Calculation Of Thermodynamic Properties Research Articles

Investigation of cathode properties of two-dimensional NbS2Cl2 for Li and Na-ion batteries using density functional theory

Exploring novel two-dimensional materials (2D) for electrode and electrochemical storage applications stands as a pivotal pursuit in advancing renewable energy technologies. While recent research has predominantly focused on anode materials, cathode materials have received comparatively lesser attention. This study delves into the potential cathode applications of the novel two-dimensional material NbS2Cl2 using density functional theory. Fundamental properties, encompassing electronic and thermodynamic attributes, were scrutinized to comprehend the material’s characteristics. Our investigation extended to examining the adsorption and diffusion properties of these electrode materials. Comprehensive calculations of mechanical and thermodynamic properties reaffirmed the stability of this system. Upon adsorption of Li/Na atoms, the conducting nature emerged, evident through charge density difference and projected density of states. Our findings notably reveal minimal diffusion barriers of 1.5 eV and 0.35 eV for Li and Na atoms. Moreover, the observed open circuit voltages for adsorbed Li and Na ions were 4.69 V and 2.62 V, respectively. The calculated theoretical capacity for adsorbed Li-ion on 2D-NbS2Cl2 is 400 mAh g−1, while for Na-ion adsorption, it is 353 mAh g−1, awaiting validation through future experimental verifications.

Experimental Performance Comparison of High-Glide Hydrocarbon and Synthetic Refrigerant Mixtures in a High-Temperature Heat Pump

Several theoretical studies have predicted that refrigerant mixtures with glides of more than 20 K can yield COP improvements in heat pumps for operating conditions where the temperature difference between the heat source and heat sink is large, but experimental validations and quantifications are scarce. The application of high-glide mixtures (>20 K) in industrial heat pumps in the field is, therefore, still hampered by concerns about the behavior and handling of the mixtures. This study experimentally investigates hydrocarbon (HC) mixtures R-290/600 (propane/butane) and R-290/601 (propane/pentane) and compares them to previously tested mixtures of synthetic refrigerants. Comprehensive evaluations are presented regarding COP, compressor performance, pressure drop, heat transfer, and the possibility of inline composition determination. The mixtures were tested over a range of compositions at a source inlet temperature of 60 °C and a sink outlet temperature of 100 °C, with the heat sink and heat source temperature differences controlled to 35 K. R-290/601 at a mass composition of 70%/30% was found as the best mixture with a COP improvement of 19% over R-600 as the best pure fluid. The overall isentropic compressor efficiency was similar for HC and synthetic refrigerants, given equal suction and discharge pressures. Pressure drops in heat exchangers and connecting lines were equal for synthetic and HC mixtures at equal mass flow rates. This allows higher heating capacities of HC mixtures at a given pressure drop (mass flow rate) due to their wider vapor dome. A previously developed evaporator heat transfer correlation for synthetic refrigerant mixtures was applicable to the HC mixtures. A condenser heat transfer correlation previously fitted for synthetic refrigerants performed significantly worse for HC mixtures. Composition determination during operation and without sampling was possible with a deviation of at most 0.05 mass fraction using simple temperature and pressure measurements and REFPROP for thermodynamic property calculations. Overall, high-glide HC mixtures, just like mixtures of synthetic refrigerants, showed significant COP improvements for specific operating conditions despite a decreased heat transfer coefficient. Potential problems like composition shift or poor compressor performance were not encountered. As a next step, testing high-glide mixtures in pilot-plant installations is recommended.

Enhancement of the Lee–Kesler–Plöcker Equation of State for Calculating Thermodynamic Properties of Long-Chain Alkanes

Two optimization approaches to correct the physical limitations of the Lee–Kesler–Plöcker equation of state for the application to long-chain hydrocarbons are presented. The quality of the approaches is evaluated by comparisons with experimental data and reference equations of state. The calculation of thermodynamic properties for alkanes up to squalane is possible with both approaches, for some of which no highly accurate fundamental equation of state is available in the literature. For the first approach, the original parameter set was refitted with constraints guaranteeing correct behavior of the equation in the liquid state. The densities of long-chain hydrocarbons are reproduced with small deviations, while the results for some short-chain alkanes are worsened. For the second approach, existing Helmholtz energy equations of state are utilized, while keeping the linear interpolation scheme via the acentric factor. Significant improvements are achieved for all fluids considered.

