International Journal of Thermophysics最新文献

Heavy density concrete made of hematite-based aggregates commonly known as ferro-siliceous sacrificial concrete (FSSC) can be used effectively against radiation shielding in case of nuclear melt down. However, performance assessment of such concretes on exposure to elevated temperatures are not available widely. In the present study, thermo-mechanical and thermophysical properties of hematite-based FSSC concrete are evaluated on exposure to elevated temperatures. The porosity and water absorption capacity of FSSC are investigated on its exposure to higher temperatures ranging from 30 °C to 1000 °C. Similarly, various thermo-mechanical [compression, split tension, modulus of elasticity (MOE)] and thermophysical (specific heat, thermal conductivity, thermal diffusivity, and thermal effusivity) properties are evaluated on exposure to elevated temperatures. The mechanical properties of the concrete such as compression, split tension, MOE decrease monotonically with increase in the exposed temperature. Porosity and water absorption of the concrete increases with the increase in temperature. Relationship between damage and the exposed temperature can be described by Weibull model. Thermophysical property such as specific heat of the concrete increases, while thermal conductivity, thermal diffusivity and effusivity decrease with the increase in temperature. Correlations for the variation in thermal conductivity, specific heat and thermal diffusivity are proposed. The variations in the mechanical and thermophysical properties are explained through the porosity variations and correlation coefficient between porosity and various mechanical and thermophysical properties.

This investigation undertakes a thorough examination of the thermophysical properties of linalool (C₁₀H₁₈O) blended with a series of 2-alkanols (ranging from 2-propanol to 2-hexanol) across a temperature spectrum of 293.15 K to 323.15 K. The primary objective of this study is to elucidate the density and viscosity behavior of these binary systems. The experimental results reveal negative deviations from ideality in excess molar volume for linalool with 2-propanol up to 2-pentanol, and positive values for linalool with 2-hexanol, accompanied by negative viscosity deviations across all examined mixtures. The observed negative excess volume suggests the presence of strong intermolecular interactions between linalool and the 2-alkanols, which is indicative of the formation of hydrogen bonds in the mixtures. The positive values of excess molar volumes in linalool and 2-hexanol are indicative of the governing of steric hindrance effects on attractive intermolecular forces. Moreover, the Friction theory (f-theory) was utilized to model the viscosity of the binary mixtures, yielding an excellent concordance with the experimental data, with a maximum discrepancy of merely 2.25 % observed in the linalool + 2-pentanol system. This negligible deviation underscores the efficacy of the f-theory in accurately capturing the viscosity measurements, thereby validating its applicability in predicting the rheological behavior of such binary systems.

Saturation pressures of pure R-1336mzz(Z) and R-1130(E) and bubble point pressures of three R-1336mzz(Z)/1130(E) blends were measured from 265 K to 360 K. For each pure refrigerant or refrigerant blend, a total of twenty unique saturation pressures or bubble points were measured. In total 100 unique state points were obtained. Presently, no Helmholtz-energy-explicit type equation of state (EoS) is available for R-1130(E). While an extended corresponding states EoS for R-1130(E) is available to estimate the properties of the R-1336mzz(Z)/1130(E) blend, this model does not resolve the azeotropic behavior of the mixture. Therefore, the perturbed-chain statistical-associating fluid theory (PC-SAFT) EoS is used to model the vapor–liquid equilibria of the R-1336mzz(Z)/1130(E) blend. PC-SAFT model parameters are reported, and the overall performance of the model is characterized by deviations from the experimental data.

Tri-n-butyl phosphate (TBP) has remained workhorse of PUREX based nuclear recycle operations since 1956. However due to its associated disadvantages like third phase formation and tendency to react violently with nitric acid at elevated temperatures generated requirement of an alternate extractant for PUREX process. Tri-iso-amyl phosphate (TiAP) has better attributes than TBP on both the counts. Density of solutions is an important process parameter for design of equipment, process operations and control and safety analysis. In this work, experimental data on the density of binary solution of tri-iso amyl phosphate and n-dodecane are reported for several temperature levels. The related volumetric parameters were also estimated from experimental data as well as Kirkwood–Buff integrals. Derivative parameters like linear coefficients of preferential solvation (delta_{ij(i ne j)}^{o}) and local mole fractions (x_{ij(i ne j)}) at 298.15 K were also estimated and reported.

