Glycol Aqueous Solution Research Articles

Inhibition of the Corrosion of Aluminum Alloy in Aqueous Solution of Ethylene Glycol by the Rhamnolipid Biocomplex

We study the efficiency of inhibition of corrosion processes in the aluminum alloy placed in an aqueous solution of ethylene glycol by an ecologically friendly rhamnolipid biocomplex obtained as the product of biosynthesis of the Pseudomonas sp. PS-17 strain. It is shown that the biogenic inhibitor added to an aqueous solution of ethylene glycol decreases the rates of both the anodic and cathodic reactions and makes the charge-transfer resistance of aluminum alloy 2.6 times higher, which indicates the possibility of formation of durable protective films on the metal as a result of the adsorption of inhibitor molecules and the formation of complex compounds with aluminum cations. It is shown that the rhamnolipid biocomplex is an efficient corrosion inhibitor on freshly formed surfaces of the aluminum alloy, as indicated by an increase in the rate of its repassivation.

Influence of the Coolant Flow Containing Silver Nanoparticles (Ag) from an Aqueous Solution Based on Ethylene Glycol (EG50%) on the Thermal-Hydraulic Performance of an Automotive Radiator

A theoretical analysis of the influence of the flow of a coolant containing silver nanoparticle (Ag) in an automotive radiator is presented. The coolant fluid is composed of water or an aqueous solution of Ethylene-Glycol (EG50%) and silver nanoparticles. Ethylene glycol (EG) has been used in automobile radiators for many years due to its compatibility with metals and its anti-cooling properties. Silver nanoparticles are being incorporated into the development of high-precision surgical equipment. It is shown that the rate of heat transfer increases significantly using silver nanoparticles and ethylene glycol and water. There is a maximum for heat exchange between fluids in all analyzed coolant flows—the maximum moves to higher airflow rates when the coolant flow rate is increased. However, the energy dissipation in the stream also increases, but the relationship between the energy dissipated in the flow and the energy transferred in the form of heat is low, which justifies the use of silver nanoparticles and ethylene glycol, or silver nanoparticles and water as a coolant in the automotive vehicle radiator.

The Impact of the Use of Antifreeze Substances on the Heating Installation Thermohydraulic Parameters and Energy Consumption

This article discusses the effect of application of antifreeze substances on thermohydraulic parameters and energy consumption of a heating installation with convective radiators. A comparative theoretical and computational analysis is performed for water and two alternative heating mediums: a 50% aqueous solution of ethylene glycol and propylene glycol. It is indicated that antifreeze substances and their aqueous solutions may cause a reduction in the radiator heat output and an increase in hydraulic resistance, which results in the entire system higher energy consumption and lower efficiency. It is then justified that the heating installation design should take account of the use of a glycol aqueous solution instead of water to avoid an excessive drop in the installation energy indicators and prevent deterioration of the building thermal comfort conditions.

Hydrogel-based temperature sensor with water retention, frost resistance and remoldability

Conventional hydrogels will be frozen at low temperatures and lose their flexibility. At higher temperatures, hydrogels will lose water more quickly. The inherent property of hydrogels hinders its development in the field of flexible wearable sensors. In this research, we studied the anti-freezing and moisturizing mechanism of glycerol (Gly), ethylene glycol (EG) and CaCl2 aqueous solutions. The Gly solution with excellent antifreeze humectant and friendly to the organism was selected as antifreeze humectant. We introduced Gly into PVA gel to make the gel have anti-freezing and moisturizing properties, and then introduced silver nanofibers (AgNW) into the gel to obtain the temperature sensor with anti-freezing and moisturizing properties. Since the gel uses reversible physical cross-linking, the sensor has excellent remodeling ability. The temperature sensor has the advantages of high sensitivity, short response time to temperature and excellent accuracy. It is expected to be applied to temperature sensors under severe weather conditions.

