Search Results (178)

This study presents a comprehensive evaluation of miscible gas injection (MGI) strategies for enhanced oil recovery (EOR) in high-salinity reservoirs, with a focus on the Raleigh Oil Field. Using a calibrated Equation of State (EOS) model in CMG WinProp™, eight gas injection scenarios were simulated to assess phase behavior, miscibility, and swelling factors. The results indicate that carbon dioxide (CO₂) and enriched separator gas offer the most technically and economically viable options, with CO₂ demonstrating superior swelling performance and lower miscibility pressure requirements. The findings underscore the potential of CO₂-EOR as a sustainable and effective recovery method in pressure-depleted, high-salinity environments. Full article

For densities beyond nuclear saturation, there is still a large uncertainty in the equations of state (EoSs) of dense matter that translate into uncertainties in the internal structure of neutron stars. The MUSES Calculation Engine provides a free and open-source composable workflow management system, which allows users to calculate the EoSs of dense and hot matter that can be used, e.g., to describe neutron stars. For this work, we make use of two MUSES EoS modules, i.e., Crust Density Functional Theory and Chiral Mean Field model, with beta-equilibrium with leptons enforced in the Lepton module, then connected by the Synthesis module using different functions: hyperbolic tangent, generalized Gaussian, bump, and smoothstep. We then calculate stellar structure using the QLIMR module and discuss how the different interpolating functions affect our results. Full article

This study examines the equilibrium structure and stability of white dwarfs, incorporating both isotropic and anisotropic pressure distributions. The Tolman–Oppenheimer–Volkoff (TOV) equation is numerically solved using the Chandrasekhar equation of state (EoS) to analyze the effects of pressure anisotropy. A general anisotropy function is introduced to close and solve the system of differential equations. The results indicate that anisotropy remains negligible at the center and increases toward the stellar surface. Stability is assessed using the speed of sound criterion, $v_s^2=dp/d\rho$, and the Buchdahl bound, $2M/R<8/9$, confirming that white dwarfs remain within stability limits. We performed a sensitivity analysis to examine how variations in the anisotropy parameter ${\alpha }_0$ and central density affect the mass, radius, and compactness of white dwarfs. Additionally, we calculated the gravitational redshift at the stellar surface and found that it varies with anisotropy, ranging from $z_s\sim 3.15\times {10}^{-3}$ in isotropic cases to $z_s\sim 0.2\times {10}^{-3}$ in highly anisotropic models. These results link anisotropy to potentially observable features. The findings suggest that while anisotropy does not significantly affect the overall equilibrium structure, it may play a role in astrophysical scenarios involving strong magnetic fields, rotational deformations, or accretion processes in binary systems. Full article

A recently developed approach to the partition function with very high efficiency was applied to study the equation of state (EOS) of metal nickel (Ni) up to 3000 K and concurrently 500 GPa. The theoretical results agree very well with previous hydrostatic experiments at room temperature, and at high temperatures, the deviation of our calculated pressures from the latest hydrostatic experiments up to 109 GPa is less than 4.16%, 4.95%, and 5.53% at 1000, 2000, and 3000 K, respectively. Furthermore, an analytical EOS model with only two parameters was developed for common metals at high temperatures, and the analytical EOS of metal Ni was obtained to produce the map of pressure over the temperature–volume plane, which should be helpful to understand the thermodynamic properties of Ni-based alloys. Full article

Nanoporous material liquid systems (NMLSs) demonstrate promising potential for blast protection due to their high energy absorption density. This investigation numerically evaluated the use of NMLSs in mitigating blast effects on fiber–composite circular structures. The coupled Eulerian–Lagrangian method was employed to establish the numerical models of fiber alone, water–fiber, and NMLS–fiber, subjected to the internal close-field blast loading. The simulations focused on a widely studied NMLS, nanoporous silica particles immersed in distilled water. Four NMLSs, featuring varying particle-to-water ratios yet identical densities to that of water, were designed to modulate the energy absorption capacity while maintaining identical mass. These NMLSs were modeled by Equation of State (EOS) compaction. The dynamic responses of the fiber circles in the simulations were compared to evaluate the blast mitigation of different liquids. When the explosive mass was relatively small or medium, both the water and NMLSs exhibited blast mitigation. The NMLSs outperformed water because the energy absorption capacity caused a greater attenuation of blast pressure in the NMLSs. In the small-mass explosive cases, all four NMLSs could rapidly reduce the blast pressure to the infiltration pressure but their wave impedances decreased as the particle-to-water ratio increased, resulting in that a NMLS with greater energy absorption capacity, however, had inferior blast mitigation performance. When the explosive mass was relatively large, all the fiber circles experienced significant fiber failure and only the NMLS with the greatest energy absorption capacity exhibited blast mitigation. Full article

