Thermodynamic Model Calculations Research Articles

MODELING SOLAR COLLECTORS: A REVIEW OF MODERN METHODS TO IMPROVE ENERGY CONVERSION EFFICIENCY UNDER CHANGING CLIMATIC CONDITIONS

Efficiency and reliability in solar energy systems are largely influenced by the development of solar collector technologies and methodologies adopted for performance modeling under variable climatic conditions. This paper reviews recent approaches to modeling solar collectors, with a primary emphasis on the integration of solar tracking systems with advanced computational techniques such as artificial intelligence and hybrid models. The review highlights the use of long short-term memory (LSTM) models, neural networks, and AI-driven optimizations for enhancing energy conversion efficiency. It also provides an overview of the contributions of computational fluid dynamics (CFD) and thermodynamic models to the structural and thermal performance of solar collectors, mainly parabolic trough collectors (PTCs) and systems utilizing nanofluids as working mediums. Various case studies demonstrate the significant impacts of these modeling methods on improving efficiency and adapting to real-time environmental changes. The review concludes with recommendations for future work in integrating artificial intelligence (AI), hybrid model development, new material explorations, and long-term field studies to refine and enhance solar collector performance. These advancements are expected to contribute significantly to the future of solar energy, fostering sustainable and efficient energy solutions.

A simulation study on the process design and optimization pressure swing separation of azeotropic mixture methanol and toluene

Pressure Swing Distillation (PSD) is the only advanced technology that does not require the addition of third components to the system to enhance the separation of azeotropic mixtures. It outperforms homogeneous distillation for separating pressure-sensitive azeotropic mixtures. In this study, we aimed to separate methanol and toluene using the Non-Random Two-Liquid (NRTL) and Aspen Plus thermodynamic calculation models to simulate a binary homogeneous azeotropic system. The standard PSD process was employed to separate methanol and toluene. Furthermore, multiple optimization sequences were utilized to sequentially optimize the process for obtaining higher purities of methanol and toluene while reducing the Total Annual Cost (TAC) and heat energy consumption. The effects of the optimization sequence on the TAC were investigated. The best optimization sequences for graphing in Origin or Aspen Plus were found to be RR1, NR, NF1, NF2, NT1, and NT2. Additionally, the Double-Effect Distillation (DED) optimization sequence is similar, with TAC as the primary function in the simulation and methanol and toluene purities up to 99.99%. In the DED simulation, the feed position and tray number were found to be sensitive to TAC by the order NR > NF1 > NF2 and NT1 > NT2. This study simulated PSD using the NRTL thermodynamic calculation model in Aspen Plus and generated visualizations using Origin software.

Numerical, Physical, and Industrial Investigations on Hot Metal Desulphurization-From Macromixing Conditions to Reaction Rate Phenomena.

The efficiency of the hot metal pretreatment process plays a very important role in achieving high-quality and low-cost advanced steel. From macromixing phenomena obtained by numerical modeling and physical experiments to compound interaction databases from industry trials, the Authors compared fundamental relationships from the literature with their own laboratory results and plant data. A simple numerical model based on the LES turbulence approach was well-validated by water modeling. Hence for a 300-ton ladle, the mixing time and mixing power were predicted. Finally, the mass transfer controlled rate was calculated based on a computational fluid dynamics model and thermodynamic model, which indicated results limitations. Moreover, from the industry data, it was found that the rate constant of the desulfurization process varies within a wide range, affecting the efficiency of the sulphur removal degree from values 0.6 to 0.98.

Hydrogen-fueled PFI SI engine investigation for near-zero NOx emissions in de-throttled and supercharged ultra-lean burn conditions

Hydrogen-fueled PFI SI engine investigation for near-zero NOx emissions in de-throttled and supercharged ultra-lean burn conditions

A Combined Experimental and Computational Study on the Effect of the Reactor Configuration and Operational Procedures on the Formation, Growth and Dissociation of Carbon Dioxide Hydrate

Clathrate hydrate-based technologies are considered promising and sustainable alternatives for the effective management of the climate change risks related to emissions of carbon dioxide produced by human activities. This work presents a combined experimental and computational investigation of the effects of the operational procedures and characteristics of the experimental configuration, on the phase diagrams of CO2-H2O systems and CO2 hydrates’ formation, growth and dissociation conditions. The operational modes involved (i) the incremental (step-wise) temperature cycling and (ii) the continuous temperature cycling processes, in the framework of an isochoric pressure search method. Also, two different high-pressure PVT configurations were used, of which one encompassed a stirred tank reactor and the other incorporated an autoclave of constant volume with magnetic agitation. The experimental results implied a dependence of the subcooling degree, (P, T) conditions for hydrate formation and dissociation, and thermal stability of the hydrate phase on the applied temperature cycling mode and the technical features of the utilized PVT configuration. The experimental findings were complemented by a thermodynamic simulation model and other calculation approaches, with the aim to resolve the phase diagrams including the CO2 dissolution over the entire range of the applied (P, T) conditions.

