We compiled an experimental database for the surface tension of binary mixtures containing a wide variety of fluids, from the chemical classes (water, alcohols, amines, ketones, linear and branched alkanes, naphthenes, aromatics, refrigerants, and cryogens). The resulting data set includes 65 pure fluids and 154 binary pairs with a total of 8205 points. We used this database to test the performance of a parachor model for the surface tension of binary mixtures. The model uses published correlations to determine the parachors of the pure fluids. The model has a single, constant binary interaction parameter for each pair that was found by fitting experimental mixture data. It can be also used in a predictive mode when the interaction parameters are set to zero. We present detailed comparisons on the performance of the model for both cases. In general, the parachor model in a predictive mode without fitted interaction parameters can predict the surface tension of binary mixtures of non-polar mixtures such as linear and branched alkanes, linear and branched alkanes with naphthenes, aromatics with aromatics, aromatics with naphthenes, and mixtures of linear alkanes of similar sizes with an average absolute percentage deviation of about 3 % or less. Polar mixtures of halocarbons with other halocarbons and also polar/nonpolar mixtures of alkanes with halocarbons could be modeled with an average absolute deviation of less than 0.35 mN·m−1 with the use of a binary interaction parameter. The parachor model even with a fitted binary interaction parameter performs poorly for mixtures of water and organic compounds and is not recommended.

In this report, the design specifics, and performance modeling results, for a simple, solid metal block, liquid–liquid cross-flow heat exchanger, intended for high temperature applications, are given. The design consists of a solid block of metal, with cylindrical channels providing the cross-flow passageways for two non-mixing liquids. In this design, all flow channels are separated by a certain minimum thickness of the host solid block material. This particular design is limited by the length of pores that can be machined from a solid block. In this study, a simple heat transfer model, appropriate for such an exchanger, was used to estimate what values of effectiveness might be obtainable while keeping the size of the exchanger as compact as possible. The effects of channel length and spacing, liquid specific heat and viscosity and block material conductivity on exchanger effectiveness are considered and results reported. The model predicts that for a cubic exchanger of side length 8.25 cm with 50 channels per side at a diameter of 3.0 mm each, for a particular high temperature situation using molten salts, with an inlet and outlet temperature difference of around 170 K, an effectiveness of 0.4 can be achieved with a total mass flow rate of 0.5 kg\(\cdot\)s\(^{-1}\) along with a Reynolds number of less than 2000.

This study aims to establish a general-purpose thermal conductivity measurement method that can take into account the effect of heat loss under atmospheric conditions for measuring the effective thermal conductivity of lattice structures, and to clarify the effective thermal conductivity of lattice structures with different wire diameters. In this paper, calculations by finite element method and measurements using steady state comparative-longitudinal heat flow method and modified temperature profile method were performed to clarify the effective thermal conductivity of the five truncated octahedron unit-cell lattice structures with different wire diameters fabricated by additive manufacturing. The modified temperature profile method is developed to take into account the effect of interfacial thermal resistance in the measurement apparatus. The effective thermal conductivity measured using the steady state comparative-longitudinal heat flow method and calculated with finite element method analysis showed good agreement, confirming that the effective thermal conductivity is strongly dependent on the wire diameter. The effective thermal conductivity obtained by the modified temperature profile (MTP) method was 3 % to 24 % smaller than that obtained by the steady state comparative-longitudinal heat flow method, and the measurement was able to take heat loss into account more concretely. Furthermore, measurements using the MTP method enabled us to obtain reasonable values for the ratio of heat loss in each section, the fin efficiency of the sample, the heat transfer coefficient to the surroundings, and the interfacial thermal resistance between the rods and the sample.

A solar air heater is an effective way to heat air and has applications in heating rooms, drying crops, vegetables and seasoning timber. This study conducted an experiment to evaluate the impact of different slant angles (30°, 45°, 60°) and mass flow rates (0.040 kg·s−1, 0.045 kg·s−1, 0.052 kg·s−1) of fins on the thermal efficiency of finned plate solar air heaters. A Finned Plate Solar Air Heater (FPSAH) system with an inclined fin array was developed and tested for thermal efficiency. An array of fins with different slant angles was attached to the rear of the absorber plate to improve heat transfer and thermal efficiency. Results showed that the thermal efficiency increased as the slant angle decreased, with the highest thermal efficiency (70 %) and outlet temperature (58.66 °C) achieved at a slant angle of 30° and mass flow rate of 0.052 kg·s−1. The FPSAH system uses inclined fins to increase solar energy absorption and generate high air temperatures at the outlet. It performs better thermally compared to a solar air heater with a flat plate.

