Results Of Thermodynamic Modeling Research Articles

Significance of silicate liquid immiscibility for the origin of young highly evolved lithic clasts in Chang’E-5 regolith

Highly evolved lithology distributes across the Moon sparsely but serves as a critical record of the extensive differentiation processes of lunar magmas. In contrast to the Apollo-returned highly evolved rocks that essentially formed before the end of the Nectarian period, silicic lithologies detected by remote sensing within the nearside Procellarum KREEP Terrane (PKT) have cratering model age as young as ∼2.5 Ga (Chevrel et al., 2009). The formation mechanism of the young silicic magmatism remains enigmatic. Here we present a detailed study of lithic clasts with highly evolved compositions from the northwestern PKT returned by Chang’E-5 mission. Two different types of highly evolved lithic clasts were recognized: (a) Type A clasts predominately consist of granophyric intergrowths of K-feldspar and quartz. They are highly depleted in incompatible elements (except for K, Rb, Cs, and Ba) and have a V-shaped REE pattern, which can be explained by silicate liquid immiscibility (SLI) following the fractionation of merrillite from a KREEP-like melt. The microtextural features of quartz in Type A clasts indicate that they could have crystallized through relatively slow cooling at temperature below 870 °C, supporting a shallow intrusive origin. The silicic intrusion exposed in the interior, rim, and ejecta of Aristarchus crater has a cratering model age of ∼2.5–3.7 Ga, which could be the source for Type A clasts; (b) Type B clast has little MgO, high incompatible element concentrations, and an REE pattern inclined to the right. Thermodynamic calculations indicate that Type B clast likely formed through SLI of the ∼25% residual melt of Em3 basalts in the Chang’E-5 landing region. This is consistent with the crystallization age of 2.57 ± 0.26 Ga for the zirconolite in Type B clast. The highly evolved samples from Chang’E-5 regolith provide new evidence that SLI may have played an important role in the young highly evolved intrusive bodies’ formation on the Moon. Furthermore, our thermodynamic modeling results show that compared to KREEP basalt, partial melting of quartz monzodiorite/monzogabbro at ∼930–1000 °C can produce melts with composition close to lunar granites and felsites. Thus, if a series of silicic volcanisms distributed mostly within the PKT was generated through this mechanism, quartz monzodiorite/monzogabbro may also widely distribute within the lunar nearside upper crust.

Late Neoarchean TTG and monzogranite in the northeastern North China Craton: Implications for partial melting of a thickened lower crust

The petrogenesis and dynamic setting of Archean tonalite–trondhjemite–granodiorite (TTG) is widely debated. As a typical Archean terrane in the northeastern North China Craton (NCC), the southern Jilin Province area underwent multi-stage magmatism during the Neoarchean and is therefore a promising region in which to track the Neoarchean evolution of the NCC. This study investigates the petrogenesis of late Neoarchean TTGs and associated monzogranites and their tectonic implications. Zircon U–Pb dating results suggest that the TTGs and monzogranites have emplacement ages of 2.55–2.52 and 2.53–2.51 Ga, respectively. The TTGs have variable SiO2 (61.7–73.3 wt%) and MgO (0.66–2.74 wt%) contents and Mg# values of 33–50. Most have high Sr and low Y and Yb contents, with high Sr/Y and (La/Yb)N ratios. The TTGs have variable εHf(t) (+0.7 to + 8) and εNd(t) (−2.77 to + 2.79) values. These characteristics, together with the results of thermodynamic partial-melting modelling, indicate that the TTGs can be classified as medium- and low- pressure types and were likely generated by amphibole-breakdown partial melting of 2.9–2.7 Ga juvenile basaltic rocks under P–T conditions of 1.0 ± 0.1 GPa and 880 ± 50 °C. The monzogranites have higher SiO2 (66.1–76.0 wt%) and K2O (4.03–5.06 wt%) and lower TFe2O3 (0.89–4.97 wt%) and MgO (0.21–1.27 wt%) contents. They also have high Sr/Y and (La/Yb)N ratios and variable εHf(t) (+0.6 to + 5.4) and εNd(t) (−3.47 to − 0.15) values. The geochemical and Hf–Nd isotopic compositions of the monzogranites indicate that the parental magmas may have been derived through the partial melting of thickened lower crust with heterogeneous sources. The high thermal gradient (>730 °C/GPa−1), anticlockwise metamorphic P–T paths, and 3.4–3.2 Ga remanent zircons in the region suggest that a late Neoarchean thickened lower crust was the likely geodynamic setting for the generation of the TTGs and monzogranites.

