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Just like disposal of waste papers by indiscriminate dumping, stabilisation of clay soil using cement or by firing has a potential adverse effect on the environment and public health. Thus, the essence of this work was to investigate the feasibility of chemically modifying clay soils using waste papers in order to solve the disposal problems and also develop clay-based composites suitable for building purposes. Hydrothermally calcined waste paper ash nanomaterial (HCWPAN) was prepared from assorted waste papers and used to separately develop composites with white clay matrix (WCC) and yellow clay matrix (YCC) each at 0 %, 10 %, 20 %, 30 %, and 40 % volumetric proportions of replacement. Three representative samples were developed in each case. Apparent porosity, water absorption, bulk density, sorptivity, thermal conductivity, specific heat capacity, volumetric heat capacity, thermal diffusivity, thermal lag, flaking concentration, flexural strength, and compressive strength were investigated for all the samples. For satisfactory performance during service, the optimum content level of the HCWPAN was found to be 10 % in the samples. Though the WCC sample possessed greater compressive strength (4.029 ± 0.002) MPa than the value (2.895 ± 0.002) MPa obtained for the YCC sample at that level, the latter exhibited greater potential for enhancement of thermal comfort as a walling element in buildings. Also, reductions from 8.98 % to 8.00 % and 13.30 % to 12.575 % were observed in water absorption of the resulting WCC and YCC samples, respectively. From the technical–economic viewpoint, the HCWPAN is a promising material for clay soil modification for building purposes. [ABSTRACT FROM AUTHOR]

Abstract  In this article, a method for measuring the thermal conductivity of paper using a hot disk system is introduced. To the best of our knowledge, few publications are found discussing the thermal conductivity of a coated paper, although it is important to various forms of today’s digital printing where heat is used for imaging, as well as for toner fusing. This motivated an investigation of the thermal conductivity of paper coating. This study demonstrates that the thermal conductivity is affected by the coating mass and the changes in the thermal conductivity affect toner gloss and density. As the coating mass increases, the thermal conductivity increases. Both the toner gloss and density decrease as the thermal conductivity increases. The toner gloss appears to be more sensitive to the changes in the thermal conductivity. [ABSTRACT FROM AUTHOR]

Ancient documents are of historical interest because they contain valuable information for future generations. One of the most common causes of documents damage and degradation is due to the presence of fungi. Therefore, it is very important to protect them from these microorganisms. In this work, TiO2 nanoparticles (TiO2NPs) were synthesized and used along with UV treatment for application as a potential antifungal against paper damage. Transmission electron microscopy (TEM) showed an average size of 70 nm for the nanoparticles. From scanning electron microscopy (SEM) micrographs, different structures of fungi in damaged cellulose fibers were observed. Energy dispersive X-ray spectrometry (EDS) detected the presence of elements related to organic and inorganic materials. Photoacoustic spectroscopy (PAS) as a non-invasive and versatile technique was used to study ancient documents deterioration presented in this manuscript. Through this technique, pigments produced by fungi in the wavelength between 277 nm and 700 nm were detected, being PAS an important characterization tool to study biodeterioration caused by fungi. [ABSTRACT FROM AUTHOR]

This study was designed to assess the possibility of tailoring waste papers and wood dust into composite materials with plaster of Paris (P.O.P) and also determine the suitability of using the developed composites as ceiling panels in building construction. Assorted un-used papers collected as waste materials were processed into waste paper ash (WPA) which was then after utilized like untreated wood dust (UWD) and treated wood dust (TWD) as filler materials to separately, but at similar volumetric proportions, fabricate test samples with P.O.P as matrix. Static angle of repose and major chemical constituents of the fillers were determined. The results of the tests performed on the samples revealed that increase in the proportion of each filler material resulted to decrease in bulk density, thermal conductivity, thermal diffusivity, and flexural strength but increase in percentage water absorption, specific heat capacity, thermal resistance, heat penetration time, and flaking concentration. Sample developed with 36.7 % of the WPA and the one containing 25.0 % of the TWD exhibited impressive performance ability similar to sample fabricated with 18.3 % of the UWD. Though the most significant improvement in thermal insulating ability over the pure P.O.P sample was observed in the case of samples developed with the UWD, it was found that the proportion of each filler material incorporated into the P.O.P matrix can be adjusted to achieve optimum performance desired of the resulting composite panel during its usage as a ceiling in building. From technical–economic point of view, utilizing waste papers and wood dust as raw materials in the production of new and value-added engineering materials, as in the present study, is a promising possibility of reducing the cost of P.O.P for enhancement of affordable housing, thereby meeting the needs of end-users and also ensure minimization of health hazards associated with paper and wood dust wastes. [ABSTRACT FROM AUTHOR]

A self-normalized photoacoustic technique was applied for quantitative analysis of pigments embedded in solids. Paper samples (filter paper, Whatman No. 1), attached with the pigment: Direct Fast Turquoise Blue GL, were used for this study. This pigment is a blue dye commonly used in industry to dye paper and other fabrics. The optical absorption coefficient, at a wavelength of 660 nm, was measured for this pigment at various concentrations in the paper substrate. It was shown that Beer-Lambert model for light absorption applies well for pigments in solid substrates and optical absorption coefficients as large as 220cm-1 can be measured with this photoacoustic technique. [ABSTRACT FROM AUTHOR]

Recently, Al-Odat and Al-Hussien presented consideration of the critical energy of a composite superconductor in this journal. Various numerical and other deficiencies have been identified in this paper. These problems are discussed and clarified in this Comment. [ABSTRACT FROM AUTHOR]

In an office building equipped with a Variable Air Volume (VAV) system, this paper introduces a novel method for controlling the minimum supply airflow fraction in each zone's VAV box, having a capability to consider indoor CO2 level and energy consumption. The EnergyPlus simulation using the medium office prototype model was employed, which evaluated the performance of the energy and CO2 concentration for five VAV box airflow control strategies. The paper focuses on CO2 concentration-based airflow control method and compares it with other four methods including conventional single-max, reduced minimum single-max, demand-controlled ventilation(DCV), and dualmax control methods according to guidelines and common practices. The newly proposed control strategy directly correlates the minimum airflow fraction to CO2 concentration. A general trend emerged when comparing CO2 concentrations—lower minimum airflow fractions were associated with higher concentrations. The proposed control method effectively maintained low CO2 concentrations and enabled a lower airflow fraction contributing to energy consumption reduction. It was confirmed that heating energy consumption in climate zone 4A, 5B, and 6A showed a maximum saving of approximately 30% compared to the conventional single-max and dual max control strategies. It was found that cooling energy consumption in climate zone 4A and 6A can achieve a maximum saving of approximately 10% compared to the conventional control strategies. The proposed CO2 concentration-based control logic is promising as it not only improves the indoor air quality lowering the CO2 concentration in the occupied spaces, but also contributes to HVAC energy savings. [ABSTRACT FROM AUTHOR]

