Evaporation Rate Research Articles

High-efficiency electrospun PVDF@MXene composite membrane with covalent bonding and well-dispersed internal materials for solar-driven seawater desalination

Environmentally friendly and efficient solar-driven interfacial evaporation (SDIE) has been increasingly applied to seawater desalination, and the easy-to-operate electrospinning technology has attracted more and more attention. However, photothermal materials such as MXene are often combined with polymers suitable for spinning through ordinary blending. The inherent difficult dispersion of it may lead to the instability of spinning and decrease the performance of evaporators, further hindering their production and application. To address these challenges, this work designs a covalent bonding PVDF@MXene composite as the spinning raw material. Using the electrospinning technology, the high-efficiency membrane-based evaporator with well-dispersed internal materials and strong homogeneity is successfully fabricated. The membrane performance is optimal when the MXene content is 25 %, achieving an evaporation rate of 1.88 kg·m−2·h−1 and an efficiency of 94.06 % under one sun. Besides, it exhibits remarkable salt resistance, maintaining an evaporation rate of 1.81 kg·m−2·h−1 even at the salinity of up to 20 wt%. More importantly, the membrane can be immersed in oxidative reagents for 24 h without degradation or reduced performance, demonstrating its good environmental stability. Overall, this research not only provides a rational idea for addressing the dispersion issue of MXene, but also presents a potential solution to deal with the global freshwater shortage emergency.

Effect of temperature on water evaporation coefficient (E) in a thermobalance: A solar-driven steam generation approach

During this investigation, the variation of the water evaporation phenomenon with the defined drying temperature and mass of water was analyzed, five levels were studied (50, 60, 70, 80 and 90 ℃), finally a correlation between temperature and evaporation rate was generated. With the study carried out, it was defined that the water evaporation velocity can be calculated with an initial mass of 35 g at 90 ℃, while the necessary time for the determination was 120 min. In addition, it was determined that the evaporation velocity follows a quadratic behavior with temperature, according to the experiments carried out with the Sartorius MA-100 balance, while the maximum deviation recorded was 0.349 mmol/m2s for a temperature of 80 ℃. It is concluded that the determination of the water evaporation velocity is highly dependent on the temperature and mass of water. Furthermore, this study can be used as a basis for future studies aimed at improving the efficiency of processes such as steam and electricity cogeneration.

Interfacial solar‐driven steam and electricity co‐generation using Hydrangea‐like graphene by salt‐assisted carbonization of waste polylactic acid

AbstractThe interfacial solar steam generation and water evaporation–driven power generation are regarded as promising strategies to address energy crisis. However, it remains challenging to construct low‐cost evaporators for freshwater and electricity co‐generation. Herein, we report a salt‐assisted carbonization strategy of waste polylactic acid to prepare Hydrangea flower–like graphene and build a bi‐functional graphene‐based evaporator. The evaporator presents merits of good sunlight absorption, photo‐to‐thermal conversion property, water transport, good thermal management capability, and negatively charged pores for the continuous diffusion of ions. Hence, it achieves the evaporation rate of 3.0 kg m−2 h−1 and output voltage of 0.425 V, surpassing many advanced evaporators/generators. Molecular dynamics simulation result proves that more Na+ ions are attracted by functional groups, especially –COOH/C–OH, to promote Na+ selectivity in nanochannels. This work offers new opportunities to construct multifunctional evaporators for freshwater and electricity co‐generation.

Climate Warming and Mismanagement Drive the Shift of Fish Communities in the Wadi El-Rayan Arid Lakes