Enhancing the boiling efficiency helps improve the productivity of thermal systems. Given the effects of added nanoparticles and applied magnetic field on the boiling process, this study investigates the effects of nickel oxide (NiO) nanoparticle concentration with and without applied magnetic field. The studied nanofluid was synthesized by the two-step method and approved by TEM and DLS stability tests for resistance to flocculation. Five concentrations of nanofluid, namely 0.005, 0.01, 0.05, 0.1, and 0.2), were prepared using nanoparticles with an average size of 30 nm. Moreover, a DC magnetic field with a maximum current of 10 A and a strength of 1000 G in the metal core and 300 G at the center of the core was used to evaluate the effects on nanoparticle boiling. The boiling heat transfer coefficient (BHTC) of deionized (DI) water was then compared with a plot of the Rohsenow correlation in three regions to validate the results and showed remarkable consistency. Moreover, experimental data indicated that the magnetic field affected the shape of DI water bubbles during boiling while improving the fluid’s BHTC. It was also found that a 0.005 volume fraction of added NiO nanoparticles results in an average 35 % improvement, whereas at the 0.2 volume fraction, increased sedimentation drastically impacts the BHTC. The magnetic field improved the BHTC by nearly 10 % at a 0.005 volume fraction, while higher concentrations reversed the effects of the magnetic field. By hindering bubble generation, nanoparticle sedimentation on surfaces also drastically affects the BHTC.

In this study, the speeds of sound were measured in binary liquid mixtures of methyl oleate and either n-hexane or n-decane at temperature T = 303.15 K and pressures ranging from 0.1 MPa to 70 MPa. The data obtained from these measurements were used to calculate the excess speed of sound for these mixtures. The speed of sound molecular weight product, raised to a constant power \(\gamma\) was also calculated and represented as a function of molar percentage. This was done in order to determine a simple combining rule for representing the speed of sound of mixtures composed of n-alkanes and fatty acid alkyl esters.

The many constrains introduced by the F-gas Regulation and the Kigali Amendment to the Montreal Protocol have resulted in an intense search for alternatives to fluorinated greenhouses gases for air conditioning and refrigeration purposes (Mota-Babiloni A, Makhnatch P, in Int J Refrig 127:101–110, 2021). With respect to the urge of new low-GWP and low-ODP refrigerants, blends composed of hydrofluoroolefins (HFO) are considered promising possible substitutes to hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) for HVAC&R applications (Sovacool et al., in Renew Sustain Energy Rev 141:110759), but thermophysical properties data for these blends are still scarce (Bell et al., in: J Chem Eng Data, 2021). In the present study, the vapor–liquid equilibrium (VLE) for the binary system (HFO-1243zf + HFO-1234yf), for which just one set of data on the VLE is available to date in literature, has been experimentally studied by means of a vapor recirculation apparatus. The measurements have been performed at isothermal conditions in the range of temperatures between 283.15 K and 323.15 K, while the composition of both the phases in equilibrium has been measured by gas-chromatographic analysis. The experimental VLE data have been correlated by two different equations of state (EoS): the Peng-Robinson (PR) EoS combined with Mathias–Copeman (MC) alpha function and van der Waals (vdW) mixing rules, and the Helmoltz EoS with dedicated binary interaction parameters. Correlated results showed a good agreement with the experimental data for the binary system.

Nucleation and growth are phenomena that can be applied to several fields of science and technology. On the other hand, nucleation depends on the cooling rate, dislocating the equilibrium, as surface energy depends on the created and deformed surface area. The crystalline/glassy transition limit dependence on the thermal gradient is also analyzed. In this paper, under continuum mechanics, first and second-order nonequilibrium nucleation formulation models are derived, and a phase-change moving interface is considered in the thermal field. Important nucleation variables are plotted against the cooling rate for several nucleation angles. It is coupled with a theoretical model for the molar-specific heat capacity of solids to analyse its dependence on nucleation kinetics.