A solubility model of SO₂ in multi-ion electrolyte solutions has been developed by the activity-fugacity relation at vapor-liquid equilibria. The fugacity coefficient of SO₂ in the vapor phase is calculated by the equation of state (EOS) of pure SO₂, and the activity coefficient of SO₂ in the liquid phase is calculated by the Pitzer activity coefficient theory. The model can reproduce the reliable solubility data of SO₂ in pure water and multi-ion electrolyte solutions (Na⁺, K⁺, Cl⁻, ${\mathrm{SO}}_4^{2-}$) within or close to experimental uncertainties. Although the second-order and third-order interaction parameters between SO₂ and Mg²⁺ and Ca²⁺ have been adopted by an approximation, the solubility model can also be extended to predict the SO₂ solubility in seawater. In addition, combining with the EOS of a CO₂-SO₂ fluid mixture, the model can be used to predict the solubility of a CO₂-SO₂ mixture in aqueous electrolyte solutions. The calculated results are consistent with experimental data, which indicates that the solubility model has certain predictive ability. Full article

Shock-to-detonation transition (SDT) is the detonation of explosive charge triggered by the shock pressure from a nearby detonated explosive or an impact at high speed. A good prediction of SDT is a key in the design of explosives’ use, storage, and transportation. Typically, SDT simulation must use designated commercial software; therefore, a high license cost is necessary. This paper presents a simulation of SDT by a cost-effective hydrodynamic code developed on an open-source code framework, OpenFOAM. The code adopted the multi-material Eulerian method, Ignition and Growth reaction rate model, and Riemann solver to solve the shock-induced detonation phenomenon. The code was verified by a Pop plot calculation and a sympathetic detonation simulation. In the Pop plot calculation, the distance-of-run to the detonation of Composition B depending on the initial shock pressure was simulated. The reactant and product phases of Composition B were modeled by the Jone–Wilkins–Lee (JWL) equation of state (EOS). The aluminum plate used to create the initial shock pressure was modeled by shock Mie–Gruneisen (MG) EOS. The predicted distance-of-run against the initial shock pressure was in good agreement with an empirical correlation and experimental data. In the sympathetic detonation simulation, the charge explosive and nearby explosive were Composition B and were modeled by JWL EOS as in the Pop plot calculation and the plexiglass gap was modeled by MG EOS. The simulated critical gap for the sympathetic detonation was well predicted as in the other published data. This implies that the code is valid for SDT simulation. In addition, it is a cost-effective simulation, since the code was developed on open-source code, so massive computation can then be run without license costs. Full article

Equation of state (EoS) parameters of hexagonal close-packed iron (hcp-Fe), the dominant core component in large terrestrial planets, is crucial for studying interior structures of super-Earths. However, EoS parameters at interior conditions of super-Earths remain poorly constrained, and extrapolating from Earth’s core conditions introduces significant uncertainties at TPa pressures. Here, we compiled experimental static and dynamic compression data and theoretical data up to 1374 GPa and 12,000 K from the literature to refine the EoS of hcp-Fe. Using the third-order Birch–Murnaghan and Mie–Grüneisen–Debye equations, we obtained V₀ (unit-cell volume) = 6.756 (10) cm³/mol, K_T0 (isothermal bulk modulus) = 174.7 (17) GPa, $K_{T0}^{\prime }$ (pressure derivative of K_T0) = 4.790 (14), θ₀ (Debye temperature) = 1209 (73) K, γ₀ (Grüneisen parameters) = 2.86 (10), and q (volume-independent constant) = 0.84 (5) at ambient conditions. These parameters were then incorporated into an interior model of CoRoT-7b and Kepler-10b, which includes four solid compositional layers (forsterite, MgSiO₃ perovskite, post-perovskite, and hcp-Fe). The model yields the core mass fractions (CMF) of 0.1709 in CoRoT-7b and 0.2216 in Kepler-10b, suggesting a Mars-like interior structure. Extrapolation uncertainties (±10–20% in density) can change CMF by −12.6 to 21.2%, highlighting the necessity of precise EoS constraints at the super-Earth interior conditions. Full article

