Latest Results The latest content available from Springer http://fionamettini.com Latest Results http://fionamettini.com/12678 2021-09-01 12678 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">Today, hydrogen mainly originates from fossil sources (gas, oil, and coal). Room temperature water electrolysis is an interesting alternative for renewable electricity storage, even if it is well-known that high-temperature systems are more efficient. To address this issue, we studied different non-platinum group metal (non-PGM) catalysts for alkaline oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) by recording cyclic voltamperograms with a rotating disk electrode set up. Physicochemical characterizations of Ni-based and FeNi<sub class="a-plus-plus">3</sub>-based catalysts were performed using transmission electron microscopy, X-ray diffraction (XRD), and inductively coupled plasma mass spectroscopy (ICP-MS). Ni synthesized by the hot injection method is a good catalyst for HER, yet still less active than Pt/C. FeNi<sub class="a-plus-plus">3</sub> with and without a Ni surface doping is very good OER catalysts, slightly better than commercial unsupported IrO<sub class="a-plus-plus">2</sub>. Electrochemical tests under alternating magnetic field (AMF) using these nanoparticles are ongoing, as these materials are compatible with AMF activation.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">Graphical Abstract</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_616_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00616-9 2021-09-01 10.1007/s12678-020-00616-9 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">Biomass has some advantages including renewability, abundant resources, being eco-friendly, easy processing, and low cost; and it is an important step in designing electrocatalysts in fuel cells as clean energy sources. In this study, a biomass-based carbon nanofiber of <em class="a-plus-plus">Typha domingensis</em>, as available biomass source, and nickel-cobalt oxides is synthesized. The physicochemical techniques including X-ray powder diffraction, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, Barrett-Joyner-Halenda, and Brunauer-Emmett-Teller as well as electrochemical techniques are used to evaluate the surface morphology, crystal structure, and electrochemical performance of composites. The biomass-derived composite is used as a new electrocatalyst for the oxygen reduction reaction and oxygen evaluation reaction. A membrane electrode assembly is prepared by employing of the produced composite for alkaline passive direct methanol fuel cell, which characterized by polarization, power density curves, methanol crossover test, and stability test for 8 h. Electrochemical results show that the composite is an appropriate electrode material for oxygen reduction reaction in passive direct methanol fuel cells.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">Graphical Abstract</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_607_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00607-w 2021-09-01 10.1007/s12678-020-00607-w Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">Copper(I) oxide (Cu<sub class="a-plus-plus">2</sub>O) was electrochemically deposited on fluorine-doped tin oxide (FTO) glass electrode and covered with a thin layer of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The electrode was studied in the photoelectrocatalytic reduction of CO<sub class="a-plus-plus">2</sub>. Methanol was obtained as the major product with a concentration of 460 μmol L<sup class="a-plus-plus">−1</sup> with a photoconversion yield of 12% after 60 min of reaction under the conditions of UV-Vis (125 W Hg high pressure lamp) and application of 0.0 V vs Ag/AgCl in 3.0 mol L<sup class="a-plus-plus">−1</sup> KCl in buffer sodium carbonate/sodium bicarbonate 0.1 mol L<sup class="a-plus-plus">−1</sup> saturated with CO<sub class="a-plus-plus">2</sub> gas. The PEDOT:PSS has led to a significant improvement in CO<sub class="a-plus-plus">2</sub> conversion due to rapid transfer of photogenerated holes. Consequently, the thin layer of PEDOT:PSS also reduces the photooxidation of Cu<sub class="a-plus-plus">2</sub>O to CuO. The Cu<sub class="a-plus-plus">2</sub>O/PEDOT:PSS photocatalytic system was found to have excellent photostability. Similar yield of alcohol was observed after reusing the catalyst six times.