Evaporation Rate Research Articles

Molecular Dynamics Simulation of the Enhanced Evaporation Characteristics of Pure Water and Ion Solutions by the Electric Field

ABSTRACT In this study, the evaporation of pure water and NaCl solution films under different electric fields was investigated using molecular dynamics, and the intrinsic mechanism of enhanced evaporation by electric fields was analyzed from the perspectives of forces and thermodynamics. The simulations showed that, apart from a slight inhibitory effect of a direct current electric field on the evaporation efficiency of pure water, square wave electric fields promoted the evaporation of both pure water and NaCl solution, as well as direct current electric fields on NaCl solution, with the effect increasing with the strength and frequency of the field. For example, under a 200 GHz square wave electric field, the evaporation rates of the pure water and NaCl solution films were 8.33 and 2.65 times higher than under the direct current electric field, respectively; under horizontal electric fields of 0.1 V/nm and 0.3 V/nm, the evaporation rates of the NaCl solution film were 1.13 and 1.66 times higher than natural evaporation, respectively. The rate of evaporation efficiency is reflected in the change of molecular kinetic energy. The reasons for these phenomena are closely related to microscopic parameters and properties such as intermolecular forces, the number of hydrogen bonds, and the coordination number.The application of different electric fields affects the microscopic properties between molecules, leading to changes in the evaporation rate.

Mediating role of immune cells in association between volatile organic compounds and periodontitis: NHANES 2011-2014.

The relationship between humans and volatile organic compounds (VOCs) is a persistent concern due to their widespread sources and high evaporation rates. However, there is currently limited direct evidence linking VOC exposure to the development of periodontitis. This cross-sectional study analyzed 1525 participants and 21 urinary VOCs in the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014, aiming to investigate the relationship between periodontitis risk, assessed by attachment loss (AL) and probing depth (PD) and individual VOCs using logistic regression, quantile regression, and subgroup analysis. Weighted quantile sum analysis (WQS) and subgroup analysis were utilized to evaluate whether VOC mixtures were associated with periodontitis risk. Multiple linear regression models were used to examine the association between VOC co-exposure and peripheral immune cell counts. A mediation analysis was performed to evaluate whether peripheral immune cells are involved in the effect of VOC co-exposure on periodontitis prevalence. Urinary levels of 2-aminothiazoline-4-carboxylic acid, mandelic acid, and N-acetyl-S-(4-hydroxy-2-butenyl)-L-cysteine were positively associated with the risk of periodontitis after adjusting for all covariates. The WQS models demonstrated a positive correlation between the mixture of VOCs and the risk of periodontitis, wherein 2-aminothiazoline-4-carboxylic acid emerged as the most important contributor. The mediation analysis suggested that monocytes may play a role in the observed association between VOC co-exposure and the prevalence of periodontitis. Exposure to VOCs is associated with a greater prevalence of periodontitis. Monocytes' mediating role plays a crucial function in the association between the risk of periodontitis and co-exposure to VOCs. Volatile organic compounds (VOCs) are chemicals that evaporate quickly and are found all around us-from paints to cleaning products. Understanding how these compounds affect our health is crucial, especially regarding conditions like periodontitis, a common oral chronic inflammatory disease. In our study, we looked at urine samples from 1525 people who participated in a national health survey between 2011 and 2014 to find out if there is an association between VOC exposure and the risk of developing periodontitis. We found that certain chemicals in the urine, which show VOC exposure, were indeed associated with a greater risk of the disease. We further investigated the collective impact of these VOCs on the risk of periodontitis, revealing that certain chemicals exert a more significant influence than their counterparts. Additionally, our research hints at a potential role for monocytes in the interplay between VOCs and the risk of periodontitis. Our data suggest that exposure to VOCs could be associated with a greater likelihood of periodontitis, with monocytes potentially playing a role in this relationship. This study helps us better understand the potential health impacts of daily chemical exposure and underscores the importance of investigating further how our environment affects our health.