Preferential Interaction of Chymotrypsinogen in Aqueous Solutions of Polyols at 298.15 K

Preferential interactions of α-chymotrypsinogen in water and aqueous solutions of ethylene glycol, glycerol, erythritol, sorbitol, and inositol were studied from precise density measurements under conditions of constant molality and constant chemical potential; to achieve the last condition, solutions were brought under equilibrium dialysis. The density measurements were performed at 298.15 K and they were used to determine the preferential interaction parameters. The results confirm a significant correlation between the numbers of hydroxyl groups of the polyols with the stability of α-chymotrypsinogen.

Selection of cross-seasonal heat collection/storage media for wood solar drying

In order to break through the limitations of wood solar drying and its application in the tropics, the core part of a wood solar drying system (collection/storage media) should be adapted to the seasonal characteristics of the high latitudes (Harbin, China). Therefore, formulating a scheme for selecting cross-seasonal heat collection/storage media for use in a wood solar drying system is of great significance. In this study, three common industrial media were tested for heat collection and heat storage in different environmental conditions. The poplar drying process was taken as an example, and the minimum temperature of the medium required for heat collection was calculated. The cross-seasonal heat collecting/storage medium scheme was developed for drying poplar. The results show that an aqueous ethylene glycol solution (W-EG) was the optimal heat collection medium. W-EG collected 109.3% more heat than heat transfer oil (THO), and the thermal efficiency (η) was 91.1% greater than η for THO when the ambient temperature was –10 °C. When the ambient temperature ranged from 5 °C to 35 °C, water (W) was the best heat collecting medium; the heat collection and thermal efficiency were significantly higher than those provided by W-EG and THO, and the heat dissipation capacity of THO was better than W-EG. Therefore, in late autumn, winter, and early spring, W-EG is the optimal heat collecting/storage medium. In late spring, early autumn, and summer, W is the optimal heat collecting medium, and W-EG was the optimal heat storage medium.

Numerical and Experimental Study on a High-Power Cold Achieving Process of a Coil-Plate Ice-Storage System

Heat dissipation of high-power lasers needs a cold storage and supply system to provide sufficient cooling power. A compact coil-plate heat exchange device has been proposed and applied in the phase-change cold storage system with ice as the cold-storage medium and glycol aqueous solution as the coolant. The heat exchanger consists of several stacked coil-plate units and each unit is constructed with a flat plate and serpentine coils welded on the plate. A simulation model on the cold achieving process of a coil-plate unit was built and verified by the corresponding experiment. The influences of the structural parameters (tube diameter, tube pitch, and plate spacing) of the unit and the inlet temperature and volume flow rate of the coolant on the heat exchange power density were analyzed to obtain the maximal cooling effect in a limited time period. It was found that the heat exchange power density is limited when the tube pitch and plate spacing are large, otherwise, the effective cooling time period is limited. A small plate spacing can make the power density decrease rapidly in the later stage. The inlet coolant temperature can significantly affect the heat exchange power density while the coolant volume flow rate in tube has a small effect on the power density when the coolant is in turbulent state. In a time period of 900 s, for a coil-plate heat exchanger with a plate size of 940 mm ×770 mm and a tube pitch of 78 mm, when the plate spacing is 20 mm, the average heat exchange power density is 5.1 kW/m2 when the inlet temperature and volume flow rate of the coolant are 20 °C and 0.5 m3/h, respectively. The total cooling power of several stacked coil-plate units in the limited time period can match the high requirement of laser heat dissipation.

Development of a Novel Simple Gel Formulation Containing an Ion-Pair Complex of Diclofenac and Phenylephrine

