Evaporation Area Research Articles

Augmenting the performance of pyramid distiller via conical absorbing surface, reflectors, condenser, and thermal storing material

The availability of freshwater suitable for human use is a modern problem in many countries of the world. There are different methods that can be considered to overcome this problem, among them solar distillers, which are an acceptable solution in places far from urbanization and for families of medium numbers. This paper presents a different design of the pyramid distiller (PSS). This was conducted by changing the flat absorber to a conical absorber to increase the vaporization surface area of distiller. In addition, various wick materials of cotton wick and jute cloth were placed over the conical absorber to be investigated. Besides, the performance of the modified pyramid solar still (MPSS) was studied when using external mirrors to increase the input solar energy and utilizing external condenser. Finally, a paraffin wax mixed with silver nanoparticles was used as a phase change material (PCM) under the conical absorber of MPSS to be tested. The results revealed that using the modified conical absorber increased the evaporative surface area of MPSS by around 14 %. Also, using the jute cloth material is suggested to be used instead of cotton cloth as a wick material for the MPSS due to its better operation, where the distillate of MPSS with cotton and jute wicks was increased by 66 % and 69 % over that of the PSS. While the daily yield of the MPSS with reflectors and external condenser was reported as 10,250 mL/m2·day compared to only 3950 mL/m2·day for the PSS. As a result, the combination of mirrors and external condenser with the MPSS improved the yield by 159 % over that of the PSS. Finally, the best performance of MPSS was obtained under the conditions of using mirrors and condenser, where the daily yield improvement and distiller efficiency were 159 % and 55.5 %, respectively.

Experimental study on the performance of pyramid solar still with novel convex and dish absorbers and wick materials

Solar still is a famous technique of the desalination methods, but it suffers from the low productivity. In this paper, novel structured convex absorbers were proposed in a pyramid solar still. The performance of the pyramid solar still (PSS) was experimentally investigated when using a convex cylinder absorber shape (CCPSS) and dish shape of absorber (CDPSS) instead of the flat absorber. The proposed absorber shapes increased the surface areas of exposure and evaporation and reduced the water depth to minimum inside the distiller. Also, the experimentations were conducted when using different heights of convex dish shape (5, 10, 15, and 20 cm) to obtain the optimum convex height of the dish absorber. Besides, the system was experimentally investigated when using two different wick materials of cotton cloth and jute wicks that were put over the convex surface. Furthermore, the performance of CDPSS was tested when painting the absorber by black paint mixed with different nanocomposites of titanium oxide (TiO2) copper oxide (CuO) and silver (Ag). Systems performance based on economic, enviroeconomic, CO2 reduction, and energy point of view was studied. Experimental results revealed that the CDPSS provided better performance than either CCPSS or PSS. Also, the optimum height of dish absorber that obtained the best performance of CDPSS was 15 cm, where at this height (15 cm), the increase in productivity of CDPSS was 54% with jute cloth over that of the PSS. The highest productivity of CDPSS was obtained when using Ag followed by CuO and then TiO2, where the average daily productivity of CDPSS with jute and Ag was 6750 mL/m2.day compared to 3800 mL/m2.day for that of PSS (improvement = 78% and efficiency = 45.7%). Besides, the rate of CO2 mitigation for the CDPSS with Ag, CuO, TiO2 and without nanoparticles was about 13.5, 12.7, 12.5, 10.17 tons/y respectively. Also, the enviroeconomic parameter (Z^') was 147.6, 181.2, 184.1, and 195.1 per year for the (CDPSS), (CDPSS + TiO2), (CDPSS + CuO), and (CDPSS + Ag), respectively for 365 operating days and lifetime 20 years. Finally, the costs of the distilled water of PSS and CDPSS with jute cloth and silver nanoparticles were 0.018 and 0.015 $/L, respectively.