Effects of Limestone Powder on the Early Hydration Behavior of Ye'elimite: Experimental Research and Thermodynamic Modelling.

To investigate the effects of limestone powder and gypsum on the early hydration of ye’elimite, the hydration behavior of C4A3-LP-CaSO4·2H2O-H2O systems are researched. The hydration behavior of systems are researched by employing isothermal calorimetry, XRD technique and chemical shrinkage. The thermodynamic modelling method is employed to predict the equilibrium phase assemblages. The results show that the system with 5 wt.% LP has a comparable hydration heat evolution to limestone powder-free systems. Limestone powder can take part in the reaction to produce monocarboaluminate in the system with M-value (molar ratio of gypsum to ye’elimite) of 1, but monocarboaluminate is not found in the system with M-value of 2. The level off time of chemical shrinkage shortens with the increase of limestone powder dosage. Thermodynamic modelling results show that monocarboaluminate is no longer formed in all systems when M-value exceeds 1.27, which corresponds to the XRD results. This study can provide theoretical guidance for the rational utilization of limestone powder in calcium sulphoaluminate cement.

The influence of curing temperature on the strength and phase assemblage of hybrid cements based on GGBFS/FA blends

Hybrid cements are composites made of Portland cement or Portland clinker and one or more supplementary cementitious materials like slag, fly ash or metakaolin, activated with an alkali salt. To date, their hydration mechanism and the phase formation at various temperatures is insufficiently understood, partly due to the large variability of the raw materials used. In the present study, three hybrid cements based on ground granulated blast furnace slag, fly ash, Portland clinker and sodium sulfate, and an alkali-activated slag/fly ash blend were cured at 10 and 21.5°C, and subsequently analyzed by XRD, 27Al MAS NMR, and TGA. The compressive strength of the hybrid cements was higher by up to 27% after 91-day curing at 10°C, compared to curing at 21.5°C. The experimental results as well as thermodynamic modeling indicate that the differences in compressive strength were related to a different phase assemblage, mainly differing amounts of strätlingite and C-N-A-S-H, and the associated differences of the volume of hydration products. While the strätlingite was amorphous to X-rays, it could be identified by 27Al MAS NMR spectroscopy, TGA and thermodynamic modeling. The microstructural properties of the hybrid cements and the alkali-activated slag/fly ash blend as well as the compatibility between thermodynamic modeling results and experimental data as a function of curing temperature and time are discussed.

Thermodynamic modelling of the V–Ti–B system

Thermodynamic modelling is an effective approach to accelerate the development of novel materials such as V-based alloys. In the present work, the results of thermodynamic modelling of the ternary system V–Ti–B using the “CALculation of PHAse Diagrams” (CALPHAD) method are presented. The thermodynamic descriptions of the binary systems V–Ti, V–B, and Ti–B are based on available publications whereas thermodynamic parameters for the ternary system stem from the iterative approximation to the experimental investigations, which further serve for verifying the calculated phase diagram. Thus, eight different alloys in the compositional range of 10–40 at.% Ti and B were analyzed aiming at identifying the evolving phases. A set of thermodynamic parameters is proposed. The calculated isothermal phase diagram at 1673 K exhibits a high degree of agreement with the literature and experimental observations. In our further work, the thermodynamic data generated in this study will be useful to develop the quaternary V–Ti–Si–B system.

Designing Magnesium Phosphate Cement for Stabilization/Solidification of Zn-Rich Electroplating Sludge.

