Paint Research Articles

Thermal Performance of Spiral Flat Plate Solar Water Collector

Water stream flow is the major factor that affects the performance of a spiral solar water collector, it can be maximize the collector performance by decreasing the water stream flow velocity. The water stream flow was in two spiral tube arrangements of length 15 m, diameter 0.012 m, and number of coils (11). The inner surface of the solar collector was coated with matte black paint with a mixture of nanomaterial (thermal dye with 5% TiN). The experimental rig placed in Babylon - Iraq, at longitude (44.4 E) and latitude (32.4 N) in the best experimental conditions for the province during the month's (2,3,4,5). Also, a simulation program was made to extract the results in the case of a single flow, where the geometry was drawn in the Solid Work program and then entered into the ANSYS program, where the same practical cases were applied. The experimental results were compared with the numerical results which gave a good agreement with an error percent of 11% and 8.8% in the closed and opened system, respectively. The experiment included two parts, the first part: the flow of water in four different levels at case of the closed system (1, 1.5, and 2) L/min. The second part: the flow of water was at the same levels but at case of open system. The results showed that a decrease in the mass flow rate leads to increase in exit temperature and thus increase in the temperature difference between (inlet and outlet). The maximum temperature difference in the closed system was 25.2℃ for a water flow rate of 1 L/min. The maximum temperature difference in the open system was 12.3℃ for the water flow rate of 1 L/min.

Deterioration of graffiti spray paints applied on granite after a decade of natural environment

Graffiti spray paints are commonly used in contemporaneous mural paintings in public spaces, contributing to the transformation of sites and urban life. These outdoor artworks are now beginning to show different deterioration forms, such as physical-mechanical alteration (loss of material and cohesion, etc.) and chromatic changes. However, the deterioration has not been formally characterized, and the influence of the paint composition and underlying substrate are not known. In this study, three non-metallic (red, blue and black) alkyd graffiti spray paints and one metallic (silver) polyethylene graffiti spray paint were applied to two granite stones with different mineralogy and texture and exposed to a natural urban-marine environment near Vigo (NW Spain) for one decade (2010−2020). Physical changes were evaluated by stereomicroscopy, colour spectrophotometry, measurements of gloss, surface roughness and static contact angle, and peeling test. Mineralogical changes were determined by x-ray diffraction and molecular changes by Fourier transform infrared spectroscopy. Moreover, micromorphological and chemical characterization of the surfaces was conducted by scanning electron microscopy.Physical-mechanical changes, such as craquelure and paint loss, depended on the texture of the granite. More specifically, paint on the granite with the finest grain size showed most intense cracking and loss of material. Chemical changes, which were not related to the granite substrate, were most intense in the red and silver paint coatings. In the red paint, loss of binder was accompanied by an intense fading of the colour (due to titanium dioxide relative enrichment), while in the silver paint coating, chemical changes occurred in both the organic binder and aluminium particles, thus darkening the colour. Fewer chemical changes were observed in the blue and black paints. Physical and chemical changes detected in these paints were not correlated.

Pengaruh Material Reflektor Terhadap Kinerja Kompor Energi Surya

The use of solar energy in Indonesia is the right choice as an alternative energy for energy needs in industry or to meet daily energy needs in households. To utilize solar energy for cooking purposes, a solar cooker can be used. Factors that affect the performance of this solar cooker in addition to the length of time it shines and the intensity of thermal radiation from the sun are the reflexivity of the collector material, the surface area of ​​the collector, the geometric shape and location of the focal point of the collector, the normal direction of the collector surface to the incoming sunlight, and the amount of heat loss to the surroundings. The materials used as reflectors in the research on this solar cooker are zinc (aluminum and galvanized) AL-Zn and black paint back ground mirror glass. This material is re-glued on top of a ready-made parabolic dish from the market. Then look for the focal point that corresponds to the diameter of the parabola. From the results of the study, it can be concluded that the back ground mirror glass material with black paint is better to use than the AL-Zn zinc plate if it is used as a raw material for the surface material (reflector) of solar cooker. Likewise, the efficiency of the solar oven in terms of the amount of heat that is converted into energy for heating the pot is better for a solar oven than a reflector with black paint back ground mirror glass material. And the efficiency of the solar cooker from the black paint back ground mirror on the first day is 16.4% to 25.7% on the second day, while the efficiency of the solar cooker from the AL-Zn zinc plate on the first day is 16.4% to second day 22.8%. The emissivity of the solar stove with AL-Zn zinc plate reflector on the first day was 0.02906 and on the second day 0.02892, while the emissivity of the solar cooker with black paint back ground mirror reflector on the first day was 0.01812 and the second day was 0 0.02544.