Assembling graphene aerogel hollow fibres for solar steam generation

Solar vapor generation, a cost-effective way to harvest solar energy for purifying polluted or saline water, has attracted great attention in recent years. However, during the harsh environment (e.g. high-salinity brine), challenges still remain in limited water evaporation, complicated/compromised systems between water transport, evapor area and salt accumulation. Herein, graphene aerogel hollow fibers (GAHF) are developed and assembled into a solar steam generator which demonstrates exceptionally high efficiency for water evaporation and salt rejection under sun irradiation. Inspired from the capillary water transportation system in trees, the mesophase-ordered GAHFs are spun from their liquid crystalline suspension, and subsequently assembled into a roll of unidirectionally aligned bundles and then embedded in a transparent polydimethylsiloxane (PDMS) matrix. The synergistic effects between GAHFs, serving as 1D-confining micro-channels for water transport and broadband solar absorbers, and PDMS matrix, as an light refractor and “canyons”-like evaporation area, improve the water flow and absorption of solar energy and maximize the evaporation surface area. As a result, the GAHF arrays expedite remarkable transpiration, achieving continuous steam generation (∼3.29 kg m−2 h−1) and outstanding salt-rejection performance for high-salinity brine (e.g. saturated solution) desalination. This GAHF based solar steam generation system provides a facile and high-performance device for self-generating seawater desalination.

Parameters Affecting the Efficiency of Solar Stills—Recent Review

Although water is the second most important fluid, after air, found on the Earth, there is a vital problem in the availability of water for many organisms, and this problem faces the whole world. As a result, scientists have developed many methods of purifying the saline/brackish water to be suitable for different uses in addition to the purpose of drinking. Fortunately, solar distillation is very rewarding in terms of operating costs and costs for a liter of freshwater distillated with using clean and environmentally friendly energy. Solar distiller is one of the solar distillation systems devices, which is simple in construction, cheap, and easy to use but it has the drawback of low productivity. This article aims to provide a summary of the different ideas and works on solar stills through different variables that affect the performance of distillers. In contrast to the review papers dealing with this topic, this paper contains comprehensive and complete details and careful reviews of all the variables that affect the performance of distillers. Therefore, it is like a ladder in front of the authors until they reach the recent of what has been studied on the distillers in a simplified way to save time and effort, which will help them to come up with different ideas that were not easily studied. Thus, this paper introduces an overview on the detailed parameters affecting the performance of solar stills. These parameters are climatic, design, and operating factors. Climatic factors consist of solar radiation, ambient temperature, air speed, and dusty and cloudy weather. While the design factors include the evaporative and exposure surface areas, glazing cover material, inclination, and thickness, distiller material, and of insulating material and thickness. Whist, the operating parameters consist of the water temperature, feed water temperature, applying vacuum, temperature difference between water and glass cover, and hybrid systems. From the extensive literature, it is concluded that the climatic, design, and operating factors significantly affect the performance of the solar still. Finally, some points are proposed for further investigation.

Designing 3D ribbed evaporating layer of solar-driven multistage desalination device for enhanced evaporation performance

Solar-powered passive multistage distillation devices demonstrated outstanding potential in freshwater production, but improving evaporation performance remained a major challenge. In this study, we found that the extended evaporation area was effective in improving evaporation performance. Therefore, a multistage distillation device with a three-dimensional ribbed evaporation layer was fabricated and explored. The ribbed evaporation layer was found to produce more evaporation flux with lower temperature and heat loss compared to the planar shape. As a result, the single-stage device demonstrated an evaporation rate of 1.19 kg m-2h−1 with an energy conversion efficiency of 81.5 % under 1 kW m−2 light intensity. In particular, the ribbed evaporation layer enhanced the efficiency of latent heat transfer and utilization in multistage devices. Therefore, the stable evaporation rate of the 10-stage device reached 4.12 kg m-2h−1, which was about 1.6 times that of the original device. In summary, we explored a new method to improve the evaporation performance of MSD devices, which is of great significance for efficient seawater desalination.

