Thermodynamic Simulation Research Articles

Compositional diversity of TTGs controlled by heterogeneous accumulation of accessory minerals

The compositional diversity of Archean tonalite-trondhjemite-granodiorite (TTG) rocks is generally attributed to partial melting of mafic rocks at various depths or magmatic differentiation driven by the accumulation of plagioclase and/or amphibole. Our investigation of the approximately 130 km2 Paleoarchean Stolzburg pluton in the Barberton area of South Africa reveals a substantial compositional variability that cannot be explained by those processes. The variable Sr/Y and La/Yb ratios can correspond to high-, medium-, and low-pressure types based on pressure-dependent classification criteria, thus conflicting with partial melting simulations and ruling out the model of variable melting depths for such a small, single pluton. Instead, an integrated study incorporating petrographic analysis, mineral mapping, and thermodynamic simulation suggests that the heterogeneous accumulation of accessory minerals during crystal-melt separation in the magma chamber is the leading cause of the compositional variation of the ca. 3.45 Ga TTG pluton. This study highlights the critical role of accessory minerals in intrinsic magmatic differentiation within individual TTG plutons and advise caution when using bulk-rock compositions of TTGs to infer melt physochemical conditions and tectonic settings.

Exploring the taste presentation and receptor perception mechanism of salty peptides from Stropharia rugosoannulata based on molecular dynamics and thermodynamics simulation

The taste presentation and receptor perception mechanism of the salty peptide of Stropharia rugosoannulata were predicted and verified using peptide omics and molecular interaction techniques. The combination of aspartic acid (D) and glutamic acid (E), or peptide fragments composed of arginine (R), constitute the characteristic taste structural basis of salty peptides of S. rugosoannulata. The taste intensity of the salty peptide positively correlates with its concentration within a specific concentration range (0.25–1.0 mg/mL). The receptor more easily recognizes the first amino acid residue at the N-terminal of salty peptides and the aspartic acid residue in the peptides. GLU513, ASP707, and VAL508 are the critical amino acid residues for the receptor to recognize salty peptides. TRPV1 is specifically the receptor for recognizing salty peptides. Hydrogen bonds and electrostatic interactions are the main driving forces for the interactions between salty peptides and TRPV1 receptors. KSWDDFFTR has the most potent binding capacity with the receptor and has tremendous potential for application in sodium salt substitution. This study confirmed the taste receptor that specifically recognizes salty peptides, analyzed the receptor-peptide binding interaction, and provided a new idea for understanding the taste receptor perception of salty peptides.

Combining thermodynamic modeling and experiments to characterize the effect of ceramic polishing powder in cement-based materials

Ceramic polishing powder (CPP), a by-product of ceramic tile production, has the potential to prepare building materials. While the hydration and thermodynamic properties of CPP remain largely unexplored, thereby limiting its widespread application. This study utilized R3 tests to demonstrate that CPP exhibits pozzolanic activity comparable to that of fly ash. Then it analyzed the effects of substituting 10–20 % of cement with CPP on the hydration products, microstructure, and mechanical properties of composite materials, utilizing a synergistic approach that combines thermodynamic simulations with experimental investigations. The findings showed that adding CPP does not generate new crystalline products but enhances the formation of C-S-H through the pozzolanic reaction, which consumes calcium hydroxide. However, adding over 25 % CPP significantly lowered the pH of the pore solution, altering hydration products and causing volume contraction. In addition, CPP improved the microstructure at later ages, particularly by increasing micropores, leading to enhanced mechanical properties at 28 and 90 days. For instance, at a w/b ratio of 0.5, the 90 days compressive strengths of composite mortars CPP10, CPP15, and CPP20 were recorded at 67.0 MPa, 63.3 MPa, and 65.1 MPa, respectively. These values represented increases of 17.3 %, 10.9 %, and 14.0 % over the control group (57.1 MPa). Conversely, this also resulted in increased autogenous shrinkage due to higher capillary pressure. Notably, the 6 days shrinkage of CPP15 and CPP20 was about 50 % higher compared to that of the pure cement mortar. These findings highlight the necessity of balancing CPP content for optimal performance.