Improved surface temperature of absorber plate using metallic titanium particles for solar still application

Solar distillation technique by using solar stills is the most feasible and environment friendly way to supply fresh water in arid and remote regions. One of the key challenges in solar distillation is to enhance productivity of solar still. In this study, effect of metallic titanium (Ti) particles has been investigated for surface temperature of solar still absorber to increase the distillate production. Ti particles of various concentrations have been blended with black paint and applied on absorber plate. The morphology of the surface and phase identification of powder received have been studied and verified using SEM and XRD. The characteristics of light absorption were examined using Uv–vis Spectroscopy. Extensive outdoor and indoor testing (using improvised solar simulator) have been carried out to optimize the concentration. The highest temperature of 100.39 °C at 1000 W/m2solar irradiation in indoor conditions has been recorded for 7 wt% Ti specimen in black paint which is 11.87% higher compared to only black paint coated aluminum plate and 54.35% higher than bare aluminum plate. The 7 wt% Ti specimen temperature increased up to 77.58 °C in comparison to the aluminum plate having black paint. Further increase in concentration did not increase surface temperature due to excessive convective heat losses.

Oil crystallization properties as an index for monitoring early stage curing of oil-based paints: DSC analysis on linseed oil systems

In this work, we propose to follow the crystallization capability of oils in oil-based paints, during curing, as an indirect index of the matrix status in the early stages of paint film formation that usually are indicative and crucial to understand the process evolution. To proof the concept, the oil crystallization properties were investigated through DSC measurements on samples of both unpigmented linseed oil and two model paints, composed by lead white + linseed oil (LWLO) and ultramarine blue + linseed oil (UBLO), at different ageing time at room and oxygen-limiting conditions. The results indicate that the curing process strongly affects the oil’s ability of forming crystals in the paint layers, and the proposed experimental approach is rather suitable and sensitive enough to discriminate differences between the action of pigments and environmental conditions. On the other hand, despite the simplicity and the potentiality, this approach is limited at the early stages of paint curing offering an index of the overall matrix status and therefore must be intended as a complementary method that has to be integrated with other approaches if the aim is to explore in detail the chemical and physical aspects of the curing process.

Experimental and Theoretical Study of Parabolic Trough Solar Collector Performance Without Automatic Tracking System

In this research, a practical and theoretical study was conducted to evaluate the performance of parabolic trough collectors (PTCS) of length (3 m) and width (2.67 m) for three solar collectors connected in parallel, and the absorber tube is made of stainless steel with an internal and external diameter (0.028 m), (0.031 m), respectively. The absorber tube of length 11 m, was painted with un shiny black paint to increase the absorption of sunlight and reduces the thermal radiation. The working fluid is transferred through the receiver tube and located at the focus area of the three collectors. The collector width aperture width was 0.8 meters, and 2.40 meters length with rim angle of Ø = 90°, and concentration ratio of 8.02. The collector surface was covered with aluminum foil which is available in the local market (3M SA-85), which covers galvanized iron sheets with a thickness of 2 mm. A computer program in Fortran language was built to calculate the performance of the solar collector. Experimental results of the test showed that the performance factor of the solar collector is less than the typical type, where notes that there is a large deviation between the theoretical and experimental results, especially in the winter, where the deviation in the morning at ten o'clock about 78%, while it was 5% at noon. The large deviation value mentioned resulting from the assumptions that have been developed to simplify the equations that were used in the theoretical side of research, also the reasons that the theoretical results are taken on the assumption that weather conditions are clear sky and that contrary to reality in the winter. ةThe best efficiency of the solar collector was between solar time (12:00) and time (1:00) at night for two seasons, and the obtained results showed that the increase of mass flow rate of fluid from the amount of (0.033) kg/sec to the amount of (0.066) kg/sec increases the efficiency of solar collector, but leads to reduce the temperature difference between the inlet and exit, as well as the results showed that an increase in solar flux increases the useful energy obtained from the solar collector.