The Wadi El-Rayan lakes are important aquatic environments located at the border of the great North African Sahara. Quantifying the temporal changes in these lakes due to natural and/or anthropogenic stressors is critical when assessing potential impacts on aquatic ecosystem health and the sustainability of fisheries. To detect the changes in fish communities and their drivers, the landing composition of the Wadi El-Rayan lakes over the past 30 years was quantitatively analyzed. The areas of the lakes dramatically decreased from 110 km2 in 1991 to 73 km2 in 2019. The loss of the lake area was attributed to climate warming, where the evaporation rate exceeded the volume of recharge and the recharge decreased due to an increase in agriculture and aquaculture. The total landing significantly increased in the past three decades due to an increase in the fishing effort (number of licensed boats). Nile tilapia, mullet, and grass carp dominated the landings. The pelagic-to-demersal ratio indicated a shift in the fish community composition towards demersal species. This shift was attributed to an increase in the eutrophication level. The fish communities of the landing data were clustered into four distinct groups. These clusters were significantly differentiated (p < 0.001) in both a PERMANOVA test and a PCA plot. There was a gradual replacement of the dominant species among these clusters. The most recent cluster (2018–2019) was characterized by rare species dominating the community. This shift in species composition suggests that target taxa may have been overexploited. The total landing also decreased, which may have been a result of climate warming. Furthermore, the presence of alien and warm-water species significantly increased. The fish community structure and composition shift could be attributed to anthropogenic (mismanagement) and natural climatic changes (warming).

Critical assessment of water enthalpy characterization through dark environment evaporation.

Comparative evaporation rate testing in a dark environment, commonly used to characterize a reduced vaporization enthalpy in interfacial solar evaporators, requires the assumption of equal energy input between cases. However, this assumption is not generally valid, leading to misleading characterization results. Interfacial evaporators yield larger evaporation rates in dark conditions due to enlarged liquid-vapor surface areas, resulting in increased evaporative cooling and larger environmental temperature differentials. Theoretical and experimental evidence is provided, which shows that these temperature differences invalidate the equal energy input assumption. The results indicate that differences in evaporation rates correspond to energy input variations, without requiring enthalpy to be reduced below theoretical values. These findings offer alternative explanations for previous claims of reduced vaporization enthalpy and contradict enthalpy-related conclusions drawn from differential scanning calorimetry. We conclude that postulating a reduced vaporization enthalpy using the dark environment method is inaccurate and that re-evaluation of vaporization enthalpy reduction is required.

An Experimental Study of Zinc Evaporation from Bottom Zinc Dross at Atmospheric Pressure and in Inert Atmosphere with Integrated CFD Modelling.

In the present study, the recycling process of bottom zinc dross was performed by evaporation and subsequent condensation at 800 °C for 30 min with an observed argon flow rate of 100-400 mL/min to ensure an inert atmosphere, to observe the evaporation rate and final form of the product. Under the set conditions of over 98% zinc purity, products in the form of nanofibres (thickness 500 nm), powder (size of spherical particles 2-5 μm), dendrites, and metallic forms were obtained. The employed mathematical modelling (via Ansys 2023R1 software) predicted the behaviour of the argon flow current in the quartz tube, as well as the temperature gradient in the quartz tube and in the close vicinity of the zinc sample. Via Inventor 2014 software, the rate of zinc sample heating was calculated. All the simulations were compared with the physical measurements and correlation was proven.

Urban trees left high and dry – Modelling urban trees´ water supply and evapotranspiration under drought

Abstract Long-lasting extreme weather conditions are expected to occur more frequently in the future owing to climate change, as demonstrated by the recent heat waves. In particular, the decrease in precipitation during the summer months had a significant impact on urban tree water availability. Therefore, it is imperative to develop methodologies for determining the available water supply and evaporation rates for urban trees. We mapped data from 49 urban small-leaved linden trees with varying characteristics including groundwater levels, shading situations, tree pit sizes, pavement materials, and sealing ratios. By combining these data with an adapted Penman-Monteith method to calculate evapotranspiration, we simulated the soil water storage and evapotranspiration rates of these trees during the very dry year of 2018 as an example. Model validations were performed using lysimeter and sap-flow studies on Tilia cordata trees in 2022.
During the growing season, most trees experienced water stress on > 85% of the days because of weak precipitation events that failed to refill soil water storage. In contrast, trees with additional water supply through capillary rise reached water stress approximately 45 d later. The model results suggest that many trees will require additional water supply during predicted droughts in the future, which could have significant implications for urban forestry management. This model approach can be used to test and refine future water supply management strategies, making it a useful planning tool for improving the water efficiency of trees in urban areas and blue-green infrastructure.

