Concentrated Methanol Solution Research Articles

Pt/C protection by Fe-N-C via Fenton reaction for direct methanol fuel cells operated under high concentrated methanol with high performance

In this paper, a hierarchical cathode catalytic layer (CCL) composed of Pt/C and Fe-N-C was proposed to mitigate severe methanol crossover in direct methanol fuel cells (DMFCs). Several validation experiments and electrochemical analysis were conducted to reveal that the reactive oxygen species (ROS) produced by Fe-N-C via Fenton reaction in an incomplete four-electron transfer in oxygen reduction reaction (ORR) can be utilized to oxidize methanol nearby Pt/C efficiently, thus protecting ORR active sites from poisoning in concentrated methanol solution. Based on this strategy, the optimized DMFC outputs a high peak power density of 22.5 mWcm−2 at 10 M methanol, which is among the highest performance achieved merely by CCL design. Additionally, the reaction of ROS with methanol is confirmed to protect the Fe-N-C CCL from the potential attack of ROS, leading to a great stability of the DMFC. This work is of great practical significance for the design of DMFCs with high specific energy density and good stability for portable application.

Crystal structure characterization, Hirshfeld surface analysis, and DFT calculation studies of 1-(6-amino-5-nitronaphthalen-2-yl)ethanone

The title compound, C12H10N2O3, was obtained by the deacetylation reaction of 1-(6-amino-5-nitronaphthalen-2-yl)ethanone in a concentrated sulfuric acid methanol solution. The molecule comprises a naphthalene ring system bearing an acetyl group (C-3), an amino group (C-7), and a nitro group (C-8). In the crystal, the molecules are assembled into a two-dimensional network by N...H/H...N and O...H/H...O hydrogen-bonding interactions. n–π and π–π stacking interactions are the dominant interactions in the three-dimensional crystal packing. Hirshfeld surface analysis indicates that the most important contributions are from O...H/H...O (34.9%), H...H (33.7%), and C...H/H...C (11.0%) contacts. The energies of the frontier molecular orbitals were computed using density functional theory (DFT) calculations at the B3LYP-D3BJ/def2-TZVP level of theory and the LUMO–HOMO energy gap of the molecule is 3.765 eV.

A hybrid cathode catalytic layer composed of M–N–C and Pt/C for direct methanol fuel cells with high methanol tolerance

Pt/C based direct methanol fuel cells (DMFCs) always suffer from a serious methanol crossover under a high concentration of methanol solution. In this paper, we report a novel hybrid cathode catalytic layer (CCL) consisting of a physical blend of Pt/C and Fe-N-C. DMFC based on the hybrid CCL with an optimized loadings (0.25 mg cm−2 Fe-N-C and 2 mgPt cm-2Pt/C) outputs a high power density of 28.87 mW cm−2 at 10 M methanol, and the single Pt/C based cell only shows a low power density of 12.04 mW cm−2 in comparison. Such a large improvement attributes to the increasing amount of reactive oxygen species (ROS), which is produced by Fe-N-C via an incomplete four-electron transfer process in oxygen reduction reaction (ORR). Inspired by this strategy, several M−N−C catalysts were synthesized, among which Cu-N-C shows the most brilliant performance to enhance the methanol tolerance of Pt/C. The peak power density of DMFC with Cu-N-C based hybrid CCL exceeds 31 mW cm−2 at 10 M methanol, which is superior to that of cells with Fe-N-C based hybrid CCL. This work provides a new approach for designing DMFCs with high energy density, which is practical for applications of portable power devices.

Chemical components of different solvent extracts of Asclepias curassavica L. and antibacterial effect of the extracts on tomato pathogens