Background and Aim: Since the pharmacological effects of diclofenac (DF) are short-lived because of its short half-life, prolongation of the pharmacological effect in a topical formulation is needed for more appropriate clinical use. For the enhancement of dermal accumulation and prolongation of the pharmacological effect of drugs, the aim of this study was to develop a simple gel formulation containing an ion-pair complex of DF and phenylephrine (PHE), which induce constriction of the vascular smooth muscles. Materials and Methods: The ion-pair complex was prepared by mixing sodium DF and an ethanolic solution of PHE. The formed complex was characterized by powder X-ray diffraction (PXRD) and Fourier-transform infrared (FT-IR) spectroscopy. The ion-pair complex for the gel formulation was prepared by mixing an equimolar concentration of 50% 1,3-butylene glycol and distilled aqueous solution of 2% xanthan gum, which was characterized by proton nuclear magnetic resonance (¹H-NMR). Skin permeation and accumulation of DF and PHE were evaluated by in vitro and in vivo studies. Results: From the results of PXRD and FT-IR, it was suggested that new crystalline peaks formed by the ion-pair complex and their complex interacted with the carboxyl group in DF and the amino group in PHE. In the gel formulation, the ion-pair complexes were detected by ¹H-NMR. The ion-pair complex enhanced the accumulation of DF in the skin in the in vitro study. On the other hand, PHE accumulation in the dermis increased with the ion-pair complex, as exhibited by the in vivo study. Conclusion: A new gel formulation containing the ion-pair complex of DF and PHE was developed, which improved the accumulation of DF in skin.

Hydrogen bonding in chitosan/Antarctic krill protein composite system: Study on construction and enhancement mechanism

The main of the work concerns the reason for the interpretation of the tensile strength of chitosan (CS) enhanced by Antarctic krill protein (AKP). We found a new mixed solvent, 2 wt% glacial acetic acid, and 2 wt% ethylene glycol aqueous solution, to prepare a stable CS/AKP composite solution. Then we obtained CS/AKP fiber by wet-spinning on a lab-scale wet-spinning machine. The tensile strength of blended fibers is 2.53 cN/dtex in the dry state, which is improved by 11.9% compared with the CS fibers. We found that the increased tensile strength of the blended fibers is relative to the hydrogen bond formed between CS and AKP. Specifically, illustrate the restructured hydrogen bonds in CS/AKP system in Fourier transform infrared curve fitting. The hydrogen bond probably benefits on crystalline growth of CS along the fiber axis and is the main drivable factor in removing the water molecules in blended fibers.

Optical measurement of concentration-dependent diffusion coefficients of binary solution using an asymmetric liquid-core cylindrical lens

An optical method for measuring concentration-dependent diffusion coefficients of binary solution is introduced in this paper. The concentration spatial and temporal profiles (Ce(z, t)s) are obtained from a single experiment using an asymmetric liquid-core cylindrical lens. The concentration-dependent diffusion coefficient is assumed to be a polynomial D(C) = D0 × (1 + α1C + α2C2 + α3C3 + …), where D0 is diffusion coefficient in infinite dilute solution, α1, α2 and α3 are under-determined parameters. The finite difference method (FDM) is applied to solve numerically Fick diffusion equation, the calculated concentration profiles (Cn(z, t)s) by varying the under-determined parameters are compared with the profile Ce(z, t), the parameters(α1, α2, α3, …) corresponding the minimum concentration standard deviation are selected to determine D(C). To verify the proposed method, we have carried out the diffusion experiment of ethylene glycol aqueous solution, the obtained concentration-dependent diffusion coefficients are in good agreement with literature values. On the other hand, the obtained polynomial D(C) has been used to calculate refractive index profiles (nn(z, t)s). Based on the nn(z, t)s, ray tracing method has been applied to simulate the diffusion images, which fit the experimental images very well over a wider range of diffusion time, demonstrating that the proposed method is reliable in rapidly measuring concentration-dependent liquid diffusion coefficients with high accuracy and stability.

Experimental study on steam side vacuum capillary concentrated ethylene glycol aqueous solution

ABSTRACT The separation system is designed to separate and concentrate the aqueous glycol solution under a low-temperature heat source. The experiment found that the pore size of the capillary wick, the verticality of the evaporator, as well as the degree of vacuum and the inlet flow rate of the working fluid are important factors for the success of the experiment. At a vacuum of 10 kpa and a flow rate of less than 5 mL/min, the ethylene glycol aqueous solution was separated and concentrated at a temperature between 90 and 105℃, and the ethylene glycol content in the condensate was less, reducing the loss of ethylene glycol. The steam side vacuum capillary evaporation system proposed in this paper utilizes the difference of the surface force between the metal porous structure and the binary solution, thereby causing excess increase of the relative volatility of the two solution components, and strengthening the separation effect of the binary solution, meanwhile, the system can uses industrial waste heat as heat source, which has great potential to be a new kind of binary solution separation method.