Nanofiber aerogel with layered array with structure coupled photothermal/magnetothermal effect for continuous seawater desalination

The solar evaporation is susceptible to intermittent solar irradiation as well as salt crystallization deposition on the surface severely limits the evaporation efficiency. In this work, subject to inspiration of the transpiration, groove array structure and antifouling performance of banana leaves, a multifunctional photothermal/ magnetothermal coupled three-dimensional(3D) aerogel evaporator with layer-by-layer array structure was prepared by blow-spun technology which can achieve mass produced. The unique super hydrophilic vertical array structure has multi-scale high-efficiency water transport channels and the SnSe-Fe3O4 evaporation layer realizes super hydrophobic self-cleaning and excellent photothermal and magnetothermal conversion performance, which can achieve all-weather seawater desalination. The vertical array structures facilitate the reflection and refraction of light and promote the seawater convection and salt crystals absorption coupling. It could improve the photothermal conversion efficiency and salt resistance of the evaporator. Which resulted in an evaporation rate of 2.53 kg m−2h−1 under 1 sun, with solar energy conversion efficiency of 105 % and the evaporation rate is about 4.54 kg m−2h−1 at a magnetic field. Furthermore, it could purify organic pollutants in industrial wastewater and use waste heat to generate electricity. This evaporator provides a new economical and environmentally friendly solution for seawater desalination and sewage treatment.

Apple leaf-inspired bilayered Janus wood evaporator with decoupled light-vapor interfaces for high-efficiency solar steam generation

Solar-driven interfacial evaporation technology provides a facile and promising strategy for producing clean water from seawater. Wood-based evaporators have recently been extensively explored for solar desalination due to the structural merits and sustainability of natural wood. However, the light absorption and water evaporation functions are commonly integrated at the same surface for a traditional wood-based solar evaporator, which definitely causes mutual interference between the incident sunlight and the generated vapor leading to inevitable energy loss. Herein, inspired by the unidirectional transpiration of hypostomatic apple leaves, a bilayered Janus wood evaporator with decoupled light absorption and water evaporation surfaces was subtly engineered to avoid the sunlight-vapor interference for efficient solar evaporation. The bilayered evaporator consists of a longitudinal wood piece as the water transport layer and a carbonized transverse wood piece infiltrated with polydimethylsiloxane (PDMS) as the photothermal layer. The hydrophilic longitudinal piece with vertically aligned channels can continuously wick water to the evaporation surface, while the hydrophobic transverse piece with horizontal channels enables efficient heat transfer given its high thermal conductivity. Thanks to the unique bilayered configuration, the developed evaporator demonstrates an excellent evaporation rate of 2.12 kg m−2 h−1 with an evaporation efficiency of 92.3 % (1 sun), surpassing most of the traditional wood-based evaporators. Moreover, the bilayered evaporator exhibits good salt resistance and can effectively purify diverse wastewaters including organic dye solutions and oil–water emulsions. This Janus-interface structural design provides a novel strategy for developing high-performance solar evaporator toward clean water production.

Innovative 3D Janus foam design achieves high-efficiency and stable solar desalination with improved salt resistance and heat management

SDIE technology is an effective means to address freshwater scarcity, but faces challenges such as thermal management, salt scale resistance, and high energy efficiency. Herein, a 3D Janus Foam with a hydrophobic surface layer and a hydrophilic inner layer was synthesized for efficient seawater desalination. Such strategic layering provides effective thermal management, resulting in a heat loss of only ∼1.13 % throughout the photothermal conversion process. The Janus Foam’s ability to prevent salt accumulation while maintaining high evaporation efficiency over extended periods is a critical improvement over current technology. Under 1 kW m−2, the evaporation rate of the Janus Foam is as high as 1.7898 kg m−2 h−1 with an efficiency of 96.87 %. Even under actual seawater conditions, the evaporation rate of the foam remains at 1.7426 kg m−2 h−1 with an efficiency of 91.83 %, demonstrating its high energy efficiency and adaptability to different operating environments. In conclusion, the innovative design of the 3D Janus foam offers a promising avenue for addressing global freshwater scarcity through enhanced solar interfacial evaporation processes.

Boosted Near-Infrared Photothermal Conversion in Rare Earth Ions-Doped 2D SnSe Nanosheets for Solar-Powered Water Evaporation Systems.

