Performance and exergy analysis of solar-operated vacuum fan and external condenser integrated double-slope solar still using various nanofluids.

Productivity, distillate exergy, and energy efficiency of the conventional passive single-basin double-slope solar still is minimum, due to low evaporation and condensation rate. This research article attempts to increase the production rate, distillate exergy, and energy efficiency of the single-basin glasswool-insulated double-slope solar still by attaching novel solar-operated vacuum fan, external condenser and adding 0.1% volume concentration of copper oxide, aluminium oxide, and zinc oxide nanofluid. Inclusion of vacuum fan and external condenser enhances the production rate in the modified solar still. It is evident that as the vacuum fan exhales the vapour in the basin, the temperature of water in the basin and transparent glass are reduced significantly and so the vaporization amount increases considerably. It makes that a large amount of vapour is extracted by the vacuum fan and allowed to pass though the condenser, and therefore, the entire condensate of the solar still is increased significantly. To attain a comparative study, conventional and modified double-slope solar still of identical dimensions were developed utilizing aluminium and an experimental investigation carried out during the peak of summer. The inclusion of solar-operated vacuum fan and external condenser in the modified glasswool insulated double-slope solar still enhances the maximum energy efficiency, exergy efficiency, and cumulative production by 28.37%, 78.60%, and 64.29% due to enhancement in the evaporation rate of liquid in the solar still basin. Also, the addition of 0.1% volume concentration of copper oxide, aluminium oxide, and zinc oxide nanofluid in the conventional double-slope solar still possess the maximum increase in the energy efficiency and exergy efficiency by 20.96%, 18.01%, 10.76% and 52.53%, 38.52%, 30.35% as compared to conventional solar still without nanofluid. It is primarily due to increase in the thermal conductivity and radiative property of nanofluid. The result also signifies that the addition of 0.1% volume concentration of copper oxide, aluminium oxide, and zinc oxide nanofluid in the modified double-slope solar still possess the maximum enhancement in the energy efficiency and exergy efficiency by 21.33%, 19.36%, 17.03% and 50.11%, 36.82%, 23.75% as compared to modified solar still without nanofluid. Combined effect of using solar-operated vacuum fan, water cooled condenser, and 0.1% volume concentration of copper oxide, aluminium oxide, and zinc oxide nanofluid in the double-slope solar still enhances the maximum production rate and cumulative production by 59.26%, 55.56%, 51.85% and 96.43%, 82.14%, 75% as compared to conventional double-slope solar still. Among the three different nanofluids, the copper oxide nanofluid produced the highest cumulative production, energy efficiency, and exergy efficiency.

Performance analysis of a solar dryer integrated with thermal energy storage using PCM-Al2O3 nanofluids.

Solar energy will assist in lowering the price of fossil fuels. The current research is based on a study of a solar dryer with thermal storage that uses water and waste engine oil as the working medium at flow rates of 0.035, 0.045, and 0.065 l/s. A parabolic trough collector was used to collect heat, which was then stored in a thermal energy storage device. The system consisted of rectangular boxes containing stearic acid phase change materials with 0.3vol % Al2O3 nanofluids, which stored heat for the waste engine oil medium is 0.33 times that of the water medium at a rate of flow of 0.035 l/s which was also higher than the flow rates of 0.045 and 0.065 l/s. The parabolic trough reflected solar radiation to the receiver, and the heat was collected in the storage medium before being forced into circulation and transferred to the solar dryer. At a flow rate of 0.035 l/s, the energy output of the solar dryer's waste engine oil medium and water was determined to be roughly 12.4, 14, and 15.1, and 9.8, 10.5, and 11.5 times lower than the crops output of groundnut, ginger, and turmeric, respectively. The energy output in the storage tank and the drying of groundnut, ginger, and turmeric crops with water and waste engine oil medium at varied flow rates of 0.035, 0.045, and 0.065 l/s were studied. Finally, depending on the findings of the tests, this research could be useful in agriculture, notably in the drying of vegetables.

Synergistic Effect of Nanofluids and Surfactants on Heavy Oil Recovery and Oil-Wet Calcite Wettability.

