Investigation Of Thermophysical Properties Research Articles

Investigation of Thermophysical Properties and Thermal Performance and Pressure Drop of of Nanofluid including Functionalized Graphene with Polyvinyl Alcohol

Investigation of Thermophysical Properties and Thermal Performance and Pressure Drop of of Nanofluid including Functionalized Graphene with Polyvinyl Alcohol

Experimental investigation of thermophysical properties and heat transfer characteristics of hybrid nanofluids based on particle size

In heat transfer applications, nanofluids are utilized to increase thermal conductivity and heat transfer coefficient. The difficulty of nanoparticle stabilization in the fluids is a significant problem in heat transfer applications. Heat exchanger materials may wear and erode as a result of the additional nanoparticle. When compared to mono nanofluids, this can be lowered by using hybrid nanofluids. In this work, hybrid nanofluids are used in a radiator under laminar flow at 75?C, and the effect of volume concentration on heat transfer enhancement is investigated. The thermophysical characteristics of hybrid nanofluids are investigated using SiC and Al2O3 at 0.1 vol.% and 0.2 vol.%. The results revealed that a hybrid nanofluid with a higher volume concentration improves heat transfer. Finally, regression analysis for laminar flow is carried out and correlations for experimental Nusselt number and friction factor values were developed. The impact of particle size, flow rate, and temperature on the radiator?s heat transfer enhancement is investigated using hybrid nanofluid at 75?C. It is observed that the size of the nanoparticle has a substantial effect on heat transfer characteristics. It is concluded that using smaller-sized hybrid nanoparticles of Al2O3/SiC-S with less volume concentration enhances heat transfer and reduces radiator size compared to conventional coolants.

Investigation of Thermophysical Properties of Nanomagnetite-based Polymer Materials

In this work, samples of magnetite nanoparticles are synthesized using various synthetic methods. It is shown that of the existing methods of magnetite synthesis, the most widespread is the method of coprecipitation of Fe2+ and Fe3+ salts. Less common, but of interest due to the slower and more controlled kinetics of particle nucleation, is the Fe2+ oxidation method. However, magnetite is unstable and under external influences its phase transition to maghemite can occur, which leads to a change in magnetic characteristics and a change in biological responses. After analyzing the results of the study of samples by the XRD method, the following conclusions can be drawn: The magnetite phase was identified by the characteristic peaks in the diffraction patterns for all samples, except for the sample with EDTA, which may be a consequence of an insufficient amount of the introduced oxidant, or poor diffusion of the oxidant to iron ions due to the formed chelate complex. It can be concluded that magnetite is a promising material for its use in industry and medicine.

Investigation of Thermophysical Properties of Zr-Based Metallic Glass-Polymer Composite

Composites based on Zr65Cu17.5Ni10Al7.5 metallic glass (MG) and polytetrafluoroethylene (PTFE) were prepared by ball milling. Different composites (30/70, 50/50 and 70/30) were produced. Samples for dynamic mechanical analysis and laser flash analysis were fabricated in the supercooled region of the metallic glass and viscous region of the polymer. Spark plasma sintering (SPS) was performed at the supercooled region for the metallic glass powder. Characteristics such as thermal, mechanical, and structural properties were studied. A formation of the Zr2Cu and Zr2Ni intermetallic was found in the metallic glass after SPS. A formation of the nanocrystalline Zr2Cu was found in composite samples. Dynamical mechanical analysis (DMA) was used to study the mechanical behavior of the material. It was concluded that the 70/30-MG/PTFE composite sample had better thermal conductivity than the other composite samples. The thermal conductivity of the metallic glass was the highest among the samples and it increased with the MG content in composites.

