Liquid Glycol Research Articles

Determination of the Conformational Composition of Ethylene Glycol by RAS Spectroscopy and DFT Calculations

The objectives of the study of ethylene glycol (EG) are to determine the Raman lines of glycols that can be used to analyze the conformational and isomeric composition of molecules, as well as to assess the conformational composition of glycol molecules. Based on the calculations, it was found that the Raman lines in the region of about 800 cm−1are indicators of the presence of EG molecules in conformations of the xGyor xG'y type, where x and y can be t, g or g'. In the experimental Raman spectra of liquid EG, this line is highly intense, therefore, molecules in the indicated conformations are present in large quantities in liquid EG. This result is also confirmed by the obtained contents of EG molecules in various conformations based on calculations. In order to describe the 2600-4000 cm−1 region of the Raman spectra of glycols, it is necessary to take into account intermolecular interactions.

Combine thermal performance based on dust particles and Hall and ion slip currents including tetra-hybrid nanoparticles on Howarth's wavy pipe

The flow of a three-dimensional incompressible Carreau model by inserting iron oxide, titanium, copper and aluminum in a stretched wavy cylinder is inspected in this research by mixing the nanoparticles in two phases i.e. dust and fluid phase. The rheology of the Carreau model is considered to present the behavior of ethylene glycol liquid. The contribution of Hall current with the ionization of ion slips under convective boundary conditions by utilizing the comportment of radiation and external heat source in thermal transport expression is considered. Numerically, an implicit finite difference-based approach (FDBA) namely the finite element method (FEM) is used to handle nonlinear ODEs and several graphs are plotted against numerous emerging parameters. Moreover, shear stresses and heat transfer coefficient are calculated and their behavior is discussed. The velocity field's inclination is depicted graphically by augmenting the values of the Biot number, which further describes the comparative study for dust and fluid phases to monitor motion.

Synergistic modulation of alkaline aluminum-air battery based on localized water-in-salt electrolyte towards anodic self-corrosion

A long-term hurdle for Al-air batteries is the severe open-circuit corrosion, irreversibly self-discharging more than 80% per month depending on the battery design. In this work, we introduce an ionic liquid-ethylene glycol system as a local water-in-salt electrolyte to modify the conventional aqueous solution. At the same time, synergistic effect between morin and ionic liquid is employed to further reduce the salt component, as well as improving the performance. Experiments such as electrochemical test, surface analysis and theoretical calculations prove that the additives can modulate the anodic interface and restrain the free water molecules through hydrogen bond. Thus, Al-6061 anode suffers low parasitic corrosion rate and gains stable surface. Furthermore, the performance of assembled aluminum air battery is greatly improved with an excellent specific capacity of 2010 mAh/g, reliable cycle stability and anode utilization.

Droplet Motion Driven by Liquid Dielectrophoresis in the Low-Frequency Range.

Electrohydrodynamic wetting manipulation plays a major role in modern microfluidic technologies such as lab-on-a-chip applications and digital microfluidics. Liquid dielectrophoresis (LDEP) is a common driving mechanism, which induces hydrodynamic motion in liquids by the application of nonhomogeneous electrical fields. Among strategies to analyze droplet movement, systematic research on the influence of different frequencies under AC voltage is missing. In this paper, we therefore present a first study covering the motion characteristics of LDEP-driven droplets of the dielectric liquids ethylene glycol and glycerol carbonate in the driving voltage frequency range from 50 Hz to 1600 Hz. A correlation between the switching speed of LDEP-actuated droplets in a planar electrode configuration and the frequency of the applied voltage is shown. Hereby, motion times of different-sized droplets could be reduced by up to a factor of 5.3. A possible excitation of the droplets within their range of eigenfrequencies is investigated using numerical calculations. The featured fluidic device is designed using larger-sized electrodes rather than typical finger or strip electrodes, which are commonly employed in LDEP devices. The influence of the electrode shape is considered simulatively by studying the electric field gradients.

