Measurement Of Thermophysical Properties Research Articles

Thermal wave propagation through nanofilms in ballistic-diffusive regime by Monte Carlo simulations

Investigations on ultrafast heat conduction are of great importance not only for the theoretical understanding of thermal transport, but also the applications of ultra-short pulse laser including the micromachining and the measurements of thermophysical properties of micro/nanomaterials where phonons propagate in ballistic-diffusive regime. In this work, the thermal wave in phonon ballistic-diffusive regime is systematically studied by the Monte Carlo (MC) simulation method. Simulation results show significant influence of the phonon boundary emission conditions, i.e. boundary conditions of phonon Boltzmann transport equation (BTE), on the thermal wave propagation. The MC simulations with phonon Lambert emission (LE) predict a dispersive dissipative thermal wave while the MC simulations with directional emission (DE) predict a non-dispersive dissipative thermal wave. Temperature peak in the MC simulations with LE damps more rapidly than that in DE cases, and heat flux in MC simulations with DE damps exponentially while that in with LE does not. Dispersion relations and wave vector spectrums of thermal waves are determined by the phonon boundary emission, proven by theoretical analyses based on the phonon BTE. The indexes of energy mean square displacement (MSD) relation with respect to time are larger than 1 but less than 2 and decrease as time increases, showing that phonons propagate in ballistic-diffusive regime and evolve from ballistic to diffusive. Effects of the reflection boundary on thermal wave propagation are also investigated and it is found that the temperature overshooting phenomena, due to the wave propagation of heat, is significantly influenced by the properties of both emission and reflection boundaries.

Reliability of thermal conductivity measurement of liquids by using transient hot-wire, photon-correlation spectroscopy and the laser flash method

Measuring the thermal conductivity of liquids is important, but not easy, because of the complexity of and the natural convection in liquids, and reliable thermal conductivity measurements in liquids under various sample conditions is essential for data accuracy. We have introduced and developed a validation chain for measuring the thermal conductivity of liquids by using three different experimental methods: the transient hot-wire (THW), the photon correlation spectroscopy (PCS) and the laser flash (LF) methods in the temperature range from −30 to 90 °C. We checked the performance of the validation chain developed in this study by measuring the thermal conductivity of liquid toluene. We found good agreement between the thermal conductivity data obtained by using the THW, PCS and LF methods. To demonstrate the use of this validation chain for measurements of thermophysical properties in liquids, we also showed its use in measuring the specific heat of a volatile liquid, toluene which can be extracted from thermal conductivity, thermal diffusivity, and density measurements without any effects of volatilization.

Convective heat transfer characteristics of water–ethylene glycol mixture with silver nanoparticles

We report the convective heat transfer characteristics of water–ethylene glycol mixture fluids seeded with silver nanofluids under laminar, transitional and turbulent regime in this work. The volume concentrations of silver nanoparticles viz. 0.05%, 0.1%, 0.15%, 0.3% and 0.45% are considered. Thermophysical properties measurements such as thermal conductivity, viscosity, density and specific heat capacity were carried out using conventional techniques. Convection measurements were carried out in a tube in tube counter flow heat exchanger using nanofluids as the hot fluid. The effect of nanofluid mass flow rate ranging from 5g/s to 45g/s and inlet temperature of nanofluid at 35°C and 45°C on the convective heat transfer coefficient were investigated. The convective heat transfer coefficient was considerably increased with increasing Reynolds number, particle concentration and inlet temperature. The maximum enhancement of convective heat transfer coefficient of nanofluid is observed to be ∼42% at 0.45vol% compared with pure basefluid. The pressure drop of nanofluid increases marginally for a nanofluid volume concentration up to 0.15vol%. When compared with the base fluid, the difference of pressure drop is insignificant so that the use of nanofluid has limited penalty on the pressure drop up to 0.15vol% loading of silver nanoparticles. However, beyond 0.15vol% the pressure drop increases significantly which limits the use of these nanofluids at higher concentration for engineering applications.