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">Graphical Abstract</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_612_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00612-z 2021-09-01 10.1007/s12678-020-00612-z Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">The effects of the nanoscale particle size of RuO<sub class="a-plus-plus">2</sub> in thermally prepared RuO<sub class="a-plus-plus">2</sub>-coated Ti anodes on electrochemical kinetic parameters such as the active surface area and Tafel slope for oxygen evolution in sulfuric acid solutions were investigated. RuO<sub class="a-plus-plus">2</sub>/Ti anodes with four different average sizes of RuO<sub class="a-plus-plus">2</sub> particles—5.6 nm, 6.8 nm, 14.6 nm, and 21.2 nm—were prepared. The double-layer charge corresponding to the active surface area for oxygen evolution of the anodes was shown to increase with decreasing average RuO<sub class="a-plus-plus">2</sub> particle size. The polarization curves of the anodes showed that the oxygen evolution current density at a certain potential increased with decreasing average RuO<sub class="a-plus-plus">2</sub> particle size, meaning that oxygen evolution, especially in the high-current-density region, where it mainly depends on the mass transfer rate, accelerated with decreasing RuO<sub class="a-plus-plus">2</sub> particle size. The Tafel slope obtained for the anodes was shown to decrease with decreasing average RuO<sub class="a-plus-plus">2</sub> particle size, indicating that the change in particle size affected the electron transfer rate for oxygen evolution. The present study reveals that changes in the nanoscale size of RuO<sub class="a-plus-plus">2</sub> affect not only the mass transfer process but also the electron transfer process for oxygen evolution in sulfuric acid solutions.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">Graphical abstract</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_610_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00610-1 2021-09-01 10.1007/s12678-020-00610-1 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">The electrochemical and corrosion characterization of Ti<sub class="a-plus-plus">0.97</sub>Ru<sub class="a-plus-plus">0.03</sub>O<sub class="a-plus-plus">2</sub>/Ti electrodes modified with WO<sub class="a-plus-plus">3</sub> was reported. Modification of Ti<sub class="a-plus-plus">0.97</sub>Ru<sub class="a-plus-plus">0.03</sub>O<sub class="a-plus-plus">2</sub>/Ti electrodes with WO<sub class="a-plus-plus">3</sub> was previously described as improving the effectiveness of an azo dye degradation in a photoelectrochemical treatment. Thus, the effect of WO<sub class="a-plus-plus">3</sub> introduction to oxide film on electrode surface on electrochemical behaviour and stability of the modified electrodes was investigated. Moreover, corrosion behaviour of Ti<sub class="a-plus-plus">0.97</sub>Ru<sub class="a-plus-plus">0.03</sub>O<sub class="a-plus-plus">2</sub>/Ti electrodes modified with WO<sub class="a-plus-plus">3</sub> was evaluated with the application of potentiodynamic polarization sweep method and open circuit potential measurement. Electrodes modified with WO<sub class="a-plus-plus">3</sub> revealed higher anodic and cathodic peak currents in K<sub class="a-plus-plus">4</sub>[Fe(CN)<sub class="a-plus-plus">6</sub>] solution (by 35% for 6%WO<sub class="a-plus-plus">3</sub> content) indicating higher electroactive surface area and faster electron transfer reaction. An increase in WO<sub class="a-plus-plus">3</sub> amount in the oxide layer caused an increase in the number of active sites determined in Na<sub class="a-plus-plus">2</sub>SO<sub class="a-plus-plus">4</sub> and most of them (more than 80%) were located in the outer and more accessible surface. The investigation of the tested electrodes at high potentials at which oxygen evolution is observed, allowed their classification in the following order showing an increase in their activity towards oxygen evolution reaction: Ti<sub class="a-plus-plus">0.97</sub>Ru<sub class="a-plus-plus">0.03</sub>O<sub class="a-plus-plus">2</sub>/Ti &lt; Ti<sub class="a-plus-plus">0.94</sub>Ru<sub class="a-plus-plus">0.03</sub>O<sub class="a-plus-plus">2</sub>-W<sub class="a-plus-plus">0.03</sub>O<sub class="a-plus-plus">3</sub>/Ti &lt; Ti<sub class="a-plus-plus">0.91</sub>Ru<sub class="a-plus-plus">0.03</sub>O<sub class="a-plus-plus">2</sub>-W<sub class="a-plus-plus">0.06</sub>O<sub class="a-plus-plus">3</sub>/Ti. Although the electrode modification with WO<sub class="a-plus-plus">3</sub> resulted in lower resistance to corrosion in Na<sub class="a-plus-plus">2</sub>SO<sub class="a-plus-plus">4</sub> solution regarding corrosion potential, corrosion current densities were clearly lower in comparison with the non-modified electrode, especially after longer immersion in the solution. ASTs showed that even a small addition of WO<sub class="a-plus-plus">3</sub> increased the lifetime of the electrodes. The Ti<sub class="a-plus-plus">0.97</sub>Ru<sub class="a-plus-plus">0.03</sub>O<sub class="a-plus-plus">2</sub>/Ti electrode modification with WO<sub class="a-plus-plus">3</sub> seemed to be advantageous for their application in electrochemical and photoelectrochemical degradation of organic pollutants.