Investigation of thermophysical properties of natural zeolite plates enhanced with graphite powder for thermal management of PV thermal systems

The use of natural zeolite plates for heat management and energy storage in PV thermal (PVT) systems is proposed for the first time. In this study, the production process of the natural zeolite plates were informed. The TGA results of the different grain sizes of natural zeolites, graphite powder and their mixtures were analyzed. The effects of the enhancement of the natural zeolites by graphite powder on the thermo-physical properties were investigated. Specific heat values the natural zeolites and graphite powder at different temperatures were reported. The variation of the thermal conductivity (W/mK) of the natural zeolites with different granule sizes and graphite with temperature were investigated and the variations of the thermal diffusivity (m2/s) and heat capacity (J/m3C) of the natural zeolites and graphite powder with temperature were analyzed. The variations of the thermal conductivity values of natural zeolite mixtures and plates enhanced with graphite powder with the ratio of 2, 5, 10, 15, and 20%. As the graphite ratio increases, the thermal conductivity value of the natural zeolite plates increases. The thermal conductivity values have been reached as 0.745 W/mK for 20% ratio of graphite powder enhancement for the natural zeolite plates.

Experimental investigation of thermo-physical properties of MgO-MWCNT (75–25%)/10W40 as a new nano-lubricant

Experimental investigation of thermo-physical properties of MgO-MWCNT (75–25%)/10W40 as a new nano-lubricant

Experimental Investigation of Thermo-Physical Properties of Tri-Hybrid Nanoparticles in Water-Ethylene Glycol Mixture

In recent years, research has focused on enhancing the thermo-physical properties of a single component nanofluid. Therefore, hybrid or composite nanofluids have been developed to improve heat transfer performance. The thermo-physical properties of the Al2O3-TiO2-SiO2 nanoparticles suspended in a base of water (W) and ethylene glycol (EG) at constant volume ratio of 60:40 and different volume concentrations were investigated. The experiment was conducted for the volume concentrations of 0.05, 0.1, 0.2, and 0.3% of Al2O3-TiO2-SiO2 nanofluids at different temperatures of 30, 40, 50, 60, and 70 °C. Thermal conductivity and dynamic viscosity measurements were carried out at temperatures ranging from 30 to 70 °C by using KD2 Pro Thermal Properties Analyzer and Brookfield LVDV III Ultra Rheometer, respectively. The highest thermal conductivity for tri-hybrid nanofluids was obtained at 0.3% volume concentration, and the maximum enhancement was increased up to 9% higher than the base fluid (EG/W). Tri-hybrid nanofluids with a volume concentration of 0.05% gave the lowest effective thermal conductivity of 4.8 % at 70 °C temperature. Meanwhile, the dynamic viscosity of the tri-hybrid nanofluids was influenced by volume concentration and temperature. Furthermore, tri-hybrid nanofluids behaved as a Newtonian fluid for volume concentrations from 0.05 to 3.0%. The properties enhancement ratio (PER) estimated that the tri-hybrid nanofluids will aid in heat transfer for all samples in the present. The new correlations for thermal conductivity and dynamic viscosity of tri-hybrid nanofluids were developed with minimum deviation. As a conclusion, the combination of the enhancement in thermal conductivity and dynamic viscosity for tri-hybrid at 0.3% volume concentration was found the optimum condition with more advantage for heat transfer than other concentrations.

Investigation of thermophysical properties of ZrO2-Sm3TaO7 ceramics

ABSTRACT This study investigates rare earth RE3TaO7 ceramics and shows that these materials may be optimal for thermal barrier coatings. ZrO2-Sm3TaO7 ceramics were prepared through a solid-state reaction. X-ray diffusion and structural refinement revealed a phase structure with an ordered orthorhombic phase for the Ccmm space group. The degree of structural disorder increased with increasing ZrO2 content. Gaussian function fitting of the oxygen 1s X-ray photoelectron spectra showed that the Sm3+ and Ta5+ ions were replaced by Zr4+ ions. At high temperatures, 8 mol% ZrO2-Sm3TaO7 has a high thermal expansion coefficient (10.9 × 10−6 K−1). The thermal conductivities of ZrO2-Sm3TaO7 (1.17 − 1.75 W·m−1 K−1) are lower than those of 7–8 wt.% yttria-stabilized zirconia, while those of 2% ZrO2-Sm3TaO7 are the lowest. The oxygen vacancies maintain the charge in equilibrium and enhance phonon scattering while decreasing the thermal conductivity. These results indicate that Sm3TaO7 can be used as a TBC.