First-principles calculations of electronic, vibrational, and thermodynamic properties of nitrogen-rich salt of 3,6-dinitramino-1,2,4,5-tetrazine [(DAG)2(DNAT)·H2O

In recent years, nitrogen-rich salts as green and efficient energetic materials have garnered widespread attention. This study focuses on a novel green synthesized salt, (DAG)2(DNAT)·H2O, which obtained through DNAT synthesis. Employing first-principles calculations, we conducted theoretical investigations to elucidate the electronic structure, vibrational, and thermodynamic properties of (DAG)2(DNAT)·H2O. Our computed lattice parameters align with experimental values from literature data. Analysis of the band structure and electronic states of atoms within the compound was performed. Vibrational modes for each peak in the infrared and Raman spectra were meticulously described, accompanied by phonon dispersion curves and phonon density of states plots for phonon contribution analysis. Thermochemical functions including enthalpy (H), heat capacity at constant volume (CV), Helmholtz free energy (F), Debye temperature (θ), and entropy (S) were computed based on vibrational characteristics, providing essential references for future research endeavors.

First principles calculations of structure, vacancy defects, thermodynamic and mechanical properties and near-infrared luminescence properties of Li2CaGeO4 and Er3+: Li2CaGeO4 crystals

Li2CaGeO4 and Er3+: Li2CaGeO4 crystals were successfully grown by TSSG method. The electronic structure, vacancy defects, near-infrared luminescence, thermodynamic stability, and mechanical properties of the crystals were characterized and analyzed by first principles calculation and experimental tests. The results show that Li2CaGeO4 and Er3+: Li2CaGeO4 crystals are typical wide-gap direct bandgap crystals (3.64 and 3.96 eV). The effect of two cationic vacancy defects on crystal properties was studied. The results show that the defects of O2− or Li+ vacancy leads to the change of band structure, and the coupling degree between conduction band and valence band is reduced, and the degree of hybridization is reduced. The probability of non-radiative transition increases greatly and the luminescence intensity decreases. Spectral tests show that the Er3+: Li2CaGeO4 crystal is an excellent laser crystal with a high near-infrared optical output at 1550 nm (4I13/2 → 4I15/2) and long fluorescence decay lifetime (5.804 ms). The thermal vibration and elastic constants of Er3+: Li2CaGeO4 crystal are calculated by simulation. The results show that Er3+: Li2CaGeO4 crystal is a kind of crystal material with easy processing, good brittleness, good thermal stability, and excellent thermal conductivity. Therefore, it has a very high application prospect in the field of laser or thermoelectric.

Vapor-liquid equilibrium and thermodynamic properties of saturated argon and krypton from Monte Carlo simulations using abinitio potentials.

Vapor-liquid equilibria and thermodynamic properties of saturated argon and krypton were calculated by semi-classical Monte Carlo simulations with the NpT + test particle method using abinitio potentials for the two-body and nonadditive three-body interactions. The NpT + test particle method was extended to the calculation of second-order thermodynamic properties, such as the isochoric and isobaric heat capacities or the speed of sound, of the saturated liquid and vapor by using our recently developed approach for the systematic calculation of arbitrary thermodynamic properties in the isothermal-isobaric ensemble. Generally, the results for all simulated properties agree well with experimental data and the current reference equations of state for argon and krypton. In particular, the results for the vapor pressure and for the density and speed of sound of the saturated liquid and vapor agree with the most accurate experimental data for both noble gases almost within the uncertainty of these data, a level of agreement unprecedented for many-particle simulations. This study demonstrates that the vapor-liquid equilibrium and thermodynamic properties at saturation of a pure fluid can be predicted by Monte Carlo simulations with high accuracy when the intermolecular interactions are described by state-of-the-art abinitio pair and nonadditive three-body potentials and quantum effects are accounted for.

Using maximum likelihood estimation approach to adjust parameters of CARTE thermochemical code.