A Multiscale Porous 3D‐Fabric Evaporator with Vertically Aligned Yarns Enables Ultra‐Efficient and Continuous Water Desalination

AbstractSolar steam generation has emerged as an environment‐friendly and promising strategy to overcome the freshwater and energy crisis. However, simultaneously attaining the satisfied evaporation rate, durability and energy utilization in a single system is challengeable, but crucial to the practical application. Herein, inspired by the carpet weaving technique and benefiting from “fiber–yarn–fabric” hierarchical structures, a 3D fabric evaporator with vertical hemp‐yarn arrays is innovatively constructed, featuring a combined structure of multiscale pores from tunable spacing between adjacent fibers or yarns, the vertically aligned architecture coated with superhydrophilic MXene‐sandwiched layer and the adjustable side height/areas. These structures work cooperatively, surprisingly achieving the integrated functions of excellent light capture, the balanced evaporation area and vapor escape space, the additional energy adsorption from the environment and the salt exchange along or between micro/macro pores. Consequently, the 3D evaporator exhibits an outstanding evaporation rate (3.95 kg m−2 h−1 under one‐sun illumination) and extremely high outdoor evaporation (47.04 kg m−2 for 8 h), accompanied with outstanding salt‐resistance (continuous 120 h in 14% brine without salt accumulation), anti‐oilfouling and anti‐bacterial (efficiency over 99.9%) performances. Finally, through rationally assembling multi‐function modules with a condenser, an all‐in‐one “desalination–thermoelectricity–irrigation” platform is built, realizing the maximum utilization of steam condensation enthalpy.

Evaluation of Subcritical Organic Rankine Cycle by Pure and Zeotropic of Binary and Ternary Refrigerants

The simulation configuration and process analysis of the Subcritical Organic Rankine Cycle (SORC) system are carried out for the potential comparison between pure, binary, and ternary zeotropic mixtures of R1234ze(E), R1234yf, and R134a as refrigerant working fluids based on applying the flue gas as a heat source with medium temperature. The compression pressure was selected as an optimized variable input parameter of SORC with the lower limit of boundary condition (1.4 MPa); to mitigate air ingress and sub-atmospheric pressure that led to approach optimum net power output generated. Increasing the compression pressure has a positive relationship with the superheated temperature and the mass enthalpy change in the evaporation and, therefore, in the expansion process. In parallel, the enthalpy and entropy changes in the flue gas and cold water positively correlate with exergy efficiency. So, R1234ze(E)/ R1234yf/R134a with 68.35% and R1234yf/ R134a with 69.29% as the lowest and highest exergy efficiency in the highest compression pressure; furthermore, the SIC consequences of increasing the cost of each component of the SORC system that has a direct relationship with the PPC and the required exchanger area of evaporation and condensation process and generating a net power output of the turbine. As a result, the maximum to the minimum value of specific investment cost (SIC) achieves R134a with 5807402.18-22455670.61 $.kW-1 and R1234yf with 16.82-17.38% reduction, respectively. To sum up, the lowest payback period (PBP) was R1234yf with 302 days.

Performance enhancement and economic analysis of pyramid solar still with corrugated absorber plate and conventional solar still: A case study

Solar energy is utilized to convert brackish or saline water into drinking water in solar stills. Recent years have seen a lot of attention paid to developing new designs for solar stills to overcome the constraints of the lower yield. Pyramid solar still (PSS) is a design of solar still having triangular glass cover to receive sun rays. The present research article shows enhancement of the yield of the PSS by increasing the evaporation area by using corrugated plate. Due to the addition of corrugated sheet as absorber plate, it is called as pyramid solar still with corrugated absorber plate (PSSCAP). Its performance has compared with conventional solar still (CSS) in climate conditions of Patan, Gujarat, India, from March to July 2018. The experimental results revealed that the yield of PSSCAP is found higher than that of a CSS due to the corrugated absorber due to increment of water temperature. According to the results, the yield of PSSCAP found 4.5 L/day, whereas the yield of CSS was 2.95 L/day. A comparative study found that the PSSCAP produced a 52.54% higher yield than a CSS due to the corrugated sheet used as an absorber plate. Furthermore, the average thermal efficiency for the PSSCAP and the CSS found 45.5% and 31.5%, respectively. The estimated cost of 1L of yield for a PSSCAP and a CSS is approximately 0.53 and 0.68 INR, respectively, from research work.