Optical, structural and thermal performances of black nickel selective coatings for solar thermal collectors

In the present study, the possibility of devising efficient and durable black nickel selective coating based solar thermal collectors (STCs) at ambient temperature was explored. For this, NASA electrochemical bath initially formulated by Peterson and Lin [Final Report: NASA-CR-149928, 1976] was employed. Quality of the STCs were optimized by evaluating pH, temperature, electric current density (Id) and deposition time (Td) dependence of optical, structural and thermal performance of the black nickel coating on the copper sheets and tubes. The optical measurements in the UV–Vis–NIR and NIR-MIR ranges inferred us that at pH ≈ 5.8, temperature in the range 20–25 °C, 2 mA/cm2 ≤ Id ≤ 4 mA/cm2 and 5 min. ≤ Td ≤ 7 min. result in reasonably good black nickel coatings with optimal selectivity factor. Moreover, from the analysis of XRD spectra, for the first time we observed the significantly larger crystallites size of coatings on Cu sheets than that of the coating on tubes. Observed thermal performances (evaluated by measuring the collector efficiencies) indicate that the electro-deposited black nickel-based STCs were superior by more than 20% over black paint based STCs.

Circular economy in marble industry: From stone scraps to sustainable water-based paints

Huge amounts of sludge waste are produced every day during the sawing and processing of carbonate ornamental stones. Most of these materials are landfilled and create serious environmental and health hazards. Thus, it is mandatory to find alternative solutions to recycle them. Since calcium carbonate is the most widely used mineral filler for interior and exterior emulsion paints, this investigation focused on the feasibility of trying out innovative methods of circular economy in a waste processing area. Focusing in the Orosei Marbles’ producing area (North-East Sardinia, Italy), the aim of this study was to compare the performance of water-based paints, through the use of marble sludge waste, as mineral fillers, rather than commercial CaCO3. According to standard normative tests were carried out on paint samples, prepared according to an experimental formulation, after a preliminary chemical and physical characterization of the fillers. The results indicate that the marble sludge waste can be successfully used as mineral filler in water-based paints, and that it requires only light pre-treatments consisting of deagglomeration and mechanical dispersion in a wet medium, thus confirming its environmental and economic benefits.

Energy and exergy analysis of a vertical solar air heater with nano-enhanced absorber coating and perforated baffles

In this work, the effect of applying nano-enhanced absorber coating on the energetic and exergetic performance of an unglazed vertical solar air heating system has been analyzed numerically and experimentally. In the first step of the research, various configurations of vertical solar air heaters including hollow, baffled and perforated baffled systems have been surveyed by using computational fluid dynamics. According to the numerically obtained findings, the system with perforated baffles gave the best performance metrics. In this regard, two heating systems with perforated baffles have been manufactured. One of the system was painted with a regular matt black paint while CuO nano-embedded black paint applied to the other solar heater. Fabricated heaters have been experimentally surveyed at three different flow rates. Thermal efficiency values for the heaters with and without nanoparticles were found between 58.10-76.22% and 54.96–72.05%, respectively. Applying nano-embedded coating increased the exergy efficiency in the range of 9.25–10.58%. In addition, maximum deviation of numerically and experimentally attained outlet temperature values was calculated as 4.74%. Moreover, general findings of this research showed the successful utilization of nano-enhanced absorber coating.

Eco-friendly synthesis of low-cost antibacterial agent (brown attapulgite-Ag nanocomposite) for environmental application

This work includes the eco-friendly synthesis of brown attapulgite-Ag nanocomposite by the in situ bio reduction of Ag ions using leaf extract of ziziphus spina christi L. The resulted nanocomposite was characterized using XRD, SEM, EDX-mapping and TEM. The results prove the presence of silver nanoparticles with a diameter of 27–44 nm and attapulgite rods within the nanocomposite. The brown attapulgite-Ag nanocomposite was used as a colorizing antibacterial agent for pentalite emulsion paint (pep). Four different weights of nanocomposite (0.1, 0.5, 1.5 and 3 g) was added to 10 ml of pep and suspended in 10 ml of water. The antibacterial results show that this paint is useful to inhibit the bacteria growth in the presence of brown attapulgite-Ag nanocomposite. The thermal stability of brown attapulgite-Ag nanocomposite was studied at 100 °C and the XRD measurement proves that there is no change occurred for brown attapulgite-Ag nanocomposite after thermal treatment. Furthermore, the acid and base stability of brown attapulgite-Ag nanocomposite were examined and the results of ICP-OES prove the stability of the prepared nano colorizing additive. .