The paper outlines the essential conditions required to achieve measurements of low uncertainty for the thermal conductivity of solids using the transient hot-wire technique. The paper aims to provide rigorous guidelines for the correct implementation of this technique for solids. For solid materials, the study shows that an uncertainty of as little as ± 1 % is attainable across a broad temperature range by employing the finite element method to solve the pertinent heat transfer equations within the experimental setup. Importantly, the paper discusses the necessary steps to verify that the experimental conditions conform to the theoretical model. [ABSTRACT FROM AUTHOR]

Mass and thermodiffusion are transport phenomena in fluid mixtures important in many applications. In this paper it is argued that these transport phenomena have even become more interesting in view of some surprising discoveries from fluctuating hydrodynamics leading to possible new emerging issues in non-equilibrium thermodynamics. A short review of the history of this subject is presented. The paper then addresses the problem that the conventional mass and thermodiffusion coefficients depend on the frame of reference. A simple solution to this problem is elucidated. [ABSTRACT FROM AUTHOR]

The noise caused by various temperature effects in the sensitive frequency band will cause errors in the detection results of space gravitational wave. Therefore, it is important to suppress the temperature noise of space-borne gravitational wave detectors. In this paper, a method is proposed to suppress temperature noise using a multi-layer composite structure consisting of low thermal conductivity material (R) and high specific heat capacity material (C). The arrangement in which heat flow passes through high specific heat capacity material first is "CR." The thermal simulation model is established to study the temperature noise transfer characteristics, and accuracy of the model is verified by experiments. The results show that the temperature noise of CRC is 90 % lower than that of RCR. The arrangement which heat flow passes through high specific heat capacity material first has an optimal high specific heat capacity material's proportion of 60 % to 70 %. When the number of composite layers is not less than 3 layers, the more the composite layers' number is, the better the suppression effect of multi-layer composite structure on temperature noise is. However, there is a limit to the way of obtaining noise reduction effect by increasing the number of layers. This paper provides a guidance for the suppression of temperature noise in gravitational wave detection. [ABSTRACT FROM AUTHOR]

It is emphasized that the formulation developed by Liu by taking into account the variation of the Anderson-Grüneisen parameter with volume for the temperature dependence of thermal expansivity is not consistent with the earlier studies performed by Anderson and coworkers. The results obtained from the Liu formulation do not present any improvement over the Anderson model which is based on the constant value of the Anderson-Grüneisen parameter independent of temperature for a given material. [ABSTRACT FROM AUTHOR]

Oscillating-body viscometers have been used in the past to measure, in an absolute way, the viscosity of molten materials at high temperatures, from salts, metals, alloys, and semiconductors. However, the simultaneous use of basic or incomplete mathematical models, to mimic the experiment, and less careful engineering solutions for the design and operation of the instruments, led in the past to high discrepancies between the data obtained in several laboratories. This was caused by the incorrect use of the method's theory, less accurate solutions of the complex solutions, that involve solid state and fluid mechanics, and unreal instrument design. From these types of viscometers, oscillating-cup instruments have had the most success in measuring viscosity at high temperatures, and they will be the object of this paper. It was written as a resource for workers interested in transport properties of materials when considering its use for the absolute measurement of fluids viscosity in their work, or in judging the results of others' work when comparing data with their own. The paper starts with the most accurate theory of the method's description, followed by a discussion of its validity, application to instrument design, and consequent operation. Several constraints were identified and recommendations were made to minimize the effects of failing to satisfy them. Finally, a discussion about the uncertainty budget calculations for a real experiment is made. If all these points are followed in the design and operation of the instrument, results in global uncertainties Ur(η) between 0.02 and 0.04 are possible to obtain, up to high temperatures. If these constraints are not satisfied, erroneous measurements can be made, making comparisons and quality assessment difficult. [ABSTRACT FROM AUTHOR]

This paper presents new wide-ranging correlations for the viscosity and thermal conductivity of acetone (2˗propanone or dimethyl ketone) based on critically evaluated experimental data. Both correlations are designed to be used with a Helmholtz-energy equation of state (EOS) that extends from the triple point to 550 K, at pressures up to 700 MPa. The viscosity correlation is valid from the triple point to 550 K and up to 162 MPa pressure, while the thermal conductivity is valid from the triple point to 550 K and 700 MPa. The estimated uncertainty (at a 95 % confidence level) for the viscosity varies from a low of 2 % for the low-pressure gas (p < 0.5 MPa) to 5.5 % for the liquid phase at pressures up to 162 MPa, and for thermal conductivity varies from a low of 3.5% for the low-pressure gas up to 6.2% for the thermal conductivity at pressures up to 700 MPa. [ABSTRACT FROM AUTHOR]

This paper presents the results of thermal conductivity characterization of six high oleic soybean oil (HOSO) and four high oleic canola oil (HOCO)-based hybrid nanofluids formulated with four types of nanoparticles (Graphene nanoplatelet (xGnP), TiO2, MoS2, and Al2O3) at nanoparticles wt% concentration from 1 % to 7 % in 1 % increment using the two-step method for use in MQL machining of difficult-to-cut metals. Thermal conductivity of the formulated hybrid nanofluids were measured using Thermtest Transient Hot Wire Liquid Thermal Conductivity Meter at temperatures from 25 °C to 75 °C in increment of 10 °C. Obtained results showed that thermal conductivity of all nanofluids decreases linearly with temperature, while the thermal conductivity enhancement increases nonlinearly with increase in wt% concentration, following second order polynomial. At 7-wt% nanoparticle concentration, hybrid nanofluids xGnP-TiO2/HOSO gave the highest thermal conductivity enhancement (109.73 % and 103.31 % at 25 and 75 °C) followed by xGnP-TiO2/HOCO (101.36 % and 97.52 % at 25 °C and 75 °C), xGnP-MoS2/HOCO (101.36 % and 97.52 % at 25 °C and 75 °C), xGnP-MoS2/HOSO (96.3 % and 96.89 % at 25 °C and 75 °C), xGnP-Al2O3/HOCO (91.62 % and 83.23 % at 25 °C and 75 °C), xGnP-Al2O3/HOSO (91.25 % and 83.23 % at 25 °C and 75 °C). xGnP hybrid nanofluids are recommended for MQL machining. TiO2–MoS2/HOSO, TiO2–MoS2/HOCO, MoS2–Al2O3/HOSO, TiO2–Al2O3/HOSO hybrid nanofluids gave the lowest thermal conductivities and are not recommended as base fluids due to their insignificant thermal conductivity enhancement. Thermal conductivity of the hybrid nanofluids is lower than that of mono-nanofluids, but there are other inherent properties that could be beneficial. [ABSTRACT FROM AUTHOR]