Mathematical model for constructing a matrix of coefficients thermal conductivity under low-temperature influence on the multilayer epidermis of biological tissue

Objective. The purpose of the study is to develop a mathematical model for constructing a matrix of thermal conductivity coefficients under low-temperature exposure to the multilayer epidermis of biological tissue. Method. The research is based on methods of thermo dynamic analysis, full-scale and computational modeling of processes under low-temperature influence. Result. A mathematical model of the matrix of thermal conductivity coefficients under low-temperature effects on biological tissue has been developed. Heat transfer in a multilayer medium under low-temperature influence on biological tissue is presented as a process with a discrete step in time and coordinate. Thermal properties are evenly distributed throughout the volume of layers of biological tissue. For exposure to cold, layers of the epidermis of biological tissue were used, divided into uniform identical cells, where the cell area of the biological tissue was taken to be equal to one. Conclusion. The results obtained in this work can be useful to specialists who deal with modeling problems with free boundaries.

Thermoelectric installation for lifting objects from shallow reservoirs using the freezing method

Objective. The purpose of the study is to develop the design of a thermoelectric installation for lifting objects from shallow reservoirs using the freezing method, as well as its calculation, analysis of parameters and electrical and thermophysical characteristics. Method. The research is based on the use of methods of thermodynamic analysis, full-scale and computational modeling of cryogenic equipment in order to find optimal solutions for the reliability and service life of low-temperature installations. Result. The installation includes a waterproof probe, on the end surface of which, facing the bottom of the reservoir, thermoelectric modules are installed, heat is removed from the hot junctions of which by means of a heat removal system made in the form of an all-metal heat pipe or in the form of a thermal thermosiphon. The connection between the object lifted from the reservoir and the thermoelectric installation is carried out through a cold wall by freezing. The thermoelectric installation was calculated and its parameters were determined. Graphs were constructed and dependencies were obtained describing the main characteristics of TEMs included in the thermoelectric installation. The graphs are presented at a temperature of the hot junctions of the TEM of 300 K and the achievement of such values of the thickness of frozen water ice on the cold wall of the technical device that would allow lifting objects from a reservoir up to 4 m deep. Conclusion. The installation parameters have been determined: the number of TEMs of the DRIFT-1.2 type is 8, the operating power range of a single TEM of the DRIFT-1.2 type is from 14 to 40 W with an average temperature difference between the junctions of 45 K, the supply current is from 3.8 to 7 .6 A with power consumption from 50 to 200 W, coefficient of performance - from 0.1 to 0.45, minimum temperature of the cold wall of the TU - 248 K, a domestically produced thermal thermosyphon is used as a heat removal system from the hot junctions of the TEM.

Probing the formation mechanism of hierarchical microstructures in experimental Ni-based superalloys

Probing the formation mechanism of hierarchical microstructures in experimental Ni-based superalloys

Design and optimization of space nuclear power system with sCO2 Brayton cycle on Mars

Design and optimization of space nuclear power system with sCO2 Brayton cycle on Mars

Efrigeration Systems using the Potential of night radiative cooling

Objective. Night radiative cooling (Radiative cooling) is based on the phenomenon of Earth's effective radiation, in which heat is removed into the atmosphere and partially carried away into outer space, which leads to a decrease in the temperature of objects located on the Earth's surface below the air temperature in the surface layer.Method. The research is based on methods of thermodynamic analysis, full-scale and computational modeling of processes and objects of refrigeration and cryogenic technology. On the basis of the method developed by the authors and the existing method, a computational and theoretical analysis of radiative cooling for the Euro-Asian continent was carried out. As a result, the regularity of the change in the radiative cooling potential depending on the geographic latitude was determined, starting from the equator to the northernmost point of the continent. Schematic solutions and designs of refrigeration systems of various functional purposes for various regions with yearround use of radiative cooling have been developed. Theoretical and experimental studies of installations with radiative cooling are presented. for food storage and air conditioning was carried out.Conclusion. On the basis of the developed computer model, an analysis of the energy efficiency of refrigeration systems for food storage and air conditioning, in which the object is cooled by radiative cooling and a vapor compression refrigeration machine, was carried out using the simulation of the annual operation cycle in continental climatic conditions.

