Understanding the phase behaviour of (CO2 + water + permanent gas) systems is critical for implementing carbon capture and storage (CCS) processes, a key technology in reducing CO2 emissions. In this paper, phase behaviour data for (H2O + N2) and (CO2 + H2O + N2) systems are reported at temperatures from 323 to 473 K and pressures up to 20 MPa. In the ternary system, the mole ratio between CO2 and N2 was 1. Experiments were conducted in a newly designed analytical apparatus that includes two syringe pumps for fluid injection, a high-pressure equilibrium vessel, heater aluminium jacket, Rolsi sampling valves and an online gas chromatograph (GC) for composition determination. A high-sensitivity pulsed discharge detector installed in the GC was used to measure the low levels of dissolved nitrogen in the aqueous phase and low water levels in the vapour phase. The experimental data were compared with the calculation based on the γ-φ and SAFT-γ Mie approaches. In the SAFT-γ Mie model, the li... [more]

The AQWA software is often used to perform hydrodynamic analysis, and it is highly convenient for performing frequency domain simulations of Pelamis-like wave energy converters. However, hydraulic power take-off (PTO) must be simplified to a linear damping model or a Coulomb torque model when performing a time domain simulation. Although these simulation methods can reduce the computational complexity, they may not accurately reflect the energy capture characteristics of the hydraulic PTO. By analyzing system factors such as the flow and pressure of each branch of the hydraulic PTO, the output torque of the hydraulic cylinder to the buoy, and the electromagnetic torque of the generator, a relatively complete hydraulic PTO model is obtained, and the model is applied to AQWA using the FORTRAN language. Comparing and analyzing the simulation results of the linear damping model, the Coulomb torque model, and the hydraulic PTO, we found that the simulation results obtained by the linear dam... [more]

In this paper, the design and analysis of a 30 kW, 30,000 r/min high-speed permanent magnet motor (HSPMM) for compressor application are provided. In order to provide a reasonable electromagnetic design scheme, the electromagnetic performances of the HSPMM under different structures are analyzed and compared by the finite element method (FEM). The thermal performances and cooling system of the HSPMM are, respectively, analyzed and designed by computational fluid dynamics (CFD). Finally, the HSPMM’s rotor strength is studied by both FEM and analytical methods, and the influencing factors of which are also researched in this paper.

Exhaust is generated by engine flows through a turbocharger, front exhaust pipe, and selective catalytic reduction (SCR) post-treatment device. The structure of the front exhaust pipe affects the temperature, velocity, and turbulent kinetic energy of exhaust and the Sauter Mean Diameter (SMD) of urea water solution (UWS). A high temperature and turbulent kinetic energy in the exhaust will promote the decomposition of UWS, and further accelerate the evaporation and atomization effect of the UWS droplets. Therefore, in order for the exhaust to reach a high temperature and turbulent kinetic energy, a double-layered pipe structure with air insulation was designed. The flow field and the atomization of UWS in the double-layered pipe based on hydroforming processing was investigated through numerical simulation. The thermal insulation simulation was verified by the temperature measurement system and the temperature drops between the double-layered pipe and the volcanic rock-wrapped pipe were... [more]

This study aims to analyze the actual heating energy consumption according to the location and size of apartment houses. The study shows the variation in heating energy consumption in accordance with the living pattern of residents in such apartments. By calculating the average annual heating energy consumption and distribution of the measured heating energy of two years, it was found that the outdoor temperature was inversely proportional to the average heating energy consumption. Moreover, the lowest/highest floors and corner houses were the most vulnerable since they had a lot of area exposed to the outside air and, thus, consume a huge amount of heating energy. According to this study, the heating load had relevance to the factors such as wall loss, window loss, ventilation loss, and solar radiation gain that were analyzed in accordance with the growth in house size. Based on the survey outcome on the living pattern and number of residents, a simulation was conducted to analyze the... [more]

A novel hybrid machine learning technique is proposed for the protection of three-phase power transformers in this study. Here, the developed model was tested across several types of current signal fault cases from different fault conditions and examined based on a laboratory-constructed transformer system, in which internal and external faults were created. The data gathered on signals were used to develop a novel hybrid model. A process for optimal feature identification was put forward, with machine learning classifiers being trained to classify faults. The methods used included orthogonal matching pursuit and discrete wavelet transform for extraction of statistical characteristics from unprocessed data. Following this, the bees algorithm (BA) was used to create an optimized subset, minimizing the amount of data needed and making the model more accurate. In order to distinguish normal operational conditions (inrush current) from faults, an optimized feature set was used as an input... [more]

A porous volumetric receiver is the key component in concentrated solar power systems. In this paper, we investigate the effects of volumetric parameter models on the heat collection efficiency of the volumetric receiver by numerical simulations with the combination of local thermal non-equilibrium and discrete ordinate methods. Seven volumetric convective heat transfer coefficient models and three extinction coefficient models were investigated. The efficiencies calculated using these models were compared among each other. The results show that volumetric convective heat transfer coefficient models have significant effects with a maximum difference of 27.7% in receiver efficiency for these models. Extinction coefficient models have less effects on receiver efficiency with a maximum difference of 7.3%.

The Equivalent Consumption Minimization Strategy (ECMS) is a well-known control strategy for the definition of optimal power-split in hybrid-electric vehicles, because of its effectiveness and reduced calibration effort. In this kind of Energy