Measurement of high temperature phase stability and thermophysical properties of alloy 740

In the present study, the characterisation of phase stability and measurement of different thermophysical properties of alloy 740 has been carried out. The transformation temperatures including liquidus/solidus and corresponding enthalpy of transformation have been measured for different phase changes up to melting using dynamic calorimetry. Further, the enthalpy increment data have been measured in the temperature range of 473–1473 K to obtain the heat capacity using static calorimetry. The present calorimetric data have been analysed in corroboration with the results obtained using JMatPro and Thermo-Calc simulation. In addition, the temperature dependence of other thermophysical properties such as thermal expansivity, density, thermal diffusivity and thermal conductivity are also measured in the range of 300–1473 K using thermomechanical analyser and laser flash method.

Thermophysical properties of USi to 1673 K

Consideration of uranium silicide compounds as candidate nuclear reactor fuels requires the accurate knowledge of their thermophysical properties as a function of temperature. Stoichiometric USi has received little attention in the literature with regard to property characterization. This absence of data prevents modeling and simulation communities from predicting performance of uranium silicide fuels that are either nominally USi itself, or are designed with other uranium silicide phases but may include appreciable fractions of USi introduced as a result of the fuel synthesis or fabrication process. This study was undertaken to quantify the thermal expansion coefficient, specific heat capacity, thermal diffusivity, and thermal conductivity of USi from ambient conditions to just below the peritectic decomposition of the compound. Stoichiometric samples that were prepared by arc melting and powder metallurgical routes for thermophysical property measurements exhibited 94% USi phase, with the balance being U3Si5 phase that likely formed during the solidification process. An energetic phase transformation was observed at 723 K, which is attributed to the inclusion of the secondary U3Si5 phase.

Thermophysical Property Measurement: A Call to Action

Thermophysical Property Measurement: A Call to Action

Measuring the Thermal Diffusivity of Multi-Layered Graphene Nanoplatelets (GNPs) by a Periodic Heating Method

The present paper describes ways of increasing the accuracy of measurements of thermophysical properties (namely, thermal diffusivity) of materials. The knowledge of these characteristics is very important for modeling industrial processes, since their high-accuracy determination can reduce wasteful consumption of energy resources while developing novel thermal insulation materials, technologies, as well as methods for building construction. The method proposed herein is based on periodic heating and can be used to improve the measurement accuracy and find the optimal parameters for producing thermal insulation materials. Periodic temperature oscillations were generated by means of the Peltier element. Mathematical and physical models were developed, and the measurement setup was automated using the LabView graphical programming environment. The analysis of possible error sources was performed, and the ways of decreasing error values were suggested. The equipment was experimentally calibrated using a standard material (Plexiglas), and the obtained data proved the appropriateness of the developed mathematical model. Moreover, a number of tests were performed with a nanomaterial, namely, graphene nanoplatelets (GNPs). The proposed method and the experimental measurement setup made it possible to reveal a strong dependence between the thermal diffusivity of the GNPs and the moisture content. This finding will be considered in further studies concerning the above-mentioned nanomaterial.

Effect of cerium on the thermophysical properties of AMg2 alloy

Results of measurements of thermophysical properties and thermodynamic functions of the AMg2 alloy doped with cerium determined in the regime of cooling are brought out.

Non-Contact Measurement of Thermophysical Properties of Fe, Fe–C, and Fe–C–Mn Alloys in Solid, Supercooled, and Stable Liquid Phases

Non-Contact Measurement of Thermophysical Properties of Fe, Fe–C, and Fe–C–Mn Alloys in Solid, Supercooled, and Stable Liquid Phases

114 水産品の凍結プロセスの簡易予測技術の構築に向けた異なる水産品の熱物性値の計測

114 水産品の凍結プロセスの簡易予測技術の構築に向けた異なる水産品の熱物性値の計測

Thermodynamic properties of indan: Experimental and computational results

Measurements leading to the calculation of thermodynamic properties in the ideal-gas state for indan (Chemical Abstracts registry number [496-11-7], 2,3-dihydro-1H-indene) are reported. Experimental methods were adiabatic heat-capacity calorimetry, differential scanning calorimetry, comparative ebulliometry, and vibrating-tube densitometry. Molar thermodynamic functions (enthalpies, entropies, and Gibbs energies) for the condensed and ideal-gas states were derived from the experimental studies at selected temperatures. Statistical calculations were performed based on molecular geometry optimization and vibrational frequencies calculated at the B3LYP/6-31+G(d,p) level of theory. Computed ideal-gas properties derived with the rigid-rotor harmonic-oscillator approximation are shown to be in excellent accord with ideal-gas entropies derived from thermophysical property measurements of this research, as well as with experimental heat capacities for the ideal-gas state reported in the literature. Literature spectroscopic studies and ab initio calculations report a range of values for the barrier to ring puckering. Results of the present work are consistent with a large barrier that allows use of the rigid-rotor harmonic-oscillator approximation for ideal-gas entropy and heat-capacity calculations, even with the stringent uncertainty requirements imposed by the calorimetric and physical property measurements reported here. All experimental results are compared with property values reported in the literature.

