Specific Heat Capacity Measurements Research Articles

A New Approach for Measurement of the Low-Temperature Specific Heat Capacity

A New Approach for Measurement of the Low-Temperature Specific Heat Capacity

The thermal properties of hydrothermally altered andesites from La Soufrière de Guadeloupe (Eastern Caribbean)

The heat flux of an active volcano provides crucial information on volcanic unrest. The hydrothermal activity often responsible for volcanic unrest can be accompanied by an increase in the extent and intensity of hydrothermal alteration, which could influence the thermal properties of the volcanic edifice. Therefore, an understanding of the influence of alteration on the thermal properties of rocks is required to better interpret volcano heat flux data. We provide laboratory measurements of thermal conductivity, thermal diffusivity, and specific heat capacity for variably altered (intermediate to advanced argillic alteration) andesites from La Soufrière de Guadeloupe (Eastern Caribbean). We complement these data with previously published data for altered basaltic-andesites from Merapi (Indonesia) and new data for altered rhyodacites from Chaos Crags (USA). Our data show that thermal conductivity and thermal diffusivity decrease as a function of increasing porosity, whereas the specific heat capacity does not change systematically. Thermal conductivity decreases as a function of alteration (the percentage of secondary minerals) for the rocks from La Soufrière and Merapi (from ~1.6 to ~0.6 W·m−1·K−1 as alteration increases from ~1.5 to >75 wt%), but increases for the rocks from Chaos Crags (from ~1.1 to ~1.5 W·m−1·K−1 as alteration increases from ~6 to ~15 wt%). Although the thermal diffusivity of the rocks from Chaos Crags increases from ~0.65 to ~0.75–0.95 mm2·s−1 as alteration increases from ~6 to ~15 wt%, the thermal diffusivity of the rocks from La Soufrière and Merapi does not appear to be greatly influenced by alteration. The specific heat capacity is not significantly affected by alteration, although there is a slight trend of increasing specific heat capacity with alteration for the rocks from La Soufrière. We conclude that the decrease in thermal conductivity as a function of alteration in the rocks from La Soufrière and Merapi is the result of the low conductivity of the secondary mineral assemblage, and that a combination of the high thermal conductivity of cristobalite and the reduction in porosity as a result of the void-filling mineral precipitation can explain the increase in thermal conductivity in the rocks from Chaos Crags. Calculations show that an increase in alteration of a dome or edifice can result in decreases and increases in heat flow density, depending on the type of alteration. Therefore, alteration-induced changes in the thermal properties of dome or edifice rocks should be considered when interpreting volcano heat flux data. We conclude that it is important not only to monitor the extent and evolution of alteration at active volcanoes, but also the spatial distribution of alteration type.

Specific Heat Capacity Measurements of Selected Meteorites for Planetary Surface Temperature Modeling

AbstractSpecific heat capacity Cp(T) is an intrinsic regolith property controlling planetary surface temperatures along with the albedo, density, and thermal conductivity. Cp(T) depends on material composition and temperature. Generally, modelers assume a fixed specific heat capacity value, or a standard temperature dependence derived from lunar basalts, mainly because of limited composition‐specific data at low temperatures relevant to planetary surfaces. In addition, Cp(T) only appears to vary by a small factor across various materials, in contrast with the bulk regolith thermal conductivity, which ranges over ∼3–4 orders of magnitude as a function of the regolith physical state (grain size, cementation, sintering, etc.). For these reasons, the impact of the basaltic assumption on modeled surface temperature is often considered unimportant although this assumption is not particularly well constrained. In this paper, we present specific heat capacity measurements and parameterizations from ∼90 to ∼290 K of 28 meteorites including those possibly originating from Mars and Vesta, and covering a wide range of planetary surface compositions. Planetary surface temperatures calculated using composition‐specific Cp(T) are within 2 K of model runs assuming a basaltic composition. This 2 K range approaches or exceeds typical instrumental noise or other sources of modeling uncertainties. These results suggest that a basaltic assumption for Cp(T) is generally adequate for the thermal characterization of a wide range of planetary surfaces, but possibly inadequate when looking at leveraging subtle trends to constrain subsurface layering, roughness, or seasonal/diurnal volatile transfer.