The use of environmentally friendly and sustainable agricultural methods in the control of diseases and pests is of great importance. In both conventional and organic agricultural production systems, the utilization of various plant extracts as part of integrated pest management has gained significance in recent years. The chemical constituents of various solutions derived from the flowers, leaves, and roots of the Asclepias curassavica L. plant were investigated, along with the possibilities of utilizing these solutions in the control of tomato plant pathogenic bacteria. As a result of the analysis, acetic acid in 60% and 80% ethanol solutions, as well as acetic acid methy ester in 60% and 80% methanol solutions, were detected in the flowers, leaves, and roots. The effects of A. curassavica flower, leaf, and root extracts, prepared using three different solvents (water, methanol, and ethanol), were investigated on eight different pathogenic bacteria (Agrobacterium tumefaciens, Clavibacter michiganensis, Dickeya zeae, Pectobacterium caratovorum, Pseudomonas phaseolicola, Pseudomonas tomato, Pseudomonas viridiflava, and Xanthomonas euvesicatoria) that cause diseases in plants. Several main compounds such as acetic acid, acetic acid. methyl ester, Furfural, 2-Furanmethanol, 4H-Pyran-4-one. 2.3-dihydro-3.5-dihydroxy-6-methyl-, Glycerin, Benzo furan. 2.3-dihydro- and 5-Hydroxy methyl furfural were identified as analyzed by GC-MS with different concentrations of ethanol and methanol solutions used for the flower, leaves and root of A. curassavica plants. The flower extract prepared with 80% ethanol exhibited a higher inhibition zone (ranging from 1.5 mm to 5.3 mm) in all pathogens, compared to other applications. The successful suppression effect of A. curassavica flower extracts on this disease is promising, especially in organic farming areas. Additionally, since it is environmentally friendly and sustainable, it can be included in integrated control methods to prevent the loss of productivity caused by diseases.

Precise Preparation of CdS Thin Films for Efficient Sb2S3–ySey Thin-Film Solar Cells

In this work, CdS thin films were prepared by chemical bath deposition (CBD) and Sb2S3–ySey thin films were prepared by a hydrothermal method. Solar cells with the architecture of FTO/CdS/Sb2S3–ySey/spiro-OMeTAD/Au were fabricated to evaluate the quality of CdS thin films as the electron transport layer. The precise preparation strategy with the combination of adjusting the thickness of CdS thin films prepared by CBD and changing the concentration of the CdCl2 methanol solution in the post-treatment process was first proposed. When the CdS thin-film thicknesses were 100, 80, 65, and 40 nm and the CdCl2 methanol solution concentration was 20 mg·mL–1, the power conversion efficiencies (PCEs) of the corresponding solar cells were 7.32% of 100 nm, 7.62% of 80 nm, 8.00% of 65 nm, and 7.55% of 40 nm. When the CdS thin-film thickness was 40 nm and the CdCl2 methanol solution concentrations decreased to 15, 13.3, 10, and 5 mg·mL–1, the PCEs were 7.98% of 15 mg·mL–1, 8.46% of 13.3 mg·mL–1, 7.71% of 10 mg·mL–1, and 7.31% of 5 mg·mL–1. Therefore, the 40 nm thick compact and full-coverage CdS thin film without the appearance of residual CdCl2 can be successfully obtained using the precise preparation strategy and achieved an optimal PCE of 8.46%. The precise preparation strategy is also valuable to develop the ultrathin, compact, and full-coverage CdS thin film as the electron transport layer for CdTe thin-film solar cells.

Crosslinked PAEK-based nanofiber reinforced Nafion membrane with ion-paired interfaces towards high-concentration DMFC

To increase the energy density of DMFC system, increasing the methanol concentration is an excellent solution. However, the severe methanol crossover problem limits the application of Nafion in DMFCs with a highly concentrated methanol solution. Here, we proposed a feasible approach to overcome this challenge where Nafion membrane was reinforced with a covalently crosslinked quaternized poly (arylene ether ketone) (PAEK) nanofiber mat for establishing acid-base ion-paired interfaces between them. Firstly, the bromomethylated PAEK precursor was prepared into a three-dimensional fibrous support material using electrospinning. The nanofibers were then quaternized and covalently crosslinked to embed in the Nafion matrix while maintaining their fiber morphology. During the membrane fabrication, the ion-paired interfaces were established between the –N(CH3)3+ on the nanofibers and –SO3- groups of Nafion matrix. The strong ion-paired interaction resulted in low membrane swelling and methanol permeability. TEM confirmed that the hydrophilic ionic clusters were aggregated with controllably distribution along the nanofibers to create long-range and efficient proton transport channels. Therefore, the hybrid membrane F-CQPAEK@Nafion-1.0 showed a high proton conductivity of 0.21 S cm−1 at 80 °C. In 2 M DMFC, the maximum power density (PDmax) of this membrane reached 119.38 mW cm−2, 2.78 times higher than that of recast Nafion. In 10 M DMFC, the PDmax of this hybrid membrane reached 65.31 mW cm−2, which was 3.54 times higher than that of recast Nafion. The results illustrate the possibility of running Nafion-based hybrid membranes in DMFCs with a broad operational flexibility from low concentration to high concentration methanol solutions.