The Role of Latent Heat Buffering in the Generation of High-Silica Rhyolites

Abstract The physical process of crystal-melt separation is responsible for the accumulation of small to very large volumes (>100 km3) of eruptible rhyolitic melt in the shallow crust. Granitic intrusions, although providing a terminal, time-integrated image of melt segregation processes, host an unmatched record of the physical properties controlling mechanisms and rates of interstitial melt extraction from a crystal-rich source. We applied mass balance calculations and thermodynamic modeling simulations to an extensive bulk rock geochemistry dataset (>150 samples) collected in a Permian upper-crustal granitoid intrusion of the Italian Southern Alps. Textural and geochemical evidence indicate that this intrusion constituted a single, zoned magma body, with a crystal-rich base and a thick (~2 km), high-silica cap (75–77 wt% SiO₂). The large compositional variability of the crystal-rich materials suggests variable degrees of melt extraction efficiency and corresponding terminal porosities. Specifically, the loosely bimodal distribution of porosity values (φ) indicates that at least two distinct melt segregation mechanisms were operating in this system, which produced both high (0.65–0.45) and low terminal porosities (0.45–0.25) in the crystal-rich, cumulate materials. Modeling of latent heat budget shows that coexistence of cumulate products with differing terminal porosity signature can be explained by melt segregation processes taking place at different depths across a thick, interconnected magmatic reservoir with an initial homogenous water content (~4 wt% H2O). Deep in the mush column, low water activities (aH₂O < 0.5) promoted thermal buffering of cooling magma at high crystallinities, enabling residual melt extraction by percolation through a crystalline framework accompanied by compaction. Instead, at shallower depths, high water activities (aH₂O > 0.5) ensured prolonged magma residence at porosities that promoted crystal melt separation via hindered settling. Distinct melt extraction processes, acting synchronously but at different depths in vertically extensive silicic mush columns, can account for the large volumes of residual, haplogranitic melt mobilized during the relatively short lifespan of upper crustal magma reservoirs (~105 years).

Binary solid wastes derived clinker: Raw feed system design validation and thermodynamic simulation investigation

Solid waste derived clinker design methodology was established based on thermodynamic simulation and experiment validation via the recycling of incinerated sewage sludge ash (ISSA) and recycled concrete fine (RCF). Compared with 1000 °C and 1100 °C, 1200 °C was the optimum temperature for C2S-rich clinker synthesis due to the highest simulated belite content after sintering. A utilization rate of 95 % was achieved, accomplishing the maximization of solid waste recycling. Due to the CaCO3 phase formation by the reaction of high-content belite (46.8 %) with CO2, carbonated 1200ARS eco-cement showed higher compressive strength than OPC and other eco-cements. The lowest porosity (18.1 %) with dense microstructure was also obtained by carbonated 1200ARS. Benefiting from the high CO2 reactivity of belite, 1200ARS displayed the optimum CO2 sequestration capacity with a higher carbonation degree (30.1 %) than other batches, providing a promising direction for future development of the low-carbon cement industry to achieve environmental sustainability.

Analysis of Power-to-gas-to-X systems with metal hydride storage based on coupled electrochemical and thermodynamic simulation

Power-to-gas-to-X systems consisting of photovoltaic cells, proton-exchange membrane electrolysis, hydrogen storage based on metal hydrides, proton-exchange membrane fuel cells and buffer batteries could be used to meet heat and electricity demands of homes, businesses, or small districts. The actual size of the individual components and their interplay have to be optimized for the technical and economic feasibility of the overall system. A simulation-based optimization workflow would be a suitable way to accomplish this task, but there are hardly any tools that can simultaneously simulate power, fluid and heat flows of such systems and efficiently perform their optimization. In this paper, a multiphysical energy system simulation and optimization tool is introduced which models electrochemical and thermodynamic processes simultaneously, including modern equations of state and an own numerical solver for the arising differential–algebraic system of equations, and provides new methods for the calibration of parameters of the metal hydride storage, proton-exchange membrane electrolyzer and fuel cell as well as a metamodel-based approach for sizing optimization. As a demonstrator for the novel tool, a simulation model of a hydrogen lab is successfully set up based on experimental results. The novel tool is able to extract polarization and jump curves of the fuel cell, determine a first temperature and pressure dependency of the efficiency of the electrolysis coupled with the metal hydride storage and speed up sizing optimization through metamodeling by a factor 262.1 at 4.9% and 32.7 at 3.3% accuracy.

