Water Glycol Research Articles

Correlations for Total Entropy Generation and Bejan Number for Free Convective Heat Transfer of an Eco-Friendly Nanofluid in a Rectangular Enclosure under Uniform Magnetic Field

In this paper, focusing on the study of entropy generation (EGN), the convection flow of an eco-friendly nanofluid (N-F) in a rectangular enclosure is studied numerically. The nanoparticles (N-Ps) used are silver N-P, which are obtained in an eco-friendly manner from natural materials. By suspending these N-Ps in an equal mixture of water and ethylene glycol (E-G), the N-F has been prepared. There are two constant-temperature triangular obstacles with height w and base H that are placed on the hot wall. There is a magnetic field (M-F) in the x-direction. To simulate the N-F flow, eco-friendly N-P relations are used, and the equations are solved using the volume control method and the SIMPLE algorithm. The variables include Rayleigh number (Ra), Hartmann number (Ha), H, W, and the volume fraction of silver N-Ps. The effect of these parameters is evaluated on the EGN and Bejan number (Be). Finally, a correlation is expressed for the EGN for a range of variables. The most important results of this paper demonstrate that the addition of silver eco-friendly N-Ps intensifies the EGN so that the addition of 3% of N-Ps enhances the EGN by 3.8%. An increment in the obstacle length reduces the Be barrier while increasing the Ha, which enhances the Be when the convection is strong. Increasing the height of the obstacle intensifies entropy generation.

Solubility study of lamotrigine in the aqueous mixture of choline chloride based deep eutectic solvent at different temperatures

Solubility and thermodynamic properties of lamotrigine as a practically insoluble drug in binary mixtures of choline chloride / propylene glycol deep eutectic solvent and water are determined by shake-flask method followed by a spectrophotometric method at the temperature range of 293.2–313.2 K. The acquired molar data are correlated to the linear and non-linear solubility models including van’t Hoff, the mixture response surface, the Jouyban-Acree, the Jouyban-Acree-van’t Hoff, the modified Wilson and the λh equations. The accuracy of each model is tested by the mean relative deviation of the back-calculated solubility data. Moreover, the apparent thermodynamic properties of lamotrigine dissolution are also calculated based on the van't Hoff and Gibbs equations.

Heat Transport Improvement and Three-Dimensional Rotating Cone Flow of Hybrid-Based Nanofluid

The current research aims to study the mixed convection of a hybrid-based nanofluid consisting of ethylene glycol-water, copper (II) oxide (CuO) and titanium dioxide (TiO2) in a vertical cone. A hybrid base blend model is used to examine the nanofluid’s hydrostatic and thermal behaviors over a diverse range of Reynolds numbers. The application of mixed nanoparticles rather than simple nanoparticles is one of the most imperative things in increasing the heat flow of the fluids. To test such a flow sector, for the very first time, a hybrid-based mixture model was introduced. Also, the mixture framework is a single-phase model formulation, which was used extensively for heat transfer with nanofluids. Comparison of computed values with the experimental values is presented between two models (i.e., the model of a mixture with the model of a single-phase). The natural convection within the liquid phase of phase change material is considered through the liquid fraction dependence of the thermal conductivity. The predicted results of the current model are also compared with the literature; for numerical results, the bvp4c algorithm is used to quantify the effects of nanoparticle volume fraction diffusion on the continuity, momentum, and energy equations using the viscous model for convective heat transfer in nanofluids. Expressions for velocity and temperature fields are presented. Also, the expressions for skin frictions, shear strain, and Nusselt number are obtained. The effects of involved physical parameters (e.g., Prandtl number, angular velocity ratio, buoyancy ratio, and unsteady parameter) are examined through graphs and tables.

Stagnation point flow of a micropolar fluid filled with hybrid nanoparticles by considering various base fluids and nanoparticle shape factors