Comparing Preferred Temperatures and Evaporative Water Loss Rates in Two Syntopic Populations of Lacertid Lizard Species

Many reptiles actively regulate their body temperature. During thermoregulation, they suffer evaporative water loss (EWL). Since evaporation increases with temperature, EWL could limit the activity of ectotherms when water is not available. In this study, we compared the preferred body temperatures (Tp) and EWL of two lacertid lizard species, Darevskia praticola and Podarcis muralis, at the western edge of D. praticola’s range, where they live in syntopy. We hypothesized that D. praticola, a species that inhabits forested and humid environments, would have a higher EWL than the more widespread P. muralis. Our results show that D. praticola prefers lower temperatures (mean Tp = 28.1 °C) than P. muralis (mean Tp = 30.6 °C). Despite the differences in their thermal preferences, both species showed similar total EWL (2.76% for D. praticola and 2.67% for P. muralis), although their daily patterns of water loss differed. Our results suggest that D. praticola has developed mechanisms to control water loss and that its lower thermal preference may be due to both historical factors and local adaptations. These results contribute to the understanding of how environmental factors influence the physiology of lizards, which in turn has implications for predicting the effects of climate change on species distribution.

Polyanionic Electrolyte Ionization Desalination Empowers Continuous Solar Evaporation Performance.

Solar evaporation contributes to sustainable and environmentally friendly production of fresh water from seawater and wastewater. However, poor salt resistance and high degree of corrosion of traditional evaporators in brine make their implementation in real applications scarce. To overcome such deficiency, a polyanionic electrolyte functionalization strategy empowering excellent uniform desalination performance over extended periods of time is exploited. This 3D superhydrophilic graphene oxide solar evaporator design ensures stable water supply by the enhanced self-driving liquid capillarity and absorption at the evaporation interface as well as efficient vapor diffusion. Meanwhile, the polyanionic electrolyte functionalization implemented via layer-by-layer static deposition of polystyrene sodium sulfonate effectively regulates/minimizes the flux of salt ions by exploiting the Donnan equilibrium effect, which eventually hinders local salt crystallization during long-term operation. Stable evaporation rates in line with the literature of up to 1.68kg m-2 h-1 are achieved for up to 10 days in brine (15‰ salinity) and for up to 3 days in seawater from Hangzhou Bay in the East China Sea (9‰ salinity); while, maintaining evaporation efficiencies of ≈90%. This work demonstrates the excellent benefits of polyanionic electrolyte functionalization as salt resistance strategy for the development of high-performance solar powered seawater desalination technology and others.

Self-template manufacturing of on-skin electrodes with 3D multi-channel structure for standard 3-limb-lead ECG suit

Wearable electrocardiogram (ECG) devices are the mainstream technology in the diagnosis of various cardiovascular diseases, in which soft, flexible, permeable electrodes are the key link in human-machine interface to capture bioelectrical signals. Herein, we propose a self-template strategy to fabricate silver-coated fiber/silicone (AgCF-S) electrodes. With a simple dissolving-curing-redissolving process, the polyvinyl acetate shell around the AgCF core is in-situ removed to form a three-dimensional (3D) multi-channel structure. The conductive fibers overlap each other and pass through the silicon substrate in a network state, so that the electrode can be bent to 180° or stretched to 30%. The 3D multi-channels in AgCF-S adhesive is further coupled with a Kirigami-design structure of flexible substrate, to maintain high flexibility without sacrificing air-permeability, enabling an excellent water evaporation rate of 1.8 μg/mm2/min, and non-allergenic adhere on pigskin after 24 h. Combined with the self-developed standard 3-limb-lead ECG suit, multi-lead signals with high signal-to-noise ratio (SNR) and low variance (σ2), can be transmitted in real-time via Bluetooth and displayed in the client. Typical heart diseases such as coronary, arrhythmia, myocardial infarction, etc., are detected by our ECG equipment, revealing a huge promise in future medical electronics.