In recent years, unconventional oils have shown a huge potential for exploitation. Abundant reserves of carbonate asphalt rocks with a high oil content have been found; however, heavy oil and carbonate minerals have a high interaction force, which makes oil-solid separation difficult when using traditional methods. Although previous studies have used nanofluids or surfactant alone to enhance oil recovery, the minerals were sandstones. For carbonate asphalt rocks, there is little research on the synergistic effect of nanofluids and surfactants on heavy oil recovery by hot-water-based extraction. In this study, we used nanofluids and surfactants to enhance oil recovery from carbonate asphalt rocks synergistically based on the HWBE process. In order to explore the synergistic mechanism, the alterations of wettability due to the use of nanofluids and surfactants were studied. Nanofluids alone could render the oil-wet calcite surface hydrophilic, and the resulting increase in hydrophilicity of calcite surfaces treated with different nanofluids followed the order of SiO2 > MgO > TiO2 > ZrO2 > γ-Al2O3. The concentration, salinity, and temperature of nanofluids influenced the oil-wet calcite wettability, and for SiO2 nanofluids, the optimal nanofluid concentration was 0.2 wt%; the optimal salinity was 3 wt%; and the contact angle decreased as the temperature increased. Furthermore, the use of surfactants alone made the oil-wet calcite surface more hydrophilic, according to the following order: sophorolipid (45.9°) > CTAB (49°) > rhamnolipid (53.4°) > TX-100 (58.4°) > SDS (67.5°). The elemental analysis along with AFM and SEM characterization showed that nanoparticles were adsorbed onto the mineral surface, resulting in greater hydrophilicity of the oil-wet calcite surface, and the roughness was related to the wettability. Surfactant molecules could aid in the release of heavy oil from the calcite surface, which exposes the uncovered calcite surface to its surroundings; additionally, some surfactants adsorbed onto the oil-wet calcite surface, and the combined role made the oil-wet calcite surface hydrophilic. In conclusion, the study showed that hybrid nanofluids showed a better effect on wettability alteration, and the use of nanofluids and surfactants together resulted in synergistic alteration of oil-wet calcite surface wettability.

Zinc oxide nanofluids: The influence of modality combinations on prostate cancer DU145 cells.

AIM: The combination of phototherapy and chemotherapy (chemophototherapy), presents a promising multimodal method for comprehensive cancer treatment. The aim of this study is to investigate the influence of low doses of zinc oxide (ZnO) nanofluids and ultraviolet A (UVA) irradiation on the cytotoxicity and cellular uptake of doxorubicin (DOX) on human prostate cancer DU145 cells. MATERIALS AND METHODS: ZnO nanoparticles were prepared by the solvothermal method and 10% bovine serum albumin was used as the dispersant. The cytotoxic effect of DOX alone and in combination with different concentrations of ZnO nanofluids (0.95-15.6 µg/ml) in the presence and absence of UVA irradiation on DU145 cells was evaluated by -(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. DOX residue inside and outside of DU145 cells was explored by fluorescence microscopy and UV-Vis absorption spectroscopy, respectively. The role of ZnO nanofluids and UVA irradiation in DOX-induced apoptosis and cell cycle arrest were evaluated by DAPI staining, comet assay, and flow cytometry. RESULTS: The results revealed that low dose of ZnO nanofluids (0.95 µg/ml) accompanied with irradiation enhanced the cytotoxicity and intracellular delivery of DOX in DU145 cells. The percentage of chromatin fragmentation/condensation and DNA tail of DU145 cells treated simultaneously with DOX and ZnO nanofluids was increased after UVA irradiation, whereas no significant changes in cell cycle progression were observed. CONCLUSION: The results indicate that ZnO nanofluids in the presence of UVA irradiation could increase DOX efficiency in DU145 cells, suggesting such modality combinations as a promising approach in cancer treatment.

Facile Use of Silver Nanoparticles-Loaded Alumina/Silica in Nanofluid Formulations for Enhanced Catalytic Performance toward 4-Nitrophenol Reduction.