PurposeThe boundary-layer analysis is required to reveal the fluid flow behavior in several industrial processes and enhance the products’ effectiveness. Therefore, this research aims to investigate the buoyancy or mixed convective stagnation-point flow (SPF) and heat transfer of a micropolar fluid filled with hybrid nanoparticles over a vertical plate. The nanoparticles silver (Ag) and titanium dioxide (TiO2) are scattered into various base fluids to form a new-fangled class of (Ag-TiO2/various base fluid) hybrid nanofluid along with different shape factors.Design/methodology/approachThe self-similarity transformations are used to reformulate the leading requisite partial differential equations into renovated non-linear dimensionless ordinary differential equations. The numerical dual solutions are gained for the transmuted requisite equations with the help of the bvp4c built-in package in MATLAB software. The results are validated by comparing them with previously available published data for a particular case of the present study.FindingsThe impact of various pertaining parameters such as nanoparticle volume fraction, material parameter, shape factor and mixed convective on temperature, heat transfer, fluid motion, micro-rotation and drag force are visualized and scrutinized through tables and graphs. It is observed that dual or non-uniqueness outcomes are found for the case of buoyancy assisting flow, whereas the solution is unique in the buoyancy opposing flow case. Additionally, the fluid motion and micro-rotation profiles decelerate in the presence of nanoparticle volume fraction, while the temperature augments.Originality/valueThe mixed convective stagnation point flow conveying TiO2/Ag hybrid nanofluid with micropolar fluid with various shape factors is the significant originality of the current investigation where multiple outcomes are obtained for the assisting flow. The various base fluids such as glycerin, water and water–ethylene glycol (50%:50%) are considered in the present problem. The bifurcation values of the considered problem do not exist, probably because of various base fluids. To the best of the authors’ knowledge, this work is new and original which were not previously reported.

Multipoint fiber optics refractive index sensor based on multimode interference effects.

We demonstrate a fiber optics sensing structure for the measurement of the refractive index of liquid samples at multiple spatial locations simultaneously. The sensing architecture is all-fiber and consists of standard single-mode-multimode-single-mode multimodal interference (MMI) devices working in parallel. The spectral response of each MMI device is carefully engineered to have nonoverlapping responses, such that the entire system can be interrogated with a single broadband light source and single optical spectrum analyzer. In proof-of-concept experiments, we tested the proposed system with aqueous saline solutions and binary solutions of water-glycerol and water-ethylene glycol. Our results validate the use of the proposed platform for the simultaneous monitoring of the refractive index of liquid samples at different locations.

Applying Artificial Neural Network and Response Surface Method to Forecast the Rheological Behavior of Hybrid Nano-Antifreeze Containing Graphene Oxide and Copper Oxide Nanomaterials

In this study, the efficacy of loading graphene oxide and copper oxide nanoparticles into ethylene glycol-water on viscosity was assessed by applying two numerical techniques. The first technique employed the response surface methodology based on the design of experiments, while in the second technique, artificial intelligence algorithms were implemented to estimate the GO-CuO/water-EG hybrid nanofluid viscosity. The nanofluid sample’s behavior at 0.1, 0.2, and 0.4 vol.% is in agreement with the Newtonian behavior of the base fluid, but loading more nanoparticles conforms with the behavior of the fluid with non-Newtonian classification. Considering the possibility of non-Newtonian behavior of nanofluid temperature, shear rate and volume fraction were effective on the target variable and were defined in the implementation of both techniques. Considering two constraints (i.e., the maximum R-square value and the minimum mean square error), the best neural network and suitable polynomial were selected. Finally, a comparison was made between the two techniques to evaluate their potential in viscosity estimation. Statistical considerations proved that the R-squared for ANN and RSM techniques could reach 0.995 and 0.944, respectively, which is an indication of the superiority of the ANN technique to the RSM one.

Thermal conductivity and heat capacity of nanofluid based on water modified by hybrid material of composition detonation nanodiamonds-carbon nanotubes

For the first time, the rheological and thermophysical properties of stable nanofluids based on water and ethylene glycol modified by the DND-CNT hybrid material and obtained without surfactants have been investigated. It was found that at the maximum concentration of the DND-CNT hybrid material 0.5 wt. % for water and 0.3 wt. % for ethylene glycol was increased in thermal conductivity at 50 to 84% and 44%, respectively, without changing the dynamic viscosity. It is shown that the use of a hybrid material can reduce the freezing point by 11 in the case of water and by 7 in the case of ethylene glycol.

Fabrication and Characterization of Chitosan-Polyethylene Glycol (Ch-Peg) Based Hydrogels and Evaluation of Their Potency in Rat Skin Wound Model.

