Thermodynamic Criteria Research Articles

Thermodynamics analysis and temperature response mechanism during methane hydrate production by depressurization

Methane hydrate is expected as a future energy to satisfy the long-term energy needs worldwide. Yet, the thermodynamics behaviors and temperature response mechanism during methane hydrate production by depressurization are still unclear. In this study, four methane hydrate-bearing sandy sediments with different initial pressures (6.0, 5.5, 4.8 and 4.2 MPa) are depressurized to 3.0 MPa at a slow rate, and the temperature decreases with the depressurization progresses and will be accelerated from the hydrates start to dissociate. The dissociation rate of hydrates gradually increase to and keep at a highest value under a rated production flux, when the temperature is strictly response to the pressure and the pressure and temperature trajectories are parallel to the hydrate phase equilibrium line. At this stage, the external heat transfer is almost used for the hydrate dissociation, and it is called stationary state of hydrate dissociation in this study. When the pressure turns constant, the hydrate dissociation changes to a lower rate than the depressurization stage, and then the declined dissociation rate consumes less heat and therefore can warm the whole sediment. The results reveal the temperature response differences before, in and after the hydrate dissociation process and provide direct thermodynamic criterion for the field monitoring of methane hydrate production.

Practical Approbation of Thermodynamic Criteria for the Consolidation of Bimetallic and Functionally Gradient Materials

This study concerns the key problem of determining the conditions for the consolidation or fracture of bimetallic compounds and high-gradient materials with different coefficients of thermal expansion. The well-known approach to determining the strength is based on the assessment of the critical energy release rates during fracture, depending on the conditions of loading (the portion of shear loading). Unfortunately, most of the experimental results cannot be used directly to select suitable fracture toughness criteria before such a connection is made. This especially applies to the region of interphase interaction, when it is required to estimate the internal energy of destruction accumulated during the preparation of the joint in the adhesion layer within the range of 20–50 μm. Hence, criteria for the adhesive consolidation of bimetallic compound layers were obtained on the basis of the thermodynamics of nonequilibrium processes. The analysis of the quality of the joint using the obtained criteria was carried out on the basis of the calculation of isochoric and isobaric heat capacities and coefficients of thermal expansion of multiphase layers. The applicability of the criteria for the qualitative assessment of the adhesion of layers is demonstrated in the example of bimetallic joints of steel 316L—aluminum alloy AlSi10Mg obtained by the SLM method at various fusion modes.

Multi-objective thermo-economic optimization of Collins cycle

Many large scientific projects are emerging worldwide with the development of high energy physics nowadays. The indispensable subsystem, helium cryo-plants for such projects require extremely high energy consumption and total annual cost (TAC). In order to reduce energy consumption and TAC, multi-objective thermo-economic optimization that adopted non-dominated sorting genetic algorithm-II (NSGA-II) for helium cryo-plants is proposed in this work. As a typical helium liquefaction cycle, Collins cycle is selected as the optimization object. Both the exergetic efficiency (ηEx) and the TAC are set as objective parameters. The decision parameters, which include discharge pressure of compressor, flow fraction of expanders and effectiveness of heat exchangers, are optimized simultaneously. Linear programming technology of multidimensional analysis preference (LINMAP) is utilized as an example to select the optimal solution from the multi-objective optimization results. Compared to the maximum ηEx result, the LINMAP result reduces the TAC by 23.95% at the cost of 9.03% reduction in ηEx. In the proposed approach, eight decision parameters can be optimized simultaneously and the designed cryo-plant considers both economic and thermodynamic criteria, which is feasible for practical engineering project. Besides, alternative solution under limited investment situation is provided.