Measurements of Specific Heat Capacity of Beryllium in the Temperature Range of 260–870 K

Measurements of Specific Heat Capacity of Beryllium in the Temperature Range of 260–870 K

Measurements of isochoric specific heat capacity for 3,3,3-trifluoroprop-1-ene (R1243zf) at temperatures from (250 to 300) K and pressures up to 10 MPa

In this paper, a total of 86 isochoric specific heat capacity (cv) data of 3,3,3-trifluoroprop-1-ene (R1243zf) at temperatures from (250 to 300) K and pressures up to 10 MPa were measured using an adiabatic batch calorimeter. The standard uncertainties of temperature, pressure and isochoric specific heat capacity were estimated to be 12 mK, 5 kPa and 0.95%, respectively. A comparison was conducted between the experimental cv data and values calculated by three equations including the Helmholtz energy EOS (Akasaka and Lemmon, 2019) in REFPROP 10.0, the generalized equation (Zhong et al., 2019) and the corresponding states equation (Sheng et al., 2020) with the average absolute relative deviations (AARDs) of 2.43%, 0.91% and 0.84%, respectively. Among three equations, the corresponding states equation developed by Sheng et al. gives the best predictive performance for the liquid heat capacity of R1243zf.

Experimental Study on the Specific Heat Capacity Measurement of Water- Based Al2O3-Cu Hybrid Nanofluid by using Differential Thermal Analysis Method

Background: Researchers working in the field of nanofluid have done many studies on the thermophysical properties of nanofluids. Among these studies, the number of studies on specific heat is rather limited. In the study of the heat transfer performance of nanofluids, it is essential to raise the number of specific heat studies, whose subject is one of the important thermophysical properties. Objective: The authors aimed to measure the specific heat values of Al2O3/water, Cu/water nanofluids and Al2O3-Cu/water hybrid nanofluids using the DTA procedure, and compare the results with those frequently used in the literature. In addition, this study focuses on the effect of temperature and volume concentration on specific heat. Methods: The two-step method was tried to have nanofluids. The pure water selected as the base fluid was mixed with the Al2O3 and Cu nanoparticles and Arabic Gum as the surfactant, firstly mixed in the magnetic stirrer for half an hour. It was then homogenized for 6 hours in the ultrasonic homogenizer. Results: After the experiments, the specific heat of nanofluids and hybrid nanofluid were compared and the temperature and volume concentration of specific heat were investigated. Then, the experimental results obtained for all three fluids were compared with the two frequently used correlations in the literature. Conclusion: Specific heat capacity increased with increasing temperature, and decreased with increasing volume concentration for three tested nanofluids. Cu/water has the lowest specific heat capacity among all tested fluids. Experimental specific heat capacity measurement results are compared by using the models developed by Pak and Cho and Xuan and Roetzel. According to experimental results, these correlations can predict experimental results within the range of ±1%.

Precise measurements of specific heat capacity of beryllium in temperature range 260–870 K

The possibility of using beryllium as a means of storing and transferring a unit of specific heat capacity and extending the range of values of heat capacity measures from 1654 to 2900 J/(kg·K) towards the upper limit is estimated. The temperature dependence of the specific heat capacity of beryllium samples of known composition in the temperature range of 260–870 K has been determined. The reproducibility of the thermophysical properties of beryllium over time and under repeated heating in the specified temperature range is analyzed. The results obtained are relevant for the field of metrological support in the field of measurements of thermophysical quantities.

National Standard and New Reference Material for Specific Heat Capacity Measurements.

