Measurement Of Thermophysical Properties Research Articles

Experimental Analysis of Heat Transfer by Using Nanofluid and Impact of Thermophysical Properties

The scope of the project is to analyse the heat transfer behaviours by using shell and tube heat exchangers and measurements of various thermophysical properties of carbon nanotube nanofluid. The nanofluid is created using different volume fractions at different operation temperatures. The research focuses on theoretical and experimental research on CNT nanofluids, with the goal of improving thermophysical parameters such as thermal conductivity, specific heat, and viscosity. The thermophysical characteristics of CNTs were investigated using this theoretical method. Various tests were carried out to investigate the thermophysical qualities, and they were found to have an impact. The improved characteristics of carbon nanotubes (CNTs) have the potential to save energy and reduce CO2, NO2, and SO2 emissions in industrial settings. Improving heat exchange performance in the thermal sector would result in a high heat‐to‐power conversion efficiency. Nanofluids can considerably enhance critical heat flux (CHF) in heat transfer systems.

Tuning thermal and electrical properties of MXenes via dehydration.

Recently, MXenes (a class of two-dimensional transition metal carbides) have attracted great attention in various applications such as humidity sensors, owing to their unique electrical and thermal properties. However, previous studies of MXenes mostly focus on their humidity-sensing characteristics such as the mechanical response, and only few reports on their electrical and thermal response are available. Herein, we present novel transient electrothermal experiments to demonstrate that a transition from a negative to a positive resistance-temperature relationship can take place when the MXene sample becomes fully dehydrated. This surprising and unusual phenomenon was elucidated through non-equilibrium molecular dynamics simulations and attributed to water absorption/desorption onto the chemically active MXene surface. A linear relationship was also found between electrical/thermal properties and environmental humidity, which could be related to water adsorption on the surface of the MXene sensor. We further decomposed the total measured thermal conductivity and found that phonons were the dominant thermal carriers in the MXene sample. The main breakthrough of this work is the discovery of the unusual resistance-temperature relationship, which should be applicable to the design of MXene-based sensors for various applications.

Upgrading the PLINIUS platform toward smarter prototypic-corium experimental R&D

In the recent years, CEA Cadarache PLINIUS prototypic corium platform has been upgraded: more powerful induction generator for e.g. MCCI experiments, development of thermitic melting, e.g. for new corium spreading tests in VULCANO, new MERELAVA facility for corium flooding, new VITI setups for thermophysical property measurements, KROTOS FCI test with full depth X-ray visualization of water pool. Main features of these facilities are described. Designs for further improvements such as the new FUJISAN and VITAE setups for characterizations of the aerosol released during prototypic fuel debris cutting, as well as the design of STROMBOLI test section for studying Lower Head pool stratification inversion evolution are also presented.

Measurement and study of thermophysical properties of nanofluids with carbon nanotubes

This article is devoted to the study of the thermophysical properties of nanofluids with single-walled and multi-walled carbon nanotubes (CNT). Their weight concentration varied from 0.05 to 0.2%. Nanofluids, based on ethylene glycol and water, were studied. Dispersants were also used. The diffusion of CNT had been systematically investigated by the method of dynamic light scattering and their effective hydrodynamic dimensions were determined. The rheology and viscosity of all nanofluids were studied. It is shown that nanofluids are either pseu-doplastic or viscoplastic. Their rheology changes with increasing CNT concentration and temperature. However, in all cases, the viscosity of nanofluids with single-walled CNTs is signifi-cantly higher than that of nanofluids with multi-walled CNTs. In the last part, the electrical conductivity of all these nanofluids and the dispersants effect on it are investigated.

Development of High Temperature Multi-Layer Laser Flash Artefacts

Delamination of the interlayers of multi-layer systems can cause a degradation in functionality, stability and life span of that system. This is even more pertinent for systems at high temperature. Laser flash analysis (LFA) has long been used for thermophysical properties measurements at high temperatures. Multi-layer reference artefacts, with and without, debonded regions are required for validating the thermal characterisation of such systems using LFA. Although some high-temperature bulk candidate reference materials were developed and studied, e.g. in the European Metrology Research Programme (EMRP) funded Joint Research Project (JRP) ENG08 Metrofission, they were not able to meet the requirements for validating thermal measurements of multi-layer systems using LFA. In the European Metrology Programme for Innovation and Research (EMPIR) funded JRP 17IND11 Hi-TRACE project, the National Physical Laboratory is developing multi-layer reference artefacts, including both fully bonded and partially de-bonded systems for validating thermal characterisation of multi-layer systems at temperatures from room temperature to above 1000 °C using LFA. This paper details the methodology of production, measurement and validation of isotropic graphite and hafnium based multi-layer systems with, and without, partial debonding. Reproducibility, thermal stability and sensitive parameters concerning the thermal response of the artefacts will be discussed, with recommendation on the usage criteria as LFA multi-layer reference artefacts.