The influence of thermophysical conditions on the formation of wax models in moulds from polymer composite materials

Investment casting has always been referred to as mass casting. This circumstance is associated with the high cost of moulds. The paper deals with materials from polymer composite materials for the manufacture of moulds. Investigations of thermophysical properties of polymer composites under cyclic loads under heating-cooling conditions have been performed. The results obtained have been implemented in real industrial production and can be used for one-off production with a significant reduction in the cost of tooling and, as a consequence, castings.

Experimental investigation of thermo-physical properties of drilling fluid integrated with nanoparticles: Improvement of drilling operation performance

Undoubtedly, the extraction of oil and gas from the reservoirs requires drilling processes. Drilling fluid is also required to perform drilling processes. The drilling fluid has several applications and one of its functions is to cool the bit. Normally, drilling fluids used in the world have a relatively low ability to transfer the heating from the bit. Therefore, cooling the bit is not done well. Therefore, solutions to increase the efficiency of drilling fluids in the field of heat transfer should be proposed. It is obvious that specific surface area is one of the variables affecting heat transfer. In other words, if the specific surface area of the drilling fluid molecules increases, the rate of heat transfer will increase. Since nanoparticles have a very high specific surface area, their use can be suggested. Because nanoparticles have a very high specific surface area, they can be used in the structure of drilling fluid components. Therefore, in this study titanium dioxide nanoparticle and carbon nanotube have been used to change the thermo-physical properties of drilling fluid. Results show the amount of specific heat increases about 1.26% by decreasing the size of titanium dioxide nanoparticles from 76 nm to 54 nm. In addition, experimental results show that the ratio of convective heat to conductive heat for drilling fluid integrated with carbon nanotubes is about 30% higher than drilling fluid integrated with titanium dioxide nanoparticles. Results show that the rate of heat transfer coefficient increases from about 2900 W/m2. oC to about 4000 W/m2. oC by decreasing the size of titanium dioxide nanoparticles from 76 nm to 54 nm. Also, it has been observed that the convective heat transfer coefficient increases from 2950 W/m2. oC to 3360 W/m2. oC by decreasing the average size of the carbon nanotubes from 76 nm to 54 nm.

Synthesis, characterization and heat transfer study of reduced graphene oxide-Al2O3 nanocomposite based nanofluids: Investigation on thermal conductivity and rheology

Investigation of thermophysical properties of reduced graphene oxide-Al2O3 (rGO-Al2O3) nanocomposite based nanofluid along with convective heat transfer study and associated pressure drop has been done in the present work. Formation of the rGO-Al2O3 nanocomposite was confirmed with the help of various characterization techniques like UV/Vis, XRD, FTIR, Raman spectroscopy, TEM, Elemental mapping and XPS analysis. Thermal conductivity at different temperatures of various volume % (0.01−0.1%) of the prepared rGO-Al2O3 nanofluid was measured by dispersing and ultrasonicating the nanocomposite in deionized water. Thermal conductivity increased with increase in temperature as well as concentration of the rGO-Al2O3 nanofluid. These nanofluids exhibited non-Newtonian behavior as found from their rheological study. Different viscosity models also were employed to predict the viscosity at a range of applied shear rate (0-2000 s−1). Convective heat transfer study at a wall condition of constant heat flux was done at different concentration and Reynolds number of the rGO-Al2O3 nanofluid. Maximum value of heat transfer coefficient of 5461.602 W/m2℃ was achieved at the exit of test section by using 0.05 vol.% rGO-Al2O3 nanofluid flowing at Reynolds number of 7510.