Regulating strength and ductility of additively manufactured Inconel 718 alloy via adding nano-TiC and deep cryogenic treatment

The morphology and size of Laves phases play a crucial role in influencing mechanical properties of the additively manufactured Inconel 718 alloy. The current study explores the effects of deep cryogenic treatment (DCT) and the addition of nano-TiC on the microstructure and tensile properties of Inconel 718 alloy manufactured through direct energy deposition (DED). It is found that the addition of 1.5 wt% nano-TiC is conducive to transforming long-striped Laves phases into granular shapes, and the reduced porosity and finer grains are obtained. Compared to the Inconel 718 alloy, the 1.5 wt% nano-TiC/Inconel 718 composite exhibits an enhancement in ultimate tensile strength by approximately 46.81 MPa. Through the thermodynamic simulations, the microstructural evolution induced by the addition of nano-TiC is discussed, which includes the suppression of Laves phases and precipitation of MC particles. Moreover, finer Laves phases and uniform distribution of dislocations are observed in the Inconel 718 alloy after DCT. Dynamic recrystallization occurs within the Inconel 718 alloy during the DCT process, and the grain refinement mechanism is facilitated by a high dislocation density. Consequently, the elongation increases by about 24.8 %, while the strength remains virtually unchanged. Furthermore, the synergistic effect of the addition of nano-TiC and the DCT on Inconel 718 is investigated, and the elongation of nano-TiC/Inconel 718 composite is increased by about 32.7 % with more uniform fracture dimples. This study provides guidance for DED-fabricated Ni-based alloys with excellent strength and ductility.

Advancing railway infrastructure maintenance: Thermodynamic parameter inversion of ballast bed and feasibility assessment of fouling detection via infrared thermography (IRT)

The fouled ballast bed significantly impacts the operational condition of the ballasted track. Timely detection of the fouled ballast bed can greatly reduce maintenance workloads and capital expenditure. This study aims to assess the feasibility of employing infrared thermography (IRT) for detecting fouling. Nonetheless, existing research has been conducted under conditions noticeably different from the actual field. Moreover, the climatic conditions surrounding the ballasted track are beyond control. Hence, this paper innovatively utilized thermodynamic simulation to simulate as many conditions as possible. Firstly, temperatures and external meteorological data were obtained on a newly constructed railway line using an infrared thermal imager, temperature sensors, and a weather station. Thermodynamic inversion models were then established based on field structures to determine crucial thermodynamic parameters. The results demonstrate excellent alignment with the existing literature. Expanding upon this groundwork, the study explored the impact of various meteorological factors and weather conditions on the detection effectiveness of IRT. The results indicate that the solar radiation intensity (S) and air temperature (T) have the most significant effect on the surface temperature of the ballast bed (STB) and the temperature difference between the clean and fouled ballast beds (CF-TD). The rainfall (R) can change the thermodynamic properties of the ballast bed. Without considering R, the higher the S or T, the greater the CF-TD. Specifically, on sunny days, the maximum CF-TD can achieve 3.26 °C, while on cloudy days or at night, it is only 0.79 °C and 0.28 °C, respectively. Furthermore, the impact of wind speed (W) on the CF-TD was found to be disregarded in regions with low wind speeds but significant in regions with high wind speeds. In summary, IRT shows promise for rapid initial assessments of ballast bed conditions on sunny days, particularly following rain. While on cloudy days or at night, higher resolution infrared thermal imagers may be required, or other detection indicators may need to be investigated.

Transformation behavior of hazardous jarosite into recyclable hematite in a solution with high concentrations of K+ and Na+