Electroplating sludge is a hazardous waste due to its high potential to leach toxic elements into the natural environment. To alleviate this issue, we tailored magnesium phosphate cement (MPC) as a low-carbon material for stabilization/solidification (S/S) of Zn-rich electroplating sludge. The interaction between MPC and ZnO was investigated to clarify the precipitate chemistry, microstructure transition, and chemical environment of Zn species in the MPC-treated Zn sludge system. Comprehensive characterization (by X-ray diffraction (XRD), 31P nuclear magnetic resonance (NMR), and extended X-ray absorption fine structure spectroscopy (EXAFS)) and thermodynamic modeling results revealed that the incorporated ZnO preferentially reacted with phosphate to form Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O, changing the orthophosphate environment in the MPC system. Stronger chemical bonding between Zn and phosphate in comparison to the bonding between Mg and phosphate also resulted in the formation of amorphous Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O. Zn3(PO4)2·4H2O precipitate appears to predominate at high {K+}{H+}{HPO42-} values, and the formation of Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O competed for the Mg sites in the MPC system, leading to the inhibition of formation of Mg-phosphate precipitates. Overall, this work uncovers the precipitate chemistry and microstructure transition of Zn species in the MPC system, providing new insights into the sustainable S/S of Zn-contaminated wastes by adopting MPC.

Thermodynamic modeling of gas hydrate phase equilibrium of carbon dioxide and its mixture using different equations of states

In this work, the fugacity-based approach of the Klauda and Sandler model was used to predict the equilibrium conditions of gas hydrates formation for carbon dioxide and its mixtures with nitrogen, methane, ethane, and propane. In order to calculate the Langmuir constants and empty hydrate vapor pressure, the correlations presented by Munck et al., (1988) and Dharmawardhana et al., (1980) were used, respectively. Hence, six well-known equations of state (EOS) including PR, PRSV, SRK, PT, VPT and translated and consistent versions of the Peng-Robinson (tc-PR) had been used to calculate the thermodynamic properties. The thermodynamic modeling results were compared with numerous experimental data in the literature. These results showed that although all EOSs could successfully predict the equilibrium pressure of carbon dioxide, there is a deviation, less than 3.3 %, in all of them. In the case of mixture hydrates, such as CO2/CH4 and CO2/C2H6, the equilibrium pressures from the models had a good agreement with experimental data, except for PT EOS with a relatively high average absolute deviation in CO2/CH4 mixture hydrates. The predicted equilibrium pressure from the different EOSs showed excellent results for structure I, including CO2/C3H8 mixture hydrates. In addition, it has been concluded that this modeling can’t predict the equilibrium pressure structure I of CO2/N2 mixture hydrate at high pressures.

Evaluation of solar energy transmission and heat-mass transfer in a floating solar concentrated distillation configuration

The solar energy transmission and heat-mass transfer play significant roles in affecting the performance of a solar concentrated distillation device. This paper aims to evaluate the solar energy transmission and heat-mass transfer processes based on a novel floating solar concentrated distillation configuration, providing a comprehensive energy-mass analysis for improving and forecasting the system performance. Firstly, the impact of surface optical parameters and incidence angles on the solar energy transmission process has been quantitatively analyzed by the optical simulation. Then, the heat convection and heat-mass transfer relationships are obtained through the thermodynamic model and experimental results. Experimental results show that the freshwater yield is 16.2 g/h under the steady irradiance of 800 W/m2, while the theoretical yield is 15.24 g/h with a deviation < 6% compared with the experimental value. In the outdoor condition, the total yields of experimental and theoretical values are 134 g and 134.05 g, respectively. The average deviation of the 30-minute yield is 19.4% and the total yield deviation is 0.04%, proving the accuracy of obtained relationships in predicting the water yield under the actual weather. This paper provides essential theoretical support for predicting and improving the performance of direct solar-concentrating desalination systems of different scales.

Petrogenetic evolution of early Paleozoic trachytic rocks in the South Qinling Belt, Central China: Insights from mineralogy, geochemistry, and thermodynamic modeling