Thermal analysis and calorimetry share a close relationship in the field of thermal research. With regards to the specific heat capacity, researchers have been able to realize absolute measurement techniques by utilizing drop, conduction, and adiabatic methods that are used in calorimetry. Furthermore, it is possible to optimize differential scanning calorimetry, which is a comparative measurement technique for the specific heat capacity used in thermal analysis, by improving the absolute measurement techniques. At the National Metrology Institute of Japan (NMIJ), we developed a new certified reference material (CRM) for comparatively measuring the specific heat capacity, the single-crystalline silicon-NMIJ CRM 5806a, using a new type of cryogenic adiabatic calorimeter equipped with a pulse-tube refrigerator working in the temperature range from 50 to 350 K. This CRM was produced in accordance with the quality specifications of NMIJ, and complies with the ISO/IEC 17025, ISO 17034, and ISO GUIDE 35 standards. This paper reports on the procedure for fabricating this CRM and using it to perform specific heat capacity measurements at low temperatures. The specific heat capacity was measured using a differential scanning calorimeter in the temperature range from 280 to 340 K. NMIJ CRM 5806a was used to calibrate the heat flow. It was found that the uncertainty evaluation became easier because one factor of the uncertainty evaluation could be removed using the CRM. We show that the development of the CRM using the adiabatic calorimeter has led to an improvement in the specific heat capacity measurement results obtained by the differential scanning calorimeter.

Calorimetric study of critical behaviour near the smectic A to nematic phase transition in a polar-polar binary system

ABSTRACT Studies on critical behaviour associated with different phase transitions are of fundamental importance in condensed matter physics and may suitably be explored in the realm of soft materials. In this work, we report on high-resolution measurements of specific heat capacity (C p) from modulated differential scanning calorimetry (MDSC) to investigate the critical behaviour at the smectic A to nematic (SmA–N) phase transition in a binary system consisting of nonyloxy-cyanobiphenyl (9OCB) and heptylcyanobiphenyl (7CB). All the investigated mixtures exhibit detectable SmA–N heat capacity anomaly with gradually increasing peak height with enhancement in the concentration of 9OCB. Critical exponent α, obtained from the analysis of temperature dependence of the specific heat capacity data at the SmA–N phase transition, has been observed to assume values between those predicted for the 3D-XY and tricritical systems. The outcomes are also compared with those obtained from the high-resolution optical birefringence measurements.

Magnetic structures, spin-flop transition, and coupling of Eu and Mn magnetism in the Dirac semimetal EuMnBi2

We report here a comprehensive study of the AFM structures of the Eu and Mn magnetic sublattices as well as the interplay between Eu and Mn magnetism in this compound by using both polarized and non-polarized single-crystal neutron diffraction. Magnetic susceptibility, specific heat capacity measurements and the temperature dependence of magnetic diffractions suggest that the AFM ordering temperature of the Eu and Mn moments is at 22 and 337 K, respectively. The magnetic moments of both Eu and Mn ions are oriented along the crystallographic $c$ axis, and the respective magnetic propagation vector is $\textbf{k}_{Eu} = (0,0,1)$ and $\textbf{k}_{Mn}=(0,0,0)$. With proper neutron absorption correction, the ordered moments are refined at 3 K as 7.7(1) $\mu_B$ and 4.1(1) $\mu_B$ for the Eu and Mn ions, respectively. In addition, a spin-flop (SF) phase transition of the Eu moments in an applied magnetic field along the $c$ axis was confirmed to take place at a critical field of B$_c$ $\sim$ 5.3 T. The evolution of the Eu magnetic moment direction as a function of the applied magnetic field in the SF phase was also determined. Clear kinks in both field and temperature dependence of the magnetic reflections ($\pm1$, 0, 1) of Mn were observed at the onset of the SF phase transition and the AFM order of the Eu moments, respectively. This unambiguously indicates the existence of a strong coupling between Eu and Mn magnetism. The interplay between two magnetic sublattices could bring new possibilities to tune Dirac fermions via changing magnetic structures by applied fields in this class of magnetic topological semimetals.