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">Graphical Abstract</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_615_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00615-w 2021-09-01 10.1007/s12678-020-00615-w Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">The generation of novel mesoporous materials with well-defined structure and accessible pore networks is helpful in both fundamental and energy-related research. Nanocasting mesoporous earth-abundant materials and their composite materials offer opportunities to make electrochemically active materials that allow scalable production and cost-effectiveness. Recently, due to their intrinsic open pore structure as well as high surface areas, various mesoporous cobalt-based ordered materials have been applied to electrocatalysis, rechargeable batteries, and supercapacitors. In this review, we have critically evaluated the advancements made specifically in three- and two-dimensionally (3D/2D) electrode Co-based materials (oxides, nitrides, phosphides, and sulfides). We outline foreseeable challenges and issues for the utilization of mesostructured cobalt-based electrode materials. This review also provides guidelines for further work to those who work on energy-related applications of mesoporous cobalt-based materials.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <strong class="a-plus-plus caption-number">Graphical Abstract</strong> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">Nanocast cobalt-based mesoporous materials hold great promise in the application of energy conversion and storage. Herein, recent advances of two-dimensional and three-dimensional mesoporous cobalt-based mesoporous oxides, nitrides, phosphides, and sulfides used for electrocatalysis, rechargeable batteries, and supercapacitors were discussed. Moreover, the structure-property relationships of these materials and current challenges in both nanoarchitecture design and their applications in electrochemical energy devices are proposed. An outlook is provided for future research.</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_608_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00608-9 2021-09-01 10.1007/s12678-020-00608-9 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">The synthesis of AgPd bimetallic nanoparticles was carried out by a simple polyol method in order to obtain an improved control of the morphology and the particle size. The nanoparticles were characterized using aberration-corrected scanning/transmission electron microscopy (STEM). Also, parallel beam X-ray diffraction analysis was carried out to evaluate the crystallographic structure. High-angle annular dark field (HAADF)-STEM images of the AgPd bimetallic nanoparticles were obtained. The contrast of the images shows that the nanoparticles have an alloy structure with an average size of 10.17 nm and icosahedral morphology. Electrochemical characterization was carried out to analyze the catalytic behavior of the bimetallic nanoparticles. Ag<sub class="a-plus-plus">2</sub>Pd<sub class="a-plus-plus">1</sub>/C bimetallic nanoparticles showed a better catalytic activity towards oxygen reduction reaction than Ag/C at room temperature. Furthermore, simulations based on DFT method have been used to describe the crystalline structure of nanoparticles, revealing that the electronic structure is significantly affected by the elemental distribution.