With the enhancement of integration and functionality of high-power electronic devices, heat dissipation has become a critical bottleneck limiting performance improvement. In particular, under high power density conditions, interface thermal resistance has emerged as a prominent factor in overall thermal management. In this paper, the interfacial energy transport characteristics of Si/Ge is investigated based on the Boltzmann Transport Equation (BTE). The quality of interfacial energy transport is analyzed using Boltzmann statistical entropy and the losses that occur at the interface during energy transmission is also explored. The results indicate that the mismatch and high degree of localization of interface phonons increase the irreversible loss of energy phonons during transport across the interface, which leads to a significant entropy increase at the interface. Furthermore, the degree of irreversibility in energy loss is related to the thermal transport pathway; the lower the phonon matching at the interface, the greater the thermal transport resistance and the larger the irreversible loss. This research offers a comprehensive analysis of the irreversibility of energy loss, providing novel theoretical frameworks and research avenues for enhancing energy efficiency in high-power electronic devices. [ABSTRACT FROM AUTHOR]

The efficient heat dissipation capacity of phase-change cooling offers a reliable solution for cooling high heat flux devices. Nevertheless, the evolution of phase-change fluid frequently encounters volatile states, resulting in considerable pressure fluctuations. This paper seeks to enhance the pipes active cooling efficiency of phase change by examining the weight ratios of pipe structural parameters on heat transfer, pressure drop, and comprehensive performance. Simulation model based on the Volume of Fluid (VOF) methodology was constructed to investigate the heat transfer and pressure reduction performance of the pipes. A comprehensive performance factor that considering both pressure drop and heat transfer characteristics was developed. The contributions of pipe structural parameters to the objective functions of pressure drop, heat transfer, and comprehensive performance are evaluated using a combination of orthogonal experiments and the Signal-to-Noise ratio (SNR) function. The accuracy of the numerical model was validated using quartz lamp thermal experiments. The findings suggest that when formulating the objective function based on comprehensive performance, the principal influencing factor for micro-pipe is wall thickness, accounting for up to 42.7 %. Conversely, for mini-pipes, the primary influencing factor is coolant flow velocity, contributing 43 %. Due to the effects related to size, the factors influencing the overall performance of micro/mini-pipes differ. They are primarily influenced by alterations in vapor volume fraction generated by phase change inside the pipeline. This study proposes an evaluation method considering multiple factor levels, furnishing crucial technical support for phase-change heat transfer technology. [ABSTRACT FROM AUTHOR]

This paper considers the necessary conditions for using a derivative of a transient hot-wire (termed a needle probe) approach to measure the thermal conductivity of electrically conducting fluids at high temperatures, especially molten halide salts. The focus is on the development of a new theory based on a multi-layer system necessary to ensure electrical isolation of electrical wires from the surrounding fluid. This includes the use of a thin annulus of fluid to minimize convective heat transfer modes within the fluid of interest, which was inspired by the concentric cylinder method. Good measurements require the following considerations: concentricity of the probe and surrounding crucible to ensure a consistent fluid gap, accounting for corrections for deviation of the model at early times, and modeling radiation heat transfer through transparent fluids. Uncertainties are larger than transient hot-wire methods because of the deviations from experimental conditions that can easily match an analytical approximation. An appropriate estimation of the measurement uncertainty can be obtained through careful design of the instrumentation, thorough uncertainty analysis, and limiting the measurements to only the applicable thermal property ranges of the approach. The 1D model used to interpret measured temperature data has been shown to be reliable for thermal conductivity measurements ranging from at least 0.39 W (mK−1) to 0.92 W (mK−1) and for temperatures from 293 K to 1023 K. The approach is used to present thermal conductivity data of the molten salts NaCl–KCl (51–49 mol%) and LiCl–NaCl (72–28 mol%). [ABSTRACT FROM AUTHOR]

This paper is a combined experimental and modeling study aimed at exploring the densities, sound speeds, and refractive indices of the ternary system MTBE + n-hexane + cyclohexane and its binary subsystems at a temperature of 298.15 K under ambient pressure conditions. Experimental data were used to derive essential properties such as excess molar volumes, excess isentropic compressibilities, and refractive index deviations. The excess and deviation properties provided invaluable insights into the interactions occurring among the mixture components. Redlich–Kister and Cibulka's equations were employed to correlate these properties for binary and ternary systems, respectively. Remarkably, the standard deviations consistently fell below the estimated uncertainties associated with the corresponding properties, attesting to the robustness of the correlations. Additionally, the Perturbed Chain Statistical Associating Fluid Theory was applied to model the density of both binary and ternary mixtures. The study also compared Schaaff's collision factor theory and Nomoto's relation in their ability to predict sound speeds for the investigated mixtures. Various mixing rules, including Lorentz-Lorenz, Gladstone-Dale, Laplace, and Eykman, were employed to model the refractive indices of the mixtures. The efficacy of these models in predicting the properties was evaluated using the average absolute percentage deviation between the experimental and calculated values. The modeled densities matched well with the experimental data, with overall deviations of 0.19 %, 0.38 %, and 0.25 % for the binary systems MTBE + n-hexane, MTBE + cyclohexane, and n-hexane + cyclohexane, respectively, and 0.21 % for the ternary system MTBE + n-hexane + cyclohexane. Notably, Nomoto's relation exhibited superior performance in predicting both binary (overall deviation of 0.65 %) and ternary (deviation of 1.10 %) sound speeds. In contrast, any of the four tested mixing rules performed equally well for predicting binary and ternary refractive indices. This work contributes to the understanding of interactions between components in mixtures. It also provides valuable data for petrochemical and environmental engineers involved in designing extraction processes, processing equipment, and formulating gasoline blends that meet the industry's rigorous standards and align with environmental sustainability goals. [ABSTRACT FROM AUTHOR]