Experimental study on isobaric specific heat capacity of subcritical and supercritical fluids using flow calorimetry

Accurate measurement of isobaric specific heat capacity of supercritical fluids is essential for many scientific researches and engineering applications. Based on the flow calorimetry method, an online experiment system for measuring isobaric specific heat capacity for subcritical and supercritical fluids was established. The relative expanded uncertainty of isobaric specific heat capacity was estimated to 2.44%–2.70% (coverage factor k ​= ​2). Based on the verification of the reliability of the measurement system by using pure water, cyclohexane and pentane, the isobaric specific heat capacity of carbon dioxide (CO2) in the temperatures range of (25.0–60.0) °C and pressures range of (6.7–12.0) MPa was measured. The experiment platform can provide accurate data measurement support for further scientific investigations and engineering designs.

High-Pressure Crystal Growth, Superconducting Properties, and Electronic Band Structure of Nb2P5

Orthorhombic (space group: Pnma) Nb2P5 is a high-pressure phase that is quenchable to ambient pressure, which could viewed as the zigzag infinite P chain-inserted NbP2. We report herein the high-pressure crystal growth of Nb2P5 and the discovery of its superconducting transition at Tc ~ 2.6 K. The electrical resistivity, magnetization, and specific heat capacity measurements on the high-quality crystal unveiled a conventional type-II weakly coupled s-wave nature of the superconductivity, with the upper critical field Hc2(0) ~ 0.5 T, the electron-phonon coupling strength {\lambda}ep ~ 0.5 - 0.8, and the Ginzburg-Landau parameter \k{appa} ~ 100. The ab initio calculations on the electronic band structure unveiled nodal-line structures protected by different symmetries. The one caused by band inversion, for example, on the {\Gamma}-X and U-R paths of the Brillouin zone, likely could bring nontrivial topology and hence possible nontrivial surface state on the surface. The surface states on the (100), (010) and (110) surfaces were also calculated and discussed. The discovery of the phosphorus-rich Nb2P5 superconductor would be instructive for the design of more metal phosphides superconductors which might host unconventional superconductivity or potential technical applications.

Experimental measurement of thermal diffusivity, conductivity and specific heat capacity of metallic powders at room and high temperatures

Because of the complications associated with metal additive manufacturing process, comprehensive modeling is done to improve the process. Thermo-physical properties such as heat capacity, thermal conductivity and diffusivity of metallic powder is very crucial for the models to be accurate. Due to challenges associated with measuring these properties at high temperature, available analytical models are often used to determine these temperature dependent thermo-physical properties. This study is conducted to fill this gap and provide experimental information that has been missing from the bulk of the literature for variety of metallic powders commonly used in additive manufacturing processes. Additionally, a comparison between these experimental data and analytical models are conducted to determine the correlation and accuracy of these models. Analysis revealed that all the thermal properties of the powders show a non-monotonic behavior at high temperature. A regression analysis is conducted to predict thermal conductivity at higher temperatures.

Analysis of the Multivalued Measure of Thermal Conductivity

We analyze a new class of instruments aimed at measuring heat quantities based on the use of a multivalued measure of thermal conductivity of solid bodies. On the example of measuring of the thermal conductivity of solids, we illustrate the incorrectness of application of the principle of multivaluedness for the measures of intensive heat quantities. To prove this fact, we present relations for the thermal conductivities of elements of a heat sensor realizing a multivalued measure of thermal conductivity and perform the limit transition in these relations. By using two methods, we show that the thermal conductivity of the indicated measure does not depend on the value of the supplied heat flux. It is shown that the accuracy of the method of measurements of thermal conductivity and specific heat capacity with the use of multivalued measures disagrees with the actually attainable levels of accuracy and the accuracy of reproduction of the unit of surface density of heat flux with the help of the GET 172-2016 State Primary Standard. The currently attainable accuracy of measurements of the thermal conductivity of solids is estimated.