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">Graphical Abstract</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_613_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00613-y 2021-09-01 10.1007/s12678-020-00613-y Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">Incorporation of precious metallic nanoparticles onto a carbon support material is used to obtain an electrocatalyst for ethanol oxidation. A composite material of spherical palladium nanoparticles (Pd NPs), reduced graphene oxide (rGO), and polydopamine (PDA) on three-dimensional nickel foam (NF) substrate (Pd/rGO/PDA@NF) has been synthesized for ethanol electrocatalysis. The Pd nanoparticles were obtained via reduction of precursor K<sub class="a-plus-plus">2</sub>PdCl<sub class="a-plus-plus">4</sub> using ascorbic acid at 60 °C for 80 min. The rGO with large specific surface area was used in catalysts to provide large amounts of active sites for Pd NPs. Meanwhile, Pd NPs as an effective ingredient in catalyst exhibited excellent electrochemical activity of ethanol oxidation. Local surface plasmon resonance was carried out to determine the optimal concentration of precursor K<sub class="a-plus-plus">2</sub>PdCl<sub class="a-plus-plus">4</sub> aqueous solution, and the absorbance peak of Pd NPs was found at about 340–370 nm by UV-visible spectroscopy. An enhanced property of the composite material Pd/rGO/PDA@NF was demonstrated to catalyze the ethanol oxidation reaction in alkaline electrolyte solution. A higher ratio of forward scan peak current intensity (<em class="a-plus-plus">I</em><sub class="a-plus-plus">f</sub>) to reverse scan peak current intensity (<em class="a-plus-plus">I</em><sub class="a-plus-plus">b</sub>) was 1.59, which demonstrated the significant anti-poison effect to carbonaceous intermediates of the Pd/rGO/PDA@NF. The value of <em class="a-plus-plus">I</em><sub class="a-plus-plus">f</sub> can maintain 90.6% after 400 cycles, indicating the higher cycling stability and better electrocatalytic performance toward ethanol oxidation.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <strong class="a-plus-plus caption-number">Graphical Abstract</strong> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">Pd/rGO/PDA@NF was synthesized by a simple method with great elecrocatalytic performance and tolerance against carbonaceous intermediate species toward ethanol oxidation.</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_611_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00611-0 2021-09-01 10.1007/s12678-020-00611-0 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">Herein we report a label-free amperometric immunosensor based on reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) hybrid material co-modified by gold and iron-oxide magnetic nanoparticles (Au/MNPs-rGO-TEPA) for detection of carcinoembryonic antigen (CEA). The Au/MNPs-rGO-TEPA nanomaterials were prepared and coated on the working electrode as a sensing platform for antibody (anti-CEA) immobilization and signal amplification. This nanomaterial exhibited some excellent functionalities, such as magnetic and enhanced electrical properties due to its large specific surface area and favorable conductivity. Thionine (Thi) molecule was attached onto rGO-TEPA via π-π stacking and was used as an electrochemically active substance. The immunosensor was developed based on the increase in quantity of CEA captured, proportional to the decrease in peak currents of Thi. Under optimal conditions, the Au/MNPs-rGO-TEPA/Thi-based immunosensor showed impressive linear range from 0.1 pg/mL to 150 ng/mL. In addition, the proposed method had excellent linearity, high sensitivity, and relatively good stability, thereby offering a good platform for early clinical analysis.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <strong class="a-plus-plus caption-number">Graphical Abstract</strong> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">A novel label-free binary nanoparticle-decorated reduced graphene oxide-tetraethylene pentamine-based electrochemical immunosensor was developed. Au/MNPs-rGO-TEPA/Thi was used as electrochemical sensitive platform for quantitative detection of CEA.</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_604_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00604-z 2021-09-01 10.1007/s12678-020-00604-z Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">In proton exchange membrane fuel cells, the utilization of supporting materials for Pt-based catalysts is an effective approach to improve the oxygen reduction reaction (ORR) performance. In this study, a doped porous carbon (DPC) as a support was prepared with polyaniline as the main carbon source, iron nitrate nonahydrate as a metal doping source, and dicyandiamide as a nitrogen doping source in the presence of 20 nm silica bead as a template. The carbon support showed fairly high specific surface area (~ 740 m<sup class="a-plus-plus">2</sup> g<sup class="a-plus-plus">−1</sup>), well-defined pore structure, and a proper nitrogen doping (~ 4.9 at.