Thermodynamic criteria of alloying elements elimination during recycling end-of-life zinc-based products by remelting

Elimination of alloying elements in the end-of-life (EoL) zinc-based products is essential for the resource efficiency of zinc recycling. Using a thermodynamic method, the elimination behavior of 34 alloying elements during the recycling of EoL zinc-based products by the remelting process was quantitively evaluated. The influence of all the thermodynamic parameters was considered and extensively discussed. It was found that the remelting process with treatment using chloride flux or oxide slag is efficient in alloying elements elimination. However, eliminate alloying elements, such as antimony, bismuth, cadmium, cobalt, copper, germanium, gold, indium, iron, lead, nickel, silver, and tin is difficult. These elements will contaminate the remelted zinc metal once mixed in the collected EoL products.Moreover, promoting the elimination of these alloying elements is difficult by adjusting the remelting conditions such as temperature, chlorine partial pressure, and flux composition. To increase the recycling efficiency of zinc, in addition to improving metallurgical refining technology, establishing an advanced recycling system to achieve a horizontal alloy-to-alloy recycling and changing the current trend of product design of excessive mixing is essential. The thermodynamic criteria of alloying elements elimination can provide basic information for these tasks.

High pressure phase evolution under hydrostatic pressure in a single imperfect crystal due to nanovoids

In this paper, the evolution of high pressure phase (HPP) in an imperfect single crystal due to the existence of nanovoids is investigated. The nanovoid misfit strain and its stress are properly linked to its radius. The Ginzburg-Landau coupled with elasticity equations are solved for the HPP evolution. The energy barrier between the HPP and the low pressure phase, entropy jump, transformation strain function and the relation between critical and equilibrium temperatures are determined based on the phase transformation (PT) equilibrium and instability pressures and the HPP transformation strain. The obtained PT pressure which shows an exponential reduction vs. the radius and a linear increase vs. temperature, is found mostly smaller than the theoretical solution. The HPP grows from the nanovoid surface and along the line of zero shear transformation strain. Above some critical radius, the HPP growth is promoted and continues along the boundaries. The transformation work distribution reveals a faster initial growth for larger radii. The HPP growth is evaluated based on the thermodynamic equilibrium and instability criteria. The growth rate and velocity of the HPP tip nonlinearly decrease with temperature. Interestingly, the average shear stress varies very similar to the HPP concentration. The HPP growth is also investigated for different applied pressures so that above some pressure, the HPP growth proceeds along the boundaries and the growth rate increases as the pressure increases. The current study can be used to better understand the PT nano mechanisms of various HPPs.

Consistency between dynamical and thermodynamical stabilities for charged self-gravitating perfect fluid

The entropy principle shows that, for self-gravitating perfect fluid, the Einstein field equations can be derived from the extrema of the total entropy, and the thermodynamical stability criterion are equivalent to the dynamical stability criterion. In this paper, we recast the dynamical criterion for the charged self-gravitating perfect fluid in Einstein-Maxwell theory, and further give the criterion of the star with barotropic condition. In order to obtain the thermodynamical stability criterion, first we get the general formula of the second variation of the total entropy for charged perfect fluid case, and then obtain the thermodynamical criterion for radial perturbation. We show that these two stability criterion are the same, which suggest that the inherent connection between gravity and thermodynamic even when the electric field is taken into account.

Structure and properties of KNi–hexacyanoferrate Prussian Blue Analogues for efficient CO2 capture: Host–guest interaction chemistry and dynamics of CO2 adsorption

Potassium Nickel hexacyanoferrate Prussian Blue Analogues (K-NiFe-PBAs) offer an excellent platform for efficient CO2 capture due to their porous nature and accessible channels. Herein, the effect of Ni:K atomic ratio on the structure and the CO2 storage capacity was studied by employing K-NiFe-PBAs with Ni:K ratio of ca. 2.5 and 12. The porosity and the isosteric heat of CO2 adsorption can be modulated and optimized by varying the Ni:K atomic ratio in the PB framework and thus, covering the thermodynamic criterion for easy CO2capture and release with acceptable energy costs. The synthesized K-NiFe-PBAs containing only trace amounts of K+ ions (with Ni:K = 12) shows an adsorption capacity (∼3.0 mmol g–1 CO2 at 273 K and 100 kPa) comparable to other well established CO2 adsorbents. In situ FTIR spectroscopy was further employed to elucidate the host–guest interaction chemistry and the dynamics of K-NiFe-PBAs within CO2 and H2O. The analysis enabled, to the best of our knowledge, is the first FTIR spectroscopic observation of the high sensitivity of the material to structural distortions induced by small changes under water vapor pressure. It was found that H2O hardly affects CO2 adsorption and the materials are perspective for CO2 capture in the presence of water.