Early Paleozoic volcanic–intrusive rocks in the South Qinling Belt, central China, consist of bimodal alkaline suites ranging in composition from basalt to trachyte, with an apparent scarcity of intermediate silicic components (the so-called “Daly gap”). A series of trachytic rocks have been identified in the Quanxi area of the South Qinling Belt. In this work, we combine mineralogical evidence with whole-rock major- and trace-element data, Sr–Nd–Pb isotope data, and the results of thermodynamic modeling to gain a better understanding of the petrogenesis and evolutionary process of the Quanxi trachytic rocks, as well as their compositional discontinuity with coeval mafic rocks. Our samples can be clearly classified into two lithological groups based on their phenocryst content: Group 1, phenocryst-poor trachytes (<5 vol% phenocrysts; SiO2 = 63.91–66.13 wt%) and Group 2, trachytic tufflavas (30–45 vol% pyroclasts; SiO2 = 53.34–59.03 wt%). All of the samples exhibit typical oceanic island basalt-like enrichment in light rare earth elements and high field strength elements, as well as marked depletion of Ba, Sr, and Ti. A cogenetic metasomatized lithosphere source for the Quanxi trachytic rocks and contemporaneous mafic rocks is indicated by their homogeneous isotopic features (εNd(t) = +2.3 to +3.4; initial 206Pb/204Pb = 17.92–18.69; initial 207Pb/204Pb = 15.53–15.57; initial 208Pb/204Pb = 37.96–38.99) and linear geochemical variations, with protracted fractional crystallization regarded as the key mechanism for the compositional variations among these cogenetic rocks. The results of Rhyolite-MELTS modeling predict 72%–80% crystallization involving plagioclase, pyroxene, biotite, apatite, and FeTi oxide, to yield the magmatic compositions from an evolved mafic progenitor to the Quanxi trachytes under conditions of low pressure (1.5–2 kbar), high H2O content (2–3 wt%), and high fO2 (FMQ–0.5). Some incompatible elements in trachytic tufflavas deviate markedly from the liquid lines of descent from coeval mafic rocks to the Quanxi trachytes: this deviation is attributed to a combination of the involvement of large proportions of alkali-feldspar pyroclasts and post-magmatic hydrothermal alteration. The presence of the “Daly gap” in early Paleozoic alkaline suites can be explained by an accelerated differentiation rate (i.e., dSiO2/dt) in the SiO2-intermediate field, which is driven by the simultaneous separation of a considerable scale of SiO2-poor phases.

Fluid-rock interactions leading to the formation of the epithermal Ag-Pb-Zn veins: A perspective of thermodynamic modeling

Although vein-type silver-lead-zinc ore deposits have been extensively studied, the factors controlling their formation are still poorly understood and their genesis is a matter of ongoing debate. In this contribution, I present new mineralogical data and the results of thermodynamic modeling that constrain the conditions of metal transport and deposition for the Aerhada epithermal Pb-Zn-Ag deposit (reserves of >1,000 t Ag@58 g/t and 1.0 Mt Pb+Zn@5.2%) in NE China. Three primary paragenetic stages have been identified, the second of which (Stage II) is the main base metal and silver mineralization. Freibergite, argentite, pyrargyrite, and canfieldite are the main Ag-bearing minerals and are spatially associated with an alteration assemblage of quartz-muscovite ± chlorite ± epidote. Dissolution textures and evidence of compositional heterogeneity for freibergite suggest that its decomposition may have redistributed the Ag and contributed in part to the high Ag grade ores in the deposit. Thermodynamic calculations indicate that there was extensive silver ore deposition from a strongly reducing (e.g., ∆log fO2 (HM) of <-8.6 to -2.4) and nearly neutral to weakly alkaline (e.g., pH of 5.5 to 6.8) aqueous fluid at temperatures between 220 °C and 170 °C. These calculations reveal that a reduction in fO2 and decreasing temperature, both as a result of fluid-rock interactions, were the key factors leading to silver and base metal mineral deposition. Further path modeling showed that the sole evolution of a magmatic-derived fluid is capable of forming the large Ag-Pb-Zn veins via fluid-rock interactions, which is contrary to the conclusions of some other studies that the mixture of an externally derived fluid is required to explain their formation. The genetic model for Ag-Pb-Zn ore formation developed in this study is applicable to other polymetallic vein-type deposits in comparable geological settings elsewhere.

Phase Relations in Spinel Lherzolite KLB-1 According to Results of Thermodynamic Modeling up to 30 GPa: Peculiarities of Mineral Assemblages and Geodynamic Effects

