Ethanol-water Binary Mixtures Research Articles

Heat transport characteristics of a flat-evaporator loop heat pipe for use in a thermal management system of electric vehicles

In this work, a flat-evaporator loop heat pipe (FELHP), with a 100 cm2 rectangular thermal interface and an overall length of approximately 2 m was devised for the thermal management of electric vehicles. A simple rectangular-cuboid evaporator was devised using a novel stepped-flat wick structure, and the heat transport characteristics were systematically investigated in terms of the heat load, relative height of the evaporator to the condenser (i.e., position), heat sink temperature, and working fluid. In particular, water-ethanol binary mixtures with different compositions were tested to find an optimum low-freezing-temperature working fluid for use in thermal management system of the electric vehicles driving outdoors. Over the tested heat load range, a significant position dependence of the operating temperature was observed with a thermal resistance change from 0.21 K/W ± 0.02 K/W to 0.14 K/W ± 0.01 K/W for a 0.4 m change in the position. In contrast, the operating temperature of the FELHP was insensitive to changes in the heat sink temperature. A binary mixture containing 20% water and 80% ethanol (by volume) resulted in comparable heat transport characteristics to those of pure water but had a much lower freezing temperature (e.g., a thermal resistance of 0.25 K/W ± 0.03 K/W at 450 W and a freezing temperature of approximately -59 °C), demonstrating that this was an optimum composition of the water-ethanol mixture working fluid of the FELHP.

Determination of protonation constant value of thiabendazole in ethanol-water binary mixtures by green RPLC method

Determination of protonation constant value of thiabendazole in ethanol-water binary mixtures by green RPLC method

Use of green analysis methods to determine the ionization constant values of isoxazolyl penicillins

In this study, an environmentally friendly analysis of penicillinase-resistant antibiotics oxacillin, dicloxacillin, and cloxacillin was carried out by liquid chromatography methods using ethanol solvent that is not harmful to human health and the environment. Ionization constant (wwpKa) values of isoxazolyl penicillins in ethanol–water binary mixtures containing 20–35% (v/v) ethanol at 37 °C were obtained by green reverse phase liquid chromatography and micellar liquid chromatography methods known as green chromatography. The developed methods are based on a model that relates the chromatographic behavior of the identified analytes to pH. The linear relationship between the microscopic solvatochromic parameter ETN and the retention values of the compounds was determined depending on the change of organic solvent in the mobile phase. Using the obtained chromatographic data, conditions that ensure the simultaneous separation of the compounds for both methods were determined. The relationship between the calculated sspKa values and the macroscopic properties of ethanol was investigated. The agreement between the pKa (wwpKa) values in the water medium determined by this approach was determined by t-test at a 95% confidence level for both methods. The wwpKa values of the compounds at 25 °C were also estimated using Abraham solute parameters without any experimental work.

Real-Time Complex Dielectric Constant Measurement of Liquids Using Epsilon-Near-Zero Supercoupling Channels

This article proposes a device for real-time measurement of the complex dielectric constant of liquids at X-band. The device consists of a narrow waveguide channel operating at the cut-off frequency to achieve a large field enhancement based on Epsilon-Near-Zero (ENZ) supercoupling theory. A micro-3D-printed sample holder is placed inside the channel and connected to feeding tubes that are designed to prevent energy leakage from the channel. The field enhancement and confinement inside the channel creates a strong interaction with the liquids under test, thereby providing very sensitive measurements over a wide range of permittivities (approx. 1-65). Two variations of the device are fabricated. One that provides a higher accuracy and another that provides a higher sensitivity. A full-wave simulation based forward model is developed and optimized using a constrained Nelder-Mead simplex. An inversion is performed based on the optimized forward model to find the complex permittivity from the measured scattering parameters. Two sets of experiments are performed, one of static liquid mixtures and another of time-varying liquid mixtures. The static measurements are done with binary mixtures of ethanol-water and methanol-water. The time-varying measurements are done with ethanol-water-sugar mixtures and ethanol-water mixtures. The measured results are consistent between the two devices and are in very good agreement with the published literature over the entire range of dielectric constants tested.

Relationship between Onset of Sliding Behavior and Size of Droplet on Inclined Solid Substrate.