P28] Revision of assessment of the Pd-Sn binary: replacing of polynomial description of liquid by association model

This work reports thermophysical properties measurements of binary mixtures of N,N-dimethylacetamide with 2-propanol and 2-butanol. Density, ρ, speed of sound, u, refractive index, nD, and kinematic viscosity, ν, were measured over the whole composition range at the temperatures (283.15, 298.15 and 313.15) K and at atmospheric pressure p = 0.1 MPa. Experimental data were used to calculate the following properties: excess molar volume, VE, excess isentropic compressibility, κSE,refractive index deviation, ΔnD, and viscosity deviation, Δη. These properties were correlated with the Redlich-Kister equation. Excess molar volumes were positive for both mixtures. Refractive index deviations were positive for N,N-dimethylacetamide + 2-propanol and negative for N,N-dimethylacetamide + 2-butanol. Excess isentropic compressibilities and viscosity deviations were negative for the two systems. Finally, the results obtained were interpreted based on both structural and energetic effects.

Numerical Analysis of Transient Temperature Response of Soap Film

Measurements of thermophysical properties of thin liquid films are important to understand interfacial phenomena due to film structures composed of amphiphilic molecules in soap film, phospholipid bilayer of biological cell and emulsion. A transient hot-wire technique for liquid films less than 1 $$\upmu $$ m thick such as soap film has been proposed to measure the thermal conductivity and diffusivity simultaneously. Two-dimensional heat conduction equations for a solid cylinder with a liquid film have been solved numerically. The temperature of a thin wire with liquid film increases steeply with its own heat generation. The feasibility of this technique is verified through numerical experiments for various thermal conductivities, diffusivities, and film thicknesses. Calculated results indicate that the increase in the volumetric average temperature of the thin wire sufficiently varies with the change of thermal conductivity and diffusivity of the soap film. Therefore, the temperature characteristics could be utilized to evaluate both the thermal conductivity and diffusivity using the Gauss–Newton method.

Measurement of thermophysical properties coupled with LCA assessment for the optimization of a historical building retrofit

Historical buildings are a significant part of the Italian building stock and, in most cases, need deep refurbishment interventions to reach the energy criteria required by the current standards. A workflow that integrates on-site surveys and building modeling is mandatory to obtain effective energy saving measures. This work describes the analysis and modeling of the San Vito alla Rivera church, a XIV century building that was damaged during 2009 L'Aquila earthquake, suffering a partial collapse of the façade and of the roof. The latter was selected for a complete restoration that could improve its thermal performance while maintaining, as much as possible, the original structure. Several elements of the roof were collected in situ in order to measure, in laboratory, its thermophysical properties applying standard techniques and alternative methods based on infrared thermography. The accurate characterization of the materials was the starting point for the estimation of the environmental impact of the retrofit aimed to reach a defined thermal transmittance. A model of the building was created with TRNSYS software to calculate the energy consumption before and after the intervention. A Life Cycle Assessment (LCA) analysis was conducted on different insulation materials to determine the one with the lowest impact.

Thermophysical properties of ethylene glycol based yttrium aluminum garnet (Y3Al5O12–EG) nanofluids

The paper presents results of measurements of basic thermophysical properties of ethylene glycol based yttrium aluminum garnet (Y3Al5O12–EG) nanofluids. Nanofluids used in presented experiments were prepared with two-step method based on commercial nanoparticles. Basic rheological properties were investigated on HAAKE MARS 2 rheometer (Thermo Electron Corporation, Karlsruhe, Germany). Dynamic viscosity curves in the range of shear rates from 10 to 1000s−1 at a constant temperature of 298.15K were determined. Additionally, the temperature dependence of the viscosity in the range from 273.15K to 333.15K was measured. To determinate thermal conductivity of nanofluids a KD2 Pro Thermal Properties Analyzer (Decagon Devices Inc., Pullman, Washington, USA) was used. The dependence of thermal conductivity of Y3Al5O12–EG nanofluids on the concentration of nanoparticles was measured at constant temperature of 298.15K.