Measurement of the thermophysical properties of liquid metals is a highly challenging task due to numerous problems encountered above the fusion point. Properties such as density and surface tension have been widely investigated, while few studies address thermal diffusivity. In this paper we describe an original methodology for estimating the thermal diffusivity of metals in the liquid state. The proposed experimental setup is based on the traditional flash method. Its design ensures that samples of liquid metal are self-contained, preventing contamination and allowing measurements at high temperature. Results for both solid and liquid iron and 304 stainless steel are presented and compared to data suggested by the literature for validation. Then, for the first time, thermal diffusivity measurement of liquid zirconium is performed giving results up to 2450 K. Giving the high sensitivity of the results to the thickness variation we propose a numerical approach to deal with this issue. [ABSTRACT FROM AUTHOR]

Alternative sources for an industrial production of essential substances represent an exciting field of study for many researchers. Based on the previous research, itaconic acid and its esters were intensively studied as one of the sources. This paper relates to a determination of the basic physical–chemical properties of bis(2-methylbutyl) itaconate and bis(3-methylbutyl) itaconate that are produced from itaconic acid and 2-methylbutan-1-ol and 3-methylbutan-1-ol, respectively, from biomass. According to our best knowledge, physical–chemical properties of these substances, such as density, viscosity, and saturated vapor pressure, are not presented in the literature, and these are important for the future research of their production. [ABSTRACT FROM AUTHOR]

Viscosity is a thermophysical property of paramount importance, being essential for many scientific and industrial applications. The most common instruments for its measurement are glass capillary viscometers. Therefore, the use of capillary viscometers is widespread both in industry and in research. The range of viscosities of interest range from lower than that of water to several orders of magnitude higher values, the measurement of which requires different capillary viscometers. Most of the practical applications concern routine instruments, mainly for quality control. One main issue for the utilization of capillary viscometers relates to the need for their calibration, assuring its traceability to the water primary viscosity standard, to certify its worldwide validity. The present paper focuses on capillary instruments dedicated to perform viscosity measurements on Newtonian organic liquids at atmospheric pressure, as it is assumed that is the most widespread type of application for these viscometers. Capillary viscometry has a completely well-defined working equation, namely, the Hagen–Poiseuille equation. However, the practical performance of the measuring instruments deviates from that working equation. Most of those deviations are currently considered by many users. However, some of those deviations have not reached that status yet, like those concerning the effects due to the surface tension of the sample on the measurements. All these aspects are summarized and analyzed in the present article, together with a brief general description of the most common types of capillary viscometers, namely, the Ostwald and the constant-level or Ubbelohde instruments. [ABSTRACT FROM AUTHOR]

This paper presents an experimental method for determining the effusivity values of different scratched coaxial temperature sensors. These sensors have a response time on the order of microseconds (50 μs) with a rise time of less than 0.3 μs. Two types of scratch were used, mainly abrasive papers with different grit sizes and scalpel blades with different thicknesses to form the sensor junctions. The effect of the scratch technique on the sensor's effusivity is also investigated. The sensors were tested and calibrated in the test section of a shock-tube facility at different operating conditions. It was observed that the effusivity of a particular sensor depends on the Mach number, scratch technique, scratch direction, junction location, as well as on the enthalpy condition. It was also noticed that a scratched sensor using the scalpel blade technique does not require an individual calibration. However, for a sensor scratched using the abrasive paper technique, a calibration for each sensor is likely to be required. The present results have provided useful and practical data of the effusivity values for different scratched temperature sensors. These data are beneficial to experimentalists in the field, and can be used for accurate transient heat transfer rate measurements. [ABSTRACT FROM AUTHOR]

Thermal diffusivity is an essential thermophysical factor for designing thermal protection materials. At present, the laser flash method is widely employed for measuring thermal diffusivity, and reasonable determination of experimental parameters is a prerequisite for accurate measurement. In this paper, high-purity graphite is used as the reference specimen, and measurement temperature ranges from 25 °C to 1500 °C. Besides, experimental investigations on the influence of the laser flash method such as specimen thickness, laser pulse energy, and temperature increase rate on the measurement of thermal diffusivity for high-purity graphite are carried out. The results indicate that for high-purity graphite samples, a sample thickness of 3 mm is more appropriate. Additionally, the setting of laser pulse voltage and width is related to the measurement temperature, and the measurement results are more easily affected by the laser pulse width. When measuring temperatures below 600 °C, it is necessary to set both the laser pulse width and voltage to the smallest possible values, provided that a stable signal can be collected. When the temperature is above 600 °C, the laser pulse voltage does not affect the measurement results, but the influence of laser pulse width still needs to be considered to a certain extent. It is only when the measured temperature exceeds 900 °C that neither the laser pulse voltage nor the laser pulse width influences the measurement results. Furthermore, the temperature increase rate has a relatively small impact on the measurement results and can be adjusted according to the measured temperature. The research results can provide a basis for the calibration of experimental parameters in the high-temperature flash method measuring instrument. [ABSTRACT FROM AUTHOR]

The paper describes the theory and practice associated with the torsional quartz-crystal viscometer for the measurement of the viscosity of Newtonian Fluids. It is an instrument that has been less often used than its quality merits, but it has the distinct advantages, shared with the vibrating-wire device, that it involves no bulk motion of fluid or a solid and that all measurements can be electrical. The temperature range that can be covered by the instrument is from 2 to 650 K and pressures have reached as much as 100 MPa. The review summarizes the most recent theory of the instrument and carefully sets out all of the many conditions that have to be satisfied by design so that a practical instrument conforms to the theory. Most of the conditions are readily satisfied. Two working equations are presented that could be used to evaluate the viscosity using the frequency at resonance of the crystal and the bandwidth of that resonance when the crystal is immersed in the fluid and in vacuo. It is explained that at present only one of these equations should be used for the evaluation. Several configurations of instruments that have been employed for measurements over a wide range of conditions are briefly described as well as the corrections necessary to operate the instrument with the highest accuracy. The overall relative uncertainty attainable with the instrument ranges from 0.005 to 0.02 at a 95% confidence level, depending upon the fluid density. [ABSTRACT FROM AUTHOR]