Experimental study and recognition of natural gas hydrate chemical reagent - CO2 exploitation

Abstract In order to solve the problems of slow replacement rate and low degree of substitution in the process of CO2 displacement by natural gas hydrate, a method of chemical reagent-CO2 displacement combined mining experiment was proposed. Taking the thermodynamic methanol inhibitor as an example, three groups of experiments were carried out: critical temperature pressure condition for CH4 decomposition at different methanol concentrations, CH4 hydrate decomposition under the condition of methanol reagent at 30% concentration, and methanol reagent-CO2 combined mining. Experiments show that: (1) The concentration of methanol plays a decisive role in hydrate recovery. Methanol reagent has the property of highly reducing the formation temperature of hydrate. Methanol solution concentration is positively correlated with the critical temperature drop of hydrate decomposition and formation pressure. (2) The methanol solution decomposition of hydrate can be roughly divided into three stages: the initial stage of rapid decomposition, the competitive stage of hydrate decomposition and stable transformation, and the stable stage of decomposition. Through experimental simulation, it is concluded that formation pressure is a direct factor affecting the decomposition ability of methanol reagent to hydrate. By changing formation pressure, the rate of CH4 hydrate recovery can be improved. (3) A higher hydrate decomposition rate can be obtained based on the methanol reagent-CO2 displacement mining method. In the action of the methanol reagent, the subsequent injection of CO2 still promotes the decomposition of CH4, that is, the displacement of CO2 hydrate after the decomposition of the hydrate based on the methanol reagent is feasible. The research results are of great significance especially for large-scale mine test mining of permafrost natural gas hydrate chemical reagent method.

High methanol resistance semi-crystalline sulfonated poly(ether ketone) proton exchange membrane for direct methanol fuel cell

Three new sulfonated and semi-crystalline poly(ether ketone)-type copolymers (Cr-SPEK) with densely sulfonated microblock of different length are synthesized and evaluated as proton exchange membranes. The relationship between molecular structure of copolymers, microscopic morphology and macroscopic performance of membranes are studied: The increase in the length of the hydrophilic sulfonated microblock facilitates constructing well-connected ionic transport channels, which improves the proton conduction of Cr-SPEK membranes. And expanding the size of hydrophobic poly(ether ketone) (PEK) block promotes higher crystallinity of copolymers, resulting in enhancing dimensional stability, mechanical tensile, oxidation stability and methanol resistance of Cr-SPEK membranes. The tCr-SPEK membrane with longest hydrophilic microblock and maximum crystallinity (15.2%) exhibits best comprehensive performance. The proton conductivity and swelling ratio of the tCr-SPEK membrane measured under fully hydrated state at 80 °C are 146.7 mS cm−1 and 11.9%, respectively. And the methanol permeability of tCr-SPEK membrane is only 1.1 × 10−7 cm2 s−1, which is nearly one-sixteenth of that of Nafion 117 membrane. The single cell performance of tCr-SPEK membrane in direct methanol fuel cells (DMFCs) continuously grows with the higher concentration of methanol solution until 12 M. Therefore, the tCr-SPEK membrane represents great potential for application in DMFCs.

Understanding Carbon Dioxide Transfer in Direct Methanol Fuel Cells Using a Pore-Scale Model

Abstract The gas flow of carbon dioxide from the catalyst layer (CL) through the microporous layer (MPL) and gas diffusion layer (GDL) has great impacts on the water and fuel management in direct methanol fuel cells (DMFCs). This work has developed a liquid–vapor two-phase model considering the counter flow of carbon dioxide gas, methanol, and water liquid solution in porous electrodes of DMFC. The model simulation includes the capillary pressure as well as the pressure drop due to flow resistance through the fuel cell components. The pressure drop of carbon dioxide flow is found to be about two to three orders of magnitude higher than the pressure drop of the liquid flow. The big difference between liquid and gas pressure drops can be explained by two reasons: volume flowrate of gas is three orders of magnitude higher than that of liquid; only a small fraction of pores (<5%) in hydrophilic fuel cell components are available for gas flow. Model results indicate that the gas pressure and the mass transfer resistance of liquid and gas are more sensitive to the pore size distribution than the thickness of porous components. To buildup high gas pressure and high mass transfer resistance of liquid, the MPL and CL should avoid micro-cracks during manufacture. Distributions of pore size and wettability of the GDL and MPL have been designed to reduce the methanol crossover and improve fuel efficiency. The model results provide design guidance to obtain superior DMFC performance using highly concentrated methanol solutions or even pure methanol.