Pore structure alteration in a reclaimed saline–sodic soil identified by multiscale X‐ray tomography

AbstractSoil structure is one of the major factors to affect soil salinization in high evaporation areas. Revealing the effects of desulfurization steel slag (DSS) on the pore structures in saline–sodic soil is critical for evaluating the remediation effects and understanding the mechanisms of various soil processes involved. In this study, the multiscale pore structure in DSS‐amended soil was quantified by multiscale X‐ray tomography. Soil macroaggregates (>5 mm in diameter) and intact soil cores (5 × 20 cm in size) were collected from a field experiment of DSS reclamation for 1 yr (T1) and 4 yr (T4), respectively. The saline–sodic soil without DSS treatments was taken as the control (CK). For soil aggregates, the difference in total porosity between T1 and T4 treatments is insignificant. For soil cores, the total porosity of the T4 treatment significantly decreased compared with the T1 treatment. The compact and homogeneous pore structures of CK benefits the ascension of the capillary water, which directly related to soil salinization. However, the alteration of pore structure in DSS‐amended soils posed negative effects on soil salinization, which could be summarized by three possible mechanisms. The elimination of the unique pore structure in the saline–sodic soil markedly reduced the ascension of the capillary water. Secondly, the DSS application significantly increased the total porosity and macroporosity in the soil. Thirdly, DSS addition enhanced the root activity and further prevented the capillary water from ascending. These findings are crucial in developing and optimizing soil reclamation strategies.

A new method of disposal of concentrated solutions by crystallization of their components

Purpose. Creation of highly efficient evaporators based on materials with capillary properties and energy of solar radiation. Methodology. The processes of evaporation from the surface of cotton, silk and linen fabrics were studied in the natural environment. The necessary equipment in the simplest case is a cloth, fixed vertically and immersed in the lower end of the concentrate. Tap water and NaCl solutions with a concentration of 100 g/dm3 were used as model solutions. Findings. Among modern methods of liquid waste disposal in the form of concentrates from various industries, thermal methods have become the most widespread, which are not critical to the chemical composition of concentrates and allow converting them into a solid state. On the other hand, thermal methods require significant energy costs, which makes the accumulation and storage of concentrates more cost-effective, despite environmental problems. Therefore, research in the field of reducing energy costs through the use of solar energy is extremely important today, especially in the context of global warming. Since it is difficult to raise the ambient temperature with large concentrates, we have proposed to increase the evaporation rate by increasing the evaporation area. To carry out this process, fabric with capillary properties were selected, due to which the liquid phase is able to rise to significant heights. In some cases, the intensity of evaporation can be increased by several orders of magnitude. Originality. The paper substantiates the possibility of using this method for evaporation of liquids and crystallization of substances contained in concentrates. The influence of temperature on the height of liquid rise through fabric capillaries and the influence of salt concentration on the intensity of their crystallization are studied. The influence of the fabric thickness on the crystallization intensity of the constituent concentrates is studied. Several designs of crystallizers are proposed, which allow increasing the efficiency of the evaporation process, automating the stages of solid phase removal and fabric regeneration. Practical value. The proposed designs of evaporators are ready for application in industrial enterprises and are especially effective in areas with warm temperatures throughout the year.

Performance comparison of solar still with inbuilt condenser and agitator over conventional solar still with energy and exergy analysis.

Demand for fresh water increases day by day. Solar desalination is one of the promising technologies to meet this demand in an economical fashion which uses solar still. For the current study, single-basin single-slope conventional solar still and a modified single-basin single-slope solar still with inbuilt condenser and agitator were designed and fabricated. Both the stills were tested under the same ambient conditions to compare the performance. Through experimental results, it was found that modified still with inbuilt condenser and agitator had 98.69% more productivity than conventional solar still. Modified still productivity was recorded as 4.856 L/m2/day and that of conventional still was 2.44 L/m2/day. The agitation effect caused by the agitator in the modified still led to an increase in the rate of evaporation. The increase in condensing area for the same evaporation area of the modified still improved the condensation rate. These two synergized effects resulted in an overall performance improvement of the modified still over the conventional still. An energy analysis revealed that modified still is 24.42% more efficient than its counterpart. The energy efficiency of modified and conventional stills was calculated as 4.82% and 2.04% respectively.

Three-Dimensional Artificial Transpiration Structure Based on 1T/2H-MoS2/Activated Carbon Fiber Cloth for Solar Steam Generation.