Experimental Assessment of a Novel Eutectic Binary Molten Salt-based Hexagonal Boron Nitride Nanocomposite as a Promising PCM with Enhanced Specific Heat Capacity

In this study, novel nanocomposites containing the pre-defined mass ratio of binary molten salt (NaNO3-KNO3: 60-40 wt. %) dispersed with hexagonal boron nitride (hBN) nanoparticles with nominal size of 70 nm, were prepared through one-phase preparation method. Four different types of samples including pure binary molten salt and binary molten salt-based hBN nanocomposites with loading concentrations of 0.5, 1 and 1.5 wt. % were prepared. The proposed amount of sodium nitrate and potassium nitrate was added to certain amount of DI water, comprising with 0.5, 1 and 1.5 wt. % concentration of hBN nanoparticles. Scanning electronic microscopy (SEM) was conducted to evaluate the uniformity of the synthesized binary molten salt-based hBN nanocomposites. The SEM images revealed uniform dispersion of hexagonal boron nitride nanoparticles and fractal-like structures were observed clearly. Specific heat capacity (cp) and melting temperature measurements were performed using a differential scanning calorimetry (DSC). The experimental achieved data for melting temperature proved that hexagonal boron nitride nanoparticles do not affect the melting temperature of the synthesized nanocomposites. The experimentally achieved data for the average cp values of the binary molten salt in solid and liquid phases were 1.14 and 1.13 J/g K, respectively. While, the average cp values for the binary molten salt-based hBN nanocomposite with the highest loading concentration of nanoparticles (1.5 wt. %) in solid and liquid phases were 2 and 3.17 J/g K, respectively. The measured average cp value in the liquid phase for binary molten salt-based hBN nanocomposite with the highest loading concentration (1.5 wt. %) of nanoparticles revealed enhancement of ~180% in comparison with pure binary molten salt. Thermal stability measurements expressed enhancement of thermal stability in binary molten salt induced with hBN nanoparticles. Binary molten salt-based hBN nanocomposite with loading concentration of 1.5 wt. % represented ~16% enhancement in thermal stability over the binary molten salt.

Measurement and analysis of specific heat capacity of lead-bismuth eutectic

The lead-cooled fast reactor is a fourth-generation nuclear system with great development potential. Lead-bismuth eutectic (LBE) is used as the coolant of lead-cooled fast reactor, and specific heat capacity of LBE is a necessary parameter for studying the heat transfer in the primary loop. However, the experimental data on specific heat capacity of LBE are limited. There are only three independent data could be found in open literature, and the measurement error of the existing data is about 5%~7%. In this paper, specific heat capacity of LBE at 30–600 °C is studied by differential scanning calorimetry and the reliability and uncertainty of the data are analyzed. The recommended value of LBE's specific heat capacity at 150–600 °C is 0.1342–0.1495 J kg−1 °C−1. The results show that the measurement error of this method is about 0.62%, the maximum composite uncertainty of LBE's specific heat capacity is 1.83%, and the expanded uncertainty is 3.66% (k = 2). The experimental data have high reliability and can provide data support for thermal-hydraulic design in lead-cooled fast reactor.

Near room temperature spin reorientation and temperature evolution of magnetic structure in Mn substituted HoFeO3

Magnetic structure and spin reorientation transition of 45% Mn substituted HoFeO3 have been investigated using bulk magnetization, neutron powder diffraction and specific heat capacity techniques. These studies confirm the presence of antiferromagnetic ordering of Fe/Mn sublattice below 336 K. The spin reorientation (SR) transition (TSR ~ 290 K) where the magnetic structure changes from Γ4(Ax, Fy, Gz) to Γ1(Gx, Cy, Az) is confirmed by Rietveld analysis of neutron diffraction patterns taken at various temperatures. Though the spin reorientation (SR) transition is happening at 290 K, the system is found to be in mixed Γ4(Ax, Fy, Gz) + Γ1(Gx, Cy, Az) phase from room temperature to 275 K. Below 275 K, the sample exhibits a pure Γ1(Gx, Cy, Az) structure in which the weak ferromagnetic component is absent. Bulk magnetization and specific heat capacity measurements also confirm the Néel temperature and spin reorientation transitions and support the neutron diffraction analysis.