Thermal burns are a major cause of death and suffering around the globe. They can cause debilitating, life-altering injuries as well as lead to significant psychological and financial consequences. Several research works have been conducted in attempt to find a wound healing therapy that is successful. At present, hydrogels have been widely used in cutting-edge research for this purpose because they have suitable properties. This study aimed to see how therapy with chitosan-polyethylene glycol (Ch-Peg) based hydrogels affected the healing of burn wounds in rats. With the concern of public health, xanthan gum (X), boric acid (B), gelatin (Ge), polyethylene glycol (Peg), chitosan (Ch), glutaraldehyde (G), and HPLC-grade water were prepared using X : Ge : G, X : Ge : Peg : G, X : Ge : Ch : G, X : Ge : Peg : Ch : G, X : Ge : B : Ch : G, X : Ge : B : Peg : G, and X : Ge : B : Peg : Ch : G. The produced composite hydrogels were examined for swelling ability, biodegradability, rheological characteristics, and porosity. The 3D structure of the hydrogel was revealed by scanning electron microscopy (SEM). After that, the structural characterization technique named Fourier-transform infrared spectroscopy (FTIR) was used to describe the composites (SEM). Lastly, in a rat skin wound model, the efficacy of the produced hydrogels was studied. Swelling ability, biodegradability, rheological properties, and porosity were all demonstrated in composite hydrogels that contained over 90% water. Hydrogels with good polymeric networks and porosity were observed using SEM. The existence of bound water and free, intra- and intermolecule hydrogen-linked OH and NH in the hydrogels was confirmed using FTIR. In a secondary burned rat model, all hydrogels showed significant wound healing effectiveness when compared to controls. When compared to other composite hydrogels, wounds treated with X : Ge : Peg : Ch : G, X : Ge : B : Peg : G, and X : Ge : B : Peg : Ch:G recovered faster after 28 days. In conclusion, this research suggests that X : Ge : Peg : Ch : G, X : Ge : B : Peg : G, and X : Ge : B : Peg : Ch : G could be used to treat skin injuries in the clinic.

Dynamical irreversible processes analysis of Poiseuille magneto-hybrid nanofluid flow in microchannel: A novel case study

In addition to solar water heating and transformers, these applications of research include heat exchangers and braking fluids, as well as acoustics and microelectronics. The mathematical model of Poiseuille hybrid nanofluid flow through a microchannel is considered with differing thermal conductivity and viscosity parameters. This mathematical model has mainly been developed to cater to the diversity of the hybrid nanofluid properties, which contains oxide and metal nanoparticles, for example, Cu and Al2O3 immersed in water (H2O) and Ethylene glycol (EG) as the base liquid. The substructure for hybrid nanofluid abides by the mixture of 20% water while the rest is filled with EG. Moreover, the perception of entropy is analyzed. The dimensional form of the current problem is deformed into a non-dimensional form using the appropriate choice of similarity transformation. Thence, the Runge–Kutta-Fehlberg method is being used to treat the numerical solution for the problem. The graphs spectacle the entropy, Bejan numbers, and physical behavior of the contributing factors to the flow phenomena. The numerical results of the rate coefficients for these parameters are shown in the table below. Furthermore, a comparison analysis is conducted to confirm the current result with prior work demonstrating a higher degree of concordance.

Numerical investigation of heat transport in Alumina–Silica hybrid nanofluid flow with modeling and simulation

The current numerical study investigates the thermal performance of four mono-component (i.e., blade-shaped Al2O3, brick-shaped Al2O3, cylinder-shaped Al2O3 or platelet-shaped Al2O3 nanoparticles in 50:50 water–ethylene glycol (EG) base fluid) and four bi-component nanofluids (i.e., blade-shaped Al2O3+SiO2/EG–water, cylinder-shaped Al2O3+SiO2/EG–water, brick-shaped Al2O3+SiO2/EG–water, and platelet-shaped Al2O3+SiO2/EG–water hybrid nanofluids) with the help of mathematical modeling. The non-Newtonian nature of these nanofluids is modeled using second grade viscoelastic fluid model accompanied by the energy equation. The highly non-linear coupled differential equations are solved by shooting method accompanied by 4th order Runge–Kutta method in MATLAB software. The numerical simulations are performed by procuring the data for thermophysical properties from the experimental studies. The effective thermal conductivity and viscosity of the four distinct alumina nanofluids are calculated by the models obtained from the experimental studies. The numerical results reveal that the nanofluid with platelet-shaped Al2O3 nanoparticles is the best heat transporter among the four alumina nanofluids The addition of SiO 2 nanoparticles further accelerates the rate of heat transfer in all four alumina nanofluids. The numerical results that illustrate the influence of nanoparticle volume fraction and thermofluidic parameters on the heat transport phenomenon are also discussed. The MATLAB code developed for the numerical solution is validated against the substantial published literature.