Electrified Solar Zero Liquid Discharge: Exploring the Potential of PV-ZLD in the US.

Current brine management strategies are based on the disposal of brine in nearby aquifers, representing a loss in potential water and mineral resources. Zero liquid discharge (ZLD) is a possible strategy to reduce brine rejection while increasing the resource recovery from desalination plants. However, ZLD substantially increases the energy consumption and carbon footprint of a desalination plant. The predominant strategy to reduce the energy consumption and carbon footprint of ZLD is through the use of a hybrid desalination technology that integrates renewable energy. Here, we built a computational thermodynamic model of the most mature electrified hybrid technology for ZLD powered by photovoltaic (PV). We examine the potential size and cost of ZLD plants in the US. This work explores the variables (geospatial and design) that most influence the levelized cost of water and the second law efficiency. There is a negative correlation between minimizing the LCOW and maximizing the second-law. And maximizing the second-law, the states that more brine produces, Texas is the location where the studied system achieves the lowest LCOW and high second-law efficiency, while California is the state where the studied system is less favorable. A multiobjective optimization study assesses the impact of considering a carbon tax in the cost of produced water and determines the best potential size for the studied plant.

Multi-fidelity simulation of aeroengine across wide operation range using auxiliary fully coupled method

Multi-fidelity simulation of aeroengine across wide operation range using auxiliary fully coupled method

Neutralization of Anthropogenic Acidic Particles by NH3 From Wildfire Over Tropical Peatland

AbstractAcidity is an essential characteristic of aerosol particles that influences chemical and physical properties. Aerosol particles in tropical Asia, such as Singapore, have been reported as highly acidic due to intense anthropogenic sulfur emissions. At the same time, the region has also been experiencing wildfire over tropical peatlands, which is recognized as an intense source of NH3. Here, we investigated the role of NH3 from wildfire on aerosol particles in Singapore by employing the aerosol mass spectrometric technique. The observation was conducted both during wildfire haze (2015 October and 2019 September–October) and non‐haze (2018 October and 2019 April) periods. The observation result demonstrated that inorganic ionic species in Singapore were neutralized by NH4+ during the haze periods. Namely, the degree of neutralization of aerosol particles (i.e., measured NH4+ concentration/predicted NH4+ concentration by assuming that NH4+ fully neutralized SO42−, NO3−, and Cl−) was lower than 0.77during the non‐haze periods. On the other hand, the corresponding values were higher than 0.93 during the haze periods. In addition, NO3− concentration during the daytime of the haze period in 2015 was higher than that in other observation periods. A thermodynamic model calculation suggested that the regime shifts from the “NH3 sensitive region” to the “NH3 and HNO3 sensitive region” or “HNO3 sensitive region” might have occurred during the haze period. In the future, continuous monitoring of both gas‐ and particle‐phase inorganic chemical species will need to be conducted to investigate the impact of wildfire haze on atmospheric chemical processes in more detail.

Calculation of a heat exchanger using heat pipes in the exhaust air heat recovery system

Objective. The purpose of the work is to develop practical recommendations for the design and manufacture of a heat exchanger using heat pipes, which could find widespread use in heating, ventilation and air conditioning systems at facilities for various purposes. Method. The research is based on methods of thermodynamic analysis, full-scale and computational modeling of processes and objects of refrigeration and cryogenic technology, air conditioning and life support systems. Result. The implementation of the practical recommendations studied in the work on the use and design of heat exchangers using heat pipes in ventilation, heating and air conditioning systems will provide significant savings in energy spent on heating and/or cooling the air supplied to the room served by the HVAC system. To reduce heat loss in a building, it is rational to maintain air balance and compensate for the exhaust air with an organized influx of outside air, to heat which the heat of the removed exhaust air is utilized. Conclusion. Compared to a heat exchanger based on a glycol recuperator, a regenerator using heat pipes is less energy-intensive, requires virtually no maintenance, and is also more energy efficient due to the absence of a pumping device that requires electricity in the design. At the same time, the ability to completely separate the supply and exhaust ventilation flows of the regenerator on heat pipes is preserved, which is extremely in demand in medical institutions, due to the need to comply with strict sanitary standards.