Thermodynamic criterion for searching high mobility two-dimensional electron gas at KTaO3 interface* *Project supported by the National Key R&D Program of China (Grant Nos. 2016YFA0300701, 2017YFA0206304, and 2018YFA0305704), the National Natural Science Foundation of China (Grant Nos. 11934016, 111921004, 51972335, and 11674378), and the Key Program of the Chinese Academy of Sciences (Grant Nos. XDB33030200 and QYZDY-SSW-SLH020).

Two-dimensional electron gases (2DEGs) formed at the interface between two oxide insulators present a promising platform for the exploration of emergent phenomena. While most of the previous works focused on SrTiO3-based 2DEGs, here we took the amorphous-ABO3/KTaO3 system as the research object to study the relationship between the interface conductivity and the redox property of B-site metal in the amorphous film. The criterion of oxide–oxide interface redox reactions for the B-site metals, Zr, Al, Ti, Ta, and Nb in conductive interfaces was revealed: the formation heat of metal oxide, , is lower than –350 kJ/(mol O) and the work function of the metal Φ is in the range of 3.75 eV < Φ < 4.4 eV. Furthermore, we found that the smaller absolute value of and the larger value of Φ of the B-site metal would result in higher mobility of the two-dimensional electron gas that formed at the corresponding amorphous-ABO3/KTaO3 interface. This finding paves the way for the design of high-mobility all-oxide electronic devices.

A Mediterranean cold front identification scheme combining wind and thermal criteria

AbstractThe goal of this study is to advance an automated and objective scheme for the identification of cold fronts over the Mediterranean based on wind‐related criteria, MedFTS, by further incorporating thermal criteria, in order to improve the identification of cold fronts on a climatological basis. These thermal criteria are related to cold advection and the thermal front parameter, and their individual or combined contribution is systematically investigated considering different threshold values. For each combination of thermal criteria and/or threshold values, the results are validated with the aid of statistical indices and metrics, and the optimum scheme configuration for the identification of Mediterranean fronts is selected. The advanced version of MedFTS, named MedFTS_DT, having incorporated both dynamic and thermodynamic criteria, is applied and validated for a decade of fronts over the Mediterranean. It was found that the number of erroneously identified cold fronts over Greece was significantly reduced from MedFTS to MedFTS_DT version by almost 40%, as indicated by the statistical metrics. Therefore, the performance of MedFTS_DT is verified to be superior to MedFTS. As a further attempt to investigate the ability of MedFTS_DT to perform adequate climatological analysis in the Mediterranean, the frequency of the cold fronts was calculated over Greece during the period 2007–2016 on a monthly and seasonal basis, demonstrating that the scheme can capture the intra‐annual variations. Finally, the contribution of the cold fronts to the precipitation over the Mediterranean for the same period was investigated, further supporting the scheme's performance.

A review on phase prediction in high entropy alloys

The formation of single phase solid solution in High Entropy Alloys (HEAs) is essential for the properties of the alloys therefore, numerous approach were proposed by many researchers to predict the stability of single phase solid solution in High Entropy Alloy. The present review examines some of the recent developments while using computational intelligence techniques such as parametric approach, CALPHAD, Machine Learning etc. for prediction of various phase formation in multicomponent high entropy alloys. A detail study of this data-driven approaches pertaining to the understanding of structural and phase formation behaviour of a new class of compositionally complex alloys is done in the present investigation. The advantages and drawbacks of the various computational are also discussed. Finally, this review aims at understanding several computational modeling tools complying the thermodynamic criteria for phase formation of novel HEAs which could possibly deliver superior mechanical properties keeping an aim at advanced engineering applications.