AbstractBased on the root–coefficient relations for a cubic function, quadratic functions are constructed that strictly relate the saturated volumes of liquid and vapor phases and the third solution from a cubic equation of state (EoS). The vapor–liquid equilibrium (VLE) calculation with a cubic EoS is thus reduced to solving a single nonlinear equation. In light of a recent finding that the “unphysical” third solution, namely the Maxwell crossover or the M-line, plays a central role as the dividing interface in the density gradient theory, here we show that it can also be used to derive explicit approximations for a VLE problem. The van der Waals EoS and the Soave–Redlich–Kwong (SRK) EoS are discussed as examples. The method proposed in this work simplifies the calculations of the traditional VLE problem with a cubic EoS. With one-time-only effort for a given system, simple explicit approximations can be obtained to avoid the repetitively iterative computations for a VLE problem. Finally, the relationship between the Widom line in the supercritical region and the M-line is briefly discussed with the SRK EoS. Graphical Abstract

Equilibrium mole fraction solubility of salicylic acid in nine aqueous-ethanolic mixtures, as well as in neat water and neat ethanol, was determined at seven temperatures from T = (293.15 to 323.15) K. Salicylic acid solubility in these mixtures was adequately correlated with well-known correlation/prediction methods based on Jouyban-Acree model. Apparent thermodynamic quantities, i.e. Gibbs energy, enthalpy, and entropy, for the dissolution and mixing processes, were computed by means of the van’t Hoff and Gibbs equations. The enthalpy–entropy compensation plot of enthalpy vs. Gibbs energy of dissolution was not linear exhibiting positive slopes from neat water to the mixture of w1 = 0.30 and from the mixture of w1 = 0.50 to neat ethanol indicating enthalpy-driven drug transfer processes but negative in the interval of 0.30 < w1 < 0.50 indicating entropy-driven drug transfer processes from more polar to less polar solvent systems. Moreover, by using the inverse Kirkwood–Buff integrals it is observed that salicylic acid is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in those mixtures of 0.24 < x1 < 1.00.

This paper presents new wide-ranging correlations for the viscosity and thermal conductivity of 1-hexene based on critically evaluated experimental data. The viscosity correlation is valid from the triple point to 580 K and up to 245 MPa pressure, while the thermal conductivity is valid from the triple point to 620 K and 200 MPa pressure. Both correlations are designed to be used with a recently published equation of state that extends from the triple point to 535 K, at pressures up to 245 MPa. The estimated uncertainty (at a 95 % confidence level) for the viscosity is 2 % for the low-density gas (pressures below 0.5 MPa), and 4.8 % over the rest of the range of application. For thermal conductivity, the expanded uncertainty is estimated to be 3 % for the low-density gas and 4 % over the rest of the range.

R-1132a is increasingly being considered as a low global warming potential component in alternative mixtures to R-23 in specialized low temperature and ultra-low temperature refrigeration systems. Though the thermodynamic properties of R-1132a were investigated in several studies up to 2018, reinvestigations have been carried out in recent years. In order to contribute toward these renewed measurements, the critical parameters of R-1132a were experimentally re-determined. Thirty-two vapor pressures from 240 K to the critical temperature, fifteen saturated vapor and six saturated liquid densities above 254 K and the PvT properties in both the vapor phase (98 points) and liquid phase (34 points) from densities of 50 kg·m−3 to 760 kg·m−3 were also measured. Specific correlations for each of these properties were optimized and compared to previously available data from the literature. Additionally, the Peng–Robinson equation of state was used to represent the aforementioned properties and further utilized to determine the enthalpy and entropy of R-1132a.

