Papers by Keyword: Entropy

Abstract: The petroleum production process emphasizes the importance of inspection, analysis, test planning, and providing feedback on rotating equipment. This study discusses the analysis of steam turbine generator overhaul (OH) for efficiency enhancement at the power plant center of refinery unit. The efficiency of steam turbines in power plants is critical for optimizing energy conversion and minimizing operational costs. This study analyzes the impact of a steam turbine generator overhaul on efficiency at a refinery unit power plant. Efficiency was evaluated using Rankine cycle calculations, comparing performance data before and after the overhaul. The findings indicate a 2.63% increase in efficiency, with entropy-temperature analysis revealing energy losses due to scaling buildup and seal strip clearance deterioration. To maintain efficiency and reduce overhaul frequency, demineralized water quality, periodic maintenance, and anti-scaling treatments are recommended. These results highlight the importance of proactive maintenance in sustaining turbine performance and minimizing long-term costs.

Abstract: This study investigates the thermodynamics of manganese ion adsorption on nanozeolite to assess the nanomaterial’s heavy metal removal efficiency from surface water, industrial water, and groundwater. Using Isothermal Titration Calorimetry (ITC), the thermodynamic profile of nanozeolite is obtained, demonstrating a low equilibrium binding affinity. The thermodynamic signature showed favorable binding mechanisms, primarily from the change of entropy, suggesting spontaneous reactions. Meanwhile, the enthalpy change of adsorption increases as temperature rises, while ∆G and T∆S decrease. Using proper thermodynamic conditions, nanozeolite may efficiently remove manganese from different water sources.

Abstract: Is it possible to quantify in General Relativity, GR, the entropy generated by Super-Massive Black Holes, SMBH, during its evaporation time, since the intrinsic Hawking radiation in the infinity that, although insignificant, is important in the effects on the thermal quantum atmosphere? The purpose was to develop a formula that allows us to measure the entropy generated during the evaporation time of different types of SMBH of: i. remnant BH of the binary black holes’ merger, BBH: GW150914, GW151226 and LTV151012 detected by the Laser Interferometer Gravitational-Wave Observatory, LIGO, and ii. Schwarzschild, Reissner-Nordström, Kerr and Kerr-Newman, and thus quantify in GR the “insignificant” quantum effects involved, in order to contribute to the validity of the generalized second law, GSL, that directly links the laws of black hole mechanics to the ordinary laws of thermodynamics, as a starting point for unifying quantum effects with GR. This formula could have some relationship with the detection of the shadow’s image of the event horizon of a BH. This formula was developed in dimensional analysis, using the constants of nature and the possible evaporation time of a black hole, to quantify the entropy generated during that time. The energy-stress tensor was calculated with the 4 metrics to obtain the material content and apply the proposed formula. The entropy of the evaporation time of SMBH proved to be insignificant, its temperature is barely above absolute zero, however, the calculation of this type of entropy allows us to argue about the importance of the quantum effects of Hawking radiation mentioned by authors who have studied the quantum effects with arguments that are fundamentally based on the presence of the surrounding thermal atmosphere of the BH.

Abstract: The presented study demonstrates the possibility of an analytical approach called the multi-optional hybrid-effectiveness functions uncertainty measure conditional optimization doctrine. This method is applied in order to obtain the known, therefore considered proven, solutions by-passing the entirely probabilistic approach. It is made in application to the stochastic process measures determination. Supposedly, the process is developing in the aircraft engine system’s element (the state condition of its material). The solution is found in the framework of the entropy paradigm. It helps assess the newly emerged materials applications rationality and the novelty technologies implementations expediency on condition of the operational options uncertainty.