The introduction of toxic chemicals into the environment can result in water pollution leading to the degradation of biodiversity as well as human health. This study presents a new approach of using metal oxides (Al2O3 and SiO2) modified with a plasmonic metal (silver, Ag) nanoparticles (NPs)-based nanofluid (NF) formulation for environmental remediation purposes. Firstly, we prepared the Al2O3 and SiO2 NFs of different concentrations (0.2 to 2.0 weight %) by ultrasonic-assisted dispersion of Al2O3 and SiO2 NPs with water as the base fluid. The thermo-physical (viscosity, activation energy, and thermal conductivity), electrical (AC conductivity and dielectric constant) and physical (ultrasonic velocity, density, refractive index) and stability characteristics were comparatively evaluated. The Al2O3 and SiO2 NPs were then catalytically activated by loading silver NPs to obtain Al2O3/SiO2@Ag composite NPs. The catalytic reduction of 4-nitrophenol (4-NP) with Al2O3/SiO2@Ag based NFs was followed. The catalytic efficiency of Al2O3@Ag NF and SiO2@Ag NF, for the 4-NP catalysis, is compared. Based on the catalytic rate constant evaluation, the catalytic reduction efficiency for 4-NP is found to be superior for 2% weight Al2O3@Ag NF (92.9 × 10-3 s-1) as compared to the SiO2@Ag NF (29.3 × 10-3 s-1). Importantly, the enhanced catalytic efficiency of 2% weight Al2O3@Ag NF for 4-NP removal is much higher than other metal NPs based catalysts reported in the literature, signifying the importance of NF formulation-based catalysis.

γ-Nanofluid Thermal Transport between Parallel Plates Suspended by Micro-Cantilever Sensor by Incorporating the Effective Prandtl Model: Applications to Biological and Medical Sciences.

The flow of nanofluid between infinite parallel plates suspended by micro-cantilever sensors is significant. The analysis of such flows is a rich research area due to the variety of applications it has in chemical, biological and medical sciences. Micro-cantilever sensors play a significant role in accurately sensing different diseases, and they can be used to detect many hazardous and bio-warfare agents. Therefore, flow water and ethylene glycol (EG) composed by γ-nanoparticles is used. Firstly, the governing nanofluid model is transformed into two self-similar nanofluid models on the basis of their effective models. Then, a numerical method is adopted for solution purposes, and both the nanofluid models are solved. To enhance the heat transfer characteristics of the models, the effective Prandtl model is ingrained in the energy equation. The velocity F'(η) decreases with respect to the suction of the fluid, because more fluid particles drags on the surface for suction, leading to an abrupt decrement in F'(η). The velocity F'(η) increases for injection of the fluid from the upper end, and therefore the momentum boundary layer region is prolonged. A high volume fraction factor is responsible for the denser characteristics of the nanofluids, due to which the fluids become more viscous, and the velocity F'(η) drops abruptly, with the magnetic parameters favoring velocity F'(η). An increase in temperature ß ( η ) of Al2O3-H2O and γAl2O3-C2H6O2 nanofluids was reported at higher fraction factors with permeable parameter effects. Finally, a comparative analysis is presented by restricting the flow parameters, which shows the reliability of the study.

Combining life cycle assessment and qualitative risk assessment: the case study of alumina nanofluid production.

In this paper the authors propose a framework for combining life cycle assessment (LCA) and Risk Assessment (RA) to support the sustainability assessment of emerging technologies. This proposal includes four steps of analysis: technological system definition; data collection; risk evaluation and impacts quantification; results interpretation. This scheme has been applied to a case study of nanofluid alumina production in two different pilot lines, "single-stage" and "two-stage". The study has been developed in the NanoHex project (enhanced nano-fluid heat exchange). Goals of the study were analyzing the hotspots and highlighting possible trade-off between the results of LCA, which identifies the processes having the best environmental performance, and the results of RA, which identifies the scenarios having the highest risk for workers. Indeed, due to lack of data about exposure limits, exposure-dose relationships and toxicity of alumina nanopowders (NPs) and nanofluids (NF), the workplace exposure has been evaluated by means of qualitative risk assessment, using Stoffenmanager Nano. Though having different aims, LCA and RA have a complementary role in the description of impacts of products/substances/technologies. Their combined use can overcome limits of each of them and allows a wider vision of the problems to better support the decision making process.