The axial thermal conductance of a cylindrical cavity supporting the propagation of hybridized guided modes along its interface with SiO\(_2\) is quantified and analyzed as a function of its radius and mean temperature. In contrast to the well-known radial thermal conductance, we show that the axial one increases with the cavity radius up to 1 cm, in which it takes its maximum that increases with temperature. A maximum thermal conductance of 289.4 nW·K−1 is found at 500 K, which is more than 3 orders of magnitude higher than the corresponding one found in the far-field regime. This top polariton thermal conductance along the cavity is comparable to the radiative one predicted by Planck’s theory and thus represents a fundamental heat transport channel driven by hybridized guided modes able to amplify heat currents along a macroscale cylindrical cavity.

An integrating sphere that yields uniform and intense radiance is needed for the spectral radiance responsivity calibration of absolute radiation thermometers. However, such an integrating sphere is difficult to realize owing to the common trade-off between spatial uniformity and throughput. Typically, the smaller sphere yields the higher throughput but worse uniformity. This paper reports a considerably uniform integrating sphere despite its small size. First, we introduce a simple approach, based on the perfect Lambertian diffuse reflection theory and the measured bidirectional reflectance distribution function of polytetrafluoroethylene (PTFE), for estimating the spatial uniformity of a 50 mm-diameter, pressed PTFE integrating sphere as a function of the incidence angle of an external light source. Based on the estimated results, we made an integrating sphere with \(45^\circ\)-incidence angle. This sphere showed the spatial uniformity of ± 0.01 % within 5 mm in diameter and the angular uniformity of ± 0.005 % over an angular range of ± \(1.58^\circ\). To the best of our knowledge, the \(45^\circ\)-incident integrating sphere with a diameter of 50 mm introduced in this study is the best design for obtaining a uniform and intense light source suitable for measuring the spectral radiance responsivity of an absolute radiation thermometer among the integrating spheres reported thus far.

AbstractPhase equilibrium data (\(p\), \(T\), \(y\)) for the binary systems of carbon dioxide + dimethyl carbonate and carbon dioxide + ethyl methyl carbonate were obtained. All systems were measured for isotherms ranging from 298.2 K to 328.2 K with pressure ranging between 0.13 MPa and 10.6 MPa. A static equilibrium technique was established with samples quantified using an offline method. The results were modeled using the Peng–Robinson equation of state with van der Waals one-fluid mixing rules.Graphical Abstract

To make more accurate predictions of the effective thermal conductivity (ETC) of the composites, a systematic method for predicting the effective thermal conductivity of metal matrix particle composites with arbitrarily shaped particles was proposed, and the geometry of random particles with controlled shape characteristics is reconstructed. In addition, the geometric vertices of the reconstructed particles are used to characterize the morphology of inclusions with complex profile in two-dimensional isotropic elasticity, and its explicit expression for the Eshelby tensor are explored. Moreover, the material mismatch between the particles and the matrix phase is simulate using a continuously distributed source field based on the Eshelby's equivalent inclusion method. The relationship between micro-structure and effective performance is established. Finally, the effective thermal conductivity of CuCr alloys was predicted using the ETC prediction model. Through the comparison of the numerical simulations, experiments, and calculations, the results show that the ETC model has reliable predictive capability.

Hydrofluoroolefins (HFOs) are a category of environmentally friendly refrigerants. The transport properties such as viscosity and thermal conductivity of pure HFOs and HFO/HFC mixtures are essential for the investigation of flow and heat transfer characteristic of fluids. Therefore, it is necessary to provide the viscosity and thermal conductivity calculation method of HFOs and HFO/HFC mixtures. In this work, the viscosity and thermal conductivity models of HFOs including R1234yf, R1234ze(E), R1234ze(Z), R1243zf, R1336mzz(Z), and R1336mzz(E) were established based on the friction theory (FT) and Peng–Robinson (PR) equation of state, and the overall ARD between the experimental values and those calculated from the model is 1.6% and 2.0%, respectively. The viscosities and thermal conductivities of HFO/HFC mixtures were predicted using mixing rule and the established FT model. Results show that the established FT model has good predictive ability for the viscosity and thermal conductivity of HFO/HFC mixtures.