Whether a droplet slides or not on inclined solid surface is mainly influenced by a balance between the adhesion force at contact area and the gravitational force exerted on the droplet. Especially as the adhesion force is a key parameter for the determination of the sliding behavior of droplets. The adhesion force is mainly estimated by experimental observation for the sliding motion of the droplet. However, at present it is unknown whether the adhesion force is a constant value regardless of the droplet size or not. In the present study, focused on the onset for sliding of water-ethanol binary mixture droplets on inclined solid surface, experimental investigation on the sliding droplets is performed by considering the droplet volumes ranging from 7 to 600 μL in order to understand the effect of the size of the droplet on the adhesive property. The results are discussed using the existing analytical models. From the results, it is found that the adhesion force increases in the case of large droplet volume, while the force reaches constant value in the case of small droplet volume. This difference is related to the degree of the droplet shape deformation, which leads to a change in the contact angle. Finally, a simple empirical model for the adhesion force including the size effect is proposed.

Kinetics Study of Co-Solvent effect in Alkaline Hydrolysis of Diethyl Pathalate Ester

The base catalyzed hydrolysis of diethyl pathalate has been carried out titrometically in water-ethanol binary solvent mixture covering range of 30 to 70% (v/v) of solvent composition at different Temperature (20 to 400C). The reaction followed second order rate constant which decreases with increase of solvent composition. The salvation and desolvation concept are used to explain the solvent influence on rate and mechanism is the reaction. The relation between changes in dielectric constant due to variation of reaction mixture and change in specific rate constant has been explained on the basis of electrostatic and non-electrostatic contribution of solvent mixture. Calculated value of Iso-composition activation energy is found to be increases with increase of solvent composition. The thermodynamic parameters (G*, H*&S*) has been determined with help of Wynne Jone and Eyring equation which show the great dependency on solvent composition.

Insight into the Structure and Dynamics of Ethanol-Water Binary Mixture Confined in Nanochannel by Mica and Graphene.

Investigation of the structural properties and dynamics of fluid mixture confined in nanochannels has become an essential topic in many fields due to potential applications in nanofluidic devices and biological systems. Here, we study the ethanol-water blend confined between the mica and single or multilayer graphene for different slit pore widths, ethanol content, and temperatures. Our molecular dynamics simulation indicates that water molecules are adsorbed at the mica surface, while ethanol molecules prefer to be adsorbed near the graphene surface. We find that distinct layers of ethanol molecules form as the channel width and ethanol content in the mixture are increased. The diffusion of confined ethanol and water molecules depends on the nanopore widths, concentrations, and temperatures. Interestingly, at nanopore widths of 1.0 and 1.3 nm, the mobility of confined ethanol molecules is greater than that of water molecules for all ethanol concentrations. In contrast, at pore width of 0.7 nm, the opposite behavior is observed at lower concentrations of ethanol (xEtOH = 0.1 and 0.3) in the mixture. Furthermore, the diffusivity of ethanol and water in the mixtures increases with increasing the temperatures. The hydrogen bond and cluster analysis imply the segregation of water molecules near the mica surface, while ethanol molecules are near the opposite pore wall (graphene).

A Sensitivity-Enhanced Sensor Based on Zeroth-Order Resonance for Liquid Characterization

A high-sensitivity planar microfluidic sensor is proposed in this paper based on composite left/right-handed transmission line (CRLH TL). By employing the series zeroth-order resonance (ZOR), the resonance of proposed sensor is only determined by surface capacitance and inductance. The short-circuit structure reduces the energy loss due to edge radiation and generates a highly concentrated electric field on the top surface of the substrate, which can be used to detect the dielectric loading samples. The presented sensor has been simulated, fabricated and tested. The sensor on the printed circuit board (PCB) is integrated with the fluidic container made of polydimethylsiloxane (PDMS) to form the test device. The water-ethanol binary mixture and sucrose solution are used to proof the concept. Finally, the prediction model for the water-ethanol mixture based on measured parameters has been established and the analysis of prediction error has been carried out. The sensor works around 4 GHz, and the maximum sensitivity reaches 1.04. Due to the high sensitivity and simple structure, the proposed structure is a competitive candidate for the applications including bio-sensing and portable biomedical device.

Optical Fiber Sensor for Monitoring the Evaporation of Ethanol-Water Mixtures.

An inline optical fiber sensor is proposed to monitor in real time the evaporation process of ethanol–water binary mixtures. The sensor presents two interferometers, a cladding modal interferometer (CMI) and a Mach–Zehnder interferometer (MZI). The CMI is used to acquire the variations in the external medium refractive index, presenting a maximum sensitivity of 387 nm/RIU, and to attain the variation in the sample concentration profile, while the MZI monitors temperature fluctuations. For comparison purposes, an image analysis is also conducted to obtain the droplet profile. The sensor proposed in this work is a promising alternative in applications where a rigorous measurement of volatile organic compound concentrations is required, and in the study of chemical and physical properties related to the evaporation process.

