The combustion phenomena are always complex in nature due to the involvement of complex series and parallel reactions. There are various methods that are involved in analyzing combustion phenomena. Viscosity is the first and foremost factor that acts as the DNA of fuel. By evaluating the viscosity, it is possible initially to understand the combustion phenomena. Thermophysical and transport properties are helpful during the intensification of the combustion process. Combustion experiments are economically infeasible and time-consuming processes. Combustion simulations demand excellent computational facilities with detailed knowledge of chemical kinetics. So far, the majority of researchers have focused on analyzing coal combustion phenomena, whereas less work has been carried out on liquid fuels, especially biodiesel combustion analysis. Traditional engine testing provides only performance parameters, and it fails to have oversight of the thermodynamic aspects. The application of therm... [more]

Due to the injection of energetic particles, such as electrons in space environment, the internal charging−discharging characteristics of spacecraft dielectrics need to be evaluated for the safety of spacecraft, and the evaluation results from experiments and simulations should be comparatively validated. An in-site pulsed electroacoustic (PEA) measurement system under high-energy electron radiation was established for evaluating the charging characteristics of thick plate samples about 3 mm, while a joint simulation method based on Geant4 and COMSOL was also proposed. The deposited charge distributions were compared through experiment and joint simulation method under 0.7, 1.0 and 1.3 MeV for 30 min and 1.0 MeV for 10, 60 and 120 min, respectively. Meanwhile, the electrostatic discharging characteristics were also comparative evaluated by both methods under 0.3 MeV for 20 min under 5, 10 and 15 µA beam current, and the total discharging times and initial discharging time were compared... [more]

Thermal solar systems are currently one of the most suitable ways to convert solar radiation into usable energy. To ensure maximum energy gain, it is necessary to correctly adjust the direction of the collectors in the southern direction. The deviation from the south is energy acceptable, but there are losses that reduce the overall efficiency of the system. A suitable tool for increasing the efficiency of solar thermal collectors is the usage of tracker systems which track the position of the Sun along the ecliptic orbit. The system is directed south towards the equator. It is important to know the effectiveness of the system in terms of assessment. For the monitored period of the equinox, the increase of the solar thermal gain of the system with rotation of the collectors represents 16.23%. One of the methods is to use simulation tools to simulate different conditions of solar energy flow. A model in the Ansys software was developed for solar thermal flat collectors. The model is bas... [more]

The tendencies and perspective directions of development of modern digital devices of relay protection and automation (RPA) are considered. One of the promising ways to develop protection and control systems is the development of fundamentally new algorithms for recognizing emergency modes. They work in accordance with the triggering rule, which is formed after processing the results of model experiments. These algorithms are able to simultaneously control a large number of features or mode parameters (current, voltage, resistance, phase, etc.). Thus, the algorithms are multidimensional. This approach in RPA becomes available since the computing power of modern processors is quite enough to process the required amount of statistical data on the parameters of possible normal and emergency operation modes of electrical network sections. The application of classical machine learning algorithms in RPA tasks is analyzed, in particular, methods of k-nearest neighbors, logistic regression, an... [more]

Distillation has relatively low thermodynamic efficiency, so it is a prime target for process intensification studies. The current research aims to study exergy losses in various heat-integrated distillation columns. A conventional industrial-scale i-butane/n-butane fractionator has been selected as a case study for the comparison of the performances of various heat-integrated designs. The Aspen Plus® process simulator is used to perform steady-state simulations and exergy analyses of the conventional distillation column (CDC), internally heat-integrated distillation column (iHIDiC), externally heat-integrated double distillation columns (EHIDDiC), and vapor recompression (VRC) systems. The results of these exergy analyses show that a modified VRC system (ηE = 10.69%) is the most efficient design for this separation. The exergy efficiency of the conventional VRC system is the same as that of the CDC (ηE = 9.27%). The EHIDDiC system (ηE = 9.77%) is somewhat better than the CDC, whereas... [more]

This paper presents the conceptual stages of the simulation and development of a modified transceiver antenna for a high-power pulsed nuclear quadrupole resonance (NQR) detector of explosives containing the 14N isotope. At a frequency of 4.645 MHz, better characteristics are obtained using a nine-turn coil shaped as half of a Fermat spiral with an outer radius of 75 mm. Using a COMSOL Multiphysics numerical parametric simulation and a materials browser, it was possible to calculate a physical system with parameters as close to reality as possible. According to the results of the experimental studies of the radio frequency (RF) energy, the proposed antenna features an increase in the working area compared to a similar antenna, the topology of the conductive coil of which has the form of an Archimedean spiral. The resulting diagrams of the distribution of the magnetic induction also indicate that the topology of the electromagnetic (EM) field does not depend on the orientation of the sam... [more]

Solid-state argyrodite electrolytes are promising candidate materials to produce safe all-solid-state lithium batteries (ASSLBs) due to their high ionic conductivity. These batteries can be used to power electric vehicles and portable consumer electronics which need high power density. Atomic-scale modeling with ab initio calculations became an invaluable tool to better understand the intrinsic properties and stability of these materials. It is also used to create new structures to tailor their properties. This review article presents some of the recent theoretical investigations based on atomic-scale modeling to study argyrodite electrolytes for ASSLBs. A comparison of the effectiveness of argyrodite materials used for ASSLBs and the underlying advantages and disadvantages of the argyrodite materials are also presented in this article.

