Measurement Of Thermophysical Properties Research Articles

Demonstration of a container-less method for investigating high-temperature alloy properties using ED-XRD.

As new alloys are being developed for additive manufacturing (AM) applications, questions related to the temperature-dependent structural and compositional stability of these alloys remain. In this work, the benefits and limitations of a unique method for testing this stability are presented. This system employs the use of polychromatic synchrotron light to perform energy-dispersive x-ray diffraction (ED-XRD) on an electrostatically levitated sample at high temperatures. In comparison with a traditional angular-dispersive setup, the container-less electrostatic levitation method has unique advantages, including quicker acquisition times, simultaneous compositional information through fluorescence emissions, a reduction in background noise, and, importantly, concurrent/subsequent measurement of thermophysical properties. This combined method is ideal for phase transition studies by holding the levitated sample at a stable position and temperature through controlled heating and temperature management. To illustrate these capabilities, we show ED-XRD data of the well-known martensitic phase transition (hcp to bcc) in Ti-6Al-4V. In addition, results from the novel alloy Ni51Cu44Cr5 are presented. This alloy is shown to maintain an fcc structure upon heating. However, the concentration of Cu is reduced at high temperatures, resulting in a decrease in the lattice constant. As concurrent thermophysical properties are probed, these preliminary structure and composition experiments demonstrate the capabilities of this technique to determine the composition-processing-structure-properties of metal alloys for AM.

Validation of 3D thermal simulations of the Double C Block, a novel composite masonry unit, using in-situ U-value measurements

Energy efficient building envelopes, particularly innovative prefabricated building components, can significantly contribute to lower the building industry energy-related emissions. In this research the composite masonry unit Double C Block (DCB) is quantitatively tested by means of three-dimensional thermal simulation validated by in-situ U-value measurements carried out in both summer and winter conditions.The simulations were enhanced by the experimental measurement of the dry thermo-physical material properties (specific heat capacity, thermal conductivity, and density) in laboratory conditions for both concrete and polyurethane. The samples were extracted from real-scale DCB prototypes. Furthermore, site-specific boundary conditions of Malta — representative a case study of a Mediterranean climate − were utilised in the simulations. Both laboratory and in-situ assessments of thermal transmittance, or U-value, had their uncertainty specified as part of the calculations.The validation exercise was performed by means of hourly recorded surface temperature and the selected indices were the root mean square error and mean absolute error. Results showed that these indices were within the recommended accuracy thresholds during both winter and summer assessments. For the hourly-based heat flux measurements, the mean bias error and coefficient of variation of the root mean square error were found lower than values reported in literature, thus supporting the robustness of the overall simulation outputs. Hence the 3D CVM simulation was experimentally validated by in-situ assessments.The convergence value of the experimental U-value provided respectively 1.51 ± 0.20 W/m2K (winter) and 1.44 ± 0.19 W/m2K (summer). Then, the validated 3D CVM model was adapted to calculate the theoretical U-value of DCB, using monthly values of recorded surface temperatures obtained by the test cells (in both seasons). The predicted thermal transmittance was of 1.47 W/m2K, in both conditions, and this almost matches the above-mentioned experimental assessments and thresholds established in previous works.

Contactless surface tension measurement of molten oxides using oscillating drop method in an aerodynamic levitator

Aerodynamic levitation stands as a contactless method for thermophysical property measurement of molten oxides at high temperatures, offering the advantage of eliminating sample contamination and enabling surface tension measurement through the oscillating drop method. However, the presence of oscillation mode splitting results in an underestimation of surface tension. By improving levitation stability and optimizing the acoustic excitation method for the levitated drops, this study successfully eliminates oscillation mode splitting for the first time. The l = 2 resonance frequency is directly measured, which is used to calculate surface tension according to the Rayleigh equation. Taking Al2O3 as a representative of oxides, this study demonstrates the accurate surface tension measurement during the frequency scan process when oscillation mode splitting is absent. Additionally, combining damped oscillation analysis with the frequency scan reduces measurement uncertainty from 2.8 % to 1.5 %. Within the temperature range of 2336K–2923K, the surface tension of molten Al2O3 is determined to be γ = −(4.071 ± 2.688) × 10−5 (T-2327)+(0.7465 ± 0.074) N/m. Underestimation of surface tension is prevented when the l = 2 resonance frequency is used for surface tension calculations. The frequency crossover method which is used for surface tension measurement is also found to be affected by oscillation mode splitting.

