Investigation Of Thermophysical Properties Research Articles

Microstructure and Physico-Mechanical Properties of Biocompatible Titanium Alloy Ti-39Nb-7Zr after Rotary Forging

The evolution of microstructure, phase composition and physico-mechanical properties of the biocompatible Ti-39Nb-7Zr alloy (wt.%) after severe plastic deformation by rotary forging (RF) was studied using various methods including light optical microscopy, scanning and transmission electron microscopies, X-ray diffraction, microindentation, tensile testing and investigation of thermophysical properties during continuous heating. The hot-rolled Ti-39Nb-7Zr with initial single β-phase structure is subjected to multi-pass RF at 450 °C with an accumulated degree of true deformation of 1.2, resulting in the formation of a fibrous β-grain structure with imperfect 500 nm subgrains characterized by an increased dislocation density. Additionally, nano-sized α-precipitates formed in the body and along the β-grain boundaries. These structural changes resulted in an increase in microhardness from 215 HV to 280 HV and contact modulus of elasticity from 70 GPa to 76 GPa. The combination of strength and ductility of Ti-39Nb-7Zr after RF approaches that of the widely used Ti-6Al-4V ELI alloy in medicine, however, Ti-39Nb-7Zr does not contain elements with limited biocompatibility and has a modulus of elasticity 1.5 times lower than Ti-6Al-4V ELI. The temperature dependences of physical properties (elastic modulus, heat capacity, thermal diffusivity) of the Ti-39Nb-7Zr alloy after RF are considered and sufficient thermal stability of the alloy up to 450 °C is demonstrated.

Experimental investigation of thermophysical properties of propylene glycol based secondary fluids for ground source heat pumps and indirect refrigeration systems

More than 1.7 million ground source heat pumps are currently in operation in the European Union and a large majority of systems is using propylene glycol as secondary fluid. In this study the thermophysical properties of propylene glycol solutions with specific freezing points between −5 and −50 °C are investigated at low temperatures of interest for refrigeration and heat pump applications. The experimentally determined data are compared to a large number of data from the literature. It has been found that the freezing point results for all concentrations were in very good agreement with both Melinder (2010) and ASHRAE (2021) data. Moreover, the literature data and present study for concentrations above 40 wt-% have different density curve slopes compared to ASHRAE data. The viscosity results for concentrations below 40 wt-% were up to 21.5 % higher than ASHRAE data and the viscosity results for solutions with concentrations above 40 wt-% were lower by up to 9.7 %. The thermal conductivity results for concentrations above 40 wt-% were 10 % higher than ASHRAE (2021) data. The experimental specific heat capacity curves and other studies do not have the same linear trend as Melinder (2010) and ASHRAE (2021) data. This difference indicates that currently available ASHRAE data have been indirectly computed from thermal conductivity data or that they have not been fully experimentally validated. Finally, more studies are required to investigate concentrations below 25 wt-% to identify solutions with higher specific heat capacity than water that could be of interest for specific applications.

Experimental investigation of thermophysical properties of synthesized Mg–Al bimetal oxide/water nanofluid

Experimental investigation of thermophysical properties of synthesized Mg–Al bimetal oxide/water nanofluid

Phase diagram study of Na2O–ThO2–P2O5 system and investigation of thermo physical properties of quaternary compounds

The subsolidus phase relations in Na2O–ThO2–P2O5 pseudo ternary system were determined at 1223 K. Synthesis of all the phases, used for drawing phase diagram, was carried out by solid state route. Formation of ternary and quaternary compounds in Na2O–ThO2, Na2O–P2O5, ThO2–P2O5 and Na2O–ThO2–P2O5 systems was confirmed at 1223 K. With the help of these compounds and phase analysis of number of synthetic mixtures, prepared by reacting different mol fractions of Na2O, ThO2 and P2O5 at 1223 K, phase diagram was drawn and phase boundaries were established. No ternary compound was identified in Na2O–ThO2 system. Formation of three quaternary phosphates, Na2Th(PO4)2, NaTh2(PO4)3 and Na5Th(PO4)3 was confirmed at 1223 K. XRD pattern of monoclinic Na5Th(PO4)3, synthesized for the first time and found iso structural with Na5Th(AsO4)3 and its lattice parameters were obtained by Le Bail method. Thermogravimetric studies of quaternary phosphates were carried out in air to investigate their thermal stability. All the three compounds decompose to ThO2 at 1673 K. Two step weight loss in TG curve of Na2Th(PO4)2 confirmed its decomposition to ThO2 via NaTh2(PO4)3 as an intermediate. To calculate thermal expansion coefficients, high temperature XRD (HT-XRD) data of Na2Th(PO4)2, NaTh2(PO4)3 and Na5Th(PO4)3 was collected in air between the temperature range of 298–1173 K. All these compounds exhibit positive thermal expansion with the average volume expansion coefficient values ranging between 30 and 60 × 10−6 K−1. Heat capacities of these compounds were measured in the temperature range of 308–873 K using Differential Scanning Calorimetry (DSC) technique.