Iron in the leaching solution with high K+ and Na+ concentrations was usually precipitated as the typical hazardous and toxic jarosite residues. However, this method of treatment has been greatly restricted by increasingly strict environmental regulations. Here we propose that iron can be precipitated from the solution with high K+ and Na+ concentrations as recyclable hematite products by adjusting the concentration ratio of sodium and potassium ions in the solution. The transformation behavior of jarosite into hematite in high concentration potassium ion and sodium ion solution was explained based on collision theory. The results indicated that in instances where the concentration ratio of Na+/K+ is ≥ 4:1, the iron present in the solution can be effectively precipitated as a recyclable hematite product, as opposed to forming the conventional hazardous jarosite residue, even under conditions where the potassium ion concentration reaches levels as high as 4 g/L. On the other hand, thermodynamic and molecular dynamics simulations indicate that at a temperature of 185 °C, the decomposition transformation of Na-jarosite (32.64 kJ and 7.25 eV) is more energetically advantageous compared to that of K-jarosite (61.07 kJ and 15.31 eV). The results were verified by the leaching solution from smelting industry. The iron content in the residues is above 58%, the sulfur content is below 4%, the zinc content is below 1%, and the total iron concentration in the supernatant is about 4 g/L, reaching the production index of the smelting industry. The green, environmentally friendly, and recyclable separation of iron in a solution with high concentrations of potassium and sodium ions is achieved, which is of great significance for the treatment of iron-containing solution and wastewater in the chemical industry and metallurgy fields.

Comparison of non-isothermal and isothermal cycles in a novel methane-assisted two-step thermochemical process

As driven by thermodynamics and reaction kinetics considerations, conventional two-step solar thermochemical processes typically rely on non-isothermal cycling conditions to effectively couple the endothermic reduction and exothermic oxidation reactions. Nevertheless, recent discussions on isothermal cycles based on thermodynamics simulation and material characterization have sparked dissenting opinions, as certain reaction processes operating under isothermal cycling conditions have demonstrated the possibility of achieving higher energy conversion efficiency. To delve further into such phenomenon and potentially unveil the underlying scientific principles, this study conducts a reaction kinetic analysis and lab-scale systematic experiments on a novel methane-assisted two-step thermochemical process using iron-based oxygen carriers. Despite the fact that the reaction kinetics analysis of iron oxides indicates that isothermal cycles at reaction temperatures of 573–1173 K do not provide significant advantages in terms of energy conversion efficiency, surprisingly, the experiments conducted with the prepared cobalt–nickel ferrite materials conclude oppositely. More specifically, the observed increase in material reactivity with rising oxidation temperature contributes to an approximately two-fold enhancement in the CO yield under isothermal conditions, as well as a noteworthy improvement of about 15% in solar-to-fuel efficiency. This energy efficiency improvement could be attributed, at least in part, to the stable reaction temperature during isothermal cycling, which effectively mitigates the challenges associated with solid-phase sensible heat recovery caused by significant temperature fluctuations, particularly when operating at high feed flow rates. Accordingly, the applicability of isothermal cycles is linked to two crucial factors: the reactivity of the oxygen carrier and the specific operating conditions employed. The experiments herein conducted showed that the catalytic activity of the material reached a relatively stable state after 24 h of reaction, resulting in a peak CO yield of 20.5 mL min−1 g−1 and a CO2 conversion exceeding 90%. Thorough analyses reveal several optimization measures for enhancing efficiency under the setting of the reaction system.

Performance analysis of methanol fuelled SI engine with boosted intake pressure and LIVC: A thermodynamic simulation and optimization approach

Methanol (CH3OH) is a low-carbon alternative fuel that can be derived through renewable power-to-fuel conversion, offering lower emissions and a higher resistance to knock in SI engines. However, the sole methanol-powered SI engine delivers less brake power. Fuels with a higher calorific value have been blended to solve this problem. However, this may cause overburden with storage, handling, and correct blending (like when methane and hydrogen are blended). To resolve this, this research suggested a novel approach for increasing the power and efficiency of a SI engine using the LIVC (late inlet valve closing) miller cycle and boosted intake pressure under 14 geometrical compression ratio (GCR) with the addition of the start of spark timing (SOI) and equivalency ratio (λ) effects. A quasi-dimensional thermodynamic model (QTDM) was applied to simulate the engine performance with respect to operating variables of 0.6–1.0 λ, 35.50 ––650 aBDC (after Bottom Dead Centre) LIVC timing, 30.00 ––150 bTDC (before Top Dead Centre) SOI Timing and 0.8–1.5 bar intake pressure. After that, design of experiments (DoE) based response surface methodology (RSM) was applied to determine optimum operating setting to maximize power and efficiency and minimize emission and fuel consumption. The results from the RSM illustrate the optimum input parameters to be 0.793 equivalence ratio, 46.900 aBDC-LIVC, 20.750 bTDC-SOI timing, and 1.5 bar intake pressure. Correspondingly, response output performances were found to be 12.36 kW-indicated power (IP), 11.20 kW- brake power (BP), 43.32 % indicated thermal efficiency (ITE), 39.32 % brake thermal efficiency (BTE), 9150.6 kJ/kWh brake specific energy consumption (BSEC), and 0.3 V%- carbon mono oxide (CO), 1247.8 ppm-nitric oxide (NO) emission at exhaust valve opening (EVO). The ANOVA regression models resulted in 95 % accuracy in forecasting output response and composite desirability of optimization of 0.83. Overall, it was found that miller-based LIVC and boosted intake pressure considerably improve the performance of SI engines, and the results projected would be helpful for further study and industry application.