Phase diagrams of bismuth ferrite barium titanate thin films with misfit strains and their improved electrical properties

Phase diagrams of BiFeO3-BaTiO3 (BF–BT) thin films were constructed via thermodynamic model calculation, as well as their electrical properties. The calculated morphotropic phase boundary (MPB) of BF–BT thin films without strain is located near the composition of 0.663BF–0.337BT, which agrees well with the experimental results of reported BF–BT ceramics (between 0.66BF–0.34BT and 0.71BF–0.29BT). The permittivity, tunability and [Formula: see text]of BF–BT thin films on Si substrates are higher than those on SrTiO3(ST) plates, which are also in accordance with the measured data in the literature. Further calculation indicates that 0.7BF–0.3BT and 0.6BF–0.4BT thin films can achieve enormous piezoelectric coefficient [Formula: see text] ([Formula: see text]1200 and [Formula: see text]1000 pm/V, respectively) by selecting the substrates with the TEC respectively of 0.3 and 3.1 × 10[Formula: see text]/[Formula: see text]C, because of the phase transition from aa phase to rhombohedral phase. Such results help to clarify the phase diagrams of BF–BT thin films, implying that huge [Formula: see text]can be achieved by choosing the composition near MPB on the substrates with small TEC.

Investigation of leaching behaviors of carbonation-cured CSA cements using an electrically accelerated leaching test

Investigation of leaching behaviors of carbonation-cured CSA cements using an electrically accelerated leaching test

Processing of phosphorites with extraction of phosphorus, obtaining calcium carbide and ferroalloy

The article considers the results of studying the thermodynamic computer modeling of the interaction of phosphorite (Karatau basin, Kazakhstan) with carbon and coke performed using the HSC-10 software package and electric smelting of the phosphorite with coke and steel shavings in an arc furnace. The modeling allowed us to determine the equilibrium extraction degrees of phosphorus into gas (Р<sub>2</sub>, Р<sub>4</sub>), silicon into ferroalloy in the form of iron silicides (FeSi<sub>2</sub>, FeSi, Fe<sub>3</sub>Si, Fe<sub>5</sub>Si<sub>3</sub>, Si) and calcium into CaС<sub>2</sub>. At temperatures above 1500 °C, regardless of the amount of iron, the extraction degree of phosphorus into gas is more 99%. The resulting ferroalloy contains 21.2-23.8% of Si, 1.6-2.8% of Al; the calcium carbide has a capacity of 288-325 dm<sup>3</sup>/kg. The extraction degree of silicon into the alloy was 89.8%, calcium in CaC<sub>2</sub> – 72.5%, phosphorus into gas – 99.4%. The ferroalloy, formed at the electric smelting of the Chulaktau phosphorite together with coke and steel shavings and containing 24.9-29.8% of Si, is FS25 grade ferrosilicon, and the formed calcium carbide has a capacity of 278-290 dm<sup>3</sup>/kg and belongs to the third and second grades. The developed technology makes it possible to increase the degree of phosphorites’ comprehensive use two times (up to 87.5%).

Computationally Guided Synthesis of MXenes by Dry Selective Extraction.

MXenes are a rapidly growing family of 2Dtransition metal carbides and nitridesthatare promising for various applications, including energy storage and conversion, electronics, and healthcare. Hydrofluoric-acid-based etchants are typically used for large-scale and high-throughput synthesis of MXenes, which also leads to a mixture of surface terminations that impede MXene properties. Herein, a computational thermodynamic model with experimental validation is presented to explore the feasibility of fluorine-free synthesis of MXenes with uniform surface terminations by dry selective extraction (DSE) from precursor MAX phases using iodine vapors. A range of MXenesand respective precursor compositions are systematically screened using first-principles calculations to find candidates with high phase stability and low etching energy. A thermodynamic model based on the "CALculation of PHAse Diagrams" (CALPHAD) approach is further demonstrated, using Ti3 C2 I2 as an example, to assess the Gibbs free energy of the DSE reaction and the state of the byproducts as a function of temperature and pressure. Based on the assessment, the optimal synthesis temperature and vapor pressure are predicted and further verified by experiments. This work opens an avenue for scalable, fluorine-free dry synthesis of MXenes with compositions and surface chemistries that are not accessible using wet chemical etching.

A step toward precision gerontology: Lifespan effects of calorie and protein restriction are consistent with predicted impacts on entropy generation

Understanding aging is a key biological goal. Precision gerontology aims to predict how long individuals will live under different treatment scenarios. Calorie and protein restriction (CR and PR) extend lifespan in many species. Using data from C57BL/6 male mice under graded CR or PR, we introduce a computational thermodynamic model for entropy generation, which predicted the impact of the manipulations on lifespan. Daily entropy generation decreased significantly with increasing CR level, but not PR. Our predictions indicated the lifespan of CR mice should increase by 13 to 56% with 10 to 40% CR, relative to ad libitum-fed animals. This prediction was broadly consistent with the empirical observation of the lifespan impacts of CR in rodents. Modeling entropy fluxes may be a future strategy to identify antiaging interventions.

Chemically-patterned steels

Chemically-patterned steels