Non-destructive investigation of thermophysical properties on the China's space station: In-orbit experiment measurements and analysis

This paper discusses the current state of non-destructive research on the density, surface tension and viscosity of molten samples using the electrostatic levitation furnace (ELF) aboard the China Space Station (CSS). To address the challenges posed by the microgravity environment during the non-destructive testing process of containerless technology, we have developed several solutions. These include a temperature correction for infrared temperature measurement, a dual-camera position correction technique for density testing, a double electrode synchronous excitation, semi-frequency excitation and fine-sweeping approach for surface tension testing, and a signal demodulation method for viscosity testing. The uncertainties of the three thermophysical properties were 0.51 %, 3.10 %, and 9.78 %, respectively. This study highlights the feasibility and accuracy of measurements conducted in the ELF on the CSS, offering valuable insights into the behavior of molten materials under microgravity conditions. The findings from this study significantly contribute to our understanding of the thermophysical properties of molten materials.

A Closed Contactless Method for Investigation of Thermophysical Properties of Metals and Alloys in the Temperature Range of 1000–2500 K

A Closed Contactless Method for Investigation of Thermophysical Properties of Metals and Alloys in the Temperature Range of 1000–2500 K

Investigation of thermophysical properties of Turkey oak particleboard for sustainable building envelopes

The article investigates the thermophysical parameters of Turkey oak particleboard with different densities and their response to varying heat pulse power to cover possible thermally dependent disturbance effects during the measurement. Samples were measured by the Pulse Transient Method using a Cuboid Model to estimate all basic thermophysical parameters. The aim was to assess the properties of the two different particleboard of high and medium density and compare them with published data. We also calculated uncertainties based on sensitivity coefficients analysis for the cuboid model. This methodology helps to assess how the input error propagates into the resulting parameter estimate and helps to optimize the experiment. The quality of oak particleboard holds significant importance in building construction. Additionally, the analysis results assess the suitability of different materials for improving energy efficiency in building construction. Interestingly even slight density differences and thickness can significantly impact the effectiveness of building insulation properties of materials.

Experimental investigation of thermophysical properties of ethylene glycol based secondary fluids

Aqueous solutions of ethylene glycol are commonly used as secondary fluids in different indirect refrigeration systems and heat pumps as well as nanofluids. A very extensive literature review has been done, including more than 90 references published from 1905 to 2023. Despite the wide application and importance, especially in the energy sector, ethylene glycol solutions seem to be less investigated in low temperature ranges and more research is required to improve the quality and quantity of available data. The novelty of this paper is to investigate the most important thermophysical properties of ethylene glycol solutions in low temperatures. In this study a different approach was made and solutions having a specific freezing point temperature (between -5 and -50 ºC) rather than specific concentration were investigates in temperature ranges applicable for different cooling applications. The concentrations giving a certain freezing point temperature seemed to deviate in some cases with 1–2 wt-% between different sources. Nevertheless, the density results were in rather good agreement with all reference data. The viscosity results were lower by up to ±10% compared to reference values. Additionally, the obtained experimental results for thermal conductivity were higher by up to 12% compared to ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) data. The specific heat capacity results were higher by up to 14.6% and 5.4% than current reference data. There is a high probability that the current ASHRAE data for specific heat are actually indirectly calculated values from thermal conductivity data and not validated using differential scanning calorimetry techniques.