Experimental measurements of fuel and water crossover in an active DMFC

This study measured polarization curves as well as the high-frequency resistance of active direct methanol fuel cell (DMFC) operates at around 80 °C with active controls of temperature, methanol concentration, airflow rate, and relative humidity. The relative humidity of the air did not have noticeable impacts on the fuel cell unless the operating temperature was near the evaporation temperature of water (100 °C). The hydrophobic water management layer (WML) between the membrane electrode assembly (MEA) and cathode air channel increases the mass transfer resistance and improves the water retention in MEA. Adding a WML increased the peak power density, decreased the ohmic resistance, and improved the fuel efficiency of the fuel cell, especially when it operated near 100 °C. This study also quantitatively measured methanol and water crossover as well as the fuel efficiency at different operating currents. The fuel efficiency increased significantly with the increase of the current density. Using a hydrophobic fuel management layer (FML) between the anode fuel channel and MEA reduced the fuel and water crossover rates and increased the ohmic resistance due to the decrease of the water content of the Nafion membrane. The FML improved fuel efficiency by reducing the methanol crossover. The combination of the FML and WML enabled the steady operation of DMFC using highly concentrated methanol solutions (up to 75 wt%).

Experimental investigations on the effect of current collector open ratio on the performance of a passive direct methanol fuel cell with liquid electrolyte layer

This paper aims to present the influence of anode catalyst supports, current collector open ratio, liquid electrolyte layer incorporated membrane, and methanol concentration on the passive Direct methanol fuel cell (DMFC) performance. Current collectors with three different opening ratios of 45.40%, 55.40% and 63.05% were considered in the present study. For the three current collectors, the fuel cell is operated with diluted methanol solution (concentration varied from 1 to 5 M) as the anodic fuel. The experimental results showed that the current collector with 55.40% open ratio at 3 M of methanol concentration produced the MPD compared to the other two open ratios. A liquid electrolyte (LE) layer was inserted in between the two half MEAs to recuce the methanol crossover. It was noticed that the LE-DMFC gave the best performance with all the three current collector having different opne ratios. Similarly, the effect of two anaode catalyst layers was also studied. From the experimental results, it was noticed that the fuel cell performance improved by using the MEA with two layers of anode catalyst of Pt-Ru/Carbon black + Pt-Ru/C.

Improvement of electrochemical oxidation efficiency through combination with adsorption processes

In this work, a three-step process (adsorption-desorption-electrolysis) is evaluated as an interesting approach for the removal of organochlorinated compounds (clopyralid, lindane and perchloroethylene) with different physical properties (solubility and vapor pressure) from low concentrated wastewater. First steps are based on the adsorptive capacity of granular active carbon (GAC) particles to retain organics and on the solvent capacity of methanol to extract them to concentrated solution and regenerate GAC. In the last step of electrolysis with conductive diamond electrodes, the degradation of pesticide is projected, as well as the recovery of methanol. Results show that clopyralid, lindane and PCE are efficiently retained in GAC, although adsorption efficiency depend on pollutant/GAC ratio and physicochemical properties of pollutant. Pretreatment allows the concentration of clopyralid and PCE solutions up to 8 times, but worse results are obtained in case of lindane solutions. Electrolysis of concentrated methanol solution seems to be more efficient than electrolysis of diluted aqueous wastes, mainly in the case of clopyralid. In all cases, electrochemical degradation fits a first order kinetics confirming mixed oxidation mechanisms with diffusion control of the direct processes and mediated oxidation. Results obtained in terms of current efficiency and energy consumption of electrolysis step point out the lower operation cost of concentrated liquid wastes and encourage further works on the development of cost-effective combined processes for the treatment of diluted solutions polluted with polar compounds (such as clopyralid).