The rapid latent heat transfer in boiling heat transfer directs its potential use in a variety of heat transfer devices. A new four-step electrodeposition technique is recommended for the development of the micro–nanostructured surface of Cu–Al2O3 nanoparticles (higher thermal conductive) to increase pool boiling heat transfer performance. The nanoparticles deposited at lower current density have increased the nucleation density and the two-step sintering has improved the physical properties of deposited nanoparticles. Thus, apart from cost effectiveness, reliability, and simplicity, the electrodeposition method is able to provide more stable micro–nanostructured surface. Therefore, the method offered in this work is a proficient method for the development of micro–nanostructured surfaces. After carrying out the surface characterization of structured surfaces, the boiling heat transfer performance is studied through experimentations. The influence of different parameters on pool boiling heat transfer (PBHT) enhancement is also analyzed. Based on the study of the achieved results, it is inferred that the fabricated micro–nanostructured surfaces are uniform in structure, achieve higher critical heat flux (92 %), and PBHT coefficient (6.1 times). Thus, the proposed heating surfaces may be considered as a prospective candidate for the cooling of microelectronics devices.

A multitude of industries, including energy and process engineering, as well as academia are researching and utilizing new fluid substances to further the aim of sustainability. Knowledge of the thermodynamic properties of these substances is a prerequisite, if they are to be utilized to their fullest potential. To date, the way to acquire reliable knowledge of the thermodynamic behavior is through measurements. The ensuing experimental data are then used to develop equations of state, which efficiently embody the gained knowledge of the behavior of the fluid substance, allow for interpolation and, to some extent, extrapolation. However, the acquisition of low-uncertainty experimental data, and thus the development of accurate equations of state, is often time-consuming and expensive. For substances for which suitable force field models exist, molecular modeling and simulation are well-suited to generate thermodynamic data or to augment experimental data, however, at the expense of larger uncertainties. The major goal of this work is to present a new approach for the development of equations of state using (1) symbolic regression, which is a machine learning based model development approach, (2) optimal experimental design, and (3) efficient data acquisition. We demonstrate this approach using the example of density data of an air-like binary mixture (\(0.2094\,\hbox {O}_{2}\,+\,0.7906\,\hbox {N}_{2}\)) over the temperature range from \({100}\,{\textrm{K}}\) to \({300}\,{\textrm{K}}\) at pressures of up to \({8}\,{\textrm{MPa}}\), which covers the gaseous, liquid, and supercritical regions. For this purpose, an experimental data set published by von Preetzmann et al. (Int. J. Thermophys. 42, 2021) and molecular simulation data sampled in this work are used. The two data sets are compared in terms of acquisition time, cost, and uncertainty, showing that an optimized combination of experimental and simulation data leads to lower cost while maintaining low uncertainties.

It is of much interest to study the heavy hydrocarbon impact on the phase behavior of hydrocarbons. Using a method of the precision adiabatic calorimetry the phase equilibria in quaternary mixtures of methane, propane, octane, and nonane have been studied. The phase diagrams for investigated mixtures have been plotted based on the experimental data. The phase transitions were localized by the finite discontinuities in temperature derivatives of the thermodynamic potentials. The heat capacity, internal energy, pressure, and temperature derivative of pressure at constant volume were measured in the range 170–320 K, up to 40 MPa. Quaternary mixtures as quasi-binary mixtures are presented. The first quasi-component of the quasi-binary mixture is the binary mixture with the constant methane/propane ratio. The second quasi-component of the quasi-binary mixture is the binary mixture of octane and nonane. Investigated hydrocarbon system is the combination of the simple hydrocarbon mixtures for the low concentration of octane and nonane. In the earlier papers we presented the simple hydrocarbon mixtures for the low concentration of octane, nonane, and decane, and quaternary mixtures of methane, propane, octane, and decane for the low concentration of octane and decane, which are the combination of the simple hydrocarbon mixtures for the low concentration of octane and decane. Our investigations show that quaternary hydrocarbon mixture for the low concentration of octane and nonane as well as the simple hydrocarbon mixtures for the low concentration of octane, nonane, and decane split into three phases, the macrophase composed of methane, propane, octane, and nonane, and two microphases formed by octane and nonane. In this system octane and nonane dissolved in the macrophase partly. Besides, the heavy components provoke a split of the liquid part of the quaternary mixture into two liquid phases.