Molecular dynamics investigation of thermo-physical properties of molten salt with nanoparticles for solar energy application

Molten salt is an important medium for thermal storage, which is widely used in concentrating solar power plants. The addition of nanomaterials becomes an effective way to overcome the unsatisfactory thermo-physical properties of pure molten salt. In the present study, molecular dynamics simulations are performed to investigate the influence of SiO2 nanoparticle on the thermo-physical properties of solar salt. Two kinds of models of solar salt nanofluids, i.e., different sizes of boxes with the same size of nanoparticles and the same size of boxes with different sizes of nanoparticles, at the mass fractions of nanoparticles of 1%, 2%, 3%, 4%, 5%, and 6% are built to analyze the size effects on the simulation results. The effects of SiO2 nanoparticles on the specific heat capacity, viscosity and thermal conductivity of the composited thermal energy storage (CTES) materials are studied extensively. The microscopic mechanism of the thermo-physical properties variation is revealed by calculating the mean square displacement (MSD), diffusion coefficient, Radial distribution function (RDF) and energy of systems. It is proved that the calculations of shear viscosity, specific heat capacity and MSD do not have size effect. An enhancement as large as 2.05% in the specific heat capacity of the CTES materials has been found with 2 wt% addition of nanoparticles. The presence of the compressed layer on the surface of the nanoparticles might be responsible for the enhancement of the specific heat capacity according to the calculation of RDF. It is also found that with the increase of mass fraction of nanoparticles, the viscosity of the CTES materials increases due to the enhancement of interaction between ions in the base fluid. Therefore, in order to avoid the negative effects caused by excessive viscosity of solar salt in thermal energy storage system, it is suggested to consider the appropriate amount of nanoparticles. The addition of SiO2 nanoparticles enhances the thermal conductivity of the CTES materials with the increase of mass fraction of nanoparticles. It is demonstrated that the enhancement of ion collision frequency in the base fluid is the main factor for the enhancement of thermal conductivity by the addition of SiO2 nanoparticles.

Experimental investigation of thermophysical properties, tribological properties and dispersion stability of nanodiamond-based nanolubricant for air conditioning systems

Compressor oil lubricant plays a vital role in enhancing the performance of air conditioning (AC) systems. Thermophysical and tribological properties, as well as physical stability, of Polyolester (POE) oil dispersed with nanodiamond (ND) have been evaluated experimentally to determine its suitability and feasibility for utilization as a nanolubricant in AC compressors. Thermophysical properties correlations were developed for the ND/POE nanolubricant with volume percentage and temperatures ranges of 0.05 to 0.5% and 10 to 100°C, respectively. The density, thermal conductivity, and viscosity were found to increase with increasing ND particle concentration and reduced with increasing preparation temperature. The developed thermophysical properties correlations showed relatively accurate predictions with a maximum mean absolute error (MAE) of 6%. The nanolubricant at 0.1 vol.% showed the lowest coefficient of friction (COF) to improve the frictional power losses. The ND/POE nanolubricant exhibited a well-dispersed stability using both the photograph image capturing approach and ultraviolet-visible spectroscopy (UV-vis) analysis. As a result of the enhanced thermal, tribological and stability qualities, prolonged lifespan and cool operation of AC compressors are anticipated when utilizing POE oil containing up to 0.1 vol.% of ND.

Preparation, characterization and experimental investigation of thermophysical properties of stable TiN nanofluid for solar thermal application

Preparation, characterization and experimental investigation of thermophysical properties of stable TiN nanofluid for solar thermal application

Investigation of thermophysical properties of synthesized SA and nano-alumina reinforced polyester composites

Synthesis and characterization of 4-[(E)-(5-bromo-2-hydroxybenzylidene) amino]-N-(4-methylpyrimidin-2-yl) benzenesulfonamide (SA) has been performed. Alumina (Al2O3) and SA reinforced polyester composites are synthesized, and characterization processes are carried out. SA formed has been characterized by Fourier transform infrared (FTIR) spektrofotometre and nuclear magnetic resonance (NMR) spectroscopy. The thermal decomposition behavior of the nanocomposites in a nitrogen environment under non-isothermal conditions from 298 to 973 K is investigated with proportional-integral-derivative (PID) system. Thermal conductivity, Shore D hardness, and thermal decomposition behaviors of the nanocomposites that are added with alumina filler and synthesized with SA reinforcement have been compared. Nano-alumina filler raises the thermal conductivity coefficient and Shore D hardness of the polyester composites. The addition of synthesized SA reduces both the thermal conductivity coefficient and Shore D hardness. The thermal conductivity coefficient has been measured at the lowest in the pure polyester (0.056 W/m·K), and highest in the nano-alumina reinforced composite (0.072 W/m·K). The lowest Shore D hardness (nearly 68) is determined in the synthesized SA reinforced composite. Also, the experimental study has been optimized with the help of response surface methodology (RSM), and the improved theoretical models have been evaluated by statistical analysis.