Polyaniline-Doped Poly (Methyl Methacrylate) Microfiber for Methanol Sensing

The main objective of this paper is to investigate the effect of Polyaniline (PANI) as a dopant in the fabrication of a polymer microfiber for sensing methanol. A simple direct drawing technique was employed in the preparation of a Poly (methyl methacrylate) (PMMA) doped with PANI microfiber. The changes of the power spectrum were measured through an optical spectrum analyzer over a range of 100–500 ppm methanol solution concentrations. It was observed that the sensor utilizing a PANI-doped microfiber had a higher response toward the changes in the methanol solution concentrations compared with its undoped counterpart with an improvement of 41.01% and more than 5 times for the sensitivity and resolution, respectively. A sensitivity of 0.047 dBm/ppm was attained with the use of a PMMA microfiber with a taper diameter and length of $3~\mu \text{m}$ and 3 mm, respectively. The field emission scanning electron microscopy proved the successful doping of PANI into the PMMA microfiber, which contributed to the increase in the performance of the sensor.

Facile coprecipitation synthesis of nickel doped copper oxide nanocomposite as electrocatalyst for methanol electrooxidation in alkaline solution

A nickel doped copper oxide (Ni–CuO) nanocomposite is prepared by the coprecipitation method for use as an electrocatalyst. The physicochemical properties of the synthesized electrocatalyst are characterized by powder XRD analysis, Fourier transform-infrared spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and N2 sorption measurements. The electrocatalytic performance of the Ni–CuO nanocomposite with respect to the electrochemical oxidation of methanol in an alkaline medium is evaluated through cyclic voltammetry and chronopotentiometry measurements. The reaction involving the electrooxidation of methanol is investigated comprehensively by varying experimental parameters such as the amount of catalyst used and the methanol solution concentration. The superior electrocatalytic activity of the Ni–CuO nanocomposite is attributable to its surface morphology and the presence of a large number of catalytically active sites on the nanocomposite surface. The results of this study suggest that the synthesized Ni–CuO nanocomposite should be suitable for use as an economical and abundant electrocatalyst in direct methanol fuel cells.

Can 2,2,2-trifluoroethanol be an efficient protein denaturant than methanol and ethanol under thermal stress?

Monohydric alcohols, such as methanol (MEH), ethanol (ETH) and 2,2,2-trifluoroethanol (TFE), have significant effects on biological processes including the protein folding-unfolding phenomenon. Among the several monohydric alcohols, TFE, a fluorine-substituted alcohol, is known to induce a helical structure in proteins. In this work, we report the heterogeneous unfolding phenomenon of a small protein Chymotrypsin Inhibitor 2 in various concentrations of methanol, ethanol and TFE solutions by performing atomistic molecular dynamics simulation studies. Our study reveals that the unfolding phenomenon of CI2 under thermal stress majorly depends on the concentration and the nature of the alcohol. The presence of alcohols in general has been noted to accelerate the unfolding process compared to pure water and TFE, among them all, has been found to speed up the unfolding time scale at low concentrations. The molecular contact frequency between protein and alcohol follows the trend, MEH < ETH < TFE at low concentrations, whereas the trend becomes MEH ∼ ETH > TFE at more concentrated solutions. The differential water-mediated and self-clustering phenomena of alcohols, diverse protein-alcohol hydrogen bond strengths and the concentration dependent restricted inhomogeneous protein-water as well as protein-alcohol hydrogen bond dynamics suggest that TFE, a well known α-helix stabilizer, could be a good competitor among its class of denaturants.

Low-Dimensional Carbon Allotropes: Ground- and Excited-State Charge Transfer with NIR-Absorbing Heptamethine Cyanine

Summary At the focal point of our studies are mutual interactions between an anionic heptamethine cyanine and individualized single-walled carbon nanotubes (SWCNTs) or exfoliated nanographene (NG). Here, we report the distinct near-infrared absorption of the heptamethine cyanine, which assists in visualizing the electronic interactions in the ground state with ease and precision. In statistical Raman assays, we conclude from downshifted 2D- and G-modes for SWCNTs, as well as upshifted 2D- and downshifted G-modes for NG, that these electronic interactions result in stable n-doping of SWCNTs and NG. Key to this shift of charge density is the electron-donating character of the heptamethine cyanine. In the excited state, a complete but metastable transfer of charges is accompanied by a radical-ion-pair state that lives for several nanoseconds. Such a time domain has not yet been realized, for example, in NG to date.