Assessment of organic Rankine cycle configurations for solar polygeneration orientated to electricity production and desalination

This work addresses the polygeneration concept integrating concentrating solar power (CSP) with an organic Rankine cycle (ORC) to produce electricity and drinking water by hybrid desalination process combining reverse osmosis (RO) and low-temperature multi-effect distillation (LTMED). Experiments carried out on a bench scale RO pilot led to determine optimal operating parameters as well as options to mitigate the main limiting factors of this technology by hybridizing with LTMED. These data helped to simulate a large scale solar polygeneration plant integrating parabolic trough collectors as CSP technology and a hybrid RO-LTMED system as desalination technology. Various ORC design proposals were simulated and the optimal configuration was pointed out on the basis of thermodynamic criteria (energy efficiency and exergy destruction) and an economic analysis by using two working fluids: an alkane commonly admitted as good candidate and an ester proposed here as green alternative. Results obtained in this work contribute positively to extending the solar polygeneration for desalination and production of energy leading to future sustainable plants.

Unveiling the Molecular Structure of Antimalarial Drugs Chloroquine and Hydroxychloroquine in Solution through Analysis of 1H NMR Chemical Shifts

Chloroquine (CQ) and hydroxychloroquine (HCQ) have been standard antimalarial drugs since the early 1950s, and very recently, the possibility of their use for the treatment of COVID-19 patients has been considered. To understand the drug mode of action at the submicroscopic level (atoms and molecules), molecular modeling studies with the aid of computational chemistry methods have been of great help. A fundamental step in such theoretical investigations is the knowledge of the predominant drug molecular structure in solution, which is the real environment for the interaction with biological targets. Our strategy to access this valuable information is to perform density functional theory (DFT) calculations of 1H NMR chemical shifts for several plausible molecular conformers and then find the best match with experimental NMR profile in solution (since it is extremely sensitive to conformational changes). Through this procedure, after optimizing 30 trial distinct molecular structures (ωB97x-D/6-31G(d,p)-PCM level of calculation), which may be considered representative conformations, we concluded that the global minimum (named M24), stabilized by an intramolecular N-H hydrogen bond, is not likely to be observed in water, chloroform, and dimethyl sulfoxide (DMSO) solution. Among fully optimized conformations (named M1 to M30, and MD1 and MD2), we found M12 (having no intramolecular H-bond) as the most probable structure of CQ and HCQ in water solution, which is a good approximate starting geometry in drug-receptor interaction simulations. On the other hand, the preferred CQ and HCQ structure in chloroform (and CQ in DMSO-d6) solution was assigned as M8, showing the solvent effects on conformational preferences. We believe that the analysis of 1H NMR data in solution can establish the connection between the macro level (experimental) and the sub-micro level (theoretical), which is not so apparent to us and appears to be more appropriate than the thermodynamic stability criterion in conformational analysis studies.

Comparative environmental impacts and emission reductions of introducing the novel organic Rankine &amp; Kalina cycles to recover waste heat for a roller kiln

Abstract In order to simultaneously utilize the flue gas and cooling gas of a roller kiln, the novel organic Rankine (ORC) & Kalina cycles (KC) with parallel double-evaporator (PD) including PD-BORC, PD-RORC, PD-KC11 and PD-KC34 are introduced for the waste heat recovery. To evaluate the environmental influences performance for the recommended thermodynamic cycles, environment impact loads and emission reductions analysis are employed from the life-cycle perspective. Also, to select a more environmentally friendly model, the system environmental influences based on thermodynamic, economic, environmental and watery criteria are investigated. Results show that under the four criteria, the pump contribute mostly to GWP (global warming potential), AP (acidification potential), EP (eutrophication potential) and HTP (human toxicity potential), evaporation unit is dominant in POCP (photochemical ozone creation potential) and SWP (solid waste potential), and both evaporation unit and pump have the main influence on SAP (soot and dust potential). Meanwhile, operation phase makes the greatest contribution to GWP, AP and HTP, construction phase has the greatest influence on POCP and SWP, and construction and operation phases account for the largest proportion of EP and SAP. It can also be concluded that SAP has the most serious impact on the environment while POCP is the least significant factor. Besides, from the perspective of environment impact load, PD-BORC is the best selection, and the system design based on environmental criterion has the minimum value. Also, in terms of the emission reduction, PD-KC34 is the priority selection, and the maximum emission reduction can be achieved under thermodynamic criterion. Furthermore, the reduction ratio of environment impact load can be increased with increasing the evaporator inlet temperature, decreasing the condenser outlet temperature, increasing the superheat degree (PD-ORCs) and decreasing the superheat degree (PD-KCs), and decreasing the ammonia concentration (PD-KCs).