Thermophysical properties of UO2-ZrO2 melt measured by aerodynamic levitation

This study addresses the measurement of thermophysical properties in molten core materials (corium), which is crucial for modeling severe accidents in light water reactors. Due to the measurement challenges at temperatures above 3000 K, there is a significant lack of experimental data for corium. Focusing on a UO2-ZrO2 melt (atomic ratio U/Zr=0.456), density and viscosity measurements were conducted using aerodynamic levitation, a non-contact method chosen to avoid interactions between the samples and container walls. Samples were prepared using the pressing sintering method and levitated by argon gas above a conical converging-diverging nozzle. Density was measured using the cooling traces method under the axisymmetric ellipsoid hypothesis, while viscosity was measured by inducing damped oscillations which occurred when the levitated droplet was forced to oscillate around its resonant frequency through acoustic excitation, followed by the cessation of the acoustic excitation. The provided data and derived equations for the density and viscosity of the UO2-ZrO2 melt contribute to enriching the thermophysical property database for materials in nuclear reactors.

Measurement and Modeling of Thermophysical Properties of the Ternary System 2-(Butylamino)ethanol + Dimethyl Sulfoxide + Water and Its Binary Subsystems

Measurement and Modeling of Thermophysical Properties of the Ternary System 2-(Butylamino)ethanol + Dimethyl Sulfoxide + Water and Its Binary Subsystems

Thermal conductivity measurements for additively manufactured AlSi10Mg and Al6061-RAM2 Aluminum composites at cryogenic temperatures

Advances in 3D printing are disruptive opportunities for material selection and component design in cryogenics. However, thermophysical property measurements for these novel materials are generally unavailable at cryogenic temperatures. This experiment explores the variation in thermal conductivities due to print direction of two aluminium composites (AlSi10Mg and Al6061-RAM). The direct linear heat flow method was utilized to calculate thermal conductivities using a measured wattage input, temperature differential, and Fourier’s Law of Conduction. A multi-measurement linear regression was applied to determine thermal conductivities at fixed average temperatures over the range of 20-100K. The AlSi10Mg composite had a greater thermal conductivity than Al6061-T6 for both printing planes by approximately 230%. The XY-plane print direction resulted in a reduction in thermal conductivity compared with the Z-plane by approximately 30%. The AL6061-RAM composite had effective thermal conductivities smaller than the machined Al6061-T6 by approximately 70% for both print directions. The thermal conductivity in the Z-plane print direction was consistently greater than the thermal conductivity in the XY print direction. Validation studies were conducted utilizing Al6061-T6 and SS-304/304L. The calculated deviation for the validation samples depicted a 20% difference from the National Institute of Standards and Technologies (NIST) recommended reference values. The calculated uncertainty of the experimental system was 5-10%, increasing as temperature decreased. These preliminary measurements depict the need for further analysis on 3D printed composite materials and reverification of common materials due to improvements in current manufacturing methods since the classic experimental measurements were carried out for SS-304/304L and Al6061-T6.

On the Importance of Using Reliability Criteria in Photothermal Experiments for Accurate Thermophysical Property Measurements

On the Importance of Using Reliability Criteria in Photothermal Experiments for Accurate Thermophysical Property Measurements

Analysis of heat flow in modified transient plane source (MTPS) measurements of the thermal effusivity and thermal conductivity of materials.