Investigation of Thermophysical Properties of Gradient Materials by the Method of Inverse Problems

Investigation of Thermophysical Properties of Gradient Materials by the Method of Inverse Problems

Investigation of thermophysical properties of milk thistle seeds and oils with the differential scanning calorimetry method

The purpose of work was to study the possibility of increasing the information content of differential scanning calorimetry (DSC) data when studying properties of various samples of milk thistle seeds and oils. The possibility of DSC method application for studying milk thistle oils thermophysical properties is shown, and the method for conducting temperature measurements is described in the work. The results of thermal analysis of milk thistle raw materials and oils obtained with cold pressing by the DSC method showed noticeable differences in oils melting profiles. When analyzing samples of milk thistle oils, differing from each other in the variety, place and growing conditions, it can be seen that the melting curves have differences with the general similarity of the profiles. The peaks of the DSC profile curves of oil stored at room temperature for six months are shifted towards higher temperatures compared to the DSC profile of freshly pressed oil, which is explained by oxidative deterioration and leads to an increase in the temperature of triacylglycerols phase transitions. This confirms the assumption that the DSC method can be used as an independent method for quality control of liquid vegetable oils. The selection of phase transitions temperatures of oils and raw materials was carried out with double differentiation. The use of the NETZSCH Peak Separation program according to the general algorithm for calculating the second melting curves derivatives and determining the endothermic peaks area made it possible to increase the information content of thermograms obtained by the DSC method. Thermal analysis showed an increased residual content of unsaturated fats in the meal obtained by cold pressing oil extracting.

Experimental Investigations of Thermophysical Properties and Convective Heat Transfer of Al2O3 and CuO Nanofluids in a Copper Tube: Proposing New Correlations

The performance of the Alumina/water and copper oxide/water nanofluids in a heat exchanger is experimentally investigated for particle weight concentrations ranging from 0.02 wt% to 0.5 wt%. The alumina/water and copper oxide/water nanofluids were prepared using two-step methods in an aqueous solution with 0.01 wt% CTAB (Cetyl Trimethyl Ammonium Bromide) as a surfactant at different concentrations and were characterized using HRTEM (High-Resolution Transmission Electron Microscopy) technique. Laminar forced convective heat transfer analysis using alumina and copper oxide nanoparticles suspended in water in a circular horizontal tube under constant heat flux boundary conditions was performed. The effect of various flow conditions and weight concentrations in the local heat transfer coefficient and pressure drop of both the nanofluids were investigated. Reynolds number varied from 1275 to 2200. Results show that 12.7 & 14.5 % thermal performance enhancement was observed with 0.5 wt% of Al2O3 and CuO nanofluids. Maximum, 50.62 % enhancement was observed in the average heat transfer coefficient by Al2O3 nanofluids, whereas 52.74 % was observed using CuO nanofluids using 0.5 wt% concentrations of the nanofluids and at Reynolds number of 2200. Correlations were proposed for thermal conductivity, viscosity, and Nusselt number for both the nanofluids with the maximum and minimum deviations of ±9 % and ±10 %, respectively.

Investigation of thermophysical properties of MWCNT-MgO (1:1)/10W40 hybrid nanofluid by focusing on the rheological behavior: Sensitivity analysis and price-performance investigation

The present study investigates the addition of MWCNT-MgO (1:1) nanoparticles (NPs) to 10 W40 oil to improve the viscosity. There are two parts of laboratory and modeling in this study. In the laboratory part, hybrid nanofluid (HNF) with solid volume fractions (SVFs) of 0.05, 0.1, 0.25, 0.5, 0.75 and 1% and different temperatures of T = 5 , 15 , 25 , 35 , 45 and 55 °C and different shear rates (SRs) are prepared. Power-law index and shear stress changes show that HNFs have non-Newtonian behavior of the shear-thinning type. Increasing the temperature from T = 5-55 °C shows that the viscosity of HNFs decreases significantly by 82%. In general, the addition of NPs increases the viscosity, but at low SVFs, such as 0.05%, the addition of NPs reduces the viscosity of HNF. The proposed modeling for viscosity and relative viscosity have correlation coefficients of 0.9963 and 0.9585, respectively. Deviation from the standard is also in the range of (−10%,+12%). MWCNT-MgO/10 W40 HNF had better economic performance compared to MWCNT-ZnO/10 W40 and MWCNT-TiO2 /10 W40 HNFs in SVF = 0.05%. In SVF = 1%, the greatest increase in sensitivity occurs.