A study of diabatic distillation in a column with a low pressure drop

This paper examines diabatic columns with a new type of tray. The design provides effective liquid reflux flow in each column tray and a low pressure drop. The contact devices comprise a stack of multi-diameter plates with raised edges. The vertical tubes of the dephlegmator integrated into the column centre pass across all plates, and are used for heat removal. Vapors of the ascending mixture partially condense onto the plate surfaces and the dephlegmator, resulting in vapor enrichment. The liquid flow down the column forms a thin layer on the surfaces of the middle and bottom plates. When the condensate drops onto the smaller-diameter top tray, it partially evaporates, is then mixed with the liquid flow on the underlying plates, and partially evaporates again. An algorithm calculation of distillation parameters for a diabatic column, with a known reflux flow rate, vapor velocity and heat transfer coefficient, is proposed and approbated. The column separation efficiency is assessed depending on the temperature and cooling-water flow rate in the dephlegmator pipe. Several approaches for enhancing the heat transfer intensity in the column dephlegmator pipe were analysed. Several heat removal methods, including liquid film flow cooling of the inner dephlegmator pipe surface, were examined. Experimental tests were carried out using an ethanol-water binary mixture and a raw spirit complex mixture. Comparison of the characteristics of the new diabatic unit and a packed column with a spiral prismatic packing showed that the plate column with the same separation efficiency has a lower pressure drop and metal consumption. The results encourage further research on this new diabatic column design.

Experimental Correlation for Splashing Condition of Droplets on Solid Substrates

Droplet splashing behaviors of water-ethanol binary mixture liquids on roughened solid surfaces were experimentally observed in order to investigate the effects of surface tension, viscosity, and wettability/surface roughness on the splashing occurrence. The range of the droplet volumes was from 1.7 μL to 32.6 μL. The ranges of the surface tension and the viscosity were from 21.1 mN/m to 71.9 mN/m, and from 1 mPas to 2.91 mPas, respectively. The surface roughness range was from 0.03 μm to 1.25 μm for Ra. The present experimental data were evaluated on the basis of the existing models. Resulting from these experiments, a simple model using the Ohnesorge number evaluated by the capillary length was proposed and the accuracy of the predicted critical values such as the critical Weber and Reynolds numbers were discussed. The result indicated that the liquid properties and the quantification of the surface condition such as surface roughness are important factors for the prediction of the splashing behavior.

Cononsolvency of Poly[2-(methacryloyloxy)ethyl phosphorylcholine] in Ethanol-Water Mixtures: A Neutron Reflectivity Study.

Molecular mechanisms underlying the cononsolvency, a re-entrant coil-to-globule-to-coil conformational transition of polymer chains in mixtures of two good solvents, of poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC) in ethanol-water binary mixtures were complementarily investigated. This was accomplished by following a statistical mechanical model for competitive hydrogen bonding combined with the cooperative solvation concept as well as neutron reflectivity (NR) experiments employing contrast variation in the cononsolvents. The experimental re-entrant aggregation of the PMPC chains in ethanol-water mixed solvents, obtained on the basis of turbidity was accurately reproduced by theoretical calculations. The calculation proved the relatively strong cooperativity of ethanol and the preferential interaction of water, while the total coverage of solvents was the lowest at an ethanol volume fraction (fethanol) of 0.90. At this level, the cononsolvency was the most significant, and the collapsed PMPC chains were solvated with more water than the bulk mixed solvent. The ethanol-water cononsolvency for the PMPC brushes on a planar silicon wafer was investigated by NR experiments, and the solvent composition involved in the collapsed PMPC brush was addressed according to the contrast variation study with mixed solvents of water, deuterium oxide, ethanol-d5, and ethanol-d6. The collapsed PMPC brushes at fethanol = 0.90 contained more water than the bulk solvent. The preferential distribution of water in the collapsed PMPC brush was consistent with the simulation results. Therefore, the molecular mechanism for the cononsolvency of PMPC in ethanol-water mixed solvents based on competitive hydrogen bonding coupled with cooperative solvation was experimentally rationalized.

Evaporation Dynamics of a Sessile Droplet of Binary Mixture Laden with Nanoparticles.