The 1D moisture diffusivity of porous materials may strongly depend on the content of moisture in the materials, varying over an order of magnitude or more. In this paper we present a new model from which the diffusivity can be evaluated, using the pore size distribution and water absorption coefficient. We point out that this is a more efficient approach than the standard Boltzmann–Matano (BM) method, because measurements of pore curves and water absorption are much shorter and rather accurate compared to moisture profile experiments needed in the BM method. As an example, we apply our model to two samples of a ceramic brick for which experimental data on both pore curves and moisture profiles had been measured. A very good quantitative agreement in the diffusivity is obtained for early stage profiles. For later stages, however, the model predicts three to four times higher diffusivity than the BM method. The reasons for this discrepancy are discussed and further tasks to validate the effectiveness of the new model are proposed. We also compare our model with the pore models of Burdine and Mualem. [ABSTRACT FROM AUTHOR]

Dry ice pulsed sublimation spray cooling (PSSCDI) is an innovative, efficient, energy-saving, and fast cooling method for the thermal management of chip-level electronic components with high thermal load in the aerospace field. Aiming at the heat transfer mechanism of dry ice sublimation spray cooling, a heat transfer model of pulsed dry ice sublimation spray cooling based on flow discretization is proposed in this paper. According to the heat transfer mechanism and the formation mechanism of dry ice reflected by the Joule–Thomson effect, the experimental platform of pulsed dry ice sublimation spray cooling was designed and built. The relationship between spray height, spray flow rate, and spray cone Angle was determined by experiments, and the best spray height was determined. The effects of mass flow rate, pulse period, and duty cycle on heat transfer characteristics of pulsed dry ice sublimation spray were investigated experimentally. The experimental results show that the instantaneous temperature change process of simulated heat source under different working conditions can be divided into three stages: heating, cooling, and constant temperature. The heat flux and heat transfer coefficient of pulsed dry ice sublimation spray cooling under high heat load increase with the increase of the duty ratio and mass flow of dry ice spray, but decrease with the increase of pulse period. However, the heat flux of the duty cycle and heat transfer coefficient of the duty cycle decrease with the increase of duty cycle, which indicates that under the premise of considering dry ice consumption, a lower duty cycle will make pulsed dry ice spray cooling have a higher heat transfer efficiency. When the mass flow rate of dry ice spray is 13 g/s, the pulse period is 0.2 s, the duty cycle is 50 %, the heating power is 40W, the relative optimal cooling heat flux is 48 W/cm2, and the relative optimal heat transfer coefficient is 5400 W/(m2·K). [ABSTRACT FROM AUTHOR]

This paper focuses on falling-cylinder viscometry, a commonly used method for measuring viscosity due to its simplicity and versatility. The review explores the development of falling-cylinder viscometers, with an emphasis on their adaptability to high-pressure environment. The theoretical foundation for an ideal falling cylinder in a fluid within a rigid tube is discussed, addressing limitations arising from geometry, eccentricity, non-verticality, and entrance/exit effects. Critical Reynolds number and transient regime, are also examined. Practical aspects, including sinker design, working equations, calibration, as well as temperature and pressure influences on the constant apparatus, are discussed. By critically assessing these aspects, this review provides insights and recommendations for the effective application of falling-cylinder viscometry in both scientific and industrial contexts. [ABSTRACT FROM AUTHOR]

The thermoreflectance method, which can measure thermal diffusivity in the cross-plane direction of thin films, mainly has two possible configurations; rear-heat front-detect (RF) and front-heat front-detect (FF) configuration. FF configuration is applicable to a wide variety of thin films including thin films deposited on opaque substrates, but this configuration has some problems in determination of the thermal diffusivity. One of the main problems is the effect of the penetration of pump beam and probe beam in thin film, which affects the initial temperature distribution near the sample's surface after pulse heating. Several studies have tried to analyze the effect but there have been no practical analytical solutions which can solve this problem in FF configuration. In this paper, we propose a new analytical solution which considers the penetration of pump beam and probe beam into thin film, and by applying Fourier expansion analysis which we developed in a previous study to thermoreflectance signals, we have determined the thermal diffusivity of thin film in the thermoreflectance method under FF configuration. We measured platinum thin films with different thickness under both FF and RF configuration and obtained consistent thermal diffusivity values from both configurations. [ABSTRACT FROM AUTHOR]

The Wet bulb globe temperature (WBGT) index is a widely used tool for estimating human heat stress. It is calculated from three measured parameters: air temperature, natural wet bulb temperature and globe temperature. Very few papers have been published on the measurement uncertainty of this index. The uncertainty estimation has to account for correlations between the input quantities i.e. the three temperatures comprising the index. In the present short paper, three example measurements, under different conditions, were made to illustrate the calculation of the expanded uncertainty of the WBGT index. The analysis presented here complements the earlier work published in the International Journal of Thermophysics (Ekici in Int J Thermophys 38:85, 2017) and refers to the same type of measurement instruments. [ABSTRACT FROM AUTHOR]

This paper focuses on the empirical modeling for viscosities of a hydrofluoroolefin refrigerant, R1234ze(Z), which is considered an environmentally friendly alternative to hydrofluorocarbons. The refrigerant has favorable thermophysical properties and a low global warming potential. A new fundamental equation of state (EoS) for R1234ze(Z) was developed in 2019, which aligns with the recent trends of developing accurate fundamental equations of state. However, previously published experimental viscosity data were reported using an old equation of state of the fluid. In this paper, the revised experimental viscosity data based on the latest EoS has been reported for R1234ze(Z). Additionally, the viscosity model of this fluid is presented using the extended corresponding states (ECS) and modified fluid-specific residual entropy scaling (RES) techniques. By using the adjustable parameters, the ECS and the modified fluid-specific RES transport equations can represent the experimental data within reported uncertainties. The average absolute deviations (AAD) for viscosity were found to be 1.40% and 1.65% using the ECS and the RES method, respectively. This study also highlights the importance of using the most accurate EoS when reporting experimental data, especially when formulating transport property models based on these techniques. [ABSTRACT FROM AUTHOR]