Thermophysical properties of the paramagnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate over an extended range of temperature and pressure

The paramagnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate [BMIM][FeCl4] was subject to multiple high-precision thermophysical property measurements under both ambient and high pressure. Density ρ(p0,T) / kg·m−3 and speed of sound u(p0,T) / m·s−1 data at ambient pressure were recorded at temperatures T = (278.15 to 343.16) K using a DSA 5000 M combined vibrating tube densimeter and speed of sound analyser with a standard uncertainty of Δρ(p0,T) = ±0.001 kg·m−3 and Δu(p0,T) = ±0.1 m·s−1, respectively. High-pressure volumetric (p,ρ,T) data were measured on an Anton Paar DMA HPM vibrating tube densimeter at T = (273.16 to 413.15) K and at pressures up to p = 140 MPa with an estimated experimental relative combined average percentage deviation (APD) of Δρ(p,T) / ρ(p,T) = ±(0.01 to 0.08) %.The specific isobaric heat capacity cp(p0,T) / J·kg−1·K−1, a caloric property, was determined at T = (273.15 to 413.15) K with an uncertainty Δcp / cp = ±0.5 % using a Perkin Elmer Pyris 1 DSC differential scanning calorimeter. To gain knowledge of transport properties, the dynamic viscosity η(p0,T) / mPa·s at ambient pressure was recorded at T = (275.03 to 413.18) K by an Anton Paar SVM 3000 Stabinger viscometer and additionally an Anton Paar rheometer MCR 302 device with uncertainties of Δη / η = ±0.35 % and Δη / η = ±1 %, respectively.The obtained data were first correlated by empirical polynomial equations of state and further processed by the application of classic thermodynamic potentials to determine isothermal compressibility κT(p,T) / MPa−1, isobaric thermal expansivity αp(p,T) / K−1, thermal pressure coefficient γ(p,T) / MPa⋅K−1, internal pressure pint(p,T) / MPa, specific heat capacity at constant pressure cp(p,T) / J⋅kg−1⋅K−1 and at constant volume cv(p,T) / J⋅kg−1⋅K−1, the difference of isobaric and isochoric heat capacity (cp–cv)(p,T) / J⋅kg−1⋅K−1, speed of sound u(p,T) / m⋅s−1 and ultimately isentropic exponent κs(p,T).This work extends knowledge about the thermophysical properties of [BMIM][FeCl4] particularly to high temperatures and pressures.

Investigation on the molecular interaction of binary mixtures of acetophenone with carboxylic acids at various temperature: Thermodynamic and spectroscopic aspects

In the present work, the molecular interactions of binary mixtures of acetophenone with carboxylic acids such as acetic and propionic acid were investigated through the measurement of thermophysical properties including, density (ρ), sound velocity (u), refractive index (nD) and surface tension (γ) at temperature ranges of (293.15–333. 15) K and pressure, p = 0.1 MPa. The thermodynamic properties of the binary mixtures were calculated from the experimental thermophysical properties as a function of acetophenone mole fraction, which were in turn used to give an understanding about the molecular interactionsexisting in the binary mixtures. The thermodynamic properties were correlated with the Redlich-Kister polynomial.The FT-IR spectrums of pure acetophenone and carboxylic acids and their binary mixtures at an equimolar composition were measured. The variations of the thermodynamic properties with acetophenone mole fraction and temperature have been discussed.