Abstract: A method has been developed for calculating the stability constants of inorganic complexes of rare-earth metals at various temperatures, based on analysis of the literature data by obtaining a linear regression equation on the form: . Using this method, the stability constants of bromide LnBr²⁺ and carbonate LnCO₃⁺ complexes of europium, terbium, and gadolinium in aqueous solutions at temperatures of 50, 75, and 100 ° C were obtained. The obtained values of the coefficients А(T₁) and В(T₁) of the linear regression equation can be used to calculate the stability constants of complexes of europium, terbium, and gadolinium with other inorganic ligands at given temperatures. Based on the temperature dependence of the stability constants of bromide and carbonate complexes, their standard entropies and enthalpies of formation were calculated. Based on the obtained values of the thermodynamic functions, an assumption was made about the outer-sphere or inner-sphere nature of the complex.

Abstract: High entropy alloys (HEAs) are equimolar multi-principal-element alloys (MPEAs) that are different from traditional solvent-based multicomponent alloys based on the concept of alloy design. Based on initial work by Yeh and co-workers, HEAs were postulated to exhibit four “core” effects: high entropy, sluggish diffusion, lattice distortion, and cocktail effect. Out of these four proposed core effects, “high entropy” and “sluggish diffusion” effects were most debated in the literature as these core effects directly affect the thermodynamic and kinetic understanding of HEAs. The initial work on HEAs by several researchers utilized these effects to indirectly support the experimentally observed “unique” properties, without independent investigation of these core effects. The presumed implications of these core effects resulted in justification or generalization of properties to all HEAs, e.g., all HEAs should exhibit high temperature stability based on high entropy effect, high temperature strength owing to limited grain growth, good diffusion barrier application due to sluggish diffusion kinetics, etc. However, many recent studies have challenged these core effects, and suggested that not all HEAs were observed to exhibit these core effects.

Abstract: In this work a new approach of analyzing epitaxial graphene layers on semi-insulating SiC through the gray-scale entropy of SEM images as a measure for the graphene inhomogeneity is demonstrated. Raman spectroscopy as a versatile and the standard tool for graphene characterization allows additionally the determination of the layer properties such as layer count, Fermi level, defect concentration and strain. It is shown that the gray-scale entropy correlates with the defect density derived from Raman measurements and thus can be used as an additional characterization technique with much higher resolution than the conventional Raman spectroscopy allows. As a consequence, the results are used to reflect the two-stepped growth itself and to conclude for advantageous growth conditions.

Abstract: The paper considers application of the physical and statistical approach to the issue of nanosystems reliability. A general method of solving the main equation in this approach is suggested and the solution in quadratures is obtained in one-dimensional stationary case. It is used to study the behaviour of entropy and the reliability function under certain assumptions. The cases of constant, linear, and quadratic degradation rates are analysed. In the first two cases the results correspond to physical intuition while in the last case (quadratic rate) the formal solution demonstrates counterintuitive behaviour. Numerical correlations between the distribution entropy dynamics and the reliability function are given.

Abstract: The possibility of applying a hyperbolic model for calculating thermodynamic characteristics (the standard molar heat capacity, standard molar entropy) to the V–O system is shown. For calculation of the molar specific heat and entropy within the bounds of the model the general concept has been used: a thermodynamic parameter is divided into two components. The first component depends on the molar mass of a compound, the second one is determined by inter particle interaction. The dependence of the inverse value for the interaction heat capacity (entropy) on composition is of linear character within one region of quasi-equilibrium solid solutions (one region combines compounds with the same or similar structure type).The use of the model allowed refining the available experimental data on vanadium oxides and predicting the values of thermodynamic characteristics for compounds poorly studied in experiment.

Abstract: The paper presents a brief overview of the thin-layer thermal insulation paints used now and their characteristics. A new composition of thin-layer heat-insulation coating is proposed. The introduction of solid phases of non-autoclaved foam concrete with the average density D150 with high values of the standard entropy of formation in it is scientifically substantiated from the point of view of increasing the thermal protection properties. It is shown that such phases have an advantage in comparison with the solid phases of the glass and ceramic microspheres used now. It is also proved that the presence of thin-layer thermal insulation coating of nanoscale particles in the form of silica in the composition favours the reflection of the incident heat flux due to the Tindal effect and provides an increase in the polydispersity of the composition. The calculation of the resulting composition by the Van Vleсk formula used in the classical science is given.