This research addresses the critical challenge of CO₂ capture by exploring innovative ways to avoid ethane (C₂H₆) co-absorption in natural gas sweetening operations. The solubility of Ethane (C₂H₆) was measured in three ionic liquids (ILs) with similar anions, 1-decyl-3-methyl imidazolium bis (trifluoro methylsulfonyl imide) [IL-1], 1-hexadecyl-3-methylimidazolium bis (trifluoro methylsulfonyl imide) [IL-2], and triethytetra-decyl ammonium bis (trifluoromethylsulfonyl imide) [IL-3]. The solubility experiments were investigated at 303.15 K and 343.15 K with pressures reaching 1.2 MPa. Among the ILs, [IL-2] exhibited the highest ethane absorption capacity due to its extended alkyl chain. The Peng-Robinson equation of state (PR-EoS) and three (3) distinct mixing rules provided robust correlations for the solubility data. Results demonstrate the inferior performance of [IL-1], [IL-2], and [IL-3] compared to Selexol/Genosorb 1753. The selectivity of Ethane (C₂H₆) over CO₂ was determined, with the overall selectivity ranking as follows: [IL-1] > [IL-3] > [IL-2]. A comparison of these selectivity values with published IL data indicated that these three ILs are most effective when used in applications targeting CO₂ capture in the absence of Ethane (C₂H₆), such as in the case of flue gas. They will most probably be used with an amine blend. Additionally, the Enthalpy and entropy of absorption provided valuable insights, demonstrating Ethane’s weaker interactions and lower solubility than CO₂. These findings emphasize the critical role of IL structure in determining ethane solubility and highlight the potential of customized ILs for optimizing gas-separation processes. Full article

The density dependence of nuclear symmetry energy $E_{\mathrm{sym}}\left(\rho \right)$ remains the most uncertain aspect of the equation of state (EOS) of supradense neutron-rich nucleonic matter. Utilizing an isospin-dependent parameterization of the nuclear EOS, we investigate the implications of the observational crustal fraction of the neutron star (NS) moment of inertia $\Delta I/I$ for the $E_{\mathrm{sym}}\left(\rho \right)$. We find that symmetry energy parameters significantly influence the $\Delta I/I$, while the EOS of symmetric nuclear matter has a negligible effect. In particular, an increase in the slope L and skewness $J_{\mathrm{sym}}$ of symmetry energy results in a larger $\Delta I/I$, whereas an increase in the curvature $K_{\mathrm{sym}}$ leads to a reduction in $\Delta I/I$. Moreover, the $\Delta I/I$ is shown to have the potential for setting a lower limit of symmetry energy at densities exceeding $3{\rho }_0$, particularly when L is constrained to values less than 60 MeV, thereby enhancing our understanding of supradense NS matter. Full article

For a new parameterization of the modified effective chiral model, developed primarily to regulate the density content of the symmetry energy and its higher order terms, equations of state (EoSs) for hyperon-rich matter (H) and delta baryon matter ($\Delta$) were obtained. The models were used to investigate the emission of gravitational waves (GWs) through f-mode oscillations in the corresponding neutron stars. We obtained the stellar structure, f-mode frequency and tidal deformability $\mathsf{\Lambda }$ for our models. We report that the $\Delta$ EoS is stiffer compared to the H EoS. We also analyzed the velocity of sound in these media. The corresponding mass–radius relationships were obtained and compared with various observations. We studied the dependence of f-mode frequencies on the stellar mass, redshift and tidal deformability. We employed the well known Cowling approximation to obtain the f-mode frequencies for $l=2,3$ and 4 modes of oscillation. We found that the f-mode frequencies of the H and $\Delta$ EoSs were almost the same in the lower mass region, while we observed a substantial difference between them in the high-mass region. We also obtained an empirical relation for the EoSs considered. The various attributes obtained for our models showed close agreement with various observational constraints from pulsars and GW events. Full article