Amine-Based Solvents and Additives to Improve the CO2 Capture Processes: A Review

The use of amine-based solvents for carbon dioxide (CO2) capture has shown significant promise; however, operational challenges such as high energy requirements, solvent degradation, and equipment corrosion highlight the need for enhanced solutions. This review focuses on identifying amine-based solvents and additives that can improve CO2 capture efficiency while minimizing costs and avoiding substantial modifications to existing industrial facilities. Specifically, the study emphasizes the development of a comprehensive database of additives to optimize CO2 capture processes. A detailed analysis of recent advancements in amine-based solvents was conducted, with a focus on (i) process optimization strategies, (ii) sector-specific CO2 emission profiles, and (iii) equipment issues associated with conventional chemical solvents. The study evaluates these solvents’ kinetic and thermodynamic properties and their potential to address critical operational challenges, including reducing corrosion, solvent viscosity, and evaporation rates. The findings highlight the pivotal role of amino group-containing compounds, particularly alkanolamines, in enhancing CO2 capture performance. The structural versatility of these compounds, characterized by the presence of hydroxyl groups, facilitates aqueous dissolution while offering kinetic and thermodynamic benefits. This review underscores the importance of continued innovation in solvent chemistry and the integration of amine-based solvents with emerging technologies to overcome current limitations and advance the implementation of efficient and sustainable CO2 capture technologies.

Improving wood surface wettability through gas-phase ozone treatment of air-dry wood

An increase in wood free surface energy enhances the wettability of wood surfaces, leading to better interaction with water-based coatings. This study investigated the effect of gas-phase ozonation on the wettability of spruce, thermo-modified pine, and birch woods. The effects of the treatment were evaluated by measuring the water contact angle and the Cobb value on the wood sample surfaces, and by determining the surface free energy of the wood surfaces using the Owens, Wendt, Rabel, and Kaelble (OWRK) calculation method. Furthermore, water absorption and evaporation rates were assessed through water immersion and subsequent drying of the wood samples. The results indicated that ozone treatment increased the surface energy, and especially its polar component, thus accelerating water spreading and absorption on the wood surfaces. The most probable cause of the observed effects is the formation of new carbonyl and carboxyl groups resulting from reactions of the ozone with the wood surface. The findings suggest that the ozone treatment technique can enhance spreading, absorption, and adhesion of water-based adhesives and coatings to wood surfaces. This research may facilitate the development and use of new environmentally friendly water-based adhesives and coatings.

An enthalpy-based model for the physics of ice-crystal icing

Ice-crystal icing (ICI) in aircraft engines is a major threat to flight safety. Due to the complex thermodynamic and phase-change conditions involved in ICI, rigorous modelling of the accretion process remains limited. The present study proposes a novel modelling approach based on the physically observed mixed-phase nature of the accretion layers. The mathematical model, which is derived from the enthalpy change after accretion (the enthalpy model), is compared with an existing pure-phase layer model (the three-layer model). Scaling laws and asymptotic solutions are developed for both models. The onset of ice accretion, the icing layer thickness and solid ice fraction within the layer are determined by a set of non-dimensional parameters including the Péclet number, the Stefan number, the Biot number, the melt ratio and the evaporative rate. Thresholds for freezing and non-freezing conditions are developed. The asymptotic solutions present good agreement with numerical solutions at low Péclet numbers. Both the asymptotic and numerical solutions show that, when compared with the three-layer model, the enthalpy model presents a thicker icing layer and a thicker water layer above the substrate due to mixed-phased features and modified Stefan conditions. Modelling in terms of the enthalpy poses significant advantages in the development of numerical methods to complex three-dimensional geometrical and flow configurations. These results improve understanding of the accretion process and provide a novel, rigorous mathematical framework for accurate modelling of ICI.

Research on Route Optimization of RO-Ro Ship Based on Ant Colony Algorithm

This study is based on an ant colony algorithm for route optimisation of roll-on roll-off (RO-RO) vessels, aiming to minimise the total cost of RO-RO shipping routes. The model takes into account factors such as port berthing cost, fuel consumption and sailing time, and ensures the stability and efficiency of the optimisation results by adjusting the algorithm parameters such as pheromone initialisation, pheromone evaporation rate and ant colony size. The results of the study provide a practical solution for ro-ro ship route optimisation, which significantly reduces the operating costs and also provides key technical support for shipping companies to compete in the global market. In addition, the study demonstrates the potential of the optimisation model to reduce transport costs, improve shipping efficiency and reduce carbon emissions, providing an effective technical support for shipping companies in an increasingly competitive global market. Through this optimisation approach, shipping companies are able to better manage their route selection, resource allocation and operational processes, enhancing market competitiveness and promoting sustainable development of the shipping industry.