СНИЖЕНИЕ ТЕМПЕРАТУРЫ ГИЛЬЗЫ ЦИЛИНДРА ЗА СЧЁТ ПРИМЕНЕНИЯ ТЕПЛОНОСИТЕЛЯ С ВЫСОКОТЕПЛОПРОВОДНЫМИ НАНОЧАСТИЦАМИ МУЛЬТИГРАФЕНА

The paper considers one of the promising ways to influence the heat transfer in the cooling system of a cylinder-piston group, which is to improve physical properties of coolants. It has been stated that the development of nanotechnology has recently made it possible to significantly increase the thermal conductivity coefficient of base coolant - an aqueous solution of ethylene glycol due to its modification by high-conductive solid multigraphene nanoparticles. The resulting stable two-phase suspensions based on the base coolant and particles of the solid phase are called nanofluids. To evaluate the increase in heat transfer at the “wall-coolant” boundary and the decrease of temperature of this wall when applying nanofluid in the engine cooling system as compared to the base fluid, an experimental setup was developed for simulating the flow of coolant in the annular channel of the cooling cavity of the cylinder liner and the conditions determining the heat transfer in its cooling cavity. As a result of conducting a series of experiments under similar test conditions, a significant increase in the heat transfer coefficient was found at the boundary of the “liner wall-liquid” due to the use of nanofluids with highly heat-conducting multigraphene nanoparticles compared to the base fluid. This led to a decrease in the temperature of the cylinder liner. Reducing the temperature of the heat-loaded engine parts allows to increase the reliability of the promising and forced diesel engines, to increase the degree of boosting at the average effective pressure while maintaining the permissible temperature level of the parts of the cylinder-piston group. Intensification of heat transfer at the “wall-liquid” interface contributes to an increase in the thermal efficiency of various heat exchangers as part of an internal combustion engine associated with the main circuit of the cooling system.

Mechanism of Superlubricity Conversion with Polyalkylene Glycol Aqueous Solutions

In this study, ultralow friction coefficient (COF, μ < 0.01) was obtained through polyalkylene glycol (PAG) aqueous solutions with different molecular weights (MWs) ranging from 270 to 3930 g·mol-1 under ambient conditions. With the increase in the MWs of PAG molecules, the threshold concentration to obtain this type of superlubric behavior gradually changed from 90 to 60 wt %. This phenomenon was closely related to the interaction between PAG chains and water molecules and the state of chemical binding. In the superlubricity system, superior load-bearing capacity was achieved at optimal threshold concentrations of all PAG aqueous solutions wherein multilayered adsorption layers that consisted of fully hydrated PAG molecules were formed on the sliding solid surfaces. With respect to the concentration below the threshold value, the existence of a shearing layer was indicated to play a significant role. Thus, the synergetic effect of sufficient adsorption of molecules and the unique shear rheology of the PAG aqueous solution were essential to achieve superlubricity.

Designing a system of liquid cooling for industrial microwave installations

The paper considers the issue on ensuring a thermal regime of the magnetron's anode unit by replacing an air-cooling system with the system of liquid cooling. It has been argued that a liquid cooling system is most suitable for magnetrons, for which currently an air-cooling system is implied, although they are not designed for a continuous operation in the structure of industrial microwave installations. Arranging the system of liquid cooling would makes it possible for a magnetron to work over long time without overheating and under favorable conditions, which rule out a possibility to clog the heat exchange surface with particles and dust, as well as the occurrence of overheating of the anode unit's surface. The basic element of the proposed system for liquid cooling is a cooling jacket, which represents an annular channel made from a heat-conducting material. Cooling jacket is mounted directly on the anode unit; in this case, a compression ratio of surfaces and the thickness of an air gap must ensure a minimum total thermal resistance. In order to determine heat transfer coefficients, an empirical dependence was established, which reflects the fact that when cooling the anode units the rational regimes are the viscous and transitional motion modes. The basic thermal characteristics of the cooling process have been defined, which include a coefficient of heat transfer, change in a heat-carrier temperature, the maximally permissible temperature at inlet. Calculations were carried out for two types of heat-carriers: water and a 54 % aqueous solution of ethylene glycol. A circuit for the system of liquid cooling has been proposed, which implies cooling from 1 to 6 magnetrons. Applying a given circuitry and choosing the rational estimated modes make it possible to solve the task on improving production efficiency, as well as reliability of microwave equipment.