The rise of solar steam generation is an effective strategy to mitigate clean water shortages. However, achieving further improvements in conversion efficiency and stability remains a challenge. Here, 1T/2H-MoS2 nanosheets were uniformly assembled on activated carbon fiber cloth (A-CFC) through a facial hydrothermal method, and a three-dimensional (3D)-artificial transpiration device (ATD) was prepared using the plant transpiration process. The combination of activated carbon fiber cloth and 1T/2H phase MoS2 exhibits high light absorption (∼97.5%), excellent mechanical stability, large evaporation area, and easy escape of vapor. Additionally, the 3D hollow cone of the MoS2/carbon fiber cloth can effectively reduce radiative and convective energy loss and then achieve the enhancement of energy collection from the environment. An outstanding evaporation rate of 1.61 kg·m-2·h-1 with an optimum conversion efficiency of 97% under one sun is reached. Based on the facile fabrication, excellent stability, and high solar conversion efficiency, this nature-inspired design of 3D 1T/2H-MoS2/A-CFC is expected to facilitate large-scale applications for seawater purification and desalination.

Tailoring pore size and interface of superhydrophobic nanofibrous membrane for robust scaling resistance and flux enhancement in membrane distillation

Electrospun nanofibrous membrane with ultrafine nanofibers, high porosity, and interconnected pores has attracted significant attention in high-flux membrane distillation (MD). However, the comparatively large pore size and low liquid entry pressure (LEP) of nanofibrous membranes often result in severe membrane scaling and wetting. In this work, superhydrophobic nanofibrous membranes with tailored membrane pore size and interface were successfully fabricated via sequential electrospinning and electrospraying approaches. Results revealed that the decreased membrane pore size and increased interface evaporation area could synchronously mitigate membrane scaling and improve water flux. Besides, the water recovery of the membrane could be further increased with the aid of antiscalant, e.g., polymer polyacrylic acid, toward treating a nearly saturated gypsum solution. The excellent concentration performance was attributed to the cooperation of the antiscalant that inhibits the nuclei formation and the engineered surface that reduced the adhesion between the membrane interface and gypsum crystals. Notably, the resultant membrane also showed a high initial flux of ∼40 L m−2 h−1 and high salts rejection efficiency of ∼100% in a continuous concentration process for over 100 h. Our study provides a promising methodology for preparing novel membrane surfaces to treat hypersaline wastewaters meeting the minimal/zero liquid charge target.

Experimental investigation and thermo-economic performance analysis of a modified solar distiller design with thermal storage material and v-corrugated absorber basin

A comparative experimental study is carried out to augment the freshwater productivity of a single-slope solar distiller. A v-corrugated basin is utilized to boost the evaporation area for effective heat transfer of saline water; meanwhile, a phase change material (PCM) is incorporated underneath the basin to extend the still's nocturnal distillate yield. Paraffin wax is utilized as a PCM, and longitudinal copper fins are embedded inside the paraffin container to improve the heat transfer processes of the wax. Besides, the proposed solar distillers are investigated under flat and v-corrugated basin configurations with and without PCM. Four distillers, namely; traditional flat basin solar distiller (TFBSD), flat basin solar distiller with rearward copper longitudinal fins immersed in the PCM container (FBSD-PCM&Fins), v-corrugated basin solar distiller without PCM (VBSD), and v-corrugated basin solar distiller integrated with PCM (VBSD-PCM) are tested at the climatic conditions of Tanta (30.47° N and 31° E), Egypt. A comparative thermo-economic analysis of the four solar distillers is also performed, including the daily energetic efficiency, freshwater production, and distillate yield cost. The present results indicate that the VBSD-PCM maximized both energo-economic performance and freshwater production among the investigated modifications. The accumulated water production and the daily energetic efficiency of the VBSD-PCM are improved by 63.57 % and 72.70 %, respectively, compared to the TFBSD. Furthermore, the economic assessment shows that the cost of freshwater production of the VBSD-PCM is reduced by 23.10 % compared to the TFBSD.