On the definition of excess electrical conductivity

It is proposed that the complex electrical conductivity of an ideal fluid liquid mixture is expressed as the sum of pure-component complex electrical conductivities weighted by their volume fractions in the mixture. The relevance of the corresponding excess property in the investigation of enhanced electrical conductivity of nanofluids is highlighted for the case where the base fluid consists of ethylene glycol–water mixtures. New measurements of the direct current conductivity were made for these mixtures at 298.15 K. It is pointed out that different published experimental measurements lead to excess electrical conductivity values with opposite signal. These discrepancies are discussed and possible explanations advanced. The proposed analysis of electrical conductivity is adapted to binary systems of nanofluid-base fluid and, using literature data, the usefulness of excess electrical conductivity is demonstrated.

Effect of Hydroalcholic Extract of Allium noeanum Reut. ex Regel on Ethylene Glycol- Induced Kidney Stone in Male Wistar Rats

We want to evaluate the effect of Allium noeanum Reut. ex Regel (Bonsor) known (traditional medicine agent) in calcium oxalate stones in kidney. 36 male rats were divided into 6 groups. I: healthy model + water, II: negative model + 1% ethylene glycol in water, III: 750 mg/kg of total extract +1% of ethylene glycol in water(Prevention), IV: 250 mg/kg flavonoid extract +1% of ethylene glycol in water (Prevention), V: 1500 mg/kg of total extract from 15th day+ 1% of ethylene glycol in water (Treatment), VI: 500 mg/kg of flavonoid extract from 15th of the study + 1% of ethylene glycol in water (Treatment).24-hour urine and blood samples were collected in 30th day for analysis. Pathology of kidneys was checked. Serum urea, uric acid, creatinine and urine calcium and oxalate were significantly increased, urine citrate was decreased in group II Vs I. (P < .05). Extract administration significantly decreased serum creatinine, urea and uric acid. Urine calcium and oxalate significantly decreased in treated groups. Urine calcium levels were significantly decreased in treated rats, but urine citrate levels were increased Vs group II. (P < .05). No crystal accumulation and tubular cast were observed in prevention groups. Hydroalcholic extract of Allium noeanum was able to reduce urine oxalate.

Study on viscosity of MWCNT dispersed in ethylene glycol at different operating conditions for thermal applications

In recent times the development of nanotechnology has taken place at an unprecedented rate. Nano-fluids are one of the remarkable outcomes of the development of new technologies that can be used to increase the efficiency of thermal systems. Nanofluids, which consist of particles in nanometre size and a base fluid, have been hailed as a superior alternative compared to a common heat transfer fluid like water due to their better thermal properties and having many potential applications in many fields, especially in HVAC, electronic cooling, solar heating and cooling etc., The MWCNT-based nanofluid with water-ethylene glycol as base fluid is prepared by two-step method, the water and ethylene glycol are mixed in the ratio 80:20 and four different concentrations of nanofluids: 0% wt, 0.015% wt, 0.15% wt, 1.5% wt are prepared. Rheology analysis are made by using rheometer with temperature ranging from from 10° C to 50° C with steps of 10° C and shear rate was controlled with shear stress varying from 0-10 N/m2. The base fluid shows the Newtonian behaviour being shifted to Non-Newtonian Behaviour, specifically shear thinning behaviour. Rate of change of shear also changes with change in temperature and change in shear stress results change in viscosity with higher concentration of nanoparticles showing higher viscosity.

A novel method of cooling a semiconductor device through a jet impingement thermal management system: CFD modeling and experimental evaluation

This study investigates the viability of a liquid jet-impingement (JI) thermal management system (TMS). The JI-TMS was used as a heat dissipation tactic to ensure a silicon semiconductor-based pulse-power device’s temperature was maintained below 80 °C during operation. The JI-TMS’s design, which is comprised of 27 nozzles (1 mm nozzle diameter), is analyzed by computational fluid dynamics (CFD) modeling, with 100 W of average power (i.e., heat generation rate). The heat transfer fluid (HTF) is pure silicone fluid with a viscosity of 20 cSt. The selected HTF has the dielectric constant which provides better electrical insulation than other common HTFs (water, water–glycol, etc.). Validation of the model was performed experimentally to ensure the accuracy of the CFD results. The results show that device’s temperature is maintained well below the maximum desired operating temperature (57.5 °C when using 0.06 kgs), showing average difference of 5.89% between numerical and experimental data. To better understand the achieved error, heat capacity analysis of the HTF was investigated with differential scanning calorimeter which shows an average deviation of 13.12% with the reported vendor value. The results from this study can be a benchmark for cooling purposes of semiconductor devices in high power densities.