Density and Viscosity of Athabasca Bitumen Samples at Temperatures Up to 200°C and Pressures Up to 10 MPa

Summary This paper presents the measurements of bitumen thermophysical properties (density and viscosity) over a wide range of temperatures (ambient to 200°C) and pressures (atmospheric to 14 MPa). The measurements have been conducted on three Athabasca bitumen samples taken from different locations. A new method was proposed to correlate the density data as a function of temperature and pressure, with a maximum absolute deviation of 1.7 kg/m3. The viscosity data were also correlated with two correlations available in literature considering the effect of pressure and temperature on viscosity of bitumen, with an average absolute relative deviation of 9.2%. The measured data and correlations are applicable for the prediction and optimization of oil recovery in the solvent- and thermal-based bitumen-recovery processes such as expanding- solvent steam assisted gravity drainage (ES-SAGD) and heated vapor extraction (VAPEX).

Modeling and measurement of thermo-physical properties for Athabasca bitumen and n -heptane mixtures

Abstract The viscosity of bitumen is extremely high at low temperature (reservoir and atmospheric conditions). Therefore, the viscosity reduction is essential for bitumen production, pipeline transportation, and processing. The aim of this study is to investigate the effect of temperature, pressure, and solvent weight fraction on the physical properties of bitumen. The experiments were conducted using Athabasca bitumen sample and n-heptane at temperatures from 22 to 190 °C and at pressures up to 10 MPa for mixtures with different n-heptane fractions. The measured density and viscosity data were examined with available models in the literature. The mixture densities were well predicted with the assumption of no volume change on mixing. Increasing n-heptane concentration results in higher deviation of model from data up to 0.5 n-heptane weight fraction. The viscosity of the bitumen significantly reduced with temperature and n-heptane dilution. The effect of pressure on the viscosity was higher at either low n-heptane weight fractions or low temperature. The viscosity data were well represented by the power law and Cragoe’s models using the volume fractions with 7.0% and 13.6% average absolute relative deviation (AARD), respectively.

Scanning thermal microscopy: A review

Fundamental research and continued miniaturization of materials, components and systems have raised the need for the development of thermal-investigation methods enabling ultra-local measurements of surface temperature and thermo-physical properties in many areas of science and applicative fields. Scanning thermal microscopy (SThM) is a promising technique for nanometer-scale thermal measurements, imaging, and study of thermal transport phenomena. This review focuses on fundamentals and applications of SThM methods. It inventories the main scanning probe microscopy-based techniques developed for thermal imaging with nanoscale spatial resolution. It describes the approaches currently used to calibrate the SThM probes in thermometry and for thermal conductivity measurement. In many cases, the link between the nominal measured signal and the investigated parameter is not straightforward due to the complexity of the micro/nanoscale interaction between the probe and the sample. Special attention is given to this interaction that conditions the tip–sample interface temperature. Examples of applications of SThM are presented, which include the characterization of operating devices, the measurements of the effective thermal conductivity of nanomaterials and local phase transition temperatures. Finally, future challenges and opportunities for SThM are discussed.

Lock-in thermography versus PPE calorimetry for accurate measurements of thermophysical properties of solid samples: A comparative study

The aim of this paper is to compare the measurement accuracy of photopyroelectric calorimetry in back detection configuration (BPPE) and infrared lock-in thermography (LT) for thermal diffusivity measurement of solid samples. For this purpose, the following materials with well-known thermal properties have been selected: glassy carbon (type G), LiTaO3 crystal and binary II–VI semiconductors (based on CdSe and CdTe). The advantages and drawbacks of the two techniques have been analyzed both theoretically and experimentally.

Thermophysical Property Measurements of Oxide Melts at High Temperature by Electrostatic Levitation Furnace on the ISS

Thermophysical Property Measurements of Oxide Melts at High Temperature by Electrostatic Levitation Furnace on the ISS