Integration of FDM and self-healing technology: evaluation of crack sealing by durability and mechanical strength

The tensile zone of concrete is prone to cracking due to its limited ability to withstand tension. To address this issue, steel reinforcement is used in these specific regions. The occurrence of little cracks might potentially facilitate the ingress of liquids and gases into the reinforcing material, hence inducing corrosion. Self-healing concrete can repair and seal minuscule cracks, thus impeding the formation of corrosion. This study investigates the potential application of fused deposition modeling (FDM) for generating novel vascular networks and tubes using polylactic acid (PLA) as the material. Poly (lactic acid) (PLA) was fabricated using three-dimensional (3D) printing techniques, and its properties were compared to those of one-dimensional (1D) and two-dimensional (2D) networks. The external diameter measured 5.6 mm, while the internal diameter measured 4 mm. utilized a 10 ml volume to apply healing agents, specifically organic polyethylene glycol liquid and nano-powder (fly ash) derived from recycled materials, to all vascular structures (1D, 2D, and 3D). This application was carried out using a planetary ball mill. Following this, the prepared tubes were incorporated into a concrete beam to introduce self-healing capabilities. The water-to-cement ratio (W/C) utilized for all concrete mixtures was 0.6%, while the definite mixture proportions were 1:2.16:2.98. The quantification of the self-healing phenomenon was conducted by evaluating the restoration of load-carrying capacity following the application of a repaired specimen to a four-point bending test. Furthermore, these enhancements resulted in improved durability, increased compressive strength, and enhanced other physical characteristics. The pipes that are manufactured can be utilized to produce innovative concrete that possesses the ability to undergo self-healing processes by combining low-viscosity healing solutions (PEG) with powders (nano fly ash) that are appropriate for this application by injection into the vascular network , making it well-suited for various self-healing applications.

Methyl and Ethyl Ethers of Glycerol as Potential Green Low-Melting Technical Fluids.

The study is dedicated to the consideration of lower alkyl ethers of glycerol as potential components of low-melting technical fluids (e.g., heat transfer fluids, hydraulic fluids, aircraft de-icing fluids, etc.). Four isomeric mixtures of glycerol ethers (GMME-monomethyl; GDME-dimethyl; GMEE-monoethyl; GDEE-diethyl) were synthesized from epichlorohydrin and methanol/ethanol in the presence of sodium and subjected to detailed characterization as pure compounds and as aqueous solutions (30-90 vol%). The temperature and concentration dependencies of density, viscosity, cloud point, boiling range, specific heat capacity, thermal conductivity, and rubber swelling were obtained. On the basis of the data obtained, a comparison was made between the aqueous solutions of glycerol ethers and of other common bases for low-melting liquids (glycerol, ethylene glycol, and propylene glycol). Pure glycerol ethers could potentially be used as technical fluids in a very wide temperature range-from -114 to 150 °C. It was further demonstrated that in low temperature applications (e.g., in low-temperature chiller systems) the glycerol-ether-based aqueous heat transfer fluids could provide enhanced efficiency when compared to the glycerol- or propylene-glycol-based ones due to their lower viscosities and favorable environmental properties.

Experimental study on low pressure heat transfer properties of water evaporator with screen separation element

Water evaporator is often used in spacecraft thermal management as heat sink. In a water evaporator, heat is transferred from the microchannels of cooled glycol liquid to the external water, which causes the phase transition of water near external fins. Due to the severe weight requirements of hypersonic vehicles, it is very important to study the heat transfer performance and water utilization of water evaporator. The present study experimentally investigated the boiling heat transfer of water evaporator on external rectangular fins (RF) at low pressure, and the heat transfer of cooled glycol liquid in microchannels with offset strip fins (OSF). At the same time, the experiment explored the effects of three types of screen devices on the heat transfer performance and water utilization efficiency of water evaporators. The heat transfer experiments of water evaporator were conducted at the pressure of 11 kPa. The inlet temperature of hot glycol liquid was controlled 85 °C, and the mass flow rate were at 1500 kg/h and 2500 kg/h, respectively. The experimental results show that when the mass flow rate of ethylene glycol is the same, the water consumption of the water evaporator significantly decreases and the water utilization efficiency increase with the increase of screen density, but it can weaken the boiling heat transfer performance. In addition, the empirical correlation of boiling in low-pressure is modified, and the maximum deviation is within ±10%. The screen separator element and the new modified correlation provide a reference for the design of water evaporator.