Selective extraction of lithium from montebrasite and clean treatment of tailings

To realize the efficient utilization of montebrasite, we conducted a systematic study of sulfuric acid roasting and water leaching processes. In this study, we propose a roasting process at a lower temperature than that proposed in previous studies, which can achieve the selective extraction of lithium from montebrasite and effective enrichment of aluminum and phosphorus. The thermodynamic simulation results of the reaction between montebrasite and sulfuric acid showed that the method was feasible in theory. Under the optimal conditions determined by theoretical analysis and experimental results, Li extraction reached 97.5 %, whereas Al and P extraction only reached 1.9 % and 0.1 %, respectively. The results of XRD characterization and analysis of roasting slag and leaching residue demonstrated that montebrasite was decomposed into Li2SO4, Al2(SO4)3, and H3PO4 by sulfuric acid. The temperature increase facilitated the conversion of these intermediates into Li2SO4 and AlPO4, confirming the absence of SO3 generation within the studied temperature range. Selective extraction of Li achieved water leaching through water leaching, resulting in a leaching residue with over 95 % AlPO4 content. The leaching liquor underwent purification and precipitation, resulting in the attainment of Li2CO3 with a purity level of 99.8 %. This process enables selective extraction of Li from montebrasite while efficiently enriching Al and P components. It represents an efficient and environmentally friendly approach for lithium extraction.

Impact of desulphurized electrolytic manganese residue-assisted cementitious materials on silicate cement hydration and environmental safety assessment

The use of electrolytic manganese residue (EMR) as a mineral admixture is an efficient way of utilization, but its high content of gypsum phase limits its utilization. In this paper, EMR was desulphurized by means of high temperature reduction roasting to remove the hindrance when utilized as a mineral admixture. The effect of desulphurized EMR (D-EMR) on the formation of major hydration products such as C–S–H and calcium hydroxide (CH), as well as on the degree of hydration of cement clinker, was explored based on mechanical properties, hydration kinetics, thermogravimetry-differential scanning calorimetry (TG-DTG) and Quantitative X-ray diffraction analysis (QXRD). In particular, the mineral phase evolution, the change rule of pore solution and the leaching behavior of heavy metals were simulated in conjunction with thermodynamics. The results show that the D-EMR content of 15 %, comparable mechanical properties and microscopic morphology to the control group can be obtained, while C3S and C2S hydration can be promoted by a factor of 1.08 and 1.28, respectively, without the risk of heavy metal leaching. Based on the thermodynamic simulation of heavy metal solidification by cement clinker minerals, it can be seen that heavy metals in D-EMR composite slurry are solidified mainly by Mn(OH)2 precipitation and weak adsorption effect, and it is safe even at the level of 30 % replacement, provided that the pH value of the leaching solution is greater than 7.5. In addition, the desulphurization technology is feasible from the perspective of environmental protection, and saves 200,000 CNY in emission costs.

Thermodynamic Simulation Calculations of Phase Transformations in Low-Aluminum Zn-Al-Mg Coatings.

This study delves into the formation, transformation, and impact on coating performance of MgZn2 and Mg2Zn11 phases in low-aluminum Zn-Al-Mg alloy coatings, combining thermodynamic simulation calculations with experimental verification methods. A thermodynamic database for the Zn-Al-Mg ternary system was established using the CALPHAD method, and this alloy's non-equilibrium solidification process was simulated using the Scheil model to predict phase compositions under varying cooling rates and coating thicknesses. The simulation results suggest that the Mg2Zn11 phase might predominate in coatings under simulated production-line conditions. However, experimental results characterized using XRD phase analysis show that the MgZn2 phase is the main phase existing in actual coatings, highlighting the complexity of the non-equilibrium solidification process and the decisive effect of experimental conditions on the final phase composition. Further experiments confirmed that cooling rate and coating thickness significantly influence phase composition, with faster cooling and thinner coatings favoring the formation of the metastable phase MgZn2.