With the increase in osteoporosis and degenerative bone and joint diseases associated with an aging population, the demand for bone tissue repair materials is rapidly increasing. Bone repair materials have evolved to composite materials with biodegradability and for emerging bone repair materials, properties such as viscoelasticity, coefficient of thermal expansion, thermal conductivity, and phase change temperature play an important role in studying the mechanical properties, thermal stability, and thus determining the application scenario of the material. Therefore, thermal analysis is necessary for bone repair. This paper reviews commonly used bone tissue repair materials and thermal analysis techniques applied to bone tissue repair studies, including thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry, and dynamic mechanical analysis. The paper highlights the key role of thermal analysis in bone repair research and summarizes the application of different thermal analysis techniques in the characterization of bone repair materials. The results of this study provide a valuable reference for the thermal analysis of bone repair materials. [ABSTRACT FROM AUTHOR]

In this work, an experimental method based on the use of pulsed thermography is proposed for the depth-resolved characterization of double-layered structures of cultural heritage items. A quantitative evaluation of the inspected features was achieved by comparing thermographic data with theoretical predictions provided by specifically developed theoretical models for the analysis of the thermographic signal. In this respect, thermographic models for both optically opaque and semi-transparent materials were employed to analyze the results obtained in copper alloys and paper-based original artworks, respectively. Thermographic inspections aimed at establishing the procedure adopted for the application of insertions in ancient bronze statues are presented. Finally, the evaluation of the depth position of graphical features buried beneath leaves of historical books is proposed. [ABSTRACT FROM AUTHOR]

The paper summarizes the conditions that are necessary to secure accurate measurements of the thermal conductivity of fluids using the transient hot-wire technique. The paper draws upon the development of the method over five decades to produce a prescription for its use. The purpose is to provide guidance on the implementation of the method to those who wish to make use of it for the first time. It is shown that instruments of the transient hot-wire type can produce measurements of the thermal conductivity with the smallest uncertainty yet achieved (± 0.2%). This can be achieved either when a finite element method (FEM) is employed to solve the relevant heat transfer equations for the instrument or when an approximate analytic solution is used to describe it over a limited range of experimental times from 0.1 s to 1 s. As well as establishing the constraints for the proper operation of the instrument we consider the means that should be employed to demonstrate that the experiment operates in accordance with the theoretical model of it. If the constraints are all satisfied then an uncertainty in thermal conductivity measurements of as little as ± 0.2–0.5% can be obtained for gases and liquids over a wide range of thermodynamic state from 0.1 MPa to 700 MPa and temperatures from 70 K to 500 K with the exception of near critical conditions. It is observed that many applications of the transient hot-wire technique do not conform to the constraints set out here and therefore may be burdened with very much greater uncertainties, sometimes large enough to render the results meaningless. [ABSTRACT FROM AUTHOR]

The theory and application of the Taylor Dispersion technique for measuring diffusion coefficients in binary systems is reviewed. The theory discussed in this paper includes both the ideal Taylor–Aris model and the estimation of corrections required to account for small deviations from this ideal associated with a practical apparatus. Based on the theoretical treatment, recommendations are given for the design of practical instruments together with suggestions for calibration, data acquisition and reduction, and the rigorous estimation of uncertainties. The analysis indicates that relative uncertainties on the order of 1% are achievable in practice. [ABSTRACT FROM AUTHOR]

This research paper refers to the study of the thermodynamic and transport properties of 3-methyl-2-butanol and normal alcohols ranging from C3–C6 (1-propanol to 1-hexanol), focusing particularly on the density and viscosity of these mixtures within a temperature range of 293.15–323.15 K. Findings indicate binary mixtures show negative excess molar volumes, which gradually become less negative with an increase in the alkyl chain length of the alcohols. In terms of viscosity, all mixtures consistently demonstrated negative deviations, becoming more negative as the alkyl chain extended. These results underscore a strong molecular interaction occurring between 3-methyl-2-butanol and short-range 1-alkanol. Additionally, the research incorporated the Cubic-Plus-Association (CPA) model to correlate the densities of binary mixtures. The model aligned well with the experimental densities, proving its effectiveness in correlating the density trends of these mixtures. The maximum difference noted between the experimental results and the CPA model's correlated values was in the 3-methyl-2-butanol and 1-hexanol mixture, with a slight discrepancy of only 0.41%. This small variance further highlights the CPA model's accuracy in mirroring experimental findings. [ABSTRACT FROM AUTHOR]

The identification of new refrigerants characterized by low GWP (< 150), as required at international level by several agreements and regulations, is still far from the conclusion. In particular, for a proper selection, the thermophysical properties of hydro(chloro) fluoroolefins (H(C)FOs) are required, but their knowledge is still scarce for several of these fluids. Amongst these, R1130(E) has recently get some attention as a component, with R1336mzz(Z), of the azeotropic binary mixture (R514A), that could be applied as a substitute for R123 in centrifugal chillers, high-temperature heat pumps, and organic Rankine cycles. R1130(E) is a hydrochloroolefin characterized by a relatively high normal boiling temperature (320.9 K) and belongs to the ASHRAE safety group B1. Its properties are still not widely studied and, in particular, a very limited number of data is available in the peer reviewed literature for the thermal conductivity. Thus, in this paper, a set of experimental thermal conductivity data, performed with a double THW apparatus, will be presented. The data are measured in the range of temperatures between 243.15 and 313.15 K, with pressures up to 8 MPa. [ABSTRACT FROM AUTHOR]

This paper reports an efficient closed-form representation of the heat capacity of linear triatomic molecules. An approximate method is proposed for factorizing the vibrational and rotational contributions to the ro-vibrational partition function using average vibrational quantum numbers. Single-valued analytical representations of the vibrational and rotational partition functions are also derived. The reliability of the proposed method for calculating heat capacity is verified by comparison with experimental data and theoretical calculations using the direct summation method with exact values of energy levels. The new approach is much more efficient than the explicit sum-over-states method. [ABSTRACT FROM AUTHOR]