A super absorbent resin-based solar evaporator for high-efficient various water treatment

Currently, water treatment has been viewed as an important way to the growing shortage of fresh water. A solar vapor generation device demonstrated enormous potential for desalination, water purification and carbon emission reduction. Nevertheless, the high cost and scalability hurdles of solar evaporators fundamentally restrict the practicality of solar-driven water treatment. In this study, an industrialized sodium polyacrylate (PAANa) super absorbent resin together with commercial carbon nanotubes (CNTs) is used to construct a PAANa-based solar evaporator. Under synergistic effects of high photothermal conversion efficiency, larger actual evaporation area, and reasonable water distribution on the evaporation surface, PAANa-based solar evaporator achieves a high water evaporation rate of 7.47 kg m−2 h−1 under 1 sun illumination (1 kW m−2) and convective flow condition. Notably, many kinds of sewage including dye-containing sewage, seawater, oil-in-water emulsion, and real industrial sewage can be effectively purified by using PAANa-based solar evaporator. Moreover, in arid and water-deficient areas, the PAANa-based evaporator with a strong water extraction capacity can easily capture water from gravel crevices and simultaneously purify it for further use. Significantly, under natural sunlight irradiation, a large-area PAANa-based evaporator (about 415 cm2) provided a sewage treatment capacity of up to 11.93 kg m− 2 for a continuous 10 h. This study will offer a new possibility for the industrialization of cost-effective and scalable solar evaporators, which can be used to alleviate the global water resources shortages.

Visualization research on influencing factors of flat heat pipes

Flat heat pipes can effectively spread a concentrated high power heat source in a small region into a larger heat dissipation area, which is widely used in the thermal management of electronic devices. In this paper, two different sintered copper powder wick structures are designed to study the effect of porous column height on the heat transfer performance. The results show that the best performance is achieved at the 30% filling ratio under the 15 ℃ cooling water with all the porous columns contacting with the condenser. The heat power is 312.7 W and the thermal resistance is 0.192 ℃/W. As the cooling water temperature increases, the evaporation rate increases, resulting in a decrease in the thermal resistance. But the decrease in temperature difference causes the decline in heat dissipation power. Through the visual observation, it is found that the porous column contacting with the condenser can not only play the role of support and liquid reflow pathway, but also serve as an effective evaporation area to improve the heat transfer performance. While the low porous column cannot transport the condensed liquid and is completely immersed by the liquid under the high filling ratio, which is difficult to promote evaporation rate. In order to improve the performance at air cooling situation, an integrated heat pipe combined the flat heat pipe and fin tubes is designed, which can achieve a heat power of 259.8 W and present excellent temperature uniformity. This research provides the guidelines to optimize the heat transfer performance of porous column wick structures.

Transient mathematical modelling and investigation of radiation and design parameters on the performance of multi-effect solar still integrated with evacuated tube collector

The advent of multi-effect solar still (MESS) provides an opportunity for improved yield, efficiency and gained output ratio (GOR) compared to the conventional still. It happens through the conservation of latent heat of evaporation from one stage to the next. In this present work, a lumped parameter model is developed to study the energy and exergy performance of the MESS. The transient solution for the varying solar energy supply is obtained using TRNSYS software. The TRNSYS and MATLAB linking available in TRNSYS software are effectively exploited to solve the heat transfer, mass transfer and exergy equations. An outdoor experiment was conducted using a MESS connected to an evacuated tube collector (ETC). The calculated results were compared with the experimental results, and a good agreement between them was observed. A maximum of 7.74% and a minimum of 1.62% error was observed between the experimental and numerical yield. Total yield, GOR and overall efficiency for a five-effect solar still were found to be 28.625 kg/m2day, 2.84 and 87.35%. The impact of the number of effects, basin size and basin water level on the yield, energy and exergy performance was also studied. The number of effects beyond seven shows no significant rise in water production. A lower amount of basin water and a higher evaporation area gives maximum yield and efficiency. However, a smaller basin area for the same quantity of water and energy supply has increased the water temperature to a higher value, eventually increasing exergy utilization. The yield, GOR and efficiency were maximum to be 8.6 kg, 3.36 and 109.01% for the basin area 0.56 m2 and 2 kg basin water quantity. The exergy efficiency was maximum to be 10.09% for the basin area of 0.16 m2 and 2 kg basin water quantity.

Review on the possible pathophysiological mechanisms underlying visual display terminal-associated dry eye disease.