High-Performance Silicone Sponge Evaporators with Low Thermal Conductivity for Long-Term Solar Interfacial Evaporation and Freshwater Harvesting.

Solar interfacial evaporation (SIE) has emerged as a highly promising approach for sustainable freshwater harvesting. However, maintaining a stable evaporation rate and achieving a high freshwater yield in high-salinity brines remain a significant challenge. In this study, we present the development of silicone sponge-based evaporators with a "free-salt" structure, designed to enhance the efficiency of SIE and freshwater collection. These evaporators, designated as PSS@Fe3O4/CNTs, were fabricated by grafting durable silicone onto a silicone sponge framework, followed by the incorporation of Fe3O4 nanoparticles and carbon nanotubes. The unique combination of exceptional photothermal properties and a controlled yolk-shell structure with low thermal conductivity enabled the PSS@Fe3O4/CNT evaporators to sustain a stable evaporation rate of 1.87 kg m-2 h-1 in real seawater over 200 h of continuous operation under 1 sun illumination. Importantly, no salt accumulation was observed on the evaporator surfaces, even when exposed to highly concentrated brines. In a closed system equipped with a condenser, these evaporators achieved freshwater production rates of 14.5 and 11.8 kg m-2 over 10 h from 10 and 20 wt % NaCl solutions, respectively, under 1 sun illumination. These values correspond to normalized production rates of 1.45 and 1.18 kg m-2 h-1, showcasing the consistent and efficient performance of the evaporators across varying salinity levels. Beyond salt rejection, the PSS@Fe3O4/CNT evaporators also demonstrated the ability to effectively remove various heavy metal ions (e.g., Cu2+ and Zn2+) and organic pollutants from contaminated water. This work provides valuable insights into innovative evaporator designs for efficient freshwater production from seawater and wastewater.

Water droplet evaporation in air: Effects of interfacial thermal and mass diffusion resistance

Evaporation of water droplets in air is a process highly relevant to a variety of environmental, industrial, and biomedical applications. In conventional hydrodynamic modeling of droplet evaporation, it is usually assumed that thermodynamic equilibrium exists at the water-air interface. However, such an assumption could result in considerable errors in predicting the evaporation rate of micro/nanoscale water droplets in air. In this work, we use the combination of kinetic theory-based model and hydrodynamic model to study the effects of interfacial resistance on the evaporation behavior of water droplets in air. The interfacial thermal resistance and interfacial mass diffusion resistance predicted by the kinetic theory-based model are first validated by MD simulation results, and then incorporated into the hydrodynamic model to predict the influence of the water droplet size, air temperature, pressure and humidity on the water droplet evaporation rate and droplet temperature. The evaporation behavior of water droplets in air predicted by our kinetic-hydrodynamic model are corroborated by MD simulation results and the recent experimental data. Our modeling results show that, at normal temperature and pressure (i.e., 25 °C and 1 atm by NIST), the equivalent length of thermal resistance and mass diffusion resistance at water-air interface are both ∼200 nm. This indicates that, at normal temperature and pressure, the effects of interfacial thermal and mass diffusion resistance on evaporation of water droplets in air cannot be ignored if the droplet diameter is less than 20 μm. The thermodynamic equilibrium assumption is only valid if the droplet diameter is greater than 20 μm. Once the droplet size is greater than 100 μm, the radiation heat transfer and convection effects must also be taken into account to give a more accurate prediction of droplet evaporation rate.