Acoustic Measurement in a Rectangular Bubble Column to Determine Bubble Size and Interfacial Area for Aqueous Solutions of Ethylene Glycol

Bubble sizes in bubble column affect the bubble induced mixing of phases, interfacial area and transfer processes. Acoustic technique is used to measure bubble size distribution in a rectangular bubble column of cross section 0.2m x 0.02m for air sparged into water and aqueous solutions of ethylene glycol. Five condenser mikes at intermediate distance of 0.05 m measured above the distributor plate were used to find out the variation of bubble size as the bubbles move up. Sauter-mean bubble diameter and specific interfacial area were estimated from bubble size distribution at several superficial air velocity, static bed height, distance above the distributor plate and ethylene glycol concentration. The BSD exhibited mono-modal distribution and indicated non-uniform homogeneous bubbling regime. Sauter-mean bubble diameter is independent of superficial gas velocity, static bed height and concentration of EG, although, the values were higher than that for air-water system. Sauter-mean bubble diameter decreases as the bubbles move up indicating bubble breakup to take place once the bubbles leave the sparger. The value of interfacial area increases as the static bed height decreases and distance above the distributor plate increases. For air-ethylene glycol solution the values of specific interfacial area are about 200% higher than that observed in case of air-water system. The acoustic technique may be used to measure local values of bubble sizes and specific interfacial area.

Nanostructured AgCu system at repeated melting

The thermal behavior of the eutectic powder particles mixture Ag-28% Cu (mass) represents the aim of this research. This comportment is studied from the point of view of the structural changes induced to the powder mixture processing by the wet mechanical alloying (WMA) technique. After 80 h of WMA in ethylene glycol aqueous solution and argon atmosphere, the initial powder mixture becomes nanostructured composite particles with bimetallic AgCu matrix reinforced by in situ processed Cu2O. The particle size distribution, depicted by laser diffraction technique, reveals the nanometric range of the composite particles between 60 and 80 nm. The phase identification, quantitative analysis as well as crystallite size measurements by XRD confirm the nanostructured feature of the bimetallic matrix, acknowledged by SEM with EDX and FIB, as well as the reinforcing components synthesis during the WMA process. Two successive melting processes have been developed to point out the increased melting point in the range of 928.00–946.10 °C. The thermal analysis, developed in argon atmosphere, highlights the thermal effects of AgCu/Cu2O nanoparticles generated by argon adsorption/desorption from the powders surface.

VISCOSITY OF MONO-, DI- AND TRIETHYLENE GLYCOL AQUEOUS SOLUTIONS AT 298.15 K

The aim of this study was to analyze the change in the complex structure formed in water-glycols mixture under mixture composition. The dynamic viscosity for various glycol (mono-, di- and triethylene glycol) aqueous solutions have been measured over wide range of concentration at temperature 25 °C and atmospheric pressure. The new scale of viscosity concentration dependences of various glycols for common description in range of low glycol composition was suggested. From experimental data, the excess viscosity (deviation in viscosity) was calculated. Excess viscosity was negative for monoethylene glycol – water mixture over the entire range of composition. In the case diethylene glycol –water mixture excess viscosity values were found to be negative between 0 and 20 mol %, then became positive in the diethylene glycol rich region. In the case triethylene glycol – water mixture excess viscosity values were negative between 0 and 10 mol %. The Grunberg-Nissan parameter was calculated. By comparing the monoethylene glycol – water hydrogen bonding, reported in literature and Grunberg-Nissan parameter variation versus glycol molar fraction, a correspondence between Grunberg-Nissan parameter and the complex varieties was established. It was shown, that concentration dependence of the Grunberg-Nissan parameter separates the different concentration regions. The variation of the Grunberg-Nissan parameter with glycol molar fraction deals with the interaction variation between water and glycol molecules, the Grunberg-Nissan parameter slop varies.