We investigate the evaporation dynamics of a sessile droplet of ethanol-water binary mixtures of different compositions laden with alumina nanoparticles and compare with the no-loading condition at different substrate temperatures. Shadowgraphy and infrared imaging methods are used, and the experimental images are postprocessed using a machine learning technique. We found that the loading and no-loading cases display distinct wetting and contact angle dynamics. Although the wetting diameter of a droplet decreases monotonically in the absence of loading, the droplet with 0.6 wt % nanoparticle loading remains pinned for the majority of its lifetime. The temporal variation of the normalized droplet volume in the no-loading case has two distinct slopes, with ethanol and water phases dominating the early and late stages of evaporation, respectively. The normalized droplet volume with 0.6 wt % loading displays a nearly linear behavior because of the increase in the heat transfer rate. Our results from infrared imaging reveal that a nanofluid droplet displays far richer thermal patterns than a droplet without nanoparticle loading. In nanoparticle-laden droplets, the pinning effect, as well as the resulting thermo-capillary and thermo-solutal convection, causes more intense internal mixing and a faster evaporation rate. Finally, a theoretical model is also developed that satisfactorily predicts the evaporation dynamics of binary nanofluid droplets.

Wettability model for water-ethanol binary mixture droplet on roughened low-surface-energy solids

Wettability of a droplet on rough solid surface exhibits complex behavior compared with a droplet on smooth solid surface. On a hydrophilic / hydrophobic solid substrate, hydrophilicity / hydrophobicity of a droplet changes as the surface roughness of the solid substrate varies. This kind of wettability is mainly discussed on the basis of Wenzel and Cassi-Baxter models where the wettability of droplets on roughened surface is analyzed by the concept of roughness ratio and contact area fraction. However, in an actual situation, it is very difficult to quantify the structure of the roughened surface and the contact area between liquid and solid surface strictly. In the present study, wettability of water-ethanol binary mixture droplet on roughened low-surface-energy solid is experimentally investigated in order to understand the wetting behavior in wide range of surface tension of liquid. A simple morphological model to quantify the surface roughness and critical surface tension of roughened solid surface is proposed. In addition, analytical model to predict the wettability on roughened solid surface is developed on the basis of the concept of adsorption of liquid molecules at solid–liquid interface, which can be applied to wetting behavior on both hydrophilic and hydrophobic roughened solid substrates.

Machine learning modeling and genetic algorithm-based optimization of a novel pilot-scale thermosyphon-assisted falling film distillation unit

Engaged in the global trend towards more energy-efficient and sustainable technologies, our research team has developed a falling film distillation apparatus with an innovative heat supply through a two-phase closed thermosyphon. In order to evaluate the performance of this energy-intensified distillation process, a supervised machine learning (ML) predictive model based on artificial neural networks is implemented for the separation of the ethanol–water binary mixture. The feed temperature, the evaporator temperature, and the feed flow rate are the three input variables of the model, whereas the ethanol mass fraction in the distillate, the distillate mass flow rate, the recovery factor, and the separation factor are the four performance indicators evaluated. The feed-forward ML has been trained, tested, and validated using a total dataset of 64 experimental runs carried out in the pilot-scale unit, covering a wide operating range of the input variables. Despite the high non-linearity, the ML approach was capable of modeling this new process accurately. The optimal topology of the ML model was achieved with a network arrangement of 10 neurons within 1 hidden layer (3:10:4), with a correlation coefficient (R) greater than 0.95 for all data. The predictive abilities of the ML model were harnessed to investigate the individual and synergistic interaction effects of the operating variables by plotting generalization graphs. Finally, the optimal operating conditions were evaluated by the genetic algorithm (GA) technique, being the feed temperature of 90.6 °C, the evaporator temperature of 109.6 °C, and the feed flow rate of 26.3 L/h, the process operating values that led the maximum of the four performance indicators, simultaneously. Under these operating conditions, a distillate mass flow rate of 4.9 kg/h, with 50.6%wt ethanol-enriched, a recovery factor of 84.9%, and a separation factor of 57.4 have been achieved, showing the high-performance feasibility of the pilot-scale unit.

Exploring the role of hydrophilic amino acids in unfolding of protein in aqueous ethanol solution.

Hydrophobic association is the key contributor behind the formation of well packed core of a protein which is often believed to be an important step for folding from an unfolded chain to its compact functional form. While most of the protein folding/unfolding studies have evaluated the changes in the hydrophobic interactions during chemical denaturation, the role of hydrophilic amino acids in such processes are not discussed in detail. Here we report the role of the hydrophilic amino acids behind ethanol induced unfolding of protein. Using free energy simulations, we show that chicken villin head piece (HP-36) protein unfolds gradually in presence of water-ethanol binary mixture with increasing composition of ethanol. However, upon mutation of hydrophilic amino acids by glycine while keeping the hydrophobic amino acids intact, the compact state of the protein is found to be stable at all compositions with gradual flattening of the free energy landscape upon increasing compositions. The local environment around the protein in terms of ethanol/water number significantly differs in wild type protein compared to the mutated protein. The calculated Wyman-Tanford preferential binding coefficient of ethanol for wild type protein reveals that a greater number of cosolutes (here ethanol) bind to the unfolded state compared to its folded state. However, no significant increase in binding coefficient of ethanol at the unfolded state is found for mutated protein. Local-bulk partition coefficient calculation also suggests similar scenarios. Our results reveal that the weakening of hydrophobic interactions in aqueous ethanol solution along with larger preferential binding of ethanol to the unfolded state mediated by hydrophilic amino acids combinedly helps unfolding of protein in aqueous ethanol solution.