AbstractUsing thermochemical codes to predict the properties of detonation products and the parameters for detonation modeling of explosives requires the use of very precise theoretical equations of state (EoS). We share the updates to the thermochemical code CARTE, which allows the calculation of thermodynamic properties and chemical compositions of detonation products over a wide range of temperatures and densities. In this paper, we focus on the theoretical EoS of pure fluids, based on the KLRR perturbation method and EXP‐6 potentials. We propose a maximum likelihood approach to fit the EXP‐6 parameters by matching a combination of shock data and static compression data. We present the results obtained on the detonation properties on nitric oxide.

Thermodynamic properties calculations of Cu‐based species

AbstractThis work focuses on the thermodynamic property calculations of seven copper‐based species, namely copper, copper oxide, copper hydroxide, copper nitrate, and copper hydroxide nitrate. The structures of these species were optimized to achieve stable geometries. The density functional theory (DFT) calculations were employed to obtain various thermodynamic properties such as entropy, enthalpy, Gibbs free energy, and heat capacity at constant pressure. A comparative investigation was performed on the temperature‐dependent behavior of key thermodynamic parameters. Species characterized by a higher quantity of atoms tend to demonstrate elevated thermodynamic properties. Copper and copper hydroxide nitrate had higher thermodynamic values than their oxides and other counterparts. It should be noted that the thermodynamic properties of copper hydroxide nitrate were newly computed, and the results showed that the thermodynamic values of the compound structure were higher than their crystalline counterparts. Moreover, due to the large structure size and solid phase, these thermodynamic values exhibited discrepancies with previously calculated computational and experimental values. The thermodynamic property values that depended on temperature were transformed into NASA 7‐Coefficient polynomials parameterization. The newly determined thermodynamic data and polynomials provide valuable insights into the thermodynamic behavior of copper‐based species. It will help better understand their surface sites and different crystalline structures. Such data can be used to better understand a variety of industrial processes, including combustion, gasification, chemical synthesis, and further to enhance efficiency, reduce costs, and minimize hazardous environmental emissions.

Neural Network Corrections to Intermolecular Interaction Terms of a Molecular Force Field Capture Nuclear Quantum Effects in Calculations of Liquid Thermodynamic Properties.

We incorporate nuclear quantum effects (NQE) in condensed matter simulations by introducing short-range neural network (NN) corrections to the ab initio fitted molecular force field ARROW. Force field NN corrections are fitted to average interaction energies and forces of molecular dimers, which are simulated using the Path Integral Molecular Dynamics (PIMD) technique with restrained centroid positions. The NN-corrected force field allows reproduction of the NQE for computed liquid water and methane properties such as density, radial distribution function (RDF), heat of evaporation (HVAP), and solvation free energy. Accounting for NQE through molecular force field corrections circumvents the need for explicit computationally expensive PIMD simulations in accurate calculations of the properties of chemical and biological systems. The accuracy and locality of pairwise NN NQE corrections indicate that this approach could be applicable to complex heterogeneous systems, such as proteins.

Modeling and Design of a Multistream Plate-Fin Heat Exchanger in the Air Separation Units by Pinch Technology

Recent years have seen considerable advancement in cryogenic technology. Air separation devices have used the cold box with heat exchanger plate-fin (PFHE) in numerous applications. Cryogenic technologies are used in many industrial processes to recover heat and reduce energy consumption. The multistream plate-fin heat exchanger (MSPFHE) is heavily utilized in the air separation plant’s (ASU) design. The plate-fin heat exchanger, one of the most important applications in the cryogenic industry, is the focus of the current investigation. The air entering this operation has been cooled by utilizing energy from streams originating from the distillation tower in the air separation unit (ASU) to reduce energy usage. The project aims to develop and create a multistream plate-fin heat exchanger (MSPFHE) that may be used in the cold box of an air separation unit practically and without limitations. The pinch technique, a method based on the usage of composite curves, was used in the creation of MSPFHE. With pinch technology, it is possible to divide a multistream exchanger into block portions that represent enthalpy intervals and identify the entry and departure sites for the streams. The correlations used in the MSPFHE thermal design model were first modeled and compared to earlier models as part of this effort. This model has been turned into MATLAB code and utilized in two case studies to yield acceptable results during the sizing step. Calculations of thermodynamic properties, heat transfer, pressure drop, choice of fin type, and final heat exchanger size were all part of the design of the MSPFHE. Finally, based on the software’s ability to reproduce the identical environmental conditions nature produces, the case study results have been validated using Aspen EDR. These findings were matched to findings from the literature and determined to be reliable and consistent.