Structural design and analysis of a passive DMFC supplied with concentrated methanol solution

This paper develops a passive direct methanol fuel cell (DMFC) structure employing the graphite plate as the porous medium in order to increase the energy density and the stable operating time of the cell. A two-dimensional model of the proposed DMFC is developed to determine the appropriate thickness of the graphite plate and the optimum feed concentration of the methanol. The simulated polarization curves and current-power profiles of the model are verified experimentally. Both the modeling results and the experimental results show that the 500 μm thick graphite plate cannot transfer enough methanol to the anode. The simulated and experimental results both illuminate that the DMFC with 300 μm thick graphite plate supplied with 10 M methanol and the one with 400 μm thick graphite plate supplied with 15 M methanol can achieve a normal performance. The energy density of the proposed DMFC is also analyzed by discharging at constant current experimentally. The DMFC with 400 μm thick graphite plate supplied with 15 M methanol has the longest discharging time. The proposed passive DMFC structure significantly improves the energy density and electrical efficiency of the cell.

Crystal structure of (perchlorato-κO)(1,4,7,10-tetra-aza-cyclo-dodecane-κ4N)copper(II) perchlorate.

The crystal structure of the title salt, [Cu(ClO4)(C8H20N4)]ClO4, is reported. The CuII ion exhibits a square-pyramidal geometry and is coordinated by the four N atoms of the neutral 1,4,7,10-tetra-aza-cyclo-dodecane (cyclen) ligand and an O atom from one perchlorate anion, with the second perchlorate ion hydrogen-bonded to one of the amine N atoms of the cyclen ligand. Additional N-H⋯O hydrogen bonds between the amine H atoms and the coordinating and non-coordinating perchlorate groups create a three-dimensional network structure. Crystals were grown from a concentrated methanol solution at ambient temperature, resulting in no co-crystallization of solvent.

Tropolone as anionic and neutral ligand in lead(II) and bismuth(III) complexes: Synthesis, structure, characterization and computational studies

Two new metal complexes, [Bi(trop)2(Htrop)(CF3SO3)] (1) and [Pb(trop)2(Htrop)] (2), have been synthesized by reaction of the respective metal triflates with an excess of tropolone (Htrop) in the concentrated methanol or dimethylsulfoxide solution. In addition, it was found that complex 1 crystallizes through the formation of unstable intermediate methanol solvated tris(tropolonato)bismuth(III) compound. The characteristic behavior of tropolone which coordinates both as the bidentate anion (trop−) and the monodentate neutral molecule (Htrop) has been revealed in 1 and 2. The crystal structures of studied compounds have been determined by single-crystal X-ray diffraction. The molecular structures of both complexes have been compared with their geometries received from DFT calculations giving a good correlation. The presented compounds show coordination number of metal ion equal to five in 2 and six in 1 and the presence of stereochemically active 6s2 lone electron pair. The complexes were characterized by FT-IR, NMR and UV–Vis techniques. IR and UV–Vis spectra of 1 and 2 were also simulated by DFT methods. TD-DFT predictions demonstrate the frontier HOMOs and LUMOs cover in the major part the tropolonate and(or) tropolone moieties which gives mainly ligand-to-ligand charge transfer (LLCT) and ligand centered (LC) character to the energy bands above 300 nm.

Analyses of electrochemical impedance spectroscopy and cyclic voltammetry in micro-direct methanol fuel cell stacks

The effects of the stack operating temperature, methanol solution feeding rate, and concentration of methanol solution on two-cell, three-cell, and four-cell micro-direct methanol fuel cell stacks were examined using electrochemical impedance spectroscopy and cyclic voltammetry. In addition to the transient techniques, both VI/PI polarization curves were obtained. Corresponding single-cell tests were conducted and used as basis/reference data for comparisons with previous studies or with the present stack results. The micro-direct methanol fuel cell stack used in the study was operated actively at the anode and passively (i.e., air breathing) at the cathode where a serpentine-type channel and novel/innovative perforated dendrite-type channel with a 80° dendrite angle flow configuration were used for both the anode and cathode. Relevant data were measured, presented, and discussed under the aforesaid operating conditions. Moreover, the results were compared with those of earlier works and found to be in good agreement. Copyright © 2016 John Wiley & Sons, Ltd.