Comparative thermoeconomic analyses and multi-objective particle swarm optimization of geothermal combined cooling and power systems

Comparative parametric and multi-objective optimization analyses of three novel geothermal systems are performed for combined cooling and power generation. The first (Configuration (a)) consists of an absorption power cycle and an ejector refrigeration cycle, the second (Configuration (b)) of a modified Kalina cycle and an absorption refrigeration cycle, and the third (Configuration (c)) of a double-flash power cycle and an ejector refrigeration cycle, in all cases for power generation and cooling, respectively. Both thermodynamic (energy, exergy) and economic criteria are compared to gain an understanding of the characteristics and performance of these systems, and to ascertain the most appropriate system for different scenarios. Results from the parametric study show that Configuration(a) has the highest power output and exergy efficiency, but lowest cooling capacity and overall (power plus cooling) thermal efficiency, while Configuration (b) has the highest cooling capacity and thermal efficiency, but lowest power output and exergy efficiency. From an exergoeconomic perspective, Configuration(a) has the lowest and Configuration (b) the highest total specific cost. Configuration (c) maintains, generally, a thermoeconomic performance in-between those of the other two systems. The optimization results indicate that if the thermal efficiency and total specific cost are considered competing objectives over a range of well conditions, the optimal solutions obtained by the LINMAP method for Configurations (a) to (c) have thermal efficiencies of 19.1%, 43.0%, 42.4%, exergy efficiencies of 57.6%, 23.6%, 33.1%, total cost rates of 436 $/h, 558$/h, 596$/h, and total specific costs of 29.7 $/GJ, 66.9 $/GJ, 43.5 $/GJ. If the exergy efficiency and total cost rate are considered competing objectives, the corresponding values are 13.0%/29.1%/10.5%, 67.3%/30.5%/37.3%, 362/353/384 $/h, and 24.9/67.5/42.7$/GJ, respectively.

Rate and Driving Forces of Grain-Boundary Migration in Solid-State Alloys

Based on the interaction of solid and liquid phases in metallic systems, the paper deals with the properties of grain boundary propagation (migration) in solid-state alloys. Using the effect of surface solid-state dispersion enables to obtain composite materials and brazed joints with a required set of physical and mechanical properties. For the first time, the authors investigate the features of boundary migration in type II systems, in which, in accordance with the thermodynamic criterion σss&lt; 2 σSL, the grain-boundary propagation is not basically allowed.

Exploring the symbol processing 'time interval' parametric constraint in a Belousov-Zhabotinsky operated chemical Turing machine.

Chemical reactions are powerful molecular recognition machines. This power has been recently harnessed to build actual instances of each class of experimentally realizable computing automata, using exclusively small-molecule chemistry (i.e. without requiring biomolecules). The most powerful of them, a programmable Turing machine, uses the Belousov–Zhabotinsky oscillatory chemistry, and accepts/rejects input sequences through a dual oscillatory and thermodynamic output signature. The time interval between the aliquots representing each letter of the input is the parameter that determines the time it takes to run the computation. Here, we investigate this critical performance parameter, and its effect not only on the computation speed, but also on the robustness of the accept/reject oscillatory and thermodynamic criteria. Our work demonstrates that the time interval is a non-trivial design parameter, whose choice should be made with great care. The guidelines we provide can be used in the optimization of the speed, robustness, and energy efficiency of chemical automata computations.