(Invited) Measurement of Thermophysical Properties of Liquid Analytes Using Microfluidic Resonators via Photothermal Modulation

Temperature, being one of the fundamental parameters in the physical characterization of a material, temperature sensors with high spatial, temporal, and thermal resolution are on great demand in the field of fundamental research, protein blotting, DNA melting, drug development, biochemistry, biomedical devices, and analytical systems. Sensitive real time measurements unveil the dynamics of the analytes in a lab-on-a-chip platform where miniaturized volumes of samples are characterized when they are either rare or volume-limited. Mechanical resonators with microscale fluidic channel integrated are widely adopted as micro/nanoscale sensing platform where the resonance frequency shift of the resonators can detect minute fluctuation of physical, chemical, and biological stimulus within medium of fluidic channel at the picogram level. Even though microfluidic channels are successfully implemented for measuring thermal properties, integration with complicated QCL and static response of resonators based on static deflection delivered the results that are prone to be affected by mechanical drift and higher noise level of the photodetector. Hence the need of a simpler experimental model and dynamic response is urged. This paper reports analysis of thermal characteristics of liquid analytes using photothermal heating effect of high-speed microfluidic cantilever. While a channel-integrated resonator is modulated by a diode laser, real-time tracking of resonance frequency shift of the microfluidic resonator allows estimation of thermo-physical properties of liquid samples where the local laser irradiation results in photothermal heating of the resonator. The heating results expansion of the liquid inside the channel induces thermal stress on the walls of the channel. This thermal stress contributes to rise of the resonance frequency of the microfluidic resonator and, therefore, the frequency shift is linearly dependent of the volumetric coefficient expansion of the liquid. Also, the heating time constant is inversely proportional to the thermal diffusivity of the liquid. In addition, a higher flexural mode displays more than 3 times improved sensitivity for thermal characterization of liquids via photothermal heating.

Effects of Recycled Fine Glass Aggregates on Alkali Silica Reaction and Thermo-Mechanical Behavior of Modified Concrete

The objective of this work is to develop a new composite material by substituting sand with recycled waste glass (RWG). Different volume percentages of RWG varying from 0 to 50% were incorporated into concrete, with maximum size that did not exceed 1.25 mm. The microscopic characterization by scanning electron microscopy SEM-EDS and optical microscopic test, as well as the durability against alkali silica reaction (ASR) test, were performed respectively to visualize the morphology and assess the damage caused by ASR. Furthermore, the mechanical and thermophysical properties measurements were carried out. The results of microscopic characterization showed the presence of cracks inside a minority of glass particles due to ASR, and ASR test indicated that expansion activity remained well below the limit expansion value of 0.15%. The obtained results also showed that, at 28 and 90 days of curing, compressive strength increased respectively by up to 1.63% and 29% for 20% of the incorporated RWG volume rate in concrete; however, beyond this rate it diminished receptively by 30% and 3.2%. This improvement with curing age was attributed to pozzolanic reaction. Regarding density, it reduced by around 5%. Furthermore, thermal conductivity and thermal effusivity decreased respectively by 36% and 8.06% at dry state and they dropped respectively by 44% and 21.28% at saturated state, related to reference concrete RC. It is therefore feasible to substitute high amount of natural sand with RWG to obtain new composite that may be successfully used as structural material in construction building.

Design and performance of a molten fluoride salt-compatible optical thermophysical property measurement system.

Accurate knowledge of molten salt thermophysical properties is crucial to optimize the efficiency, safety, and reliability of molten salt based energy applications. For molten fluorides, currently of high interest for fission and fusion reactors, data regarding these properties are either poor or non-existent. Thermal diffusivity and sound speed in particular play important roles in the modeling of a reactor's steady state, transient, and accident scenarios. Fluoride salt-compatible property measurement systems have thus far been the bottleneck in accurately obtaining these properties. We present the design of an optical system optimized for molten fluoride salt thermophysical property measurement, along with characterization of its thermal performance. Demonstration of system capabilities is achieved through acquisition of sound speed and thermal diffusivity in lithium chloride (LiCl), showing excellent agreement with literature data.

Laser-based measurement of thermophysical properties of diethyl ether and toluene with high accuracy using photo-thermal lens technique

Laser-based measurement of thermophysical properties of diethyl ether and toluene with high accuracy using photo-thermal lens technique

A Critical Review on the Development of Ionic Liquids-Based Nanofluids as Heat Transfer Fluids for Solar Thermal Energy