Solar-powered water evaporation as a clean and abundant renewable energy-efficient desalination technology provides a promising strategy to solve the shortage of freshwater resources. However, the development and application of solar vapor technology are hindered by the relatively low near-infrared photothermal conversion efficiency of existing materials and the lack of effective improvement strategies. In this work, the conductivity characteristics of 2Dsemiconductors are capitalized on the high visible light absorption and ultra-low thermal. Specifically, rare-earth ion dopants into SnSe nanosheets, significantly boosting their near-infrared photothermal conversion efficiency and solar water evaporation performance are introduced. Remarkably, the photothermal conversion efficiency of the doped SnSe nanosheets surged from 51.56% to 82.11%, surpassing many previously reported photothermal materials. Furthermore, leveraging these nanosheets with enhanced photothermal conversion efficiency, a solar interfacial evaporation system is constructed. The evaporation rate of 2.17kgm-2h-1 and the efficiency of 96.5% can be achieved at one solar irradiance, and it also has good salt-resistance properties. The findings demonstrate the potential of rare earth ion-doped 2D semiconductor nanosheets in solar water evaporation, paving the way for future sustainable desalination solutions.

Hydrodynamic solar-driven interfacial evaporation - Gone with the flow

Evaporation has been one of the most classic desalination processes on the Earth. When we try to use the power of water flow itself, the evaporation process can perform even better. Here, we report a hydrodynamic solar-driven interfacial evaporation process which water evaporation rate can achieve 6.58 kg·m-2·h-1 (over 100 times higher than natural evaporation). A waterwheel-structure solar interfacial evaporator was designed and assembled by printed filter papers. The evaporator can both rapidly distribute solution on the evaporation interface and be hydraulically driven to rotate continuously to improve the evaporation rate by water flow. The hydrodynamic solar-driven interfacial evaporation process successfully overcomes the problem of slow diffusion of water vapor, but also realizes the day-and-night operation of process and the self-cleaning of salt fouling. Apart from the application in solar desalination, the developed evaporator has great potentials in vapor production and salt recovery for industrial use.

Near-Electrode Concentration Gradients of Bicarbonate and pH within Porous Gas Diffusion Electrode for Optimized Selective CO2 Electroreduction to C2+ Products.

With high current density, the intense near-electrode CO2 reduction reaction (CO2RR) will cause the concentration gradients of bicarbonate (HCO3-) and hydroxyl (OH-) ions, which affect the selectivity of high-value C2+ products of the CO2RR. In this work, we simulated the near-electrode concentration gradients of electrolyte species with different porous Cu-based CLs (catalyst layers) of GDE (gas diffusion electrode) by COMSOL Multiphysics. The higher porosity CL exhibits a better buffer ability of local alkalinity while ensuring a sufficient supply of H+ and local CO2 concentration. Subsequently, the different porosity CLs were prepared by vacuum-thermal evaporation with different evaporation rate. Structural characterizations and liquid permeability tests confirm the role of the porous CL structure in optimizing concentration gradients. As a result, the high-porosity CL (Cu-HP) exhibits a higher C2+ Faraday efficiency (FE) of ∼79.61% at 500 mA cm-2 under 1 M KHCO3, far more than the FEC2+ ≈ 38.20% with the low-porosity sample (Cu-LP).

A simplified but improved numerical approach to determine moisture balance for plastic shrinkage cracking in concrete

This paper introduces an improved numerical approach for evaluating moisture balance on concrete surface which can initiate plastic shrinkage cracking on the surface of fresh concrete in concrete slab. Because plastic shrinkage cracks occur when the tensile stress induced from the surface drying of concrete exceeds the tensile strength in the freshly placed concrete, moisture balance calculated by the introduced approach can be used as the primary indicator for plastic shrinkage cracking. The numerical approach introduced in this paper therefore emphasized an exact evaluation of bleeding and evaporation on the concrete surface. In determining bleeding, the approach introduced in the previous study was improved through the consideration of additional influencing factors of the accelerator and steel fiber and the supplementation of additional experimental data. For reliable prediction of evaporation, an empirical relation was newly introduced. The reduction of evaporation rate with time was taken into consideration, and the use of the weighed characteristic velocity rather than the direct application of the wind velocity was recommended. Determination of an exact distribution for the weighed characteristic wind velocity on the surface of a concrete slab was based on computational fluid dynamic (CFD) analyses. In particular, the effect of installing a windscreen along the sides of the concrete slab was intensively examined. Upon verification of the introduced numerical approach through correlation studies between experimental data and numerical results, additional parametric studies were also performed to numerically examine the relative contribution of each influencing factor in plastic shrinkage cracking. Moreover, the introduced approach can effectively be used for the on-site prediction of surface drying time of a concrete slab and for the preparation of a proper curing strategy to mitigate plastic shrinkage cracking.