Rod-like Ni0.5Co0.5C2O4·2H2O in-situ formed on rGO by an interface induced engineering: Extraordinary rate and cycle performance as an anode in lithium-ion and sodium-ion half/full cells

Transition metal oxalates have attracted wide attention due to the characteristics of the conversion reaction as anode materials in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), However, there are huge volume expansion and sluggish circulation dynamics during the reversible Li+ and Na+ insertion/extraction process, which would lead to unsatisfactory reversible capacity and stability. In order to solve these problems, a rod-like structure Ni0.5Co0.5C2O4·2H2O is in-situ formed on the reduced graphene oxide layer (Ni0.5Co0.5C2O4·2H2O/rGO) in a glycol–water mixture medium via an interface induced engineering strategy. Benefitting from the synergistic cooperation of nano-diameter rod-like structure and high conductive rGO networks, the experimental results show that the prepared Ni0.5Co0.5C2O4·2H2O/rGO electrode has predominant rate performance and ultra-long cycle stability. For the LIBs, it not only exhibits an ultrahigh reversible capacity (1179.9 mA h g−1 at 0.5 A g−1 after 300 cycles), but also presents outstanding rate and cycling performance (646.5 mA h g−1 at 5 A g−1 after 1200 cycles). Besides, the Ni0.5Co0.5C2O4·2H2O/rGO electrode displays remarkable sodium storage capacity of 221.6 mA h g−1 after 100 cycles at 0.5 A g−1. Further, the extraordinary electrochemical capability of Ni0.5Co0.5C2O4·2H2O/rGO active material is also reflected in two full-cells, assembled using commercial LiCoO2 as cathode for LIBs and commercial Na3V2(PO4)3 as cathode for SIBs, both of which can show wonderful specific capacity and cycling stability. It is found in in-situ Raman experiments that the reversible changes of oxalate peaks are monitored in a charge/discharge process, which is scientific evidence for the transform reaction mechanism of metal oxalates in LIBs. These findings not only provide important ideas for studying the charge/discharge storage mechanism but also give scientific basis for the design of high-performance electrode materials.

Применение наножидкостей в качестве теплоносителя в охладителях функциональных агрегатов автотракторной техники

One of the most important elements of the cooling system of any automotive internal combustion engine is a coolant. Most often, water and a mixture of water with antifreeze are used as a coolant. Its main function is to transfer heat or to cool the engine. Nanofluids are promising heat carriers, with the help of which it is possible to reduce the metal consumption of aggregates, increase safety in emergency transient modes accompanied by boiling. (Research purpose) The research purpose is studying the possibilities, features and prospects of using innovative heat carriers as coolants of automotive equipment, which will allow overcoming the inefficiency of water and ethylene glycol mixtures, which consists in low thermal conductivity. (Materials and methods) Nanofluids consisting of a base liquid and nanoparticles of a highly heat-conducting material were proposed as innovative heat carriers. Their use in transport power plant coolers will reduce their volume and weight. Mixing of ethylene glycol and copper nanoparticles is effective, in such cases it is important to investigate the effect of the volume fraction of copper nanoparticles and the base liquid on thermal characteristics or to reduce the size of the radiator. Copper nanoparticles have better thermal conductivity than other nanoparticles (for example, aluminum oxide). (Results and discussion) It has been proved that the use of nanofluids in heating and ventilation systems can give a significant increase in heat transfer. At present the science of nanofluids is in its initial stage, for the development of this direction it is necessary to conduct comprehensive experimental studies of their chemical and physical properties, theoretical analysis, and compilation of general calculated correlations. (Conclusions) It was revealed that nanofluids can be effectively used as heat carriers of transport engines, with their use the metal consumption of coolers is reduced, the safety of units in emergency modes, including those accompanied by boiling, is increased.

BİR ISI DEĞİŞTİRİCİSİNDE FARKLI SU-ETİLEN GLİKOL KARIŞIMI KULLANIMININ ISI TRANSFER PERFORMANSINA ETKİLERİNİN DENEYSEL ANALİZİ

In this study, the effects of using different water-ethylene glycol mixture rates on heat transfer performance put in an automobile radiator as a liquid is experimentally analysed. Ethylene glycol is added in water volumetrically and experiments are conducted for 0%, 25%, 50%, 75% and 100% volumetric ratio of ethylene glycol. For all these mixture rates, 300 experiments are conducted for fluid inlet temperature between 40-80 °C, fluid inlet flow rate between 10-22 l/min and cooling air between 1-4 m/s. As a result of the experiments, it is observed that as ethylene glycol mixture ratio passing from the radiator increased, heat transfer decreased. However, as cooling air velocity, fluid inlet flow rate and radiator inlet temperature increased, heat transfer increased as well. When water-ethylene glycol mixture is used in the radiator instead of water, it is observed that radiator fluid freezing temperature decrease and radiator heat transfer performance is negatively impacted.