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This study presents a comprehensive experimental investigation aimed at elucidating the influence of magnetic fields, nanoparticle concentration, and the presence of polymer on Rayleigh–Benard convection in yield stress nanofluids. The test fluid comprises Ultrez 30 polymeric powder and Iron oxide nanoparticles. Herschel–Bulkley's model is applied to capture the rheological behaviour. The concentration of both Ultrez 30 polymeric gel and Iron oxide nanoparticles varies from 0.05 % to 0.10 %. The in-house developed experimental set-up is exposed to the magnetic field in the 0 mT to 100 mT range. Without a magnetic field, heat transfer increases with the elevation of nanoparticle fraction in the fluid. However, in the presence of a magnetic field, the convection effect weakens as the nanoparticle concentration rises. Furthermore, an optimised artificial neural network (ANN) model featuring a single hidden layer with nine hidden neurons is presented to predict the Nusselt number.

The present work reports experimental data on the thermal conductivity of the four hydrocarbons cyclohexane, n-decane, n-hexadecane, and squalane in the liquid state at ambient pressure up to temperatures of 353.15 K. Absolute measurements were performed with a steady-state guarded parallel-plate instrument (GPPI) with an average expanded (coverage factor k = 2) measurement uncertainty of 2 %. For the linear alkanes n-decane and n-hexadecane as well as the cyclic compound cyclohexane, the measured thermal conductivities agree with reference correlations in the literature, indicating the reliability of the technique used for the study of fluids with relatively low thermal conductivities and weak absorption of radiation. For the first time, experimental data are determined for the long-branched alkane squalane between (278 and 353) K, which cannot be accurately represented with estimation methods commonly used in the literature. In summary, the present measurement results confirm the existing database for representative linear and cyclic hydrocarbons and provide first experimental thermal conductivities for squalane.

A thorough evaluation of the thermophysical properties of ethylcyclohexane (ECH) mixed with 2-alkanols (2-propanol to 2-hexanol) is presented across the temperature range of 293.15 to 323.15 K. The focus of this study is on the density and viscosity behavior of these systems. The experimental results demonstrate positive deviations from ideality in excess molar volume, while viscosity deviations are negative for all examined mixtures. This observation suggests the presence of weak intermolecular interactions between ECH and the 2-alkanol. These findings are consistent with the self-association behavior of 2-alkanol and the nonpolar nature of ECH, which disrupts the associated structures of the alcohols. Furthermore, the Friction theory (f-theory) was employed to model the viscosity of the binary mixtures. The f-theory exhibits excellent agreement with the experimental data, with a maximum deviation of only 2.24% observed in the ECH + 2-butanol system. This minimal discrepancy underscores the f-theory's efficacy in accurately correlating the viscosity measurements.

A suite of measurements of refractive index (n(p, T_{90})) is reported for gas phase ordinary water H(_2)O and heavy water D(_2)O. The methodology is optical refractive index gas metrology, operating at laser wavelength (633 text {nm}) and covering the range ((293< T_{90} < 433) text {K}) and (p < 2 text {kPa}). A key output of the work is the determination of molar polarizabilities (A_{text {R}} = 3.7466(18) cdot [1 + 1.5(6) times 10^{-6} (T/text {K} - 303) ] text{cm}^3 cdot text{mol}^{-1}) for ordinary water, and (A_{text {R}} = 3.7135(18) cdot [1 + 4.4(10) times 10^{-6} (T/text {K} - 303) ] text{cm}^3 cdot text{mol}^{-1}) for heavy water, with the numbers in parentheses expressing standard uncertainty. For heavy water, this work appears to be only the second gas phase measurement to date. For both ordinary and heavy water, this work agrees within (0.15 %) with recent ab initio theoretical results for (A_{text {R}}), but the comparison is affected by imperfect knowledge of dispersion. For ordinary water, the close agreement between the present work and theory suggests problems at the (2 %) level in the low density limit of the reference formulation for refractivity.

Numerous attempts have been made to measure the viscosity of liquids under high pressure by analyzing the response of a quartz crystal resonator. However, because the response of the resonator yields the product of density and viscosity, separating each value is necessary. A procedure was devised to measure the density changes of a liquid under high pressure by considering the fact that the response of a TiO₂-coated quartz crystal resonator is correlated with density. The resonance frequency shift of the TiO₂-coated quartz crystal resonator is the sum of terms that depend on (rho ) and (sqrt{eta rho }). Each effect can be separated using plane equation fitting. By applying ethyl laurate, densities up to 300 MPa were obtained at 313 K and 333 K. These values agreed with previously reported values within ± 1 %, thereby demonstrating the effectiveness of this method. Since the pressure dependence of (sqrt{eta rho }) is also obtained in the process of obtaining density data, the pressure dependence of the viscosity (eta ) can be estimated. The viscosities of ethyl laurate at 313 K and 333 K were calculated. Although the viscosity values differed significantly from the reported values and the measurements are still inaccurate, the possibility of using this method as a density measurement method under high pressure was demonstrated. Therefore, this study introduces a method with the potential to conveniently measure high-pressure physical properties.