The current paper aimed to study the properties and interactions of liquid mixtures containing butyl lactate and 1-alkanols with carbon chains ranging from 4 to 7 (1-butanol, 1-pentanol, 1-hexanol, and 1-heptanol). Excess molar volumes and viscosity deviations were analyzed by experimental measurement of density and viscosity at varying temperatures and 0.1 MPa pressure. Solutions with butyl lactate and 1-butanol or 1-pentanol showed negative excess molar volumes, while mixtures with 1-hexanol and 1-heptanol had positive values. All liquid mixtures exhibited negative viscosity deviations that declined as 1-alkanol carbon chain lengthened. The PC-SAFT model successfully simulated pure fluid and mixture densities, with maximum 1-pentanol mixture deviations of 0.98 %. Overall, PC-SAFT accurately correlated both pure and solution densities. [ABSTRACT FROM AUTHOR]

Gypsum-based composite is a widely used material in construction applications; it is a traditional material that is frequently used in non-structural and decoration, such as dry walls and ceilings, because to its benefits, which include environmental aspects, sound and heat insulation capabilities, and fire resistance. Brittleness, poor mechanical properties, and high water absorption are the main drawbacks of gypsum-based composites, limiting their use. Fibers have been employed to improve the performance of gypsum-based composites in a number of research investigations. Natural date palm fibers (DPF) are considered efficient candidate for natural reinforcement in composites that dedicated to various applications due to many reasons, mainly, their low cost, good thermophysical and mechanical properties compared to man-made fibers. Date palm fibers-reinforced gypsum-based composites showed good overall performance and would be more commercially viable as building materials. This paper reviews previous research on date palm fiber-reinforced gypsum-based composites. This paper summarizes, evaluates, and discusses the sources and properties of gypsum and DPFs, the influence of these fibers on the mechanical and thermal properties of the composites, and it highlights the fiber surface treatments to improve the fiber–matrix adhesion. [ABSTRACT FROM AUTHOR]

This paper presents revised saturated liquid viscosities for 15 halocarbon refrigerants, that is, R11, R12, R22, R13B1, R152a, R113, R123, R123a, R143a, R114, R134a, R141b, R142b, R225ca, and R225cb, reported in our previous papers [1, 2], in which the vapor buoyancy correction for the sealed capillary viscometer was not applied. The maximum corrections amount to from 1.2% for R225cb to 17.4% for R143a. The erroneous data in our previous papers should be considered obsolete except for the low-vapor density refrigerants R11, R123, R123a, R113, R141b, R225ca, and R225cb, for which the maximum correction is 2.4%. [ABSTRACT FROM AUTHOR]

The rational use of energy is of great significance for the long-term stable development of the economy. However, energy such as solar energy and industrial waste heat are difficult to be utilized stably. The development of thermal storage technology can alleviate the instability of energy. In this paper, 96 wt% NaNO3-4 wt% NaCl (NN) was used as the thermal storage material and expanded graphite (EG) was used to adsorb NN binary phase change material (PCM). The effect of EG with different particle sizes on the thermal performance of NaNO3–NaCl/EG composite phase change material (CPCM) was studied. The results showed that the addition of EG reduced the supercooling degree of NN from 4.7 °C to 1.1 °C. The addition of EG powder increased the contact probability between fillers and provided more adsorption positions for PCM, increasing the latent heat of composites. The addition of 32 mesh EG–EG powder greatly increased the thermal conductivity of NN from 1.24 W·m−1·K−1 to 5.43 W·m−1·K−1. It is because the pores of large particle size EG are filled with EG powder, which is easy to form chain or network structure, forming more heat conduction pathways. The research provides some technical support for the application of phase change heat storage technology. [ABSTRACT FROM AUTHOR]

Negative temperature coefficient thermistor (NTC) is widely used in temperature measurement field, especially in the temperature range from 0 °C to 40 °C. For its strong nonlinearity, NTC should be calibrated in this temperature range with three or more temperature fixed points. However, in this temperature range, there are only two defined temperature fixed points in ITS-90: Gallium point and water triple phase point. In this paper, a phenol temperature fixed point was developed to make up the deficiency. Melting and freezing temperature curves are studied for the single-component phenol in a conventional size cell. The phenol melting plateau can last for more than 10 h with melt range of less than of 100 mK. The freezing plateau can last approximately 4 h with the observed temperature variation less than 5 mK within 2 h, which showed a high degree of reproducibility. Different methods were employed to accurately determine the phase transition temperature. By repeatedly realizing phenol melting plateaus and freezing plateaus, the melting point temperature was determined to be 40.6109 °C ± 0.074 °C (k = 2) with a reproducibility of less than 8.3 mK, and the freezing point temperature was 40.6348 °C ± 0.072 °C (k = 2), with a reproducibility of less than 1.6 mK. The results showed that the phenol freezing point temperature is the most suitable temperature reference standard near 40.6 °C. [ABSTRACT FROM AUTHOR]

Due to the increasing demand of climate change studies, traceability of measurements according to the International System of Units (SI) becomes fundamental to establish data quality and comparability in time. With the aim of guaranteeing the traceability, in October 2022, an on-site calibration of three thermometers operated by the Osservatorio meteorologico di Moncalieri was assessed. The calibration by comparison against traceable travelling standards was performed in a transportable thermal chamber manufactured by the Istituto Nazionale di Ricerca Metrologica (INRIM). Results showed that the main uncertainty contributions to the expanded uncertainty were the interpolation method, the chamber inhomogeneity and the repeatability of the sensors under calibration. This current calibration was compared with previous calibration in 2012 (on-site calibration) and in 2016 (laboratory calibration). The comparison analysis evidenced the drift effect on the thermometers and the importance of having an active calibration program to reduce this effect. Regarding the expanded uncertainty, both on-site calibrations presented the same order of magnitude and smaller than the correction values. This paper points out the advantage of performing an on-site calibration: since the calibration involves the same dataloggers and cables in the same environmental conditions, the calculated calibration curve represents more convincingly the real measurement conditions. [ABSTRACT FROM AUTHOR]