Modeling the vortex intensification of turbulent heat transfer in narrow engine ducts using single-row dimples was carried out within the framework of multi-block computing technologies implemented in a special VP2/3 package. The cases of a rectangular section with the placement of vortex generators—single-row packages of oval and spherical dimples on the initial hydrodynamic section and the section of the stabilized flow are excluded. The connection between the generated vortex structures and the predominant increase in heat transfer compared to the increase in hydraulic losses for various dimple layouts has been established: zigzag, ladder, and centers shifted and in a longitudinal-transverse order. The superiority in heat removal from the thickness with inclined oval dimples is shown—1.23 times compared to spherical ones with a decay in hydraulic resistance by 1.16 times.

The ceramic industry is one of the pillars of the Brazilian economy, characterized by making low-cost products and an obsolete manufacturing process from a technological point of view. Among the various stages of production of ceramic materials, drying is one of the most energy-consuming and, in general, causes structural damage to the product, compromising its mechanical performance and final quality. Despite the relevance, studies on the drying of ceramic materials are mostly conducted at the experimental level and limited to some specific operational conditions. In this scenario, this research aims to theoretically study the heat and mass transfers in industrial ceramic blocks during drying. Based on the lumped analysis method, and considering the dimensional variations of the material, new phenomenological mathematical models and their respective analytical solutions are proposed to describe the kinetics of mass loss and heating of the material. The predicted results referring to t... [more]

Wind turbines that are consistently exposed to the air displaced by moving trains have a high potential for energy generation. Researchers have developed mathematical models to simulate wind energy generation from turbines on moving trains but there are significant gaps in the developed model theory. Most models do not consider the negative effects that additional aerodynamic drag, increased weight, and modified dimensions can have on the train’s operation. To overcome the drawbacks of existing models, this work proposes a novel approach of modeling the wind turbines on trains by considering wind turbine exposure only when the train is decelerating or stationary. There are no models that consider all of these realistic physical effects as a function of time. Real-time analysis and power-system simulations showed that the proposed model could produce over 3 MJ of net energy for favorable train trips. The simulated load profile met the demand of a 1 KW generator connected to onboard elec... [more]

Compared with traditional cables, superconducting multi-stage cables have the natural advantages of greater transmission power and less energy loss, which have gradually attracted attention. However, conventional multi-stage cables are based on low temperature superconducting (LTS) technology and there is considerable scope for improvement in their performance. In this paper, a novel structure of the multi-stage high temperature superconducting (HTS) twisted cable prepared by the soldered-stacked-square (3S) wire is proposed. The AC loss characteristics of the twisted cable are deeply studied by experiments and simulation. Through the experiment, the influence of the voltage-leads on the AC loss measurement accuracy is eliminated, and frequency dependent is shown in the AC loss of the twisted cable. Besides, the simulated value of AC loss is consistent with the experimental value, which verifies the accuracy of the simulation. The AC loss of twisted cable is only 20% of that of the thi... [more]

An emerging area of interest within photovoltaic (PV) centred research is the simulation of the propagation of electromagnetic interference (EMI) and surges within PV installations. An overarching constraint in all simulation-based research is the accuracy of the models employed. In general, for PV-focussed simulations, nonlinear models are utilised for direct current (DC) analyses, whilst linearised models are employed for analyses involving surges or conducted electromagnetic interference. For large-signal electromagnetic interference and surges, the following two problems arise: (1) the aforementioned linearisation is only valid for the small-signal case, and (2) as they are constructed using only DC measurements, traditional large-signal PV models are generally only valid for DC conditions. Therefore, neither of these approaches can properly represent real-world PV behaviour under dynamic conditions. To overcome this limitation, this article proposes a more suitable model, compatib... [more]

In this paper, we present an approach for multi-level parallel-in-time (PinT) electromagnetic transient (EMT) simulation. We evaluate the approach in the context of power electronics system-level simulation. While PinT approaches to power electronics simulations based on two-level algorithms have been thoroughly explored in the past, multi-level PinT approaches have not yet been investigated. We use the multigrid-reduction-in-time (MGRIT) method to parallelize a dedicated EMT simulation tool which is capable of switching between different converter models as it operates. The presented approach yields a time-parallel speed-up of up to 10 times compared to the sequential-in-time implementation. We also show that special care has to be taken to synchronize the time grids with the electronic components’ switching periods, indicating that further research into the usage of different models from adequate model hierarchies is necessary.