Measurements of pρTx and specific heat capacity c for (R290 + R1243zf) binary mixtures at temperatures from (292 to 350) K and pressures up to 11 MPa

Abstract In this paper, isochoric pρTx and specific heat capacity (cv) for (R290 + R1243zf) binary mixtures were measured using an adiabatic batch calorimeter with intermittent heating. A total of 57 pρTx data points over temperatures from (292 to 350) K and 82 isochoric specific heat capacity data points over temperatures from (299 to 350) K were obtained for liquid with mole fractions of R290 at (0.788, 0.606, 0.435 and 0.170). The standard uncertainties were estimated to be 12 mK for temperature, 5 kPa for pressure, 0.30% for density and 0.96% for isochoric specific heat capacity. The experimental density and heat capacity data agree well with the Helmholtz equation of state (EOS) developed by Bell and Lemmon (2016), and the average absolute relative deviation (AARD) are 0.27% and 1.01%, respectively. Comparisons of the present cv data with values calculated by the generalized equation developed by Zhong et al. (2019a) was carried out as well, and the results show good agreements with deviations varying from −3.00% to 3.16% and the average absolute relative deviation (AARD) of 0.91%.

Graphene Nanoplatelets-Assisted Minimum Quantity Lubrication In Turning To Enhance Inconel 718 Surface Integrity

Inconel 718 is regarded to be a difficult-to-cut nickel alloy due to its low thermal conductivity, high hardness, and chemical reactivity with tool materials at high temperature, which, overall, cause the generation of extremely high temperature at the cutting edge, contributing to deteriorate the surface quality of the machined workpiece. With the aim of improving the alloy machinability, the present paper evaluates the effect of Minimum Quantity Lubrication (MQL) on the turning performances of Inconel 718 compared to dry and flood lubrication conditions. In particular, for the first time, the feasibility of using graphene nanoplatelets as additives to a vegetable oil to form MQL mist is assessed.After having defined the optimal concentration of two graphene nanoplatelets of different size, the nanofluids were prepared and their stability as a function of time was assessed; afterwards, they were characterized by means of viscosity and specific heat capacity measurements as a function of temperature. The cutting performances were evaluated in terms of surface integrity and chip morphology. Results showed that the use of the nanofluid with the lowest graphene nanoplatelets size provided the best surface integrity compared to the ones obtained when using just MQL without any additive and standard lubricating conditions.

Electrical resistivity measured by millisecond pulse-heating in comparison to thermal conductivity of the hot work tool steel AISI H11 (1.2343) at elevated temperature

Selected thermophysical properties of the hot work tool steel AISI H11 (1.2343) were measured in the temperature range from room temperature to the melting temperature. Thermal diffusivity was measured by the laser-flash method; heat capacity by differential scanning calorimetry; linear thermal expansion by push-rod dilatometry; and density at room temperature by an Archimedean balance. From these experimentally obtained data, thermal conductivity was calculated. Additionally, electrical resistivity of AISI H11 (1.2343) was measured by millisecond pulse-heating in the above mentioned temperature range. The measurement results of electrical resistivity as a function of specific enthalpy was combined with results of specific heat capacity measurements by differential-scanning calorimetry to obtain the relation between resistivity and temperature. Based on measured electrical resistivity and thermal conductivity, a Smith-Palmer-plot for the hot work tool steel AISI H11 (1.2343) is obtained for the ferritic and austenitic phases. No linear behaviour – as expected by the Wiedemann-Franz law – is observed in the ferritic phase region. In the high temperature austenitic region, the thermal conductivity can be computed from electrical resistivity using empirical constants of similar austenitic steels or superalloys.