Seismic isolation and damping technologies, though extensively used in buildings, are less common in large hydraulic structures, underscoring the importance of researching seismic mitigation methods for these constructions. This research first establishes that saturated sandy soil can act as a damping material through experimental and theoretical analysis. Subsequently, a novel hollow concrete gravity dam containing saturated sandy soil is proposed, utilizing the EOS (equation of state) subroutine for viscous fluids to model the liquefied sand. The findings indicate that the new-type dam exhibits a reduction in displacement of approximately 20% along the flow direction under an 8-degree seismic event compared to conventional gravity dams. This decrease correlates inversely with the characteristic wave speed of the saturated sandy soil, while the energy dissipation capacity of the saturated sandy soil is directly proportional to the soil layer’s thickness. Finally, a small-scale shaking table test revealed that saturated sandy soil effectively reduces displacement and acceleration at the dam crest. These findings were corroborated by numerical simulations, which further substantiated the reliability of both the experimental and simulated data. Utilizing saturated sandy soil for energy dissipation and seismic damping in dams offers cost benefits, high durability, and significant effectiveness, representing a promising direction for the advancement of seismic mitigation in concrete gravity dams. Full article

Steam reforming is an important industrial process for hydrogen production. Acetone, the by-product of phenol production from cumene peroxidation, is a useful source of hydrogen due to its availability and low value compared to hydrogen fuel. This study aimed to utilize the Gibbs free energy minimization method using the Soave–Redlich–Kwong (SRK) equation of state (EOS) to conduct a thermodynamic analysis of the steam reforming process for pure component acetone. The steam reforming process is temperature dependent, with increasing temperatures leading to higher hydrogen production. Competing reactions, particularly the exothermic reverse water–gas shift, impact hydrogen yields beyond 650 °C. The study identified 600 °C as the optimum temperature to strike a balance between maximizing hydrogen production and minimizing the reverse water–gas shift’s impact. The optimal hydrogen yield (70 mol%) was achieved at a steam-to-oil ratio (STOR) of 12. High STOR values shift the equilibrium of the water–gas shift reaction towards hydrogen production due to increased steam, effectively consuming acetone and favoring the desired product. Atmospheric pressure is optimum for hydrogen production because the equilibrium of gas phase reactions shifts in favor of the lighter components at lower pressures. Full article

In this paper, we find several teleparallel $F(T,B)$ solutions for a Robertson–Walker (TRW) cosmological spacetime. We first set and solve the $F(T,B)$-type field equations for a linear perfect fluid. Using similar techniques, we then find new $F(T,B)$ solutions for non-linear perfect fluids with a weak quadratic correction term to the linear equation of state (EoS). Finally, we solve for new classes of $F(T,B)$ solutions for a scalar field source by assuming a power-law scalar field and then an exponential scalar field in terms of the time coordinate. For flat cosmological cases ($k=0$ cases), we find new exact and approximate $F(T,B)$ solutions. For non-flat cases ($k=\pm 1$ cases), we only find new teleparallel $F(T,B)$ solutions for some specific and well-defined cosmological expansion subcases. We conclude by briefly discussing the impact of these new teleparallel solutions on cosmological processes such as dark energy (DE) quintessence and phantom energy models. Full article

With the continuous exploitation of offshore natural gas, the content of CO₂ produced gradually increases. It is not economical to separate more CO₂ from natural gas after transportation, and more CO₂ will aggravate the corrosion of pipelines. The commonly used decarburization process is not suitable for offshore platforms, and there are problems of high energy consumption and large space occupation. Therefore, dense phase separation of associated gas with high carbon dioxide content is a better separation method. In this paper, the equation of state is optimized by comparing the experimental and CO₂ system phase characteristics simulation. Based on the selected equation of state (EOS), a three-level separation model of phase equilibrium characteristics is established. The separation efficiency is simulated to complete the separation of CO₂ and methane. The separation process is optimized by a genetic algorithm, and the temperature and pressure under the best separation efficiency are determined. The PR-EOS was selected as the equation with the highest calculation accuracy. Through process simulation and algorithm optimization, the best separation efficiency was 72.23%. Full article