Experimental investigation of thermo-physical properties, heat transfer, pumping power, entropy generation, and exergy efficiency of nanodiamond + Fe3O4/60:40% water-ethylene glycol hybrid nanofluid flow in a tube

The synthesis method of in-situ/chemical co-precipitation was implemented for the addition of Fe3O4 nanoparticles on the surface of nanodiamond (ND) nanoparticles, and it is characterized by using x-ray diffraction, transmission electron microscopy and the magnetic property was estimated from the vibrating sample magnetometer. The 60:40% water-ethylene glycol mixture is used as a base fluid for the preparation of ND-Fe3O4 hybrid nanofluids. Experimental techniques are used to measure the thermophysical properties at various particle volume loadings, and temperatures and the obtained data is validated with literature data. The heat transfer, friction factor, and pumping power are evaluated at particle volume loadings from 0.05% to 0.2% and in the Reynolds number range from 2105 to 8126. The concepts of the second law of thermodynamics are used to evaluate the thermal entropy generation, frictional entropy generation and exergy efficiency of the hybrid nanofluids. The thermal conductivity enhancements are 5.03% and 12.79%, whereas, the viscosity enhancements are 108% and 50.84% at particle loading of 0.2% at temperatures of 20 °C and 60 °C in comparison with base fluid. The Nusselt number is augmented to 15.65%; thermal entropy generation is reduced to 20%, frictional entropy generation is augmented to 272.48% and exergy efficiency is increased to 38.24% with a maximum penalty in friction factor of 1.128-times at 0.2% particle loading and a Reynolds number of 7502 against base fluid data. New equations are modelled to evaluate the thermophysical properties, Nusselt number, and friction factor.

Investigation of Thermophysical Properties of IoNanofluids Containing Multi-Walled Carbon Nanotubes and Graphene

Thermophysical properties of base ionic liquid (C10H19F6N2P) (IL) and IoNanofluids (INF) containing different contents of (0.05, 0.1, and 0.5 wt%) multiwalled carbon nanotubes (MWCNTs) and Graphene (Gr) were measured experimentally. INF exhibited augmentation in thermal conductivity, viscosity, and heat capacity respect to the base fluid. Maximum thermal conductivity breakthrough was detected at 39%, 48% of MWCNT-IL and 0.5wt% of Gr-IL, respectively. Eventually, the experimental viscosity and thermal conductivity data were fitted with the existing theoretical models. The findings highlighted that the viscosity of MWCNTs-IL and Gr-IL was in unison with particles aggregation effect (Krieger-Dougherty model) and the both INF effective thermal conductivity are prognosticated by interfacial layer approach with sufficient accuracy.

Experimental investigation of thermo-physical properties of n-octadecane and n-eicosane

Reliable knowledge of phase change materials (PCM) thermo-physical properties is essential to model and design latent thermal energy storage (LTES) systems. This study aims to conduct a methodological measurement of thermo-physical properties, including latent enthalpy, isobaric specific heat, thermal conductivity and dynamic viscosity, of two n-alkanes, n-octadecane and n-eicosane. The enthalpy and isobaric specific heat of the materials are measured via differential scanning calorimetry (DSC) technique, using a µDSC evo7 from Setaram Instrumentation with a sample mass of 628.4 mg. The influence of the scanning rates, varying from 0.5 K/min to 0.025 K/min, in dynamic continuous mode within temperature range of 10–65 °C is investigated. The thermal conductivity and the dynamic viscosity are measured via Hot Disk TPS-2500S instrument and Brookfield rotational viscometer, respectively, up to 70 °C. The thermal analysis results via the µDSC show that the isothermal condition can be approached at a very low scanning rate, however at the cost of a higher noise level. A trade-off is observed for n-octadecane, achieving the lowest deviation of 0.7% in latent heat measurement at 0.05 K/min, as compared to the American Petroleum Table values. For n-eicosane, the lowest deviation of 1.2% is seen at the lowest scanning rate of 0.025 K/min. The thermal conductivity measured values show good agreements with a number of documented literature studies in the solid phase, within deviations of 2%. Larger deviations of 5–16% are found for the measurement in the liquid phase. The viscosity values also show a good agreement with the literature values with maximum deviations of 2.9% and 6.3%, with respect to the values of American Petroleum Tables, for n-octadecane and n-eicosane, respectively. The good agreements achieved in measurements establish the reliable thermo-physical properties contributing to the future simulations and designs.