Guarded Parallel-Plate Instrument for the Determination of the Thermal Conductivity of Gases, Liquids, Solids, and Heterogeneous Systems

In the present study, a new version of a guarded parallel-plate instrument (GPPI) for the absolute determination of the thermal conductivity under steady-state conditions is presented. It is based on an existing concept of an automated instrument and includes several modifications with the aim of further improving the achievable accuracy and experimental uncertainty while reducing the measurement time. These modifications mainly include improvements to the guard system in the upper hot part, which lead to a further suppression of parasitic heat fluxes, and the integration of flow circulation systems for the active temperature control in the periphery of the instrument. By using relatively large values for the temperature difference between the heating and cooling plates and for the sample thickness, expanded (k = 2) measurement uncertainties between (2 and 3)% could typically be achieved for the thermal conductivity. For mean temperatures from (283 to 358) K and atmospheric pressure, the measurement results agree well with reference data for liquid water, toluene, and ethylene glycol as well as air, polytetrafluorethylene (PTFE), and stainless steel 316. In addition, the applicability of the new GPPI for the determination of the effective thermal conductivity of heterogeneous systems was demonstrated using water-based nanofluids containing dispersed silicon dioxide, titanium dioxide, or copper oxide nanoparticles.

Sutterby hybrid nanofluid flow and heat transfer over a nonlinearly expanding sheet with convective boundary condition and zero-mass flux concentration

This paper examines the impacts of a nonlinearly expanding sheet on velocity, heat and mass transport for a Suttery hybrid nanoliquid (mixture of Sutterby fluid and [Formula: see text] and [Formula: see text]. The zero-mass flux concentration and convective boundary conditions are considered. Nondimensionalization of governing equations may be achieved through similarity conversions. The governing equations are solved utilizing the Optimal Homotopy Analysis Method. Graphs and tables were used to document the effects of different variables. The numerical values for skin friction, Sherwood number and Nusselt number are provided in a table for diverse relevant factors. Comparisons were made to a previous study’s findings. The results obtained are in agreement with the findings of the prior study. The outcome is that the occurrence of hybrid nanoparticles ([Formula: see text] and [Formula: see text] in ethylene glycol liquid enhances its thermal conductivity thereby increasing the thermal boundary layer thickness. The presence of hybrid nanoparticles ([Formula: see text] and [Formula: see text] in ethylene glycol liquid also increases the momentum boundary layer thickness.

The effect of liquid grinding aids on the dry fine grinding of muscovite

This paper investigates the production of a micronized muscovite to a target product size of d50~15 µm with a minimum energy consumption to suit the product requirements of the paint industry by a dry grinding process in a laboratory-scale vertical stirred ball mill. A series of batch dry grinding tests were conducted without and with two commonly used industrial liquid grinding aids, ethylene glycol (EG, C2H6O2) and triethanolamine (TEA, C6H15NO3). The results were evaluated based on particle size distribution (PSD), specific energy consumption, span value, and aspect ratio. The results showed that using liquid grinding aids resulted in a finer PSD, lower specific energy consumption, a narrower size distribution, lower span values, and a higher aspect ratio, which meant better delamination and improved grinding efficiency to that of no grinding aid. The interaction between grinding aids and ground muscovite surfaces was investigated by Fourier Transform Infrared Spectroscopy (FTIR). FTIR measurements revealed that EG and TEA were physically adsorbed on muscovite surfaces. Scanning Electron Microscopy (SEM) was also employed to determine differences between ground muscovite surfaces with and without grinding aids. SEM images indicated that grinding aids could prevent the agglomeration of ground muscovite particles while improving delamination. Adding grinding aids led to a decrease in muscovite agglomeration and an improvement in lamination owing to the adsorption of grinding aids on the particle surfaces.