%). The Pt cathode catalyst deposited on the doped porous carbon using an NaBH<sub class="a-plus-plus">4</sub> reduction method (Pt/DPC) exhibited significantly improved ORR performance in the half and single cells, compared with the conventional carbon-supported Pt catalyst. The superior ORR stability of Pt/DPC may be as a result of the particular interaction between Pt catalyst and DPC support as a doped carbon.</p> <p class="a-plus-plus"> <span class="a-plus-plus figure category-standard float-no id-figa"> <caption class="a-plus-plus caption language-en lang-en"> <em class="a-plus-plus caption-content"> <div class="a-plus-plus simple-para">Graphical Abstract</div> </em> </caption> <span class="a-plus-plus media-object id-m-o1"> <img alt="" src="http://static-content.fionamettini.com/image/MediaObjects/12678_2020_609_Figa_HTML.png" class="a-plus-plus"/> </span> </span> </p> http://fionamettini.com/10.1007/s12678-020-00609-8 2021-09-01 10.1007/s12678-020-00609-8 Latest Results http://fionamettini.com/42757 2021-06-01 42757 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">The complexity of problem of fluid flow and heat transfer over an array of circular cylinders is common in industrial applications of fluid dynamics. The complex nature of the problem encountered in industry gives rise to certain significant dimensions in fluid dynamics theory. Some of them are fluid flow interaction, interferences in flow and vortex dynamics which are typically found in compact heat exchangers, cooling of electronic equipment, nuclear reactor fuel rods, cooling towers, chimney stacks, offshore structures, hot-wire anemometry, and flow control. The mentioned structures are subjected to air or water flows and therefore, experience flow induced forces which can lead to their failure over a long period of time. Basically, with respect to the free stream direction, the configuration of two cylinders can be classified as tandem, side-by-side, and staggered arrangements. The Reynolds Averaged Navier-Stokes (RANS) equations have been used to compute the flow and Eulerian model has been used to understand phase change situation in a staggered arrangement of cylinders. In the present study, nucleate boiling has been the cause of heat and mass transfer between the phases for different cylinder configurations in staggered arrangement. The study was carried out by keeping cylinders stationary as well as rotating to understand the difference and impact of these situations on VOF. The profound effects of arrangement of cylinders, the location of cylinder surface, surface temperature of the cylinder were investigated. To have a deeper and meaningful insight into the phase change phenomenon of water into water vapor, Bayesian inference of a multivariate model involving certain significant factors such as Nusselt number (<em class="a-plus-plus">Nu</em>), Prandtl number (<em class="a-plus-plus">Pr</em>), and Stanton number (<em class="a-plus-plus">St</em>) along with volume fraction of vapor phase of water was carried out. The posterior probabilities computed from Bayesian inference for two statistically significant and experimentally verified datasets were obtained during the study. Through Principal Component Analysis (PCA) for the multivariate datasets used in the study, it was observed that some factors are positively and negatively correlated and individually contributing towards a meaningful finding from the study.</p> http://fionamettini.com/10.1007/s42757-020-0060-8 2021-06-01 10.1007/s42757-020-0060-8 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">The purpose of this work is to analyze the influence of a sudden expansion on the upstream behavior of the horizontal gas-liquid slug flow. Measurements were made on a 40 mm ID pipe with and without a sudden enlargement of aspect ratio <em class="a-plus-plus">σ</em> = 0.444. The experiments were carried out with two-phase air-water mixture. The slug lengths and frequencies were measured using a non-intrusive video technique. Upstream the sudden enlargement, it was observed that the mixture velocity has no influence on slug length. The variation of slug frequency is found proportional to the liquid superficial velocity for the two cases within this study. It was also observed that the behavior of the slug length and frequency was affected by the presence of the sudden enlargement. The comparison of the results obtained with various empirical correlations available in the literature showed that the latter are not worthwhile in the case where singularity is installed.