An iterative algorithm for the diffusion of heat in layered structures is solved in cylindrical coordinates for the geometry used in measurements of thermophysical properties of materials by the modified transient plane source (MTPS) method. This solution for the frequency-domain temperature response is then used to model the transient temperature excursion and evaluate the accuracy of the measurements. We evaluate when the MTPS method is capable of separately determining the thermal conductivity and heat capacity per unit volume of a material. For a typical sensor design, data acquisition, and data analysis, the MTPS measurement has a small sensitivity to the thermal diffusivity of the sample when the thermal diffusivity is <5 mm2 s-1. We analyze the propagation of errors from uncertainties in the thermal contact between the sensor and the sample and evaluate the limitations of the MTPS method in accurately measuring samples with extremely low thermal effusivity, e.g., low density foam insulation. We find that uncertainties in the thickness of the contact region limit the accuracy of MTPS measurements when the data are analyzed in a conventional manner based on a single parameter, m-1, the inverse of the slope of the temperature excursion as a function of the square root of time.

Remarkable undercooling capability and metastable thermophysical properties of liquid Nb84.1Si15.9 alloy revealed by electrostatic levitation in outer space.

The stable manipulation, high undercooling, and thermophysical property measurement of the liquid Nb84.1Si15.9 refractory alloy were successfully achieved by the electrostatic levitation technique on board the China Space Station. By controlling the superheating temperature, a maximum liquid undercooling up to 421K (0.18 TL) was obtained in the space environment, and two distinct solidification paths with different recalescence features were realized at metastable undercooled states. The liquid density and the ratio of specific heat to emissivity were measured in a wide temperature range from 1841 to 2346K, which displayed linear and quadratic relations vs temperature, respectively. The liquid emissivity was further deduced from the specific heat of the liquid alloy calculated by molecular dynamics simulation. In addition, both the density and structural characteristics of the undercooled liquid alloy were also analyzed by MD calculations.

Measurement and Correlation Studies of Phase Equilibria and Thermophysical Properties of 2,6-Dichlorotoluene

Measurement and Correlation Studies of Phase Equilibria and Thermophysical Properties of 2,6-Dichlorotoluene

Data reduction and uncertainty assessment of the direct pulse heating technique with both contact and radiance temperature measurements

This work presents a data reduction procedure of the direct pulse heating technique with both contact and radiance temperature measurements. The technique is applied for the measurement of thermophysical properties of electroconductive solids over a wide temperature range, i.e., from room temperature up to about 2300°C. Absolute and radiance temperatures of a tested material are measured by thermocouple and radiation thermometer, respectively and these and other experimental data are then reduced to the values of specific heat, specific electrical resistivity, hemispherical total emissivity and normal spectral emissivity of the tested material. The related data reduction and corresponding uncertainty assessment for each property is described in detail. An example of uncertainty assessment is given for the recent measurement of specific heat, specific electrical resistivity, hemispherical total emissivity and normal spectral emissivity at 900 nm of molybdenum alloy TZM specimens.

A new method to combine high-pressure vapor–liquid equilibrium and thermophysical property measurements for low-volatility liquids and a gas

Vapor-liquid equilibria measurements involving liquids with low volatility, such as many types of lubricants, ionic liquids, and various solvents are essential for process research and development in a wide variety of fields. State–of–the–art methods to measure these phase equilibria, e.g. thermogravimetric analysis or equilibrium cells, generally cannot be combined with instruments measuring thermophysical properties, e.g. density, transport properties, spectroscopic properties, etc. A novel approach was developed to measure simultaneously vapor–liquid equilibrium and thermophysical properties involving a single gas dissolved in one or more low-volatility liquids. The method is based upon a mass balance measuring liquid phase density, total masses in the system, and volumes. The governing equations of the novel approach are derived, and a detailed uncertainty analysis is presented. As an example, the solubility, density, and viscosity are measured with the new apparatus for a system of a non-volatile ionic liquid solvent saturated with the compressed hydrofluorocarbon gas, pentafluoroethane (R-125), at 25 °C and 75 °C and pressures to ∼ 3.1 MPa. The solubility data are validated by comparison to previously published literature data using a high precision gravimetric microbalance. The combination of vapor–liquid equilibria and thermophysical properties in a single experiment can significantly accelerate scientific and engineering studies.