Rapid laser printing of cost-effective, scalable and flexible carbon-based fabrics for solar water evaporation

Solar interfacial evaporation represents a sustainable, cost-effective and carbon-neutral approach for freshwater scarcity. Nevertheless, most of the solar water evaporator face challenges related to scalability, flexibility and theoretical evaporation limit. Moreover, the poor stability in harsh water environments and high-cost of evaporators significantly restrict their industrial potential. The simultaneous optimization of high evaporation rates, environmental resistance and economic viability in a single device remains a rare accomplishment. Herein, a large-area black toner-fiber (BTF) composite film was rapidly produced with laser printing technology. Benefiting from the high photoabsorption of carbon black particles and the abundance of hydrophilic sites within the fabric fibers, the solar-thermal conversion efficiency is increased from 12.0 % to 85.3 %, and the water evaporation enthalpy is reduced to 1849.8 J g−1. The BTF-based evaporator possesses an evaporation rate of high as 1.51 kg m−2 h−1 under one sun. Furthermore, the evaporator also exhibits excellent properties on desalination and removal of organic pollutants, with an ion removal rate of ≈100 %. This design strategy for carbon-based evaporator offers a cost-effective, scalable alternative for tackling drinkable-water scarcity.

Effect of volatility differences in binary mixture droplet components on evaporation dynamics

The evaporation of binary mixture droplets (BMDs) is a natural phenomenon, and this study presents a theoretical model for the evaporation of BMDs. Ethanol–water (EW) and ethylene glycol–water (EGW) BMDs are selected to investigate the impact of component volatility differences on evaporation dynamics. The dynamic evaporation processes of two BMDs on a heated substrate are simulated, and differences in internal flow structures are examined. A modified formula for the evaporation rate of BMDs is proposed, and the effects of substrate heating temperature and initial solute concentration on the evaporation dynamics are explored. The results indicate that during evaporation, EW-BMDs develop a complex and chaotic multi-vortex structure, while EGW-BMDs exhibit a pattern with only two coexisting vortices. The evaporation of EW-BMDs transitions into a water-dominated stage after an initial rapid decline in the droplet volume, while the evaporation rate of EGW-BMDs remains almost constant once they enter an ethylene glycol-dominated stage. Increasing the substrate heating temperature and initial solute concentration delays the onset time of the multi-vortex structure in EW-BMDs but accelerates its appearance in EGW-BMDs. Increasing the substrate heating temperature shortens the evaporation time of two BMDs and accelerates the evaporation rate. Increasing the initial solute concentration reduces the evaporation time of EW-BMDs but extends the evaporation time of EGW-BMDs, while also reducing the time required for the ethylene glycol mass fraction to reach 1.

Self‑supporting magnetic nanoporous silver-nickel films with broadband light absorption for efficient interfacial solar steam generation

Interfacial solar steam generation (SSG) is a promising eco-friendly strategy for freshwater production to address the global water crisis, which depends upon high-efficiency and low-cost photothermal materials. Herein, a series of self-supporting magnetic nanoporous silver-nickel (NP-AgNi) films were fabricated by one-step dealloying of specially designed Al99AgxNi1-x (x = 0.3, 0.5, 0.7) precursors. Both in-situ and ex-situ characterizations were performed to unveil the phase/structure evolution during dealloying of AlAgNi. Specially, the obtained NP-AgNi films with high porosity (>89 %) and tunable magnetic properties exhibit a unique three-dimensional bicontinuous ligament-channel Ag network with embedded Ni microparticles, as well as good hydrophilicity. Combined with the synergistic light absorption of the bimetal Ag and Ni, the NP-AgNi films exhibit good broadband absorption over the 200–2500 nm wavelength. More importantly, the NP-AgNi films show excellent SSG performance (evaporation efficiency over 89 %, evaporation rate ≥ 1.42 kg·m−2·h−1 and good cycling stability) under one sun irradiation. Additionally, the NP-AgNi films show outstanding seawater desalination and dye wastewater purification capability. This work provides an inspiration for the design and fabrication of multi-functional metal-based photothermal films in solar water treatment.

Molecular dynamics simulation of heat and mass transfer in a nano-grooved heat pipe: Focusing on filling ratios' effect.