Visual display terminal (VDT) use is a key risk factor for dry eye disease (DED). Visual display terminal (VDT) use reduces the blink rate and increases the number of incomplete blinks. However, the exact mechanisms causing DED development from VDT use have yet to be clearly described. The purpose of the study was to conduct a review on pathophysiological mechanisms promoting VDT-associated DED. A PubMed search of the literature investigating the relationship between dry eye and VDT was performed, and relevance to pathophysiology of DED was evaluated. Fifty-five articles met the inclusion criteria. Several pathophysiological mechanisms were examined, and multiple hypotheses were extracted from the articles. Visual display terminal (VDT) use causes DED mainly through impaired blinking patterns. Changes in parasympathetic signalling and increased exposure to blue light, which could disrupt ocular homeostasis, were proposed in some studies but lack sufficient scientific support. Together, these changes may lead to a reduced function of the tear film, lacrimal gland, goblet cells and meibomian glands, all contributing to DED development. Visual display terminal (VDT) use appears to induce DED through both direct and indirect routes. Decreased blink rates and increased incomplete blinks increase the exposed ocular evaporative area and inhibit lipid distribution from meibomian glands. Although not adequately investigated, changes in parasympathetic signalling may impair lacrimal gland and goblet cell function, promoting tear film instability. More studies are needed to better target and improve the treatment and prevention of VDT-associated DED.

High‐Performance Freshwater Harvesting System by Coupling Solar Desalination and Fog Collection with Hierarchical Porous Microneedle Arrays

AbstractThe maximizing daily freshwater yield on the ocean surface necessitates all‐day water harvesting technologies and materials. This is realizable by taking advantage of the natural sunlight and humid air, which can drive daytime solar desalination and nighttime fog collection, respectively. To this end, two types of hierarchically porous microneedle array structures, which demonstrate superior capabilities for efficient fog capturing and photothermal evaporation, respectively, are prepared. The gel‐forged microneedle arrays with Janus wettability are fabricated via a simple and controllable top‐down micro‐molding process on a porous platform, and porosity within microneedles is further achieved readily by additional freeze‐drying treatment. The developed microneedle structure shows an ultrahigh fog harvesting rate up to 30.5 kg m−2 h−1, enabling high flux water droplet harvesting from moisture during nighttime. In the daytime, a solar evaporation rate of 2.46 kg m−2 h−1 is realized due to the increased evaporative area of the porous microneedle arrays and enhanced photothermal conversion. By uniting these two water‐harvesting routes, a daily cycle can ideally deliver an overall water yield close to 200 kg m−2, which will offer a promising solution for sustaining future low‐cost and decentralized clean water production.

Экспериментальные исследования неуправляемого испарения углеводородов

The main purpose of the work is to study the liquids uncontrolled evaporation. Such evaporation is observed during accidental spills of various hydrocarbons. There are dozens of such accidents around the world every year. Many of them cause enormous economic and environmental damage. The most significant contribution to the understanding of the mechanism of evaporation processes was made by the German scientist R. Clausius and the Austrian-Slovenian physicist and mathematician J. Stefan. This understanding was used in the preparation and conduct of experiments on the volatile hydrocarbon evaporation. The results of the experiments practically confirmed the patterns of evaporation from the free surface. Some difference in the dependences obtained can be explained by the difference in the evaporation rates of the studied liquids. To obtain a very significant reduction in the rate of the volatile liquids evaporation is quite simple — it is required to limit the evaporation area to a low flanging (several centimeters high). This conclusion concerns relatively still air and small areas of evaporation. In the presence of even a relatively slow air flow (0.2–0.3 m/s), the evaporation rate increases dramatically. To counteract this increase, a grid was installed in the baking sheet, dividing the volume into small cells (2.5×2.5×3 cm). It is not clear whether the patterns of evaporation established by J. Stefan, and in fact confirmed by the experiments are preserved for the large areas. Even if we assume that these patterns are significantly leveled, they can still be restored using a grating above the liquid surface. Moreover, as experiments with baking sheets showed, the dimensions of the cells of this grating can be varied within relatively wide limits depending on the tasks being solved. In addition, such gratings can always be used for reliable fastening of the film coating, respectively, for the almost complete elimination of the evaporation of an accidently spilled liquid. It is obvious that the presence of such gratings in pits and pans for collecting emergency spilled liquids will significantly reduce the fire hazard, or the risk of poisoning in such accidents.