The need for new heat transfer agent for many applications, namely in the consumer electronics industry, requires materials, liquids at room temperature, with high thermal conductivity. From the different possibilities, Galinstan, a eutectic alloy of Gallium, Indium, and Tin with a melting point (Tm = 283.4 K) has been proposed for many applications, namely for replacing the toxic mercury element, used for many years. It is the purpose of this paper to report thermal conductivity measurements of Galinstan, product name Gallium/Indium/Tin Eutectic (NL-011), Ga68.4In21.5Sn10. The method used was the transient hot strip (THS), using a platinum metal-film sensor, produced by PVD in ceramic substrates, and electrically insulated with a heat-shrinkable coating. The details of the data acquisition system and measuring procedure are reported. Measurements were performed between 28 °C and 103 °C (301 K to 376 K), at atmospheric pressure, with an estimated uncertainty of 6%, and compared with available literature. Data were correlated for linear interpolation. This type of sensor is applied to molten metals for the first time, proofing to concept to future applications in molten metals and molten salts at higher temperatures. [ABSTRACT FROM AUTHOR]

This experimental method was first proposed in 1991 and is presently being used for determining thermal conductivity, thermal diffusivity, thermal effusivity, and volumetric heat capacity of solids. Under special and well-controlled conditions, it is possible to measure thermal conductivity over approximately six orders of magnitude at temperatures ranging from 25 K up to 1500 K. A feature of this method is the possibility to obtain both the thermal conductivity and thermal diffusivity from one single transient recording and in that way to open up convenient measurements of thermal transport of certain anisotropic materials. A further advantage of using a transient method relates to the possibility to eliminate the influence of the contact resistances always present between the heating element, functioning also as the temperature recorder, and the surface of the substrate under investigation. This review will touch upon the limitations of the method with an estimation of the measuring uncertainty together with a discussion on the influence of the difference between the experimental arrangement and the assumption made in the development of the analytical theory used for analyzing the experimentally recorded data. The method has turned out to be useful not only in measurements of the thermal transport but also for special quality control situations. It is used in both academic institutions and in industrial laboratories and has so far generated some 5000 scientific papers in international journals. [ABSTRACT FROM AUTHOR]

This paper describes the construction, working equations, and operation of a semi-automated high-pressure falling body viscometer used in the pressure range 0.1 MPa to 400 MPa and at temperatures between 255 K and 368 K. The viscometer employs self-centering sinkers, each a hollow cylinder with a solid hemispherical face. This results in a viscosity-independent sinker calibration constant. With sinkers of different diameters, a broad range of Reynolds numbers is accessible. The dependence of the calibration constants (A) on sinker clearance (c), A ∝ c−3, conforms with theory. It has been used for both high and low viscosity molecular liquids and viscous ionic liquids. It is hoped that a complete description may be of use to others wishing to build and operate such an instrument. [ABSTRACT FROM AUTHOR]

Many biological systems have a narrow temperature range of operation, meaning high accuracy and spatial distribution level are needed to study these systems. Most temperature sensors cannot meet both the accuracy and spatial distribution required in the microfluidic systems that are often used to study these systems in isolation. This paper introduces a neural network called the Multi-Directional Fluorescent Temperature Long Short-Term Memory Network (MFTLSTM) that can accurately calculate the temperature at every pixel in a fluorescent image to improve upon the standard fitting practice and other machine learning methods use to relate fluorescent data to temperature. This network takes advantage of the nature of heat diffusion in the image to achieve an accuracy of ± 0.0199 K RMSE within the temperature range of 298 K to 308 K with simulated data. When applied to experimental data from a 3D printed microfluidic device with a temperature range of 290 K to 380 K, it achieved an accuracy of ± 0.0684 K RMSE. These results have the potential to allow high temperature resolution in biological systems than is available in many microfluidic devices. [ABSTRACT FROM AUTHOR]

This paper reviews the 40-year evolution and application of the magnetic suspension balance (MSB) and discusses some challenging issues of the technique. An MSB, as defined herein, is a magnetic suspension coupling (MSC) connected to an analytical balance. With an MSC, an object can be weighed in a different environment than the balance itself, making it possible for contactless weighing. Over the past 40 years, the MSB has been commonly used in research areas requiring accurate object weighings, notably gas density measurements by MSB-based densimeters and gas adsorption measurements by MSB-based sorption analyzers. More than 15 MSB-based densimeters have been built to date; these are generally called two-sinker densimeter and single-sinker densimeter. They have produced highly accurate density data of many pure fluids and fluid mixtures. These data serve as the basis for the development of reference equations of state, which play an essential role in various industrial and scientific areas. Moreover, such systems are central to the metrology program of many countries. The MSB technique is also very successful in adsorption science: more than 85 MSB-based sorption analyzers have been set up in over 20 countries. The number of new MSB-based sorption analyzers, and peer-reviewed publications resulting from them, are both increasing exponentially since 2004. They have produced highly reliable gas adsorption data at high pressures for many applications, mainly in the energy and environmental sectors. Although further development of innovative instruments based on the MSB is threatened by the proprietary nature of MSB technology, the development will continue, e.g., toward cryogenic measurements and a more compact design. [ABSTRACT FROM AUTHOR]

Thermal conductivity is the only measurable parameter for a simple and restricted steady-state apparatus. To deeply explore monolithic silica aerogel's thermophysical properties, not limited to thermal conductivity, we developed a novel differentiable learning (DL) method to evaluate unsteady-state thermal insulation performance by inverse analyzing the hot surface temperature response. In this paper, the monolithic silica aerogel's temperature of hot surface is measured with limited probes, and then the thermal conductivity is obtained by Fourier's law at the steady state and small temperature differences (< 20 K). Further, the specific heat capacity is inversely deduced from the unsteady-state hot surface temperature at large temperature differences (> 100 K) through the inverse analysis of the Levenberg–Marquardt (LM) and DL methods. Herein, DL's predicted accuracy reaches the required measurement precision and keeps consistent with the LM's, but it improves 2–3 orders of magnitude in terms of computational speed, preferably adapted to the limited steady-state experimental method. The DL method is a potentially more powerful data-driven tool for inverse analysis and can be applied to complex circumstances, such as phase transition or erosion material. [ABSTRACT FROM AUTHOR]

This document is the editor's preface for a special issue of the International Journal of Thermophysics in honor of Professor Roland Span's 60th birthday. Professor Span is known for his work in thermophysical property research, particularly in the development of highly accurate equations of state for fluids and fluid mixtures. He has received numerous awards for his contributions to the field, including the Applied Energy Award and the SINTEF and NTNU CCS Award. The special issue includes 19 papers that cover various topics in thermophysics, showcasing the impact Professor Span has had on the field. The guest editors express their gratitude to the contributors and reviewers for their valuable contributions to the special issue. [Extracted from the article]