The composition of spinel lherzolite xenolith KLB-1 from the Kilbourne Hole volcanic crater, United States, which is close to the composition of the Earth’s primitive mantle, was used for thermodynamic modeling of phase relations in the Na2O–CaO–FeO–MgO–Al2O3–SiO2 system (NCFMAS) using the Perple_X software package in the temperature range of 900–2000 °C and pressures of 0.0001–30 GPa. The calculated phase diagram is in good agreement with published thermodynamic data on KLB-1 composition and reveals the peculiarities of mantle mineral assemblages at P–T parameters on which experimental data are insufficient or absent. The results showed that the mineral assemblage of garnet wehrlite (garnet + olivine + clinopyroxene), the least common type of mantle peridotite on the Earth’s surface, prevails in the upper mantle since the Archean. Mineral assemblage of garnet lherzolite (garnet + olivine + clinopyroxene + orthopyroxene), which is a variety of mantle peridotites most widely found on the Earth’s surface, is formed in the lithospheric mantle because its temperatures are lower than those of the convecting mantle. Thermodynamic modeling reveals a ringwoodite-free field in the P–T diagram (located at the bottom of the mantle transition zone), which is crosscut by Archean adiabats and by the geotherms of Archean and the hottest Phanerozoic plumes. This area causes a change, from negative to positive, in the slope of the boundary between the lower mantle and the mantle transition zone. A positive slope of the boundary in the Archean should have stimulated the ascend of lower mantle plumes through the transition zone. Conversely, this boundary has a negative slope for most Phanerozoic plumes, rising from the lower mantle, and as a result, the plumes either slow down or stop.

Uranyl Minerals from Abandoned Podgórze Mine (Sudetes Mountains, SW Poland) and Their REE Content

The Podgórze uranium deposit is located near Kowary in the Sudetes Mountains, SW Poland. The mine is located in the Karkonosze-Izera block, largely comprising Cambrian to Devonian metamorphic rocks intruded by the Variscan Karkonosze granite. Uranyl minerals from the Podgórze mine can be divided into three assemblages. The first one is associated with heavily ventilated mining galleries. The next assemblage is related to the outflow of water from fissures in the walls of the mine galleries. The last assemblage appears in the mine dump, where there is increased activity of other weathering products. The main purpose of this paper is to determine the mineralogical characteristics of uranyl minerals from the abandoned Podgórze uranium mine and reconstruct the physicochemical crystallization conditions based on the concentrations of rare earth elements (REEs) in these minerals. The results of thermodynamic modeling show that the aqueous species of uranyl ion in the mine water are represented by UO2HAsO4 (aq), UO2CO3(OH)3−, UO2CO3 (aq), and UO2OH+. The content of REEs and their distribution patterns were used to determine the crystallization conditions of uranyl minerals. Uranyl carbonates and arsenates have generally low concentrations of REEs compared to uranyl silicates, phosphates, and hydroxides, which have higher concentrations. The differences in REE concentration patterns may be related with the oxidizing nature of water circulating in the subsurface part of the deposit.

Energy and Exergy Analysis of the Performance of a Double Effect Libr-H&lt;sub&gt;2&lt;/sub&gt;O Absorption Chiller Using the Adapted Characteristic Equations Method

Various researchers have developed a model of conventional H2O -LiBr absorption machines, with the aim of predicting their performance. In this paper, the methodology of the adaptation of the characteristic equations is applied; this model is able to represent the cooling capacity of the double effect absorption chiller by means of simple algebraic linear equation. As a result, it is concluded that a good agreement between the theoretical simulation using the thermodynamic model and the results obtained on the literature. The results achieved through the adapted characteristic equations model have a deviation less than 10% for the cooling capacity and the coefficient of performance COP, and less than 15% for the heat capacity comparing to the thermodynamic model results. The developed characteristic equations and their assessment are useful for the simulation and the control purpose.

Synthesis of MgO-Belite calcium sulfoaluminate cement from phosphate mine waste rock and phosphogypsum

MgO-Belite calcium sulfoaluminate low carbon clinker (BCSAC) was successfully synthetized from a raw meal containing more than 77 wt% of phosphate by-products: 67 wt% of phosphate mining waste rocks and 10 wt% of phosphogypsum (PG: CaSO4·2H2O), while the remaining portion was Kaolin clay. The obtained clinker could be considered as an environmental friendly material. In fact, it can be synthetized at lower temperature (1250 °C) and it is physically softer than Portland cement. Ye’elimite and belite were the major cement phases in the obtained clinker. The hydration of the synthesized cements was assessed by microcalorimetry, compressive strength tests, X-ray diffraction and thermogravimetric analysis. Ettringite was identified as the main crystalline hydrate phase, which is in accordance with thermodynamic modelling results. The presence of P2O5 and the residual acidity in PG negatively influenced the strength development. However, the compressive strengths of the obtained belite calcium sulfoaluminate clinkers was higher than Portland cement at 3 and 7 days. It was explained by the high quantity of ettringite in sulfate-rich cement pastes.