Design and development of a test method for the measurement of thermo-physical properties of different materials

The guarded hot plate method is widely used to measure the thermal conductivity and thermal resistance of materials having low thermal conductivity. An experimental set-up was designed and fabricated in-house to measure these properties. The set-up was built in accordance with ASTM D5470 standards. A novel insulating material waste tire rubber/polypropylene has been developed from the solid blend of waste tire rubber powder (425–300 µm) mixed with virgin polypropylene granules in a 2.5:1 ratio. The thermal conductivity of the newly developed insulating material in cylindrical solid form has been estimated. Further, thermal conductivity of a conducting material i.e., H-13 tool steel has been found out by using the present experimental set-up. In addition, the thermal contact conductance of a well-known thermal paste i.e., silicon grease has also been estimated for a range of temperatures and pressure using the present set-up. In the present study, the procedure for measuring thermal conductivity has been demonstrated along with the strengths and weaknesses of the experimental set-up and the suitability of the method for different materials. The experimental results reveal that the test method is equally suitable for the analysis of thermal interface material, and for measuring the thermal conductivity of solid specimens giving reliable results.

Preface: CEST 2023

The Central European Symposium on Thermophysics (CEST) 2023 is a 5th scientific meeting whose scopes are thermophysical properties of materials, heat transfer, and the measurement of thermophysical and other transport properties of materials. It is a successor of the international conference Thermophysics that was organized annually since 1996. While Thermophysics was well-established and of long tradition, CEST provides a novel format in which one of the four co-chairs (R. Černý, Á. Lakatos, Z. Suchorab, and A. Trník) acts each year as the CEST chair and organizes the symposium in a different country. In 2023 it is jointly organized by• Department of Physics, Faculty of Natural Sciences and Informatics, Constantine the Philosopher University in Nitra, Slovakia.List of Committees, Organizers are available in the pdf.

Thermophysical Property Measurements with the Finite Bar

Knowledge of thermophysical properties of materials is important in the design process to meet the ambitious targets with respect to reliability and performance of many modern machinery. In this paper a simple method for the measurements of thermophysical material properties is presented. A bar of the sample material is heated at one end by a constant heat source and temperature sensors on or in the sample material at different locations record the temperature response. In the limit of small Fourier-Numbers the temperature will not rise at the adiabatic end and the comparison to the theoretical curve allows to extract thermophysical data. In the case of large Fourier-Numbers a quasi steady temperature profile in the bar allows to extract all relevant thermophysical properties simultaneously. Apart from the theory some measurement results are presented and the errors due to diabatic boundary conditions are discussed.

Thermophysical Properties Measurement of Al–22.5 wt pctCu in Reduced Gravity Using the ISS-EML

Thermophysical Properties Measurement of Al–22.5 wt pctCu in Reduced Gravity Using the ISS-EML