Thermal protection of a vertical plate using ethylene glycol film cooling flowing down on a vertical plate

This paper concerns a numerical investigation of the evaporative cooling of liquid film falling along a vertical channel. The first plate is insulated and wetted by an ethylene glycol liquid film while the second one (y = d) is dry and isothermal. A marching procedure is employed for solution of the equation of mass momentum, energy and concentration in the flow. Numerical results for air-ethylene glycol system are presented. The effects of ambient gas temperature and inlet vapor mass fraction of ethylene glycol on the heat and mass transfer and on the ethylene glycol liquid film evaporation are investigated.

Correlation between Nafion Morphology in Various Dispersion Liquids and Properties of the Cast Membranes.

Nafion is a perfluorosulfonic acid polymer that is most commonly used in proton-exchange membrane fuel cells. The processes of pretreatment and formation of such membranes strongly affect their properties. In this work, dispersions of Nafion in various ionic forms and dispersing liquids (ethylene glycol, N,N-dimethylformamide, N-methyl-2-pyrrolidone and isopropyl alcohol-water mixtures in different ratios) were obtained and studied. Membranes fabricated by casting of the various dispersions were also studied. The effect of the nature of the dispersing liquid and the counterion on the properties of Nafion dispersions, the morphology of the polymer in the dispersions and the characteristics of the membranes obtained from them has been shown. Based on the overall results, it can be concluded that the use of perfluorosulfonic acid dispersions in aprotic polar solvents is advisable for obtaining membranes by the casting procedure. This is because it provides optimal polymer morphology in the dispersion, which leads to the formation of films with good selectivity, mechanical and transport properties. The performed investigations show the relationship between the composition of dispersions, the morphology of the polymer and the properties of the membranes formed from them by the casting procedure.

Transient isogeometric heat conduction analysis of stationary fluid in a container

This article is devoted to the numerical simulation of transient heat conduction problems in fluids. A numerical formulation depending on isogeometric analysis-based GeoPDE's toolbox is employed to establish the viability of isogeometric analysis as a tool for analysing heat conduction problems. An experimental analysis is conducted on a physical model of a container for checking the change in temperature with time. Then the isogeometric analysis is used for the development of a numerical model and evaluation of unknown field variable, that is, temperature and its dependent properties. The validation of the proposed model is done by comparing it with an experimental analysis and calculating the coefficient of correlation between the two models. As a result, +0.99 value of correlation coefficient is devious out, which presents a positive relationship between the two. Based on the validated results, the proposed model is employed for the evaluation of thermophysical properties for different fluids like liquid water and ethylene glycol–water mixture. The evaluated properties of ethylene glycol–water solution are compared with existing literature values. A root mean square error is compared between evaluated and literature property values for various concentrations. The deduced values are in the range of 2.3%–8.4% for density and 0.26%–4.6% for viscosity. It is found that isogeometric analysis can be effectively applied in heat conduction problems using GeoPDE.

Unified Approach for Prediction of the Volumetric Mass Transfer Coefficients in a Homogeneous and Heterogeneous Bubble Column Based on the Non-Corrected Penetration Theory: Case Studies