Managing the heat generated in microprocessors and other similar heat-generating devices requires the design and construction of superconductors with high reliability. For this purpose, heat pipes (HPs) are a very good option. Nano-grooved micro flat plate heat pipes (FPHPs), which are in the group of vapor chambers (VCs), have received attention due to their suitable structure. In this research, an FPHP with a length of 1050nm is investigated using molecular dynamics (MD) simulation. The effects of using three metals for walls including platinum (Pt), copper (Cu), and aluminum (Al) as well as three working fluids including argon (Ar), water (H2O), and ethanol (EtOH) were investigated. Focusing on the filling ratio of the interior space, mass and heat transfer inside the HP has been fully investigated. Evaporation rate, condensation rate, temperature, density, and velocity distribution as well as heat flux have been studied. The results show that although Ar shows better mass transfer results (due to its monoatomic nature), EtOH has better thermal performance. Among the three metals used, Cu has the best thermal performance. The maximum heat flux is obtained by using Cu and EtOH and is equal to 1819 W/cm2. The optimal filling ratio is reported in different states. The maximum mass transfer rate relates to Ar and at FR = 0.3; which equals 32.5%. The highest phase change rate is obtained using platinum and water, which is equal to 74%.

The significance of evapouration heat and mass transfer through a spray sheet with two-phase transitional momentum transport and vapour dispersion

Until now, there has been a lack of two-phase velocity and vapor investigations under the evapouration condition. Therefore, this work addresses this title in order to be additive to this subject. The spray droplets are modelled using the moments method, and the gas phase is modelled using the Eulerian approach. The spray drag, breakup, and evaporation sub-models are taken into account. Based on the RANS turbulence model for the carrier gas phase and a calibrated atomisation model for the dispersed droplets, turbulence closure is accomplished. The spray tip penetration is evaluated and compared with experimental data. The fuel vapour mass fraction is calculated by using a transport equation for the droplet-gas interaction. The distribution of the fuel vapour mass fraction is compared with the KIVA code. Fortunately, there are no experimental results for the spray or gas velocity to be compared with. All presented results are investigated by their variation with positions and time to give the total behavior. The fuel vapour mass fraction distribution exhibits a bell-shaped behaviour. In close proximity to the injector, the evaporation rate is significantly higher. There was no significant increase in the evaporation rate of the pressure swirl nozzle as the distance from the injector increased. During the evapouration of spray droplets, higher fuel vapour concentrations are present at the core spray than at the peripheral edge. The droplet velocities in the outer edge’s axial and radial directions display a reduced magnitude. The droplet’s diameter is greater at the inner edge than at the outer edge. The comparisons showed that there was good agreement with both the experimental and numerical results.

Inexpensive advanced diatomite evaporator with optimal structure and density for efficient seawater desalination

The global water-scarcity crisis, exacerbated by population growth and pollution, necessitates the securing of freshwater resources. Recently, interfacial solar steam generation (ISSG) has emerged as a promising and cost-effective seawater-desalination technology with minimal secondary contamination. However, it employs high-end materials and complex structures, limiting its practical applicability. We develop an advanced diatomite evaporator (ADE) by incorporating inexpensive porous materials, such as diatomite, natural cement, and graphene nanoplatelets, which are readily available and replicable. To maximize evaporation efficiency while minimizing energy utilization, the structural density of the ADE is optimized during fabrication. Capillary-rise and geometric-modification experiments show that heat loss increases with temperature as the ADE diameter increases and the evaporation rate above a particular height saturates because of insufficient water supply. The optimal aspect ratio (height/diameter) of the ADE is approximately 4.8, with an evaporation rate of approximately 6.30 kg m−2h−1. Through the optimization of composition density and viscosity in the diatomite-cement dough, ADE achieved superior mechanical strength and durability, offering significant advantages for long-term and repeated use. The proposed ADE sustains evaporation performance for > 16 h and maintains stability after 10 repeated desalination cycles. This study will contribute to the development of a cost-effective and practical ISSG technology.