Investigation of Thermophysical Properties of Colemanite, Ulexite, and Tincal Reinforced Polyester Composites

In this research, composite material has been obtained by reinforcing colemanite, ulexite, and tincal ore from the boron factory to unsaturated polyester. The effects of these fillers, which are used in different ratios by mass, on the density, Shore D hardness, thermal conductivity coefficient, and thermal stability of the polyester composite have been investigated. According to the results obtained, as the mass ratio of the boron factory components in the mixture raised, the density, hardness, activation energy, and thermal conductivity coefficient of the polyester composite increased. Colemanite increased the density and Shore D hardness of the polyester composite more than other fillers. Besides, tincal ore raised the thermal conductivity coefficient of the polyester composite the least compared to the others. Also, the activation energy values of the polyester composite were ordered from largest to smallest as colemanite, ulexite, and tincal ore according to Coats-Redfern method. The increase in the activation energies of polyester composites is an indication of the raise in thermal stability

Comparative evaluation of AI ‐based intelligent GEP and ANFIS models in prediction of thermophysical properties of Fe 3 O 4 ‐coated MWCNT hybrid nanofluids for potential application in energy systems

Hybrid nanofluids are gaining popularity owing to the synergistic effects of nanoparticles, which provide them with better heat transfer capabilities than base fluids and normal nanofluids. The thermophysical characteristics of hybrid nanofluids are critical in shaping heat transmission properties. As a result, before using thermophysical qualities in industrial applications, an in-depth investigation of thermophysical properties is required. In this paper, a metamodel framework is constructed to forecast the effect of nanofluid temperature and concentration on numerous thermophysical parameters of Fe3O4-coated MWCNT hybrid nanofluids. Evolutionary gene expression programming (GEP) and an adaptive neural fuzzy inference system (ANFIS) were employed to develop the prediction models. The model was trained using 70% of the datasets, with the remaining 15% used for testing and validation. A variety of statistical measurements and Taylor's diagrams were used to assess the proposed models. The Pearson's correlation coefficient (R), coefficient of determination (R2) was used for the regression index, the error in the model was evaluated with root mean squared error (RMSE). The model's comprehensive assessment additionally includes modern model efficiency indices such as Kling-Gupta efficiency (KGE) and Nash-Sutcliffe efficiency (NSCE). The proposed models demonstrated impressive prediction capabilities. However, the GEP model (R > 0.9825, R2 > 0.9654, RMSE = 0.7929, KGE > 0.9188, and NSCE > 0.9566) outperformed the ANFIS model (R > 0.9601, R2 > 0.9218, RMSE = 1.495, KGE > 0.8015, and NSCE > 0.8745) for the majority of the findings. The generated metamodel was robust enough to replace the repetitive expensive lab procedures required to measure thermophysical properties. Highlights Predictions of thermophysical properties of Fe3O4-coated MWCNT hybrid nanofluid AI-based ANFIS and GEP models performed well on statistical indices ANFIS and GEP-based prognostic models validated and compared with Taylor diagrams

Investigation of Thermophysical Properties of Polyester Composites Produced with Synthesized MSG and Nano-Alumina

In this study, synthesis of a new compound, 4-[(E)-(5-Bromo-2-hydroxy-3-methoxybenzylidene) amino]-N carbamimidoylbenzenesulfonamide (MSG) has been carried out. The structures of MSG are characterized using spectroscopic methods such as Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance spectroscopy (NMR). In experimental studies, synthesized MSG has been reinforced with 1 wt.% and 2 wt.% unsaturated polyesters. Besides, 1 wt.% and 2 wt.% alumina nanoparticles, 1.5 wt.% methyl ethyl ketone peroxide (MEKP), and 0.5 wt.% cobalt octoate (Co Oc) were used to produce polyester composites. Although alumina nanoparticles increased the density of the produced polyester composite, MSG supplementation decreased it. While nano-alumina raised Shore D hardness of the polyester composite, synthesized MSG went down it. Both nano-alumina and MSG reinforcement have been increased the porosity in the surface morphology of the polyester composite. Also, nano-alumina reinforcement raised the activation energy of the polyester composite and MSG decreased it. In other words, since the alumina filler raises the activation energy, the thermal stability of the polyester composite has gone up.

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