A new energy efficient process for hydrogen purification using ZIF-8/glycol–water slurry: Experimental study and process modeling

Effective recovery of hydrogen from refinery off-gas and coke oven gas, in which hydrogen and methane are key components, is increasingly important for the development of hydrogen energy. In this paper, we introduced a new energy efficient process for hydrogen purification from CH4/H2 mixture. Firstly, we conducted a phase equilibrium experimental study for CH4/H2 in zeolitic imidazolate framework-8 (ZIF-8)/glycol–water slurry. The simple absorption and desorption configuration is adopted for the continuous separation of CH4/H2 using ZIF-8/glycol–water slurry. The multi-stage pseudo-absorption modeling approach was introduced for the modeling and simulation of the absorption–adsorption and desorption columns via using multiple flash modules in Aspen Plus. The binary interaction parameters in the thermodynamic model were fitted by experimental data within an acceptable error (4.93%). The operating conditions (i.e., the number of theoretical stages, feed stage, flash pressure, and desorption pressure) were determined to increase H2 concentration in product and H2 recovery ratio. The energy performance of the process was also evaluated. Given the feed gas contains 50 mol% H2, the gas–slurry volume ratio of 43.27 is required to produce 95 mol% H2 with a high recovery of 97.94%. The total energy consumption per unit volume of product is 0.06254 kW·h/Nm3. Results indicate that the hybrid absorption-adsorption process is a promising energy efficient technique to separate CH4/H2 in the future.

Stability and Thermal Conductivity of Tri-hybrid Nanofluids for High Concentration in Water-ethylene Glycol (60:40)

Background: Research has been focused on improving the thermal properties of single nanofluid components for recent years. Therefore, hybrid nanofluids or composites have been developed to improve heat transfer performance. Stability and thermal conductivity of Al2O3-TiO2- SiO2 nanoparticles are suspended in the fluid base of water (W) and ethylene glycol (EG) mixture with volume ratio of 60:40. Methods: Experiments were tri-hybrid nanofluid stability was investigated for volume concentration of 0.5 ~ 3.0%, and temperature conditions from 30 to 70°C for thermal conductivity measurements using a KD2 Pro Thermal Properties Analyzer. The experimental results show that the tri-hybrid nanofluid stability analysis was performed using a stable UV-Vis method for up to 30 days after preparation with 10 hour sonication time. Results: Comparison of data concentration ratios with sedimentation for single, hybrid, and trihybrid nanofluids yielding a stable tri-hybrid nanofluid with 80-90% value. Evaluation of zeta potential for tri-hybrid nanofluids yielded 63.72 mV in excellent stability classification. Sedimentation of this visual observation is influenced by the gravity of the movement of particles in the tube after 30 days. Conclusion: The highest thermal conductivity for tri-hybrid nanofluids was obtained at 3.0% and a maximum increase of up to 27% higher than that of the basic fluid (EG/W). Tri-hybrid nanofluids with a concentration of 0.5% gave the lowest effective thermal conductivity of 13.4% at 70°C.

Identification of Thermal Response of Mesoscopic Liquids under Mechanical Excitation: From Harmonic to Nonharmonic Thermal Wave

In the conventional picture, the temperature of a liquid bath in the quiescent state is uniform down to thermal fluctuation length scales. Here we examine the impact of a low-frequency shear mechanical field (hertz) on the thermal equilibrium of polypropylene glycol and liquid water away from any phase transition confined between high-energy surfaces. We show the emergence of both cooling and heating shear waves of several tens of micrometers widths varying synchronously with the applied shear strain wave. The thermal wave is stable at low strain amplitude and low frequency while thermal harmonics develop by increasing the frequency or the strain amplitude. The liquid layer behaves as a dynamic thermoelastic medium challenging the extension of the fluctuation-dissipation theorem to nonequilibrium fluids. This view is in agreement with recent theoretical models predicting that liquids support shear elastic waves up to a finite propagation length scale of the order the thermal wave.