Study on properties of porous SiO2/GO modified polyurethane coatings loaded with corrosion inhibitor

Polyurethane (PU) coating can provide physical barrier for metal surface, but the penetration of corrosive ions will affect the long-term corrosion resistance of the coating. In order to improve the corrosion resistance of the coating, it is necessary to modify the coating to reduce the internal defects of the coating and improve the corrosion resistance of the coating. Using mesoporous silica (SiO2) as the carrier to support the corrosion inhibitor 2- mercaptobenzimidazole (MBI), and using the silane coupling agent GPTS as the bridging agent to compound with graphene oxide (GO) to prepare f-GO-MBI @SiO2 composite nano-materials, f-GO-MBI @SiO2 composite nano-materials are added to the polyurethane varnish in different proportions, and the f-GO-MBI @SiO2 modified PU coating is obtained on the surface of carbon steel by spraying method to improve the carbon corrosion resistance of steel substrate. The composition and loading conditions of drug-loaded composite nanomaterials were characterized by fourier infrared spectroscopy (FTIR) and laser particle size analyzer; electrochemical impedance spectroscopy (EIS) and neutral salt spray test were used to study the properties of different coatings corrosion resistance. The results shows that the addition of f-GO-MBI @SiO2 composite nano-materials significantly improves the corrosion resistance of the coating, the low addition amount will reduce the anti-corrosion effect, and the addition of too high can easily lead to agglomeration of composite nano-materials and produce paint film defects. When the addition amount of f-GO-MBI @SiO2 is 5 wt%, the low-frequency impedance of the coating is two orders of magnitude higher than that of the pure polyurethane coating, the corrosion spread width at the neutral salt spray scratches is reduced to 1.5 mm, and the coating has the best corrosion resistance.

A novel solar absorber using activated carbon nanoparticles synthesized from bio-waste for the performance improvement of solar desalination unit

Enhancing the efficiency of low-cost solar-powered desalination technologies such as solar stills (SS) is essential to ensuring sustained access to potable water in water-stressed areas. In the present work, the potential enhancement of SS performance through the addition of different concentrations of activated carbon nanoparticles (ACNPs) to the standard black paint used to coat the absorber plate was explored. SSs were fabricated with absorber coated using black paint doped with 0, 5, 10 and 15 wt% ACNPs (denoted as CSS, MSS-5, MSS-10 and MSS-15, respectively) and the effect on water temperature and distillation efficiency determined. ACNPs were synthesized by crushing dead Kigelia Africana leaves and pyrolysis of the leaf powder in a muffle furnace at 500 °C. Absorber surface roughness analysis illustrated increasing roughness with increasing the loading of ACNPs in the nano-paint, leading to significant increase in heat transfer. Significant improvement in average water temperature (12.5%) and absorber (14.5%) was noted in the modified SS coated with 15 wt% ACNP over the CSS. The augmented temperature of this still enhanced the peak hourly and full-day water yield of MSS-15 by ⁓39.3%, compared to the conventional SS. The water quality analysis shows that the distilled water is appropriate for drinking. In conclusion, the synergetic effect of the high thermal conductivity and excellent solar absorption of the ACNP-based solar absorber improves the performance of the SS unit.

Thin liquid films on a rotary bell atomizer in surface-following coordinates

This article analyzes a published formulation of the Navier–Stokes equations cast into surface-following coordinates and provides some additional mathematical background to follow the article. Ubiquitous in the paint shops of automotive plants around the world, a high-speed rotary bell is succinctly described as a rapidly spinning concave axisymmetric surface with liquid paint supplied from a port coinciding with the center of rotation. The spinning surface transfers momentum to the paint film causing it to flow outward. Upon reaching the bell periphery, it is flung off, subsequently forming an atomized spray transferred to an automotive body through advection and electrostatics. Common analytical frameworks of rotating films were spherical or cylindrical coordinate systems where the wetted surface profile of the bell was constrained to follow a coordinate axis. This led to solutions for films modeled with conical, disk-like, or partial hemispherical profiles. An alternative was a more general case using a surface-following orthogonal curvilinear coordinate system along with its derived vector operators. In the unique case of a thin film, these results validated a simpler pattern found in common coordinate systems.