Defective TiO2 for photocatalytic CO2 conversion to fuels and chemicals.

Photocatalytic conversion of CO2 into fuels and valuable chemicals using solar energy is a promising technology to combat climate change and meet the growing energy demand. Extensive effort is going on for the development of a photocatalyst with desirable optical, surface and electronic properties. This review article discusses recent development in the field of photocatalytic CO2 conversion using defective TiO2. It specifically focuses on the different synthesis methodologies adapted to generate the defects and their impact on the chemical, optical and surface properties of TiO2 and, thus, photocatalytic CO2 conversion. It also encompasses theoretical investigations performed to understand the role of defects in adsorption and activation of CO2 and identify the mechanistic pathway which governs the formation and selectivity of different products. It is divided into three parts: (i) general mechanism and thermodynamic criteria for defective TiO2 catalyzed CO2 conversion, (ii) theoretical investigation on the role of defects in the CO2 adsorption–activation and mechanism responsible for the formation and selectivity of different products, and (iii) the effect of variation of physicochemical properties of defective TiO2 synthesized using different methods on the photocatalytic conversion of CO2. The review also discusses the limitations and the challenges of defective TiO2 photocatalysts that need to be overcome for the production of sustainable fuel utilizing solar energy.

Microstructure evolution and mechanical properties of (CoCrNi)90(AlTiZr)5(CuFeMo)5 multicomponent alloy: A pathway through multicomponent alloys toward new superalloys

Thermodynamic criteria of lattice distortion energy (ΔHel) and enthalpy of mixing (ΔHmix) were considered to design and estimate the initial phase formation and stability in (CoCrNi)100−x−y(AlTiZr)x(CuFeMo)y multicomponent alloy (MCA) system. This study aimed to chase a new alloy design pathway to develop superalloys by benefitting from the concept of multiphase MCAs. The non-equilibrium cast microstructure (CoCrNi)100−x−y(AlTiZr)x(CuFeMo)y displayed a metastable dendritic structure consisting of primary Co-Cr-Ni-rich FCC dendrites and an interdendritic eutectic mixture, comprising supersaturated cubic Laves-phase and FCC phase. The composition of the AB2-structure Laves-phase was identified as (Zr, Cr, Cu, Al, Ti)(Ni, Co)2. Following the short-term annealing, a tenuous network of Zr-rich phase with a cubic structure was formed by the decomposition of the Laves-phase structure. Phase fraction along with the morphology of the intermetallic phase was altered by treatment and eventually semi-circular islands emerged. Results of tensile and compression tests at different strain rates exhibited the detrimental effect of structural instability and dependency of rate-sensitivity to alloy microstructure. Strain-rate increment enhanced the contribution of ductile failure with slip-band indications; however, this was accompanied by activation of further deformation mechanisms and subsequent formability improvement at a higher rate.

D-bound and the Bekenstein bound for the surrounded Vaidya black hole

We study the Vaidya black hole surrounded by the exotic quintessence-like, phantom-like and cosmological constant-like fields by means of entropic considerations. Explicitly, we show that for this thermodynamical system, the requirement of the identification of the D-bound and Bekenstein entropy bound can be considered as a thermodynamical criterion by which one can rule out the quintessence-like and phantom-like fields, and prefer the cosmological constant as a viable cosmological field.

Thermodynamic foundations of wood’s operational properties

The paper shows trends in the study of building materials. Thermodynamic approaches to analysis of the condition of building materials as a thermodynamic system, including in thermal decomposition conditions, are described. As part of the experimental part, the proposed methods analysed the effect of phosphorus organic materials on the fire danger of wood. The correlation of thermodynamic criteria (Gibbs energy) and identified physical and chemical behaviors of modified wood has been revealed.