Investigation of thermophysical properties of aqueous magnesium ferrite nanofluids

Highly stable aqueous nanofluids of magnesium ferrite (MgFe2O4) have been synthesized in various concentrations through a two-step method. Their thermophysical properties are analyzed by studying viscosity and thermal conductivity with respect to the concentration and temperature. The structural analysis of MgFe2O4 nanoparticles reveals their cubic spinel structure, whereas transmission electron microscopy (TEM) analysis confirms the spherical morphology. The magnetic studies of MgFe2O4 nanoparticles show the superparamagnetic behavior. The MgFe2O4 nanofluid exhibits non-Newtonian shear thinning behavior. The viscosity values are fitted with Einstein, Wang, and Chen models. The effective thermal conductivity data of MgFe2O4 nanofluids is compared with Hamilton-Crosser model. The enhancements in viscosity and thermal conductivity with respect to concentration and temperature are investigated. A quantitative comparison of enhancement coefficients of viscosity and thermal conductivity is made to understand the heat transfer performance of MgFe2O4 nanofluids. From the enhancement ratio, it is proved that the prepared MgFe2O4 nanofluids have enhanced heat transfer efficiency.

Numerical investigation of thermo-physical properties of non-newtonian fliud in a modelled intestine

Several kinds of researches have been conducted on peristaltic flow of non-Newtonian fluid in modelled oesophagus, stomach and intestine. However, further investigation is still needed especially in the area of mechanical shear stress, the influence of inlet temperature and velocity, Nutsselt number and the history of strain rates experienced by fluid particles. This study presents the numerical investigation of thermo-physical properties of non-Newtonian fluid in a modelled intestine. The properties investigated were fluid temperature, velocity, Nutsselt number and wall shear stress. Numerical simulation was performed by solving 3D Navier-Stokes and continuity equations. The intestinal model was drawn by using Autodesk Inventor 2017 while the numerical investigation was conducted by using ANSYS FLUENT 16.0. The Computational Fluid Dynamics solver employs the Finite Element Method (FEM) to discretize the governing equations. Chyme, Hibiscus Sabdariffa Roselle (Sobo), Soymilk (Soya) and Pap (Ogi) were the working fluids used for the investigation. Analyses of the results showed that the variation of fluid temperature and heat transfer with axial position across the length of intestinal model were not significantly influenced by the variation of the inlet velocity. Expansion of the model about the pulsating part enhanced heat transfer and nutrient delivery to the intestinal walls. Variation of the inlet velocity did not affect the average Nutsselt number. Chyme and Sobo had the highest and lowest Nutsselt number, respectively. Sobo displayed the best fluid properties considering flow behaviour while Soya displayed the best properties for thermal history. The results presented in this study are of countless importance in medical, paramedical, engineering applications, thermoregulation system, thermotherapy, and biomedical disciplines, where analyses and investigation of gastrointestinal tract history can be understudied.

Investigation of Thermophysical Properties of AW-2024-T3 Bare and Clad Aluminum Alloys.

In this paper, thermophysical and viscoelastic dynamic mechanical measurements (DMA) were performed for bare and clad aluminum AW-2024-T3 alloys. Specific heat, thermal diffusivity, and dynamic module (storage and loss) tests were performed in the range of 50 to 500 °C, except for DMA ones (RT–400 °C). All tests were carried out using the following specialized measuring stands: a light flash apparatus (LFA), differential scanning calorimeter (DSC), and a dynamic mechanical analyzer (DMA). The microstructures and compositions of alloys were investigated by light microscope (LM), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDS). Furthermore, Vickers micro-hardness measurements were conducted prior to and after DSC studies. Different precipitation kinetics of the θ′ and S′ metastable phases in the bare 2024-T3 compared to the clad alloy were observed by DSC. Additionally, the DSC results for a few selected scan rates were analyzed by the Kissinger method to give activation energies for the precipitation of θ′ and S′ metastable phases in the alloys. The apparent activation energy of the θ′ and S′ phases corresponds to 137.1 ± 4.4 for the bare alloy and 131.0 ± 6.0 (exo) and 104.1 ± 2.1 (exo) (two peaks) for the clad alloy.