Dynamic mechanism of biodiesel-ethanol-graphene droplets during micro-explosion and puffing: droplet evaporation, distribution and velocity characteristics

Adding graphene to biodiesel and ethanol blends can significantly improve the combustion efficiency, which can significantly reduce pollutant emissions when applied to alternative engine fuels. The study of the droplet dynamic properties of biodiesel-ethanol-graphene blends can help to aid in a deeper understanding of the properties of the fuel, which in turn can provide a theoretical basis for the application of the fuel. In this paper, a modified tube furnace experimental platform was used to investigate the evaporation, micro-explosion, and dynamic properties of parent and child droplets of biodiesel-ethanol-graphene. The micro-explosion and dynamics mechanisms of the parent droplets and child droplets of the blended fuel were further investigated in terms of graphene content, ambient temperature and biodiesel/ethanol blend proportion. During the research, three modes of bubble growth in droplet were proposed, the number and velocity of child droplets and the intensity of micro-explosion were found to have a positive correlation trend. It is found that BD50E50(1%G) droplets show high micro-explosion effect and evaporation rate, and can be considered as a sustainable alternative fuel for airlines or oil companies. The movement law of mixed droplets is analyzed, and the internal conditions and external characterization parameters of micro-explosion are summarized.

Nanofluid-peroxydisulfate integrated volumetric solar interfacial evaporation system for water evaporation and organic pollutant removal

Solar evaporation exhibits significant potential for the treatment of high-salt organic wastewater. However, it's also confronted with challenges due to the accumulation of organic pollutants and salts in the concentrated wastewater following evaporation, which compromises the long-term stability of evaporation unit and complicates subsequent treatment processes. To address these challenges, a volumetric solar interfacial evaporation (V-SIE) system by integrating Fe3O4-H2O nanofluids and peroxydisulfate (PDS) were proposed in this study. In V-SIE system, Fe3O4 magnetic nanoparticles (NPs) were prepared as solar receivers to form a volume-absorbing solar energy interface and enhance evaporation efficiency. The results show that the evaporation rate was 1.412 kg/(m2·h) and the solar efficiency reached 93.75% as the temperature rose to 57.2 ℃. Additionally, the high thermal conductivity of Fe3O4 facilitated the effective heat transfer to the fluid and provided sufficient thermal energy to activate PDS, thereby removing 99.3% of Rhodamine B (RhB). Fe3O4 NPs effectively promoted the generation of reactive species including SO4•−, •OH, O2•− and 1O2 from PDS and the four main stages including N-de-ethylation, chromophore cleavage, ring-opening, and mineralization were proposed as the possible degradation pathway of RhB. This study provides a reference for developing V-SIE system and highlights the positive effect of nanofluids in advanced oxidation processes.

Experimental study on the spray characteristics of high-pressure liquid ammonia under different ambient conditions

As a promising carbon-free fuel, ammonia is expected to be widely applied in internal combustion engines. However, the physical properties of ammonia are quite different from those of conventional fuels, which leads to different spray characteristics. In this paper, the ammonia spray under injection pressure as high as 80 MPa was visualized by the diffused back-illumination imaging method, and the liquid ammonia spray characteristics under different ambient pressures and ambient temperatures were analyzed. The liquid spray penetration length, cone angle and tip velocity calculated from the spray images provide a reference database for numerical simulation. The results show that the development characteristics of liquid ammonia spray are significantly different under flare flash boiling, transitional flash boiling and non-flash boiling conditions. Flash boiling (especially flare flash boiling) inhibits the initial liquid spray penetration. The spray tip velocity increases first and then gradually decreases under flash boiling conditions. Ammonia spray has obvious radial expansion at the initial stage of flare flash boiling and the spray contour under flare flash boiling conditions is noticeably distorted, forming an obvious dilute region. With the increase of ambient pressure, the intensity of flash boiling reduces, the dilute region gradually disappears, and the distortion of the spray contour gradually weakens. Under non-flash boiling conditions, ammonia spray presents a dense and regular shape; there is no spray acceleration but a sharp decrease in spray tip velocity at the initial stage, and then the spray penetrates forward at a similar velocity. The spray penetration velocity decreases significantly with the increase of ambient pressure. The increase in ambient temperature accelerates the vaporization of ammonia spray. The liquid spray penetration length decreases and maintains with only slight fluctuations during the injection process as the ambient temperature increases from 300 K to 600 K because the vaporization rate and penetration velocity reach a balance.