Experimental analysis of combined utilization of CuO nanoparticles in latent heat storage unit and absorber coating in a single-slope solar desalination system

In this survey, impact of combined utilization of copper oxide (CuO) nanoparticles both in thermal energy storage unit and absorber coating (matt black paint) on the performance of a single-slope solar still has been investigated experimentally. In this context, four different solar desalination systems including a conventional solar still, solar still with thermal energy storage unit, solar still with CuO nano-embedded latent heat storage unit and solar still with CuO nano-enhanced absorber coating and thermal energy storage unit have been developed, fabricated and empirically analyzed. Experimental results showed that combined employing nanoparticles upgraded accumulated productivity as 26.77% in comparison to conventional solar still. Also, energy and exergy efficiency values were enhanced from 15.96% to 19.90% and from 1.25% and 2.01%, respectively with the use of combined modification.

Research on tribological properties of H13 steel of shield machine hob by laser shot peening

In this paper, the laser shot peening (LSP) technology of H13 steel is studied to improve the friction and wear performance of shield machine hob. And to utilize the LSP experiment and simulation analysis, the influence of LSP parameters on the friction and wear performance of H13 steel after strengthening is studied. The numerical simulation study reveals the variation law of laser parameters on residual stress and stress layer depth. Study on friction and wear characteristics of H13 steel after LSP. The results show that the maximum residual stress of H13 steel is 911 MPa, and the hardness is 650.7 HV, when there are three times of black paint absorption and LSP. Compared with the raw material, the residual stress is increased by 125%, and the hardness is increased by 18%. And its friction coefficients and wear volume were relatively lower than other schemes. The average friction coefficient and wear volume were reduced by 10.8% and 57.2% respectively.

Effect of Tin Oxide/Black Paint Coating on Absorber Plate Temperature for Improved Solar Still Production: A Controlled Indoor and Outdoor Investigation

The ever-increasing water stress and availability of fresh drinking water are becoming a major challenge in rural and urban communities. The current high-end and large-scale technologies are becoming way more expensive and not friendly to the environment. In this regard, solar still is becoming a prominent and promising future technology due to its environment-friendly nature, less maintenance and operational costs, and simple design. The technological challenge regarding solar still is its low distillate yield. In this study, an attempt has been made to investigate the effect of tin oxide (SnO2) on the absorption surface of solar still towards improvement in sunlight absorption, which would lead to high distillate production rates. Various concentrations of SnO2, i.e., 0.5wt%, 1 wt%, 3 wt%, 5 wt%, 7 wt%, 10 wt%, 15 wt%, and 20 wt%, have been mixed in black and applied on the absorber plate to further optimize the suitable concentration. The experiments have been performed in both indoor (simulated) and outdoor conditions. An increase in surface temperature of absorber plate has been observed with increasing concentration of SnO2 under both the indoor and outdoor conditions, which is due to high solar spectrum absorption properties of SnO2 in the ultraviolet (UV) and near to far-infrared (IR) regions. The highest surface temperature of 101.61°C has been observed for specimens containing 15 wt% SnO2 in black paint under indoor conditions at 1000W/m2 irradiation levels, which is 53.67% higher compared to bare aluminum plate and 16.91% higher compared to only black paint coated aluminum plate. On the other hand, the maximum temperature of 74.96°C has been recorded for the identical specimens containing 15 wt% SnO2 under uncontrolled outdoor conditions. The recorded temperature is 47.96% higher than the bare aluminum plate and 14.88% higher than the black paint-coated aluminum plate. The difference of maximum temperatures under indoor and outdoor conditions is due to uncontrolled outdoor conditions and convective losses.

El arte en la encrucijada de la historia sudafricana Resonancias a partir de la obra de Tracey Rose

The most interesting intellectual tradition of cultural studies invites us to observe the interconexion among life experiences, culture and power. In this paper we aim to analyze racism and colonialism continuities in contemporary South Africa from a feminist point of view, where official narratives about South African recent past are contested. Our starting point is the video-instalation The Black Painting: Dead White Man de Tracey Rose, presented at Goodman Gallery, Cape Town in 2015, in order to analyze the binarism as an epistemological discourse producing history and framing art as one of the possible historical narratives; simultaneously, we aim to underline the young Black artist contribution to a radical critic of South African History and its present resonances.