</p> http://fionamettini.com/10.1007/s42757-020-0068-0 2021-06-01 10.1007/s42757-020-0068-0 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">Particulated multiphase flow is a complex phenomenon analyzed using computational and experimental methods for elbow geometry. The flow behavior in the elbow region is important as the velocity of particles impacting the wall can cause severe damage to the inner surface of the elbow. The particle impact behavior is influenced by fluid velocity, solid particle size, concentration due to spatial distribution of the particles. Computational and mechanistic erosion models are currently used to predict the potential failure modes and erosional damage to the wall. CFD prediction of erosion and flow behaviors in elbow geometry at three different velocities are presented. Velocities in the elbow region have been measured using particle image velocimetry (PIV) in particle laden flows. PIV technique measures the instantaneous velocity field within an illuminated plane of fluid by scattering light from particles in the fluid. The particle and flow velocities near the wall region can provide better understanding of the fluid and wall interactions. The predicted velocity profiles are compared with PIV results showing reasonably good agreement. Further investigation will be performed to provide more quantitative comparison of the velocities.</p> http://fionamettini.com/10.1007/s42757-020-0066-2 2021-06-01 10.1007/s42757-020-0066-2 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">With high energy consumption in buildings, the emissions of greenhouse gases are also increasing. It leads to some environmental problems. To realize resource conservation and environmental protection target, latent heat thermal energy storage systems (LHTES) are introduced into all kinds of buildings. A variety of air-LHTES and water-LHTES are analyzed in this study based on the heat transfer fluid medium adopted. The results of this study indicate that the air-LHTES uses the low-temperature ambient air to store cold during nighttime and releases cold during the daytime in summer vice versa in winter with auxiliary heat sources. The water-LHTES stores the cold and heat generated by various natural sources (solar energy, nighttime sky radiation, air conditioning condensate) through the water, and then releases the cold and heat to the buildings to reduce the energy consumption of the buildings. However, for some regions with extremely hot climate, the ambient temperature is still high during nighttime in summer. It is difficult to achieve cold storage of ambient air. Accordingly, other natural cold sources should be adopted for cooling in air-LHTES. Due to the cooling effect of nighttime sky radiation, water temperature in water-LHTES could be lower enough for cold storage. Thus, a combination system of water-LHTES and air-LHTES is recommended. In this system, cold storage is achieved by collecting low-temperature, and released by supplying cooling air. The proposed system can also achieve heat storage in winter by collecting solar energy, and release heat by supplying heating air.</p> http://fionamettini.com/10.1007/s42757-020-0064-4 2021-06-01 10.1007/s42757-020-0064-4 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">A multiphase mathematic model based on realizable <em class="a-plus-plus">k-ε</em> turbulence model for subsonic flow was presented to investigate the mixing flow behaviors between gas and water in the gas-liquid ejector. The simulation was carried out to predict the pumping performance of the ejector by a commercial computational code ANSYS-FLUENT 15.0. General agreements between the predicted results and experimental data validated the present theoretical model. Using the present approach, the pressure, velocity, and turbulence intensity distribution along center-line and contours of gas and liquid volume fraction profiles were predicted. It is found that the mixing process between gas and water in ejector can be divided into three periods, co-axial flow, mixing shock flow, and bubble flow. The prediction results show that the mixing shock is a dominant position in affecting the mixing flow behavior in gas-liquid ejector and the ejector’s performances.