Thermophysical Property Measurements of Tetrabutylphosphonium Oxalate (TBPOx) Ionic Semiclathrate Hydrate as a Media for the Thermal Energy Storage System.

With increasing global power demand, thermal energy storage technology could play a role ensuring a sustainable energy supply in power generation from renewable energy sources and power demand concentration. Hydrates have high potential as phase change materials (PCMs) for the use as a thermal energy storage medium. To develop thermal energy storage technology using a hydrate-based material, further investigation of thermophysical properties and the selection of a suitable hydrate are required. Tetrabutylphosphonium oxalate (TBPOx) ionic semiclathrate hydrate contains oxalic acid in salt form, as a guest compound, which is classified as carboxylic acid group with low environmental impact. In the present study, the phase equilibrium temperature and the dissociation heat of TBPOx hydrate were measured. The highest equilibrium temperature of the solid hydrate formed was 9.4°C at the mass fraction 0.35 of TBPOx in aqueous solution. The largest dissociation heat was 186.0 ± 0.5 kJ·kg−1 at the mass fraction of 0.35. Comparing with other PCMs with close phase equilibrium temperatures, TBPOx hydrate is superior in safety and sustainability. These results indicate that TBPOx hydrate would be suitable as the thermal storage medium for the general air conditioning systems.

Investigations of thermophysical properties of submerged arc welding slag using a rutile-acidic flux system

For TiO2–SiO2–MgO and SiO2–MgO–Al2O3flux system, the thermophysical and physicochemical behaviour of submerged arc slags studied. Slag plays an essential role in shielding the weld joint from atmospheric contamination. The mass percentage of each flux ingredient evaluated by the X-ray fluorescence technique. Twenty-one slags developed based on the mixture design approach. Thermogravimetric, DSC, and Hot-disc techniques used to analyze submerged arc slags. Thermogravimetric & DSC analysis was performed from 25 ºC to 900 ºC to find the thermal properties. The density measurement of slag performed at ambient temperature. Bond-behaviour was studied by Fourier transform infrared spectroscopy (FTIR) technique. Regression models for different slag properties developed. The multi-objective technique utilized to optimize different slags.

Experimental evaluation of thermophysical properties of oil‐based titania nanofluids for medium temperature solar collectors

AbstractThermal oils are widely used as working fluids in the medium temperature heat transfer applications including concentrating solar thermal collectors. However, the weak thermal characteristics of these oils are major drawbacks in their successful application in the medium‐high temperature solar collectors. Fortunately, the emergence of nanotechnology has provided the opportunity to alter thermo‐physical properties of base fluids by adding small amount of sub‐micron size solid particles possessing better properties. This paper presents an experimental investigation of thermophysical properties of an oil‐based nanofluid to be used in the medium temperature solar collector for enhanced thermal energy transport. The colloidal suspensions were prepared by dispersing different weight fractions (0.25 wt.%, 0.5 wt.%, 0.75 wt.% and 1.0 wt.%) of Titania nanoparticles in Therminol‐55 oil using two‐step method. Shear mixing and high energy ultrasonication was employed to achieve uniform mixing and de‐agglomeration of the nanoparticles in order to enhance the stability of the colloidal suspensions. Thermophysical properties of the nanofluids were determined as a function of nanoparticles concentrations in the temperature range of 25 °C–130 °C. The experimental results demonstrated substantial improvement in thermal conductivity of the nano‐oils with an increase in nanoparticles loading which further enhanced at higher temperatures. Dynamic viscosity and effective density displayed a decreasing trend against rising temperature which indicate the effectiveness of these nanofluids for medium temperature heat supply. Nano‐oils with superior thermal properties can improve the performance of medium temperature solar thermal collectors.