Multicomponent pool fires: Trends in burning rate, flame height, and flame temperature

The composition of a multicomponent pool fire will vary over the course of burning due to preferential distillation of more volatile compounds. As a result, key fire properties like the burning rate, flame temperature, flame height, and soot emissions will change as the properties of the fuel change. This adds uncertainty about the combustion properties of the fire, especially for fuel blends with widely varying boiling points (e.g., gasoline-ethanol). The heat release rate, which is proportional to the burning rate, is essential for estimating the radiative flux to nearby structures or personnel, so understanding how fire dynamics are impacted by the composition of a fuel mixture is a pre-requisite for dealing with hazard assessments of fire scenarios involving multicomponent fuels. Continuously fed pool fire experiments were conducted in a 0.30 m diameter pan with binary mixtures of ethanol-water, ethanol-isopropanol, and ethanol-hexane. The relationship between burning rate and fuel composition was strongly dependent on vapour-liquid equilibria and relative volatility of the mixture. It was found that burning rate models dependent on fuel properties gave better predictions of the relationship between burning rate and fuel composition. Heskestad’s flame height and flame temperature correlations were found to be suitable for use in multicomponent pool fire scenarios.

Rotation of small diatomics in water-ethanol mixture: Multiple breakdowns of hydrodynamic predictions.

We study the rotational and translational dynamics of three small important linear molecules, namely, carbon monoxide (CO), nitric oxide (NO), and cyanide ion (CN-) in water-ethanol mixtures, at different compositions. Here, we report a detailed study of the dynamics of these diatomics in water-ethanol binary mixtures for the first time. We find multiple anomalous results, namely, (i) faster rotational motion of CO and NO than CN-, (ii) larger translational diffusion of CO and NO in pure ethanol than in water but the reverse for CN-, (iii) a pronounced anomaly in the composition dependence of translational-rotational dynamics at low ethanol composition, and (iv) a re-entrant type behavior in the viscosity dependence of orientational relaxation. We compare our simulation result-based observations with the existing experimental results wherever available and find that the simulation results are in reasonably good agreement with the experiments. We implement, for the first time, a calculation of the rotational binary friction following the sophisticated scheme of Evans and co-workers. We also calculate the hydrodynamic predictions for the solute molecules. On comparison with the simulation and experimental results, we find that neither the rotational binary friction nor the hydrodynamic expressions (both stick and slip) can reproduce the results. To rectify the situation, we develop a detailed mode-coupling theory and suggest that such an approach if completely implemented can provide a more reliable description than the hydrodynamic approach. Many of our results could be tested in experimental studies because these linear molecules are amenable to spectroscopic studies, such as 2D-IR.

RAFT dispersion polymerisation of lauryl methacrylate in ethanol–water binary mixtures: synthesis of diblock copolymer vesicles with deformable membranes

Diblock copolymer vesicles with deformable membranes are prepared via RAFT dispersion polymerisation of lauryl methacrylate in an 80 : 20 w/w ethanol–water mixture; visible light irradiation allows facile RAFT chain-end removal from these nano-objects.

미니채널 내 물-에탄올 혼합물로 구성된 단일 액체 슬러그 계면 깨짐 현상에 대한 실험적 연구

A two-phase flow in mini-channels is consist with various flow regimes (such as bubble slug, annular, churn flow) according to gas and liquid phase flow rates. A previous researches revealed that in a case of slug flow in hydrophobic mini-channels, gas and liquid phase are perfectly separated by interfaces and triple contact line. In this study, the single dry slug flow experiments in circular mini-channel (D = 1.018 mm) are conducted to observe interfacial break-up phenomena in high capillary number range (Ca < 0.02). The slug is consist with D.I. water or D.I. water-ethanol binary mixtures (5% and 10%, mole fraction). On the base of previous researches, we calculate the pressure drop at moving triple contact line. In an addition, a single dry slug flow is visualized by using high-speed camera. Through the experiment, three regimes of pressure drop are observed; steady, loss, separation. As a result, criteria between steady and loss regimes is closely related to capillary number, and criteria between loss and separation regimes is related to surface tension.