A critical review on the improvement of penetration theory is presented in this work. The volumetric liquid-phase mass transfer coefficients kLa in seven different liquids (1-butanol, 2-propanol, anilin, decalin, nitrobenzene, tetralin, and ethylene glycol) aerated with air in a small bubble column (BC) (inner diameter: 0.095 m) were measured at ambient conditions and further analyzed. It was found that the kLa values can be predicted satisfactorily on the basis of the classical Higbie’s penetration model. The gas–liquid contact time was defined as the ratio of the Sauter-mean bubble diameter to bubble rise velocity. Moreover, the experimental kLa values were well predicted, not only in the homogeneous regime, but also in the transition and heterogeneous regimes. This is a new finding, since to date, it was considered that the penetration theory needs a correction factor for a successful application to any liquid, even in the homogeneous regime. The predictions of the mass transfer coefficients kLa in the above-mentioned seven liquids imply that the mean bubble diameters are always ellipsoidal or spherical, which is the key condition for the applicability (without a correction) of penetration theory. In the presented (in this work) model-based kLa predictions, the Sauter-mean bubble diameters were estimated by means of the reliable correlation of Wilkinson et al., which always predicts a gradually decreasing bubble size at higher gas velocities.

Evaluation of the Skin Permeation-Enhancing Abilities of Newly Developed Water-Soluble Self-Assembled Liquid Crystal Formulations Based on Hexosomes

The present study aimed to develop polyethylene glycol–liquid crystals (PEG-LC) ointment formulations, assess their formulation characteristics, and establish their biocompatibility and impact on transdermal drug administration. PEG-LC formulations were prepared using a hydrophilic molecule, p-aminobenzoic acid (PAB). Formulation characterizations such as small-angle X-ray scattering, viscosity, pH, zeta potential, and the particle sizes of the formulations were examined to determine the physicochemical properties of the prepared formulations. The drug release profile of PEG-LC ointment formulations was assessed with a dialysis membrane. In vitro skin permeation testing was performed to establish whether the PEG-LC formulations improved drug skin penetration. The MTT and comet assays were performed to assess the biocompatibility of the formulations. Our data showed that the method is effective in forming hexosome-type PEG-LC formulations and that they were biocompatible. Furthermore, the PEG-LC formulations significantly improved PAB skin penetration when compared with commercial PEG. The PEG-LC formulation is a promising carrier for the delivery of hydrophilic drugs.

Revisiting the Surface Energy Parameters of Standard Test Liquids with a Corrected Contact Angle Method over Rough Surfaces.

Interfacial free energy is a quantitative basis for explaining and predicting interfacial behavior that is ubiquitous in nature. The contact angle (CA) method can determine the surface free energy (γ) as well as Lifshitz-van der Waals (γLW) and Lewis acid/base (γ+/γ-) components of a solid material from its CAs with a set of known test liquids according to the extended Young-Dupré equation. However, the reliability of the "known" parameters of the test liquids is questioned due to the long-neglected surface roughness effect during calibration of the liquids. This study proposed a simple and practicable two-step approach to correct the energy parameters of several test liquids by incorporating Wenzel's surface roughness relationship into CA measurement. Step 1: water and two apolar liquids (diiodomethane and α-bromonaphthalene) were used as benchmarks to calibrate the surface roughness and energy parameters of two reference solids [apolar poly(tetrafluoroethylene) and monopolar poly(methyl methacrylate)], and step 2: the reference solids were used to calibrate any other test liquids by solving the energy parameters from their CAs in the extended Young-Dupré-Wenzel model. Monte Carlo simulation was used to evaluate error transmission and robustness of the model solutions. The obtained energy parameters (γLW/γ+/γ-) of four test liquids (dimethyl sulfoxide, formamide, ethylene glycol, and glycerol) are 28.01/13.68/4.67, 34.95/3.53/37.62, 26.26/7.51/15.74, and 32.99/9.24/26.02 mJ/m2, respectively, and different from the literature values. The liquids were applied to characterize an example solid surface with true γLW/γ+/γ- values of 28.00/1.00/8.00 mJ/m2 and a roughness index (r) of 1.60. Without correction of the liquid parameters, the calculated surface energy, hydration energy, and hydrophobic attraction energy of the solid sample can deviate by 50, 13, and 27%, respectively. This proves the necessity of correcting parameters of the test liquids before they can be used in CA and interfacial energy studies in the presence of surface roughness.