Acoustic cavitation and ultrasound-assisted nitration process in ultrasonic microreactors: The effects of channel dimension, solvent properties and temperature

Experimental studies on acoustic cavitation and ultrasound-assisted nitration reaction were systematically investigated in two laboratory-built ultrasonic microreactors by tuning the microchannel dimension, solvent properties and temperature. Under ultrasound irradiation, acoustic cavitation microbubbles were generated and underwent violent oscillation in microchannel. With the decrease of channel size, acoustic cavitation was largely confined, and channel size 1 × 1 mm2 was recognized as the critical size to eliminate the confinement effect. Acoustic cavitation was also highly dependent on the properties of sonicated liquids. The onset of surface wave oscillation on gas bubble was obviously promoted with decreasing solvent viscosity and surface tension. Additionally, ultrasound-assisted nitration process of toluene was studied in a temperature-controlled ultrasonic microreactor. The effects of channel size as well as liquid properties on ultrasound intensification agreed well with the finding in cavitation research. Under ultrasound power 50 W, toluene conversion was enhanced by 9.9%–36.3% utilizing 50 vol.% ethylene glycol aqueous solution as ultrasound propagation medium, exhibiting ultrasound applicability on intensifying fast reaction processes in microreactors.

Superlubricity of Polyalkylene Glycol Aqueous Solutions Enabled by Ultrathin Layered Double Hydroxide Nanosheets.

It was previously proved that the existence of a large amount of hydrogen ions in water-based lubricants can easily lead to a superlubric state; however, it was also shown that these hydrogen ions could cause severe corrosion. As part of a large family of attractive clays, layered double hydroxides (LDHs) possess excellent tribological properties in water-based lubrication systems. In the present work, two different kinds of LDHs are dispersed in polyalkylene glycol (PAG) aqueous solutions, in two distinct forms: ultrathin nanosheets (ULDH-NS) of ca. 60 nm wide and ca. 1 nm thick (single or double layer) and nanoparticles (LDH-NP) of ca. 19.73 nm wide and ca. 8.68 nm thick. We find that the addition of ULDH-NS greatly shortens (as much as 85%) the running-in period prior to reaching the superlubricity regime and increases the ultimate load-bearing capacity by about four times. As compared to the fluid film thickness of the lubricating PAG solution, their ultrathin longitudinal dimension will not impair or influence the fluid film coverage in the contact zone. The analysis of sliding solid surfaces and the atomic force microscope microscale friction test demonstrate that the adsorption of ULDH-NS enables the sliding solid surfaces to be polished and protected because of their relatively weak interlayer interaction and increased adhesion effect. Owing to their superior tribological properties as lubricant additives, ultrathin LDH nanosheets hold great potential for enabling liquid superlubricity in industrial applications in the future.

Lubricity and Adsorption of Castor Oil Sulfated Sodium Salt Emulsion Solution on Titanium Alloy

Effective water-based lubricants for titanium alloys have been investigated. The results reveal that castor oil sulfated sodium salt (CSS) solution can decrease the friction coefficient and adhesive wear compared with water, polyalkylene glycol (PAG) aqueous solution, or castor oil. The surface morphology of the tested discs and balls were measured, and the mechanism investigated. The rubbing surface was analyzed by using time-of-flight secondary-ion mass spectrometry (ToF–SIMS), indicating that a layer of physically adsorbed film remained on the surface, the main ingredient of which was CSS molecules. The mass and morphology of the adsorbed film were explored by quartz crystal microbalance measurements with dissipation monitoring and atom force microscopy, respectively. An electrical voltage, which could change the electrostatic force of the lubricants with the metal surface, was then applied to the frictional pair to explore the mechanism driving the adsorption. The physically adsorbed film played an important role in lubrication. The results of this study indicate that CSS could represent a good water-based lubricant base stock for the design of cutting fluids for titanium alloys.