Engineering a Pseudo-26-kDa Schistosoma Glutathione Transferase from bovis/haematobium for Structure, Kinetics, and Ligandin Studies.

Glutathione transferases (GSTs) are the main detoxification enzymes in schistosomes. These parasitic enzymes tend to be upregulated during drug treatment, with Schistosoma haematobium being one of the species that mainly affect humans. There is a lack of complete sequence information on the closely related bovis and haematobium 26-kDa GST isoforms in any database. Consequently, we engineered a pseudo-26-kDa S. bovis/haematobium GST (Sbh26GST) to understand structure–function relations and ligandin activity towards selected potential ligands. Sbh26GST was overexpressed in Escherichia coli as an MBP-fusion protein, purified to homogeneity and catalyzed 1-chloro-2,4-dinitrobenzene-glutathione (CDNB-GSH) conjugation activity, with a specific activity of 13 μmol/min/mg. This activity decreased by ~95% in the presence of bromosulfophthalein (BSP), which showed an IC50 of 27 µM. Additionally, enzyme kinetics revealed that BSP acts as a non-competitive inhibitor relative to GSH. Spectroscopic studies affirmed that Sbh26GST adopts the canonical GST structure, which is predominantly α-helical. Further extrinsic 8-anilino-1-naphthalenesulfonate (ANS) spectroscopy illustrated that BSP, praziquantel (PZQ), and artemisinin (ART) might preferentially bind at the dimer interface or in proximity to the hydrophobic substrate-binding site of the enzyme. The Sbh26GST-BSP interaction is both enthalpically and entropically driven, with a stoichiometry of one BSP molecule per Sbh26GST dimer. Enzyme stability appeared enhanced in the presence of BSP and GSH. Induced fit ligand docking affirmed the spectroscopic, thermodynamic, and molecular modelling results. In conclusion, BSP is a potent inhibitor of Sbh26GST and could potentially be rationalized as a treatment for schistosomiasis.

Microstructure and Mechanical Properties of the Ductile Al\u2013Ti\u2013Mo\u2013Nb\u2013V Refractory High Entropy Alloys

A number of non-equimolar refractory high entropy alloys (RF HEAs) from the Al–Ti–Mo–Nb–V system are synthesized, with the selected compositions aimed to balance the conflicting requirements of the low-temperature ductility and high-temperature corrosion protection. Based on the thermodynamic modeling and experimental results, all the obtained alloys are characterized by the single-phase B2 structure with V acting as the main phase stabilizer. The microstructure and mechanical properties appear to be controlled mainly by the Al content, which is especially visible on the example of hardness, with a maximum value of 545 HV for Al20Ti5Mo25Nb25V25 composition. For the selected Al20Ti5Mo25Nb25V25 and Al10Ti30Mo20Nb20V20 alloys, the measured stress–strain curves indicate the highly coveted, ductile room temperature behavior, with the values of ultimate strain measured under compression mode being 9.17 and 9.00 pct, respectively, and compressive fracture strain of 13.38 and 13.25 pct, respectively. The obtained results suggest that it is possible to include Al as a vital component of refractory HEAs without compromising their low-temperature ductility. The next intended step will be the characterization of the high-temperature corrosion behavior in order to investigate the potential selective oxidation capabilities of such materials.

A thermodynamics-guided framework to design lightweight aggregate from waste coal combustion fly ash

A systematic thermodynamics-based framework was applied to recycle waste low and high-calcium coal combustion Fly Ash (FA) into synthetic lightweight aggregates (LWA) through sintering. The process to successfully manufacture synthetic LWA was investigated, which requires a delicate balance among three phenomena: (i) sufficient liquid phase formation during sintering, (ii) appropriate viscosity for the liquid-solid phase, and (iii) sufficient amount of gas emission to form pores in the LWA. Thermodynamics modeling was used to quantify the formation of the liquid phase during sintering while the fluxing agent and the temperature change. The Urbain- Kalmanovitch, Browning, and Krieger-Dougherty models were used to quantify the viscosity of the liquid and liquid-solid phase, respectively. A lower bound of 100 Pa•s for the viscosity was found to ensure spherical shape of the LWA. Using thermogravimetric analysis, it was shown that the LWA had a notable gas release potential, owing to the presence of anhydrite and hematite, which could create gas-filled pores in the LWA macro-microstructure. X-ray computed tomography (X-CT) observation revealed the formation of a porous structure for the produced LWA where high calcium FA LWA generally had larger pores compared with low calcium FA LWA. By correlating the X-CT and scanning electron microscopy (SEM) observations and thermodynamic modeling results, it was found that a minimum of 40% liquid phase content (% by mass) is necessary for the formation of gas-filled pores in FA-LWA.