Carbon dioxide phase transition blasting (CO2-PB) technology is an effective and economical technology used for breaking rocks. The use of CO2-PB can significantly reduce the vibration damage to surrounding rocks. There is little research on the shockwave generated by the CO2-PB, and simulation can better show the flow field characteristics. In order to clarify the mechanism of its blasting load process, a theoretical analysis and a numerical model were developed to study the flow-field characteristics and the impact pressure of CO2-PB. Our results show that the CO2 absorbs heat from the surrounding environment, producing a significant low-temperature area. The overpressure is significantly lower than the driving gas pressure to the ambient pressure, limiting the maximum over-pressure that can be obtained. When the pressure in CO2-PB reaches 100 MPa, the shockwave is about 4.25 MPa. As the distance increases, the peak value of the shockwave decays rapidly. As the dimensionless distance... [more]

Lithium batteries employed in lightweight fixed-wing UAVs are required to operate with large temperature variations and, especially for the emerging applications in hybrid propulsion systems, with relevant transient loads. The detailed dynamic modelling of battery packs is thus of paramount importance to verify the feasibility of innovative hybrid systems, as well as to support the design of battery management systems for safety/reliability enhancement. This paper deals with the development of a generalised approach for the dynamic modelling of battery packs via Thevenin circuits with modular hysteretic elements (open circuit voltage, internal resistance, RC grids). The model takes into account the parameters’ dependency on the state of charge, temperature, and both the amplitude and sign of the current load. As a relevant case study, the modelling approach is here applied to the Li-Po battery pack (1850 mAh, 6 cells, 22.2 V) employed in the lightweight fixed-wing UAV Rapier X-25 devel... [more]

The performance of air conditioning systems deteriorate due to the natural aging and wear caused by operating the devices. This is termed “aging degradation,” and it results from a lack of appropriate maintenance which accelerates the degree of performance degradation. The performance degradation of an air conditioning system can cause problems such as increased energy consumption, deteriorated indoor heating environment, and shortened lifespan of air conditioning equipment. To prevent such problems, it is important to establish a long-term maintenance plan to recover degraded performance, such as predicting an appropriate maintenance time by identifying the real-time performance degradation rate based on a system’s operation data. In this study, the performance degradation rate, according to the operating time, was estimated using long-term operation data for devices constituting a heat source system, and the effect of performance degradation of the heat source system’s operation and... [more]

This review deals with the simulation and optimization of the dry- and wet-torrefaction processes of lignocellulosic biomass. The torrefaction pretreatment regards the production of enhanced biofuels and other materials. Dry torrefaction is a mild pyrolytic treatment method under an oxidative or non-oxidative atmosphere and can improve lignocellulosic biomass solid residue heating properties by reducing its oxygen content. Wet torrefaction usually uses pure water in an autoclave and is also known as hydrothermal carbonization, hydrothermal torrefaction, hot water extraction, autohydrolysis, hydrothermolysis, hot compressed water treatment, water hydrolysis, aqueous fractionation, aqueous liquefaction or solvolysis/aquasolv, or pressure cooking. In the case of treatment with acid aquatic solutions, wet torrefaction is called acid-catalyzed wet torrefaction. Wet torrefaction produces fermentable monosaccharides and oligosaccharides as well as solid residue with enhanced higher heating va... [more]

This review of the state of the art aims to collect the description and main research results in the field of development and validation of control algorithms with the main purpose to solve the problem of cogging torque and main sources of electromagnetic torque ripple. In particular, we focus on electric drives for advanced and modern mechatronic applications such as industrial automation, robotics, and automotive applications, with special emphasis on work that exploits model-based design. A great added value of this paper is to explicitly show the operational steps required for the model-based design design of optimized control algorithms for electric drives where it is necessary to make up for electromagnetic torque oscillations due to the main sources of ripple, particularly cogging torque. The ultimate goal of this paper is to provide researchers approaching this particular problem with a comprehensive collection of the most effective solutions reported in the state of the art an... [more]

This paper concerns technology challenges for the wind and solar sectors and the role of computational science in addressing the above. Wind energy challenges include understanding the atmospheric flow physics, complex wakes and their interaction with wind turbines, aeroelastic effects and the associated impact on materials, and optimisation of wind farms. Concentrated solar power technologies require an optimal configuration of solar dish technology and porous absorber in the volumetric solar receiver for efficiency and durability and to minimise the convective heat losses in the receiver. Computational fluid dynamics and heat transfer have advanced in terms of numerical methods and physics-based models and their implementation in high-performance computing facilities. Despite this progress, computational science requires further advancement to address the technological challenges of designing complex systems accurately and efficiently, as well as forecasting the system’s performance.... [more]