</p> http://fionamettini.com/10.1007/s42757-020-0069-z 2021-06-01 10.1007/s42757-020-0069-z Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">The pulse water jet pump is widely used for many industrial purposes owing to the presence of pressure fluctuations that can considerably improve the erosive action of a jet. However, literature regarding the cavitating water jet flow patterns and underlaying mass transfer mechanisms remains relatively scarce due to existing measurement obstacles. To reveal underlying relationships between pump geometrical configuration and its performance, this study presents an experimental and numerical investigation of a self-excited oscillation water jet pump. Firstly, an experimental rig was built, and the performance of the pump was assessed against various operating conditions. Then, a numerical model based on the same pump geometry and operation conditions was developed to provide detailed predictions of the internal cavitating flow patterns. Reasonably good agreements were found between the numerical predictions and experimental measurements, which indicate that the developed numerical model can accurately predict the flow entrainment process in the self-excited oscillation pulse jet pump. Internal cavitating flow patterns in terms of streamlines, pressure contours, and velocity profiles were explored for different pump geometric configurations by adjusting the nozzle-throat distance. Relationships between these influential factors and pump mixing capacity were provided. This paper presents an in-depth understanding of the self-excited oscillation pulse water jet and systematically explores the impacts of pump geometries and operating conditions on its performance.</p> http://fionamettini.com/10.1007/s42757-020-0062-6 2021-06-01 10.1007/s42757-020-0062-6 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">Extensive investigations have been carried out on the thermo-hydrodynamics of nanofluid droplet interaction with heated and non-heated flat surfaces. However, the influence of shape of nanoparticles on the dynamics of droplet impingement on heated flat surfaces is yet to be explored in detail. In this study, hydrodynamics of nanofluid droplet impingement process on heated and mechanically polished aluminum substrate was studied using dissolved Al<sub class="a-plus-plus">2</sub>O<sub class="a-plus-plus">3</sub> nanoparticles having spherical as well as cylindrical shapes. Nanofluids of 0.3% volume fractions were prepared from spherical Al<sub class="a-plus-plus">2</sub>O<sub class="a-plus-plus">3</sub> particles of mean size less than 50 nm and from cylindrical Al<sub class="a-plus-plus">2</sub>O<sub class="a-plus-plus">3</sub> particles of 2–6 nm in diameter and 200–400 nm in length. It was observed that, the impact dynamics is different from that of base pure fluid owing to the presence of nanoparticles. Leidenfrost temperatures of both nanofluids were dropped drastically in comparison with pure liquid. Further, the residence time, spread factor as well as retraction height also exhibit a different behavior against the base fluid. Detailed investigations were carried out for different Weber numbers (<em class="a-plus-plus">We</em> = 18–159) and surface superheat and resul ts obtained were compared with de-ionized (DI) water.</p> http://fionamettini.com/10.1007/s42757-019-0053-7 2021-03-01 10.1007/s42757-019-0053-7 Latest Results <h3 class="a-plus-plus">Abstract</h3> <p class="a-plus-plus">New experiments have been carried out on the generic case of the flow through orifice plates. The aim has been to validate empirical correlations used for the prediction of cavitation. The new accurate experimental data base shows that earlier proposed empirical correlations work well for the prediction of cavitation, e.g., Tullis (1993), Miller (2009), and Nilsson (2011). Using the present data together with earlier data from Tullis (1993), it has been shown that, at the onset of cavitation, the ratio between the downstream and the upstream pressure over the orifice plate is a simple linear function of the orifice plate diameter ratio, <em class="a-plus-plus">β = d/D</em>. This has been shown to hold independent of flowrate, downstream pressure, orifice diameter (for 0.4 &lt; β &lt; 0.8, which corresponds to a pressure loss coefficient 1 &lt; ξ &lt; 100) and boundary conditions (e.g., upstream pipe bends), at moderate temperatures and as long as the pressure drop is large compared to the saturation pressure. A novel and simple rule-of-thumb for when the cavitation becomes a problem (i.e., in between <em class="a-plus-plus">critical cavitation and incipient damage</em>) has been demonstrated to be when the ratio between the downstream and the upstream pressure over the orifice plate equals the orifice plate diameter ratio.</p> http://fionamettini.com/10.1007/s42757-020-0059-1 2021-03-01 10.1007/s42757-020-0059-1