Enhancement of Microwave Heating Technology for Emulsified Asphalt Mixtures Using SiC-Fe3O4 Composite Material.

The application of microwave heating technology can significantly enhance the water evaporation rate of emulsified asphalt mixtures post paving. To improve the microwave absorption and curing performance of these mixtures, SiC-Fe3O4 composite material (SF) was incorporated. This addition aims to enhance the microwave absorption efficiency and accelerate the curing process of emulsified asphalt mixtures under microwave heating. This study begins with an analysis of the microwave absorption principles pertinent to emulsified asphalt mixtures. Subsequently, the microwave heating temperature fields of ordinary emulsified asphalt mixture (EAM), SiC emulsified asphalt mixture (S-EAM), Fe3O4 emulsified asphalt mixture (F-EAM), and SiC-Fe3O4 emulsified asphalt mixture (SF-EAM) were simulated using COMSOL Multiphysics finite element software (COMSOL 6.2). The early strength variations in SF-EAM under different microwave heating durations were then examined through adhesion tests, leading to the proposal of a microwave heat curing process for SF-EAM. Finally, the wear resistance, water damage resistance, rutting resistance, and skid resistance of SF-EAM post-microwave curing were evaluated through wet wheel wear tests, wheel track deformation tests, and road friction coefficient tests. The results indicate that the optimal microwave heating time is 90 s, with the microwave absorption performance of the materials ranked as follows: EAM, S-EAM, F-EAM, and SF-EAM, from lowest to highest. The road performance of SF-EAM complies with specification requirements, and its wear resistance, water damage resistance, and rutting resistance are notably improved after microwave heating.

Model-based fault detection algorithm for liquid hydrogen refueling system using CUSUM method

The global focus on the role of hydrogen energy in achieving carbon neutrality is increasing, particularly in transportation. Establishing and operating hydrogen refueling stations for fuel cell electric vehicles (FCEVs) are gaining prominence. This study proposes a model-based fault detection algorithm to enhance safety at large-capacity liquid hydrogen (LH2) refueling stations. First, the LH2 refueling system is modeled using Aspen HYSYS, estimating the heat transfer coefficient of the storage tank to meet the normal evaporation rate (NER) specification of 0.9 % per day. Second, diverse fault scenarios are identified via a Hazard and Operability Study (HAZOP), and simulation data are generated for the normal and fault scenarios. Finally, a fault detection algorithm utilizing the cumulative summation (CUSUM) is developed, with its threshold determined by risk levels analyzed in HAZOP. This allowed for tighter fault detection as risk levels increased. The algorithm successfully identified faults for all 11 scenarios.

Continuous Homogeneous Thin Liquid Film on a Single Cross-Shaped Profiled Fiber with High Off-Circularity: Toward Quick-Drying Fabrics.

Quick-drying fabrics, renowned for their rapid sweat evaporation, have witnessed various applications in strenuous exercise. Profiled fiber textiles exhibit enhanced quick-drying performance, which is attributed to the excellent wicking effect within fibrous bundles, facilitating the rapid transport of sweat. However, the evaporation process is not solely influenced by macroscopic liquid transport but also by microscopic liquid spreading on the fibers where periodic liquid knots induced by spontaneous fluidic instability significantly reduce the evaporation area. Here, a cross-shaped profiled fiber with high off-circularity, featured as multiple concavities along the fibrous longitude-axis, which enables the formation of a homogeneous thin liquid film on a single fiber without any periodic liquid knots, is developed. The high off-circularity cross-sections help overcoming Plateau-Rayleigh instability by tuning the Laplace pressure difference, further facilitated by capillary flow along the concave surface. The homogeneous thin liquid film on a single fiber is responsible for maximizing the evaporation area, resulting in excellent overall evaporation capacity. Consequently, fabrics made from such fibers exhibit rapid evaporation behavior, with evaporation rates ≈50% higher than those of cylindrical fabrics. It is envisioned that profiled fibers may provide inspiration for the manipulating homogeneous liquid films for applications in fluid coatings and functional textiles.