Conformer Selection Upon Dilution with Water: The Fascinating Case of Liquid Ethylene Glycol Studied via Molecular Dynamics Simulations.

The aqueous solution of ethylene glycol (EG) is a binary liquid mixture that displays rich conformational and structural behaviour, which has not yet been adequately explored through atomistic molecular dynamics simulations. Herein, employing an accurate force field for EG, several physical properties of this solution are calculated to be in quantitative agreement with experimental data. While 79 % of molecules in neat liquid EG exist with their central OCCO dihedral in the gauche state, this fraction increases to 89 % in the dilute aqueous solution, largely in response to the increase in the static dielectric constant of the solution from that of neat liquid EG. The increase in gauche conformers increases the mean dipole moment of EG molecules in the solution which is additionally contributed by specific conformational states of the two terminal HOCC dihedral angles.

Thermal Prandtl-Eyring hybridized [formula omitted]-[formula omitted] and [formula omitted]-[formula omitted] nanofluids for effective solar energy absorber and entropy optimization: A solar water pump implementation

The functional properties of a hybridized nanofluid offer high applications in nanotechnology advancement and efficient industrial output. Hence, this analysis focuses on the dynamical properties of a magnetized viscoplastic nanofluid of solar heat absorber for water pump. The hybridization of Prandtl-Eyring fluid, molybdenum disulfide and silicon dioxide nanoparticles in propylene glycol liquid is examined with Ohmic heating and viscous dissipation. A second order parabolic trough slip collector of radiative solar energy absorber is used to study the flowing fluid characteristics. A dimensionless mathematical model is obtained with convective cooling and slip boundary conditions via similarity quantities, and the model is solved by Chebyshev collocation technique. The optimization of entropy is determined using the thermodynamic second law. In tabular form, the results comparison is done, and the wall friction and heat gradient are presented. The hybridized nanofluid significantly lowers the entropy generation in the presence of Prandtl-Eyring material as compared to the single nanofluid.

The Implementation of MQTT Protocol using PT-100 for Monitoring the Vaccine Temperature

A vaccine has an essential role for humans because it can reduce the effect of organism infection and activate the body's immune. The limitation of temperature when the vaccine is stored becomes one of the influential factors for its quality. Since the recent technique used for checking the temperature is manual, the process of real-time temperature monitoring cannot be done and becomes the main problem in the process of storing vaccines. This research is aimed to develop a system for measuring temperature on a chiller through a temperature sensor and the internet of things automatically. The methods used in the MQTT protocol are published and subscribed. The quality of service (QoS) to measure network capability and PT-100 is the sensor in this research because it has a high accuracy level, linear signal change, and fast response. This sensor can measure glycol liquid with a temperature range of 2-8°C. Data distribution uses an ESP module to connect the data to Antares through the wifi network. The temperature value measurement using PT-100 toward vaccine chiller temperature obtains an accuracy value of 99,32%. This accuracy value shows that the result is compatible with the logger data measurement tool development used with an error result of 0.58%. Delay parameter testing on the QoS level obtains the average value of 41.91 ms, while the Packet loss parameter obtains the value of 0%.

Thermodynamics of TMU-TMU interaction in water, ethylene glycol and formamide – From pair solvophobic interaction to cluster formation

This paper focuses on the interaction between tetramethylurea (TMU) molecules in liquid water, ethylene glycol (Eg) and formamide (FA) which form the H-bond network on a supramolecular level. The virial enthalpic, heat capacity, entropic and free energy parameters of solute–solute interaction have been extracted from the experimental thermodynamic data in a wide temperature range. The second virial coefficients of the TMU-TMU pair interaction and their temperature changes have been computed both in aqueous and non-aqueous systems. Our comparative analysis indicates that the strong solvophobic interaction between two TMU molecules does exist and increases with the temperature, the effect being much stronger pronounced in aqueous solutions. This strong attraction between methyl groups of TMU leads to formation of labile clusters containing both solute and solvent molecules.