Thermodynamic property calculation for pure component hydrogen isotopologues considering tritium processing technologies in fusion fuel cycle

In this study, the thermodynamic properties calculation methods for hydrogen isotopes are presented to be used in the process simulation of tritium handling processes in the fusion fuel cycle. To define appropriate temperature and pressure ranges for the calculations, applicable technologies of subsystems are investigated. Among various approaches, specific calculation methods and models for each property are suggested based on data gathered from a literature survey. Commonly used cubic equations of state, Peng-Robinson and Redlich-Kwong-Soave, are evaluated to ensure applicability in commercial simulation software. Hydrogen and deuterium data in the NIST REFPROP database are used as validation sets for proposed calculation approaches. The results show that Peng-Robinson and Redlich-Kwong-Soave equations of state have good agreement with NIST REFPROP in saturated liquid and gas states, as well as gas conditions up to 10 bar and 1000K. Finally, the proposed methods are applied to other isotopologues, and the trends of the properties are analyzed.

EOS-CG-2021: A Mixture Model for the Calculation of Thermodynamic Properties of CCS Mixtures

Thermodynamic properties for CCS-relevant mixtures can be calculated with the fundamental equation of state presented in this work over wide ranges of pressure, temperature, and composition for gas, liquid, and supercritical states, as well as for phase equilibria. The mixture model is formulated in terms of the Helmholtz energy and is based on the EOS-CG model of Gernert and Span (J Chem Thermodyn 93:274, 2016]. The new model presented here (EOS-CG-2021) is an update and extension of the previous version, and covers the following sixteen components: carbon dioxide, water, nitrogen, oxygen, argon, carbon monoxide, hydrogen, methane, hydrogen sulfide, sulfur dioxide, monoethanolamine, diethanolamine, hydrogen chloride, chlorine, ammonia, and methyl diethanolamine. Previously published elements of the model are summarized, and new elements are validated and analyzed with the use of comparisons to experimental data and by assessing the physical and extrapolation behavior of the equations. A comprehensive study on the representation of multicomponent mixture data was carried out to show the high accuracy and application range of the EOS-CG-2021.

A fast method for the calculation of refrigerant thermodynamic properties in a refrigeration cycle

Modeling and simulating dynamic and complex energy systems that are composed of a large number of components where every component model is described by mathematical equations can take high computational time. The calculation of the refrigerant thermodynamic properties has a big impact on the computational speed of the model. In an attempt to speed up simulations, two implementation methods for the calculation of refrigerants’ thermodynamic properties were investigated, the Coolprop thermodynamic equations of state and the Implicit fitting method. A complex dynamic cascade refrigeration cycle was developed and simulated using the two fluids implementation methods. The advantages and disadvantages of each method were discussed. The results show that using the implicit fitting method instead of Coolprop for the simulations of complex dynamic systems in Dymola will accelerate the simulation by about 30 times. In addition, the implicit method is accurate and offers more flexibility for modeling complex realistic energy systems.

Detailed kinetic mechanism for nitrocellulose low temperature decomposition

In the current investigation a detailed kinetic scheme of nitrocellulose (NC) is developed. Despite being studied for decades, NC did not have a detailed model yet. Thanks to Reaction Mechanism Generator open-source software a NC decomposition scheme has been generated. Optimizations of that model have been performed including intermediates thermodynamic properties calculations with Gaussian 16 at the B3LYP 6-31G(d,p) level of theory. Model reduction and decomposition computations were achieved with Chemkin-Pro. NC detailed mechanism has been optimized thanks to experimental data available in the literature, by slightly adjusting some rate constants of relevant chemical reactions. For instance, mean deviation of NO molar fraction is about 5.64% showing that the model follows the general trend of measured results. The final NC model consists in 62 species and 803 gas phase reactions. Eventually, NC and hexogen (RDX) models have been merged to predict overpressures obtained experimentally on a RDX-NC propellant. Numerical and experimental results have been confronted regarding the ignition temperature, initial pressure and surrounding gas nature. Computed results have been congruent when compared to experimental data, especially under argon atmosphere with an ignition temperature of 1173 K. Evidences from global trends indicate that the developed model can provide encouraging computations results for future research and investigations.