In recent years, solar thermal energy (STE) has attracted energy researchers because of its higher efficacy compared to the photovoltaic solar cell. STE is one of the forms of solar energy whereby heat is transferred via a secondary medium called heat transfer fluids (HTFs). Therefore, the overall performance of STE depends on the thermophysical properties and thermal performance of the HTFs. Traditional HTFs suffer from low decomposition temperature, high melting point, and higher vapor pressure. To overcome these limitations, researchers have recently begun working on new HTFs for STE. Ionic liquids (ILs) are considered as a potential candidate for the next generation of HTFs because of their enhanced thermophysical properties, such as thermal stability at high temperature, insignificant vapor pressure, and high ionic conductivity. In addition, thermophysical properties and thermal performance of ILs can be further enhanced by dispersing nanoparticles, which is one of the emerging research interests to improve the efficiency of the solar thermal system. This paper summarizes the recent study of ILs-based nanofluids as HTFs. These summaries are divided into two sections (i) thermophysical properties studies, such as density, viscosity, thermal conductivity, and heat capacity, and (ii) thermal performance studies such as natural convection and forced convection. Synthesis of ILs-based nanofluids and thermophysical properties measurement techniques are also discussed. Based on these state-of-the-art summaries, we offer recommendations for potential future research direction for ILs-based nanofluids.

Modelling and Simulation of Thermo-Physical Property of Composite Material

Thermo-physical property measurement is a significant methodology as these properties are the input for designing thermal systems. Properties of materials like thermal conductivity, thermal diffusivity and specific heat capacity has to be estimated in prior to estimate the thermal performance of any material. In the present work, numerical simulations were performed to estimate the thermo-physical properties of a polymer based composite material using porous medium modelling. The weight fraction of the composites and fibres are incorporated into the simulations through porosity. The transient heat diffusion equation are solved using ANSYS Fluent for a polymer based composite material using semi-infinite transient conduction approach. The thermal conductivity and thermal diffusivity are estimated simultaneously for various volume fractions of polyester and banana fibre. The temporal temperature distribution data predicted from ANSYS Fluent is curve fitted using MATLAB and the obtained values of thermal conductivity and thermal diffusivity are compared with the previously reported experimental results and are found to be within a deviation of 7 % for all cases.

Measuring thermophysical properties of building insulation materials using transient plane heat source method

Thermophysical properties of building insulation materials vary with environmental and intrinsic factors, and accurate measurement of them is quite difficult and essential. This study aims to create a transient measuring method based on two transient plane heat source methods, including the constant heat rate source method and step-wise transient method through constructing a device. The present method is able to measure multiple thermophysical properties of various building insulation materials. The measurement errors of thermal conductivity are less than 3% for the EPS board and 5% for the XPS board. The measured thermal conductivities are much lower than those reported in the literatures for the foam glass board and cement foam board due to the difference in density of specimens. The measured thermal diffusivities and reference values have the same order of magnitude. A new data processing approach was investigated to obtain the thermal effusivities of the experimental materials; all measured values are close to those reported in previous studies. It is concluded that the created method is effective for the facile and accurate measurement of multiple thermophysical properties of the building insulation materials, and the findings can significantly improve the database of thermophysical properties for building insulation materials.

Interactions between 1-butyl-3-methylimidazolium cation with various anions and carboxylic acids: Physicochemical and spectroscopic aspects

In this work, the intermolecular interactions for binary mixtures of ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate with acetic and propionic acid were evaluated through the measurement of thermophysical properties, density (ρ), sound velocity (u), refractive index (nD) and surface tension (γ) at T = (293.15−333. 15) K and p = 0.1 MPa. The experimental results were used to compute the thermodynamic properties of the binary mixtures, which were then fitted to the Redlich−Kister polynomial equation. The FTIR spectra of the pure components and the binary mixtures at an equimolar composition were recorded to confirm results from thermodynamic properties. The variations of the thermodynamic properties with IL mole fraction and temperature and the effect of the IL anion and alkyl length of the carboxylic acid on the thermodynamic properties have been discussed.

Good Reporting Practice for Thermophysical and Thermochemical Property Measurements (IUPAC Technical Report).

Scientific projects frequently involve measurements of thermophysical, thermochemical, and other related properties of chemical compounds and materials. These measured property data have significant potential value for the scientific community, but incomplete and inaccurate reporting often hampers their utilization. The present IUPAC Technical Report summarizes the needs of chemical engineers and researchers as consumers of these data and shows how publishing practices can improve information transfer. In the Report, general principles of Good Reporting Practice are developed together with examples illustrating typical cases of reporting issues. Adoption of these principles will improve the quality, reproducibility, and usefulness of experimental data, bring a better level of consistency to results, and increase the efficiency and impact of research. Closely related to Good Reporting Practice, basic elements of Good Research Practice are also introduced with a goal to reduce the number of ambiguities and unresolved problems within the thermophysical property data domain.