Controlling the interactions in a cold atom quantum impurity system

We implement an experimental architecture in which a single atom of K is trapped in an optical tweezer, and is immersed in a bath of Rb atoms at ultralow temperatures. In this regime, the motion of the single trapped atom is confined to the lowest quantum vibrational levels. This realizes an elementary and fully controllable quantum impurity system. For the trapping of the K atom, we use a species-selective dipole potential, that allows us to independently manipulate the quantum impurity and the bath. We concentrate on the characterization and control of the interactions between the two subsystems. To this end, we perform Feshbach spectroscopy, detecting several inter-dimensional confinement-induced Feshbach resonances for the KRb interspecies scattering length, that parametrizes the strength of the interactions. We compare our data to a theory for inter-dimensional scattering, finding good agreement. Notably, we also detect a series of p-wave resonances stemming from the underlying free-space s-wave interactions. We further determine how the resonances behave as the temperature of the bath and the dimensionality of the interactions change. Additionally, we are able to screen the quantum impurity from the bath by finely tuning the wavelength of the light that produces the optical tweezer, providing us with a new effective tool to control and minimize the interactions. Our results open a range of new possibilities in quantum simulations of quantum impurity models, quantum information, and quantum thermodynamics, where the interactions between a quantized system and the bath is a powerful yet largely underutilized resource.

Evaluation of microstructure heterogeneity in INCONEL 625 thin-wall fabricated by Laser Powder Bed Fusion additive manufacturing

This study provides a thorough investigation of microstructural heterogeneity and its relationship to the mechanical properties of Inconel 625 (IN625) alloy in as-built Laser Powder Bed Fusion (LPBF) parts. Specifically, detailed high-resolution electron microscopy coupled with thermodynamic simulation, finite element analysis, and nano-hardness testing were carried out. Through the combination of these methods, a new method is proposed to develop a process-structure–property map to illustrate the complex relationship between spatial thermal conditions, microstructure, and mechanical properties in various areas of an LPBF IN625 sample. Different precipitates, including γ′′, Laves, NbC, and Al2O3 oxide were observed along the build direction from the bottom to the top layers of the LPBF part as a function of build height. The hardness value was shown to be minimum in the middle layers while attaining maximum values in the bottom (near the substrate) and top (near the surface) layers of the build’s height. The mechanism for the formation of precipitates during multi-layer additive manufacturing and the dependency of the mechanical properties on the type and distribution of these precipitates are discussed.

Modelling of a cargo oil pump turbine system to find the optimum pump operation capacities through the design of experiments approaches

ABSTRACT This study aims to thoroughly understand and analyze the Cargo Oil Pump Turbine (COPT) system on tanker ships through thermodynamic and numerical simulations. The goal is to find the best pump capacities to match different cargo discharge rates and properties. A parametric study has been performed on the COPT system by building a thermodynamic model including exergy analysis, and a numerical centrifugal pump model. The design of experiment applications which are factorial design and response surface methodology (RSM) have determined the the optimal pump capacity The findings demonstrate that the risky flow rate region for the cavitation, if the density and vapour pressure are close to limits, is between 3050-3500 m3/h. The factorial design finds the best operating flow rate for the high capacity demands at 4025 m3/h where the efficiencies are the highest, and the RSM calculates the optimum capacity for the low demands at 1460.34 m3/h.