Performance investigation and evaluation of an engine operating on a modified dual cycle

In this study, a novel high-performance engine cycle composed of 5 processes and including constant temperature process has been developed by using novel numerical methods and compared with the classical dual cycle. The results of the classical thermodynamic model demonstrated that the proposed cycle which has a constant temperature process is better in terms of thermal efficiency and dimensionless net work compared to the classical dual cycle. After the validation of superiority of the developed cycle over the classical dual cycle, performance investigations of the novel cycle engine have been carried out in terms of power, power density, destructed exergy, thermal efficiency, ecological coefficient of performance, effective ecological power density by developing a novel fuel-air cycle model. The influences of design and operational parameters such as cut-off ratio, compression ratio, cycle temperature ratio, equivalence ratio, engine speed, stroke length, cylinder bore, cylinder wall temperature, air intake temperature, pressure ratio, on the performance specifications have been numerically derived.

Thermodynamic modeling of iron and zinc reduction from B&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; ‒ CaO ‒ Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; ‒ ZnО melt by СО ‒ CO&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt; ‒ Н&lt;sub&gt;2&lt;/sub&gt;О mixtures

The paper presents the thermodynamic modeling results of zinc and iron reduction from B2O3 ‒ CaO ‒ Fe2O3 ‒ ZnО melts by CO ‒ CO2 and H2 ‒ H2O mixtures containing 0 – 60 % CO2 (H2O) at 1273 – 1673 K using a technique describing the reduction of metals from an oxide melt by gas in bubbling processes, under conditions that provide an approximation to real systems. Its originality is equilibrium determination for each individual portion of gas supplied into the working fluid. The reducible metals oxides content in each calculation cycle is taken from the previous data. During the calculations, changes in the content of zinc (СZnO ) and iron (СFe2O3 , СFe3O4 and СFeO ) oxides in the melt and the degree of their reduction were estimated. When using CO or H2 as a reducing agent, this process proceeds in three stages. In the first stage, Fe2O3 is reduced to Fe3O4 and FeO. CFe2O3 values decrease to almost zero, while CFe3O4 and CFeO increase simultaneously. By the end of the stage, СFe3O4 reaches its maximum value. At the second stage, the Fe3O4 → FeO transition occurs, when СFeO values reach its maximum. At these stages, there is a slight increase in the CZnO . At the third stage, the values CFeO and CZnO decrease, and iron and zinc are reduced. An increase in temperature dramatically reduces the gas consumption for zinc reduction by 2 – 3 times, and the replacement of CO with H2 reduces it by less than 20 %. In the presence of oxidizing agents (CO or H2O), only zinc is reduced. The process ends when the final content of zinc oxide in the melt corresponds to the equilibrium with the initial gas composition. The higher the temperature, the less CZnO is. The obtained data are useful for the development of technologies for the selective recovery of metals.

A micro-CHP system with organic Rankine cycle using R1223zd(E) and n-Pentane as working fluids

This paper presents an ORC-based micro-CHP system designed for use in residential houses. Two working fluids, R1223zd(E) and n-Pentane, are investigated and the performance of the ORC is compared. Experimental results show that the ORC-based micro-CHP system with R1223zd(E) used as the working fluid achieves slightly higher efficiency than with n-Pentane, with the ORC efficiencies being 7.6% and 7.3%. The system produces the electricity outputs of 0.98 kWe and 0.95 kWe at nominal operating conditions when the two fluids are used respectively. A thermodynamic model for the ORC is developed to predict its thermodynamic performance and evaluate different working fluids. The results of thermodynamic modelling show that the ORC efficiencies achieved with the two ORC fluids range from 6.6% to 13.6% and from 6.2% to 13.8% depending on operating conditions. The micro-CHP system is capable of delivering great performance with respect to overall energy efficiency, low GWP and on-site power and heating security for homes.