Effect of allergic rhinitis on sleep in children and the risk factors of an indoor environment.

Allergic rhinitis (AR) is an independent risk factor for sleep disorders in children, including abnormal sleep behaviors. We investigated the occurrence of abnormal sleep behaviors in children with AR to determine indoor environmental risk factors affecting sleep. This case-control study collected the sleep status and characteristics of the indoor environment of children aged 3-14 yearswith and without AR using a questionnaire. The differences between the two groups were compared using the Mann-Whitney U test, chi-square test, and Fisher's exact test. The indoor environmental factors affecting sleep behavior were analyzed using logistic regression analysis. Children with AR(n=427) had a higher probability of snoring (8.7 % vs. 2.9 %; P < 0.001), mouth breathing (14.1 % vs. 5.2 %; P < 0.001), restless sleep (6.6 % vs. 4.1 %; P = 0.047), sleep talking (3.3 % vs. 1.1 %; P = 0.003), and hyperhidrosis (16.4 % vs. 8.5 %; P < 0.001) than those without AR (n=1046). Emulsion wall paint (odds ratio (OR) = 2.779; 95 % confidence interval (CI), 1.332-5.796; P = 0.006) and tobacco exposure in early infancy (OR = 2.065; 95 % CI 1.079-3.950; P = 0.029) were associated with hyperhidrosis. Children with AR are more likely to have abnormal sleep behaviors than those without, including snoring, mouth breathing, restless sleep, sleep talking, and hyperhidrosis. Emulsion paint wall and tobacco smoke exposure in early infancy had a twofold higher risk of hyperhidrosis during sleep.

Preparation of wood furniture cooling coatings based on phase change microcapsules and its performance study

Due to the small thermal conductivity of wooden furniture, there is a better cooling effect in the initial contact with the human body during the summer. However, after long-term contact, heat cannot be exported, resulting in heat accumulation, which affects the thermal comfort. Phase change microcapsules (PCM) can be added to water-based coatings for wood furniture to achieve a lower contact temperature by using the heat absorption properties of its phase change process. Thus, it improves the thermal comfort of the human body for long-term use. In this study, the PCM were added to a water-based paint for wooden furniture. By testing the microscopic properties and thermal properties, it was found that the PCM powder could undergo phase change and absorb heat after dispersing in water-based paint. Secondly, fiberboard coated with different solid content of microencapsulated coatings was tested by homemade equipment at 27 °C room temperature. The results showed that the addition of PCM can significantly change the contact temperature. And as the amount of microcapsules added increased, the cooling effect was more obvious. At the same time, the addition of microcapsules can cause matting of the paint film and have an effect on the hardness of the paint film. Therefore, the cooling effect can be achieved by stacking the paint film or controlling the amount of microcapsules.

Exploring the potential of MXene-based advanced solar-absorber in improving the performance and efficiency of a solar-desalination unit for brackish water purification

Brackish water desalination using solar still (SS) is a low-cost sustainable solution to global water scarcity, but this technology suffers from low yield and efficiency. The judicious amalgamation of highly conductive materials with superior solar absorption behavior is one of the most effective approaches to overcome this limitation. In this regard, the present work synthesizes a novel multilayered 2-D MXene from 3-D MAX phase as a coating material for the solar absorber of a SS to improve its performance. Two different loadings of MXene (0.05 and 0.1 wt%) were dispersed in turpentine oil/black paint (1:4) and coated onto the solar absorber of the SS. Higher MXene loading significantly augmented the thermal conductivity and solar absorptivity of the turpentine oil/black paint solution. The 0.1 wt% MXene coated absorber provided a higher heat transfer rate from the absorber to the water, leading to a 6% increase in water temperature and a total water yield of 2.07 kg. The theoretical calculated water yield was identical to the experimental yield with a deviation of ±5%, demonstrating the accuracy of thermal modelling. The average energy efficiency of the SS with 0.1 wt% MXene in the absorber black paint coating was 36.31%. Water quality analysis has shown that the distilled water resulting from the desalination is suitable for drinking. In conclusion, MXene with its excellent thermo-physical properties and solar absorptivity will be beneficial in development of efficient solar desalination units with augmented performance for water purification.