Balance of heat management and salt-resistance on solar interfacial evaporator actively adjusted by the electric field with periodically changed direction

Interfacial desalination is one of the most promising technologies in solar energy utilization, but it usually needs to balance the heat management and the salt-resistance. Dealing with this, the electric field with periodically changed direction for various reversing times could be used to regulate the interfacial desalination. Hence, the evaporator performances including the evaporation rate, evaporation efficiency, salinity of vapor and surface salt-deposition morphology are investigated in this paper. The experimental results show that the periodical electric field has regulative mechanisms of phase change heat transfer, ion diffusion, and salt crystallization on interfacial desalination. By changing the polarity of the high potential electrode, the salt crystals are rarely observable on the evaporator surface even in the 20 wt% NaCl solution, and the evaporation performance of evaporator would be distinct with different reversing time. Besides, the performance of evaporator could be maximized by the electric field with the reversing time of 20 s, which could increase the evaporation rate up to 36.5 % and the evaporation efficiency from 61.9 % to 90.7 %. The combination of the periodical electric field and the interfacial desalination technology with extremely low consumption could be deemed as a solution for the efficient solar utilization.

3D‐Shape Recoverable Hydrogel with Highly Efficient Water Transport for Solar Water Desalination

AbstractPorous hydrogels have been developed to be highly efficient interfacial solar vapor generation materials for obtaining affordable freshwater supplies. However, realizing hydrogel materials with portability, adequate water supply, and durable mechanical properties remains challenging. Herein, a scalable and portable hydrogel with 3D‐shaped recovery, highly efficient water transport, and robust mechanical stability is reported, which is prepared by foaming polyvinyl alcohol (PVA) and modification of phosphotungstic acid (PTA). Due to the interconnected porous structure and highly permeable polymer network, the PVA/PTA‐PH hydrogel has good repetitive compressibility and rapid shape recovery when in contact with water. Combined with light‐absorbing nanoparticles, the PVA/PTA‐PH hydrogel presents an impressive solar evaporation rate of 3.876 kg m−2 h−1 and a photothermal conversion efficiency of ≈94% under 1‐sun irradiation. With 3D‐shape recovery and highly efficient water transport, the compressed hydrogel can be quickly unfolded without human intervention and restored to five times the original size for the working state. The good portability, excellent seawater desalination performance, and simple preparation process are anticipated to make the PVA‐/PTA‐PH hydrogel a promising material to continuously and conveniently produce pure water from seawater.

A large-scale-outdoor continuous release of cryogenic liquid onto ground

The accidental release of cryogenic liquids can cause several hazards to humans, assets, and the environment. Therefore, this phenomenon has drawn significant attention and has been investigated as part of quantitative risk assessment associated with the use of cryogenic liquids. However, the effects of release conditions on pool spread have not been thoroughly studied, and the mechanism of pool retraction has not been discussed. In this study, an attempt was made to address these gaps by both experimental and numerical analyses. Firstly, large-scale-outdoor release tests with a systematic measurement system were performed using liquid nitrogen to compare with large-scale release tests of liquid hydrogen. The release height and orientation were varied. It was observed that the pool shape was affected by the release orientation. However, the maximum pool size and average vaporization rate were insensitive to both the release height and orientation. The conductive heat from the ground was confirmed to be the major heat source for pool vaporization, accounting for over 90 % of the total heat transferred into the liquid pool. Subsequently, release scenarios were simulated using integral source models. Especially, several hypotheses were thoroughly discussed, implemented in the source models, and validated against experimental results to determine the most appropriate mechanism for pool retraction. The findings of this study are expected to be beneficial for the consequence estimation of cryogenic release scenarios and for the validation and improvement of source models.