CO2 capture by the slag from lignite's chemical looping gasification using carbide slag

Due to its large amount, solid waste used as an oxygen carrier in chemical looping gasification (CLG) is not generally recycled. In order not to turn solid waste into secondary solid waste, re-resourcing research of the slag from CLG is worth consideration. The slag from lignite's CLG mainly consists of CaCO3, CaO, and small amounts of Ca(OH)2. In order to further purify CaCO3 and to achieve reduction in carbon emissions, the present work proposed the use of slag from lignite's CLG to capture CO2 and obtain purer calcium carbonate. The reaction properties and the reaction mechanism of the slag from CLG for CO2 capture were investigated using thermodynamic simulations, tubular furnace experiments, thermogravimetric experiments and characterizations. After analyses, it was suggested that reaction temperature for CO2 capture using slag from CLG lied within the temperature range of 300–800 °C. Reaction mechanism of slag from CLG to capture CO2 was different at different reaction temperatures. When the reaction temperature lied within the range of 300–400 °C, <Ca(OH)2+CO2→CaCO3+H2O> and <CaO+CO2→CaCO3> were the main reactions. When the reaction temperature lied within the range of 400–800 °C, <CaO+CO2→CaCO3> was the main reaction. The present study provides a method to turn waste into treasure without the need of subsequent recycling during lignite's CLG, and promotes the realization of “International Double Carbon Policy".

Predictions of locations of flash point and calcite scaling of geothermal fluids in wellbore by chemical and thermodynamic simulations

Geothermal energy, as a renewable energy source, has been intensively developed recently because its utilization can reduce CO2 emission, climate warming and sea level rising, and be beneficial to promote sustainable development. However, scaling in the wellbores often happens during the rising of geothermal fluids. At present, the methods to explore the scaling location principally focus on real measurement techniques and numerical simulation method. In comparison with the former, the latter is extremely time- and labor-saving to predict the scaling location based on the coupling model. In this study, the flash point and scaling locations of two geothermal wells in Hebei province are numerically simulated via ECO2N equation of state module in TOUGHREACT software, and the factors affecting the flash point and scaling locations of geothermal wells are explored. At the same time, the mechanism of geothermal fluid flash is analyzed. The prediction results show that the relative errors of scaling locations in geothermal well I and II are 5.43 % and 6.82 % compared to the field measured data; the pressure and temperature of geothermal fluids at well bottom can be calculated based on the related parameters of wellhead fluid; the locations of flash point and scaling can be determined according to the sudden increases of CO2 partial pressure and scaling amount, respectively. Furthermore, the liquid mass flow rate, CO2 mass flow rate and wellbore diameter have prominent influence on the locations of flash point and scaling, while wellbore diameter have significant effect on the amount of calcite scaling. The above conclusions provide useful guidelines for the next scaling removal and control in the production wellbore during the utilization of the geothermal energy.

The magma plumbing system of the potentially hazardous Laoguipo volcano in the Tengchong Volcanic Field, SW China

The Late Pleistocene-Holocene Laoguipo volcano in the Tengchong Volcanic Field (TVF), southwestern China, displays significant geochemical and geophysical anomalies characteristics. Here we present petrographic observations, mineral chemistry, bulk rock geochemistry, thermobarometry, and thermodynamic simulation to evaluate the crystallization conditions and pre-eruptive magmatic processes occurring within the magma plumbing system. This study reveals the existence of two magma reservoirs beneath the Laoguipo volcano. The deep magma reservoir is composed of basaltic trachyandesite (SiO2 = 54–57 wt%), which is located at 15–19 km depths with 1087–1160 °C, 1.5–2 wt% H2O content, oxygen fugacity of ΔNNO+1 (Ni-NiO buffer), melt viscosity of 101.7–102.6 Pa·s, and density of 2.5–2.6 g/cm3. The formation of the deep magma reservoir is attributed to the 31% mass fractional crystallization of primitive basalt in the TVF. The shallow magma reservoir is composed of trachyte (SiO2 = 63–64 wt%), which is located at 6–11 km depths with 780–825 °C, 5.9–6.5 wt% H2O content, oxygen fugacity of ΔNNO+1 (Ni–NiO buffer), melt viscosity of 103.9–104.8 Pa·s, and density of 2.2–2.3 g/cm3. The shallow magma reservoir formed after the basaltic trachyandesite had assimilated 19% mass of the upper crustal material and fractionated 41% mass of the crystals. This study suggests that the shallow trachyte magma reservoir is being heated by the ascending deep basaltic trachyandesite magma, resulting in crystal dissolution, remobilization of crystal mush, and magma convection, which may be the main factors responsible for the geochemical and geophysical anomalies characteristics. The Laoguipo volcano is forming a mature magma plumbing system, which is of significance for forecasting future volcanic eruptions.