This study characterises materials that belong to the group of refuse-derived fuels (RDF). This group of materials regarded as an alternative fuel is derived from industrial, municipal solid and commercial wastes. The aim of this study is to evaluate the quality of waste composition, demonstrate statistically different values and the energy efficiency of the fuel derived from waste. Data on incinerated waste were collected from two different sources. The basic physical and chemical parameters of waste include density and water content. The lower heating value (LHV) of waste, chlorine concentration and ash content of two groups of incinerated waste were also evaluated and compared for a given period of time (one year, with monthly breakdown). Statistical analysis indicated the differences in the combustion of waste groups, visualized by box plots and other diagrams to show the distribution of the results. An analysis of exhaust gas parameters was carried out, both in terms of chemical c... [more]

The use of simulation and modelling has been proposed for determining the excitations to be applied in the procedures of laboratory testing of a car’s structural components, without the need to test the complete vehicle. The paper presents the general concept as well as an example of the procedure. It covers determining the spectrum and time-domain realization of a load on a selected node of the vehicle structure under durability tests. The author used both the mathematical and physical model of the tractor-semitrailer unit, where the input was considered as a random process resulting from the road profile. He calculated the transmittance modules and the power spectral densities of the vertical force on the joint between the tractor’s fifth wheel and the kingpin of the semitrailer and the extreme values of the dynamic components of this force. The inverse discrete Fourier transform makes it possible to generate the realization of the said force. It can be used in durability studies. Th... [more]

Iran is one of the most energy-consuming countries, especially in the construction sector, and more than 40% of its energy consumption is in the construction sector. Therefore, considering the very high potential of Iran in the field of solar energy, the need to pay attention to providing part of the energy required by buildings by solar energy seems necessary. The study of the effect of climate on the performance of a BIPV has not been done in Iran so far. Also, the use of ranking methods using the weighting of parameters affecting the performance of BIPV has not been done so far. The purpose of this study is to investigate the power supply of BIPV connected to the grid in the eight climates of Iran. Technical−economic−environmental energy analyses were performed by HOMER 2.81 software. In order to study different types of BIPV, four angles of 0°, 30°, 60°, and 90° were considered for the installation of solar cells. The effective output parameters of HOMER software were weighted by t... [more]

This study proposes a data-driven methodology for modeling power and hydrogen generation of a sustainable energy converter. The wave and hydrogen production at different wave heights and wind speeds are predicted. Furthermore, this research emphasizes and encourages the possibility of extracting hydrogen from ocean waves. By using the extracted data from the FLOW-3D software simulation and the experimental data from the special test in the ocean, the comparison analysis of two data-driven learning methods is conducted. The results show that the amount of hydrogen production is proportional to the amount of generated electrical power. The reliability of the proposed renewable energy converter is further discussed as a sustainable smart grid application.

Smart water flooding (SWF) is a promising enhanced oil recovery (EOR) technique due to its economic advantages. For this process, wettability alteration is the most accepted controlling effect that leads to increased recovery factors (RFs). The main objective of this work is to investigate how the relative permeability curves’ interpolant affects the SWF mechanisms’ assessment. Wettability alteration is described by shifting these curves in simulations. Numerical simulations of core flooding tests are applied to carbonate at 114.4 °C. A comparison of oil recovery factor (RF), pH and effluent composition is performed for different injection approaches. Mg2+ and SO42− are the interpolant ions and the salinity levels range from 30 to 1 kppm. A simulation of 24 scenarios, 12 for each type of interpolant, is presented. Results show that RF changes significantly, due to salinity and composition, for each interpolant. This has a relevant influence on the interpolant. The greater the dilution,... [more]

Based upon the thermodynamic simulation of a biogas-SOFC integrated process and the costing of its elements, the present work examines the economic feasibility of biogas-SOFCs for combined heat and power (CHP) generation, by the comparison of their economic performance against the conventional biogas-CHP with internal combustion engines (ICEs), under the same assumptions. As well as the issues of process scale and an SOFC’s cost, examined in the literature, the study brings up the determinative effects of: (i) the employed SOFC size, with respect to its operational point, as well as (ii) the feasibility criterion, on the feasibility assessment. Two plant capacities were examined (250 m3·h−1 and 750 m3·h−1 biogas production), and their feasibilities were assessed by the Internal Rate of Return (IRR), the Net Present Value (NPV) and the Pay Back Time (PBT) criteria. For SOFC costs at 1100 and 2000 EUR·kWel−1, foreseen in 2035 and 2030, respectively, SOFCs were found to increase investmen... [more]