Measurement of High-temperature Thermophysical Properties of Bulk and Coatings Using Modulated Photothermal Radiometry

This paper presents the development of instrumentation for the measurement of high-temperature thermal conductivity of bulk and coatings using a modulated photothermal radiometry (MPR) method, where a sample is heated by an intensity-modulated laser to probe into different layers of the sample. While MPR has been previously established, most of the prior studies only focus on the measurement at room temperature. The MPR has not been well studied for measurements of bulk and coating materials at high temperatures, which are increasingly important for a multitude of applications, such as materials used in the concentrating solar power (CSP) plants and the nuclear reactors. MPR is a non-contact technique that utilizes the intrinsic thermal emission from the specimens for thermometry, which is favorable for measurements at high temperatures in harsh environment. The authors designed and utilized a sample holder suitable for high temperature measurement up to 973 K with good temperature uniformity within the sample. The high-temperature MPR setup was validated by measuring bulk materials with known thermal conductivity. The setup and technique were then extended to the measurement of black solar-absorbing coatings of 10 to 50 μm thick on various substrates by modulating the frequency of the laser heating beam and the thermal penetration depth. The studies showed that thermal conductivities of typical solar-absorbing coatings are 0.4 ~ 0.8 W m−1 K−1, indicating a possibly large temperature drop within the coating under high solar irradiation flux, such as over 1000-sun for central solar towers in CSP plants.

Spectral Absorption Coefficient of Additive Manufacturing Materials

Abstract Active thermography techniques are of interest for quality assurance of additive manufacturing processes. However, accurate measurements of thermophysical properties of materials are required to successfully implement active thermography. In particular, the spectral absorption coefficient of materials commonly used in additive manufacturing must be known to accurately predict the spatial distribution of thermal energy generated from absorption of power emitted by a laser or pulsed flash lamp. Accurate measurements of these optical properties are also needed to develop greater understanding of additive manufacturing processes that rely on radiative heat transfer to fuse powders. This paper presents spectral absorption coefficient measurements and uncertainty estimates of fully and partially dense ABS, PLA, and Polyamide 12 samples.

Phase Diagram and Thermal Expansion of orthopyroxene-, clinopyroxene- and ilmenite-structured MgGeO3

Abstract The MgGeO3 system is a low-pressure analog for the Earth-forming (Mg,Fe)SiO3 system and exhibits recoverable orthopyroxene, clinopyroxene, and ilmenite structures below 6 GPa. The pressure-temperature conditions of the clinopyroxene to ilmenite phase transition are reasonably consistent between studies, having a positive Clapeyron slope and occurring between 4 and 7 GPa in the temperature range 900–1600 K. There are, though, significant discrepancies in the Clapeyron slope of the orthopyroxene to clinopyroxene phase transition in existing works that also disagree on the stable phase at ambient conditions. The most significant factor in these differences is the method used; high-pressure experiments and thermophysical property measurements yield apparently contradicting results. Here, we perform both high pressure and temperature experiments as well as thermal expansion measurements to reconcile the measurements. High-pressure and -temperature experiments yield a Clapeyron slope of −1.0−0.7+1.0 MPa/K for the MgGeO3 orthopyroxene-clinopyroxene phase transition, consistent with previous high-pressure and -temperature experiments. The MgGeO3 orthopyroxene-clinopyroxeneilmenite triple point is determined to be at 0.98 GPa and 752 K, with the ilmenite phase stable at ambient conditions. The high-temperature (>600 K) thermal expansion of the clinopyroxene phase is greater than that of the other phases. Debye-Grüneisen relationships fitted to the volume-temperature data give Debye temperatures for the orthopyroxene, clinopyroxene, and ilmenite phases of 602(7), 693(10), and 758(13) K and V0 of 897.299(16), 433.192(10), and 289.156(6) Å3, respectively. The Clapeyron slopes calculated directly from the Debye-Grüneisen relationships are consistent with previous thermophysical property measurements. The presence of significant anharmonicity and/or formation of defects in the clinopyroxene phase at high-temperatures, which is not apparent in the other phases, accounts for the previous contradictions between studies. The inferred increased heat capacity of the clinopyroxene corresponds to an increase in entropy and an expanded phase field at high temperatures.

高锰钢热物理性质的热分析

高锰钢热物理性质的热分析