Experimental heat transfer study of an enhanced storage medium

Phase change materials (PCMs) are suitable for storing solar energy due to their high-density energy storage and ability to operate in a wide range of temperatures. However, the lower thermophysical properties of PCMs limit their use in solar energy storage applications. Therefore, the incorporation of nanoparticles has emerged as a promising technique to enhance the storage density of PCMs.Extensive studies have been conducted on the measurement of thermophysical properties of both PCMs and nano-PCMs (PCMs with nanoparticles dispersed in them). However, there has been no comprehensive study covering the following aspects: (a) the measurement of thermophysical properties of NaNO3 (PCM) and nano-NaNO3 (nano-PCM), (b) solar energy storage of NaNO3 involving both sensible heat and latent heat in the same study, (c) the construction and implementation of an experimental rig capable of studying heat transfer in PCM and nano-PCM for solar energy storage applications (with a maximum temperature of up to 350 °C), and (d) investigating the effect of nanoparticles on large-scale solar energy storage systems. Therefore, the aim of this study is to experimentally investigate all of the aforementioned points. In order to develop and test these solar storage mediums, an experimental setup has been designed and manufactured, as mentioned earlier.Furthermore, limited studies have considered sodium nitrate salt (NaNO3) as a PCM. In this study, NaNO3 is used as the base material, and two types of materials are considered: PCM1, which consists of sodium nitrate salt (NaNO3), and PCM2, which consists of sodium nitrate salt (NaNO3) with 0.75 wt% iron oxide nanoparticles (Fe2O3) added. The experiments conducted involved both steady-state and transient conditions. The results showed that the addition of nanoparticles improved the charging and discharging by 25.6 % and 23.929 %, respectively. Moreover, the specific heat capacity and latent heat of the developed PCMs increased by 17.857 % and 9.97 %, respectively. These findings suggest that PCM2, with the presence of nanoparticles, melts and discharges energy faster compared to PCM1. Overall, this study contributes to the understanding of solar energy storage using PCMs and nano-PCMs, highlighting the potential benefits of nanoparticle incorporation in enhancing their performance.

Uncertainty Quantification of Thermophysical Property Measurement in Space and on Earth: A Study of Liquid Platinum Using Electrostatic Levitation

A study of uncertainty analysis was conducted on four key thermophysical properties of molten Platinum using a non-contacting levitation technique. More specifically, this work demonstrates a detailed reporting of the uncertainties associated with the density, volumetric thermal expansion coefficient, surface tension and viscosity measurements at higher temperatures for a widely used refractory metal, Platinum using electrostatic levitation (ESL). The microgravity experiments were conducted using JAXA’s Electrostatic Levitation Furnace (ELF) facility on the International Space Station and the terrestrial experiments were conducted using NASA’s Marshal Space Flight Center’s ESL facility. The performance of these two facilities were then quantified based on the measurement precision and accuracy using the metrological International Standards Organization’s Guide to the Expression of Uncertainty Measurement (GUM) principles.

Measurements of Thermophysical Properties of Ethanol + Hexamethyldisiloxane and Ethanol + Octamethyltrisiloxane Mixtures in the Temperature Range of 293–343 K at 100 kPa

Measurements of Thermophysical Properties of Ethanol + Hexamethyldisiloxane and Ethanol + Octamethyltrisiloxane Mixtures in the Temperature Range of 293–343 K at 100 kPa

(Invited) The Electrostatic Levitation Furnace Onboard the International Space Station for Container-Less Material Processing and Thermophysical Property Measurements at Extremely High Temperature

Electrostatic levitation is one of the container-less processing methods which utilizes Coulomb force between a charged sample and surrounding electrodes. Contrary to the other methods, electrostatic levitation cannot create a potential minimum, so high-speed feedback position control is necessary. Because of this technical difficulty, development of this method was behind to other methods, such as electromagnetic levitation, or acoustic levitation. Samples can be levitated even in ground. However, to levitate samples against gravity, huge electric field and huge surface charge on the sample are required. This creates some limitations in ground experiments. Firstly, Oxides samples are hard to levitate due to low surface charge. Secondly, experiment in inert gas environment is impossible to prevent electric discharge among electrodes. These limitations can be easily solved in microgravity. Oxides sample cane be levitated and melted. Metals and alloys can be processed in inert gas to suppress evaporation.The electrostatic levitation furnace on the International Space Station (ISS-ELF) developed by Japan Aerospace Exploration Agency, was launched to the ISS in 2015. Then, Installation to the MSPR (multi-purpose Small Payload Rack) was conducted in the next year. Since then, a variety of oxide/ metal samples have been levitated and melted in the facility. The ISS-ELF has a capability to measure thermophysical property of extremely high temperature melts. Density, Surface tension, and viscosity can be measured by this facility. Status of thermophysical property measurements is described in this presentation.