Observation and Thermodynamic Analysis of Reversible Fluid Isobars in Isolated Single Digit Nanopore Carbon Nanotubes

Recent interest in one-dimensionally confined fluids, where confinement approaches molecular dimensions, has demonstrated exceptionally high fluxes from slip flow and large distortions of fluid phase boundaries [1,2]. The Center for Enhanced Nanofluidic Transport (CENT) was recently formed as an intellectual hub for studying extreme fluid confinement in what we label Single Digit Nanopores (SDNs). To this end, in this work, we note that predicting such phenomena for a given conduit dimension has been confounded by a dearth of fundamental thermodynamic measurements and analysis as a function of confinement diameter and wall composition. Herein, we utilize Raman spectroscopy and carbon nanotubes with diameters less than 3 nm to identify and study newly observed, thermally driven, fluid adsorbed phases under conditions at constant ambient pressure, tracing what we label a fluid isobar as a function of temperature. We show that the Raman radial breathing(-like) vibrational modes (RBLMs) can serve as fluid sensors to trace the dependence of the fluid isobar and allow study of basic thermodynamics of fluid phase transition as a function of conduit curvature and confinement volume. We study fluids on the exterior and interior of double- and single- walled carbon nanotubes spanning 0.9 to 3.3 nm in diameter, showing that the fluid location can be disambiguated on double walled tubes by using an adaptation of elastic shell theory that allows deconvolution of inner and outer shell frequencies with fluid location. We find that the RBLM FWHM systematically changes as a unique signature of the location of the fluid phase near the CNT wall. A Buckingham potential is used along with electron diffraction assigned DWNT to provide a high accuracy estimate of the carbon-carbon coupling constant for two elastic shells, an important structural parameter for DWNT. The thermodynamic analysis of isobars measured for more than 25 CNTs under various environmental conditions is conducted by comparison to a new fluid equation of state that provides a continuum description of the fluid isobar under confinement. Our work sets forth a new and reliable approach for studying phase change of different fluids in large numbers of isolated single digit nanopores that may inform the refinement of fluid force fields and motivate theoretical refinements to the calculation of thermodynamic properties under confinement.[1] S. Faucher, N. Aluru, M. Z. Bazant, D. Blankschtein, A. H. Brozena, J. Cumings, J. Pedro De Souza, M. Elimelech, R. Epsztein, J. T. Fourkas, A. G. Rajan, H. J. Kulik, A. Levy, A. Majumdar, C. Martin, M. McEldrew, R. P. Misra, A. Noy, T. A. Pham, M. Reed, E. Schwegler, Z. Siwy, Y. Wang, M. S. Strano. Critical Knowledge Gaps in Mass Transport through Single-Digit Nanopores: A Review and Perspective. J. Phys. Chem. C 123, 21309–21326 (2019).[2] K. V. Agrawal, S. Shimizu, L. W. Drahushuk, D. Kilcoyne, M. S. Strano. Observation of extreme phase transition temperatures of water confined inside isolated carbon nanotubes. Nat. Nanotechnol. 12, 267–273 (2017)

Studies on synthesis, physicochemical properties, biological activities of two novel berberine-based salts with DL-mandelate and cinnamate anions

Berberine (BBR) is a natural quaternary isoquinoline alkaloid which is derived from the traditional Chinese medicine Coptis chinensis and exerts various pharmacological effects. However, low solubility in water has greatly limited its clinical application. This study prepared two novel berberine-based salts (berberine DL-mandelate ([BBR][MAN]) and berberine cinnamate ([BBR][CIN])) to improve the physicochemical properties and bioavailability of berberine. Many techniques, like 1H and 13C NMR, FTIR, ESI-MS, and thermogravimetric analyzes were utilized to characterize two salts. The solubility and octanol/water partition coefficient in water and simulated body fluids (simulated body, simulated intestinal and simulated gastric fluids) were determined. Self-aggregation behaviors of two salts in water have been investigated by conductometry at different temperatures. The obtained critical aggregation concentration (cac) was used for the calculation of various thermodynamic properties namely standard Gibbs energy change (ΔGm0), enthalpy change (ΔHm0), and entropy change (ΔSm0) in the aggregation progress. The volumetric properties including the infinite dilution apparent molar volumes (V2,φ0), infinite dilution apparent molar expansibility (Eφ0) and thermal expansion coefficient (β) for [BBR][MAN] were also determined to study its solvation behavior in aqueous solution. In addition, the antibacterial effect of two salts on three strains (Staphylococcus aureus, Bacillus subtilis and Candida albicans) was measured, and the minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were obtained. The results show that [BBR][MAN] has better antibacterial effect than [BBR][CIN]. The esterase-like activity assay demonstrated a decrease in enzyme activity of BSA in presence of two berberine-based salts. Cytotoxicity evaluation shows that two salts have potent in vitro anticancer activities against B16-F10 cancer cell lines.

