical simulations support this hypothesis, revealing that fluctuating flow, compared to constant flow with the same average velocity, enhances evaporation. Lower frequencies, higher amplitudes, and profiles with steeper gradients led to higher evaporation rates. These findings assume an idealized domain, excluding natural wind patterns. Furthermore, predictions confirmed that fluctuating flows consistently provide superior thermal comfort compared to constant flows. Fluctuating airflow with misting achieved equivalent comfort at 38% lower energy consumption compared to fluctuating flow without misting and 81% lower compared to constant flow with misting. The proposed technology has the potential to improve outdoor comfort and decrease resource consumption. It is scalable, not complex, and can be implemented into existing systems, though it may face challenges such as increased wear on fan components.