Ab-Initio Calculations of Structural, Optoelectronic, Thermoelectric, and Thermodynamic Properties of Mixed-Halide Perovskites RbPbBr3−xIx (x = 0 to 3): Applicable in Renewable Energy Devices

In the present research work, we have examined the variations in the structural, electronic, optical, thermoelectric, and thermodynamic properties of mixed halide perovskites, RbPbBr3-xIx (x = 0 to 3) by utilizing the FP-LAPW approach in the WIEN2k code within the GGA-PBE for exchange-correlation functionals. The orthorhombic halides RbPbBr3-xIx are found to exhibit direct band gap semiconducting character with band gap between 2 and 3 eV, as consensus with available experimental and theoretical results for the RbPbBr3 and RbPbI3 compounds. The thermal stability of these materials are confirmed by the thermodynamic results obtained by Gibbs approximations. Moreover, optical parameters for RbPbI3 are higher than those for other halide perovskites; encouraging its use for photovoltaic applications. The thermoelectric parameters of these materials are investigated at 300, 600, and 900 K, which reveals that RbPbIBr2 is the most efficient for thermoelectric devices among the other investigated materials.

First-Principles Calculations of Structural, Elastic, Electronic, and Thermodynamic Properties of ATiO3 (A = Ba or Pb) Perovskites

First-Principles Calculations of Structural, Elastic, Electronic, and Thermodynamic Properties of ATiO3 (A = Ba or Pb) Perovskites

First-principles calculations of phase transition, elasticity, phonon spectra, and thermodynamic properties for ThO2 polymorphs

First-principles calculations based on density generalized function theory (DFT) were used to determine the structural transformation, phonon spectra, thermodynamic properties, and elastic behavior of ThO2 under compressive and tensile loading in this work. In compressive conditions, the transition pressures and calculation of structural parameters agree with the experiment results. Phase transitions of ThO2 from the Fm3‾m phase to the Pnma, P42/mnm and Pnnm phases under tensile conditions were anticipated to happen at 23.2 GPa, −7.69 GPa, and −7.75 GPa, respectively. Within the range of pressures analyzed, both the Fm3‾m and Pnma phases of ThO2 exhibit mechanical stability, but the P42/mnm phase and Pnnm phase are unstable at high pressures, according to the mechanical stability criteria, which is validated concerning elastic constants. Under ambient pressure, the calculated phonon spectra of the ThO2 polymorphs in this study demonstrate that all of the phases taken into consideration are dynamical stability. Also, the predicted heat capacities, isothermal bulk modulus, Gibbs free energies, and thermal expansion coefficients of ThO2 polymorphs as functions of temperature are analyzed and are in comparison with relevant experiments.

Application of Multiobjective Optimization in the Analysis of the Performance of Different Temperature Functions for a Generalized Cubic Equation of State

Since the emergence of van der Waals equation of state, several equations have been proposed to represent the behavior of pure compounds and mixtures, such as GEOS, which is a new generalized cubic equation of state form that employs a temperature function dependent on two or three adjustable parameters. Recently, multiobjective optimization has started to be applied in equations of state for parameters estimation, due to the conflicting nature of the objective functions. This methodology is attractive because it can be used to compare different models or variants of the same problem, through the trade-off analysis of the so-called Pareto front. In this context, the multiobjective PSO algorithm, based on the Pareto dominance principle, is used in this work for estimating the parameters of the generalized cubic equation of state, by fitting its results to synthetic experimental data of vapor pressure and saturated liquid volume. The performance of the new estimated parameters of the three temperature functions is investigated through the calculation of thermodynamic properties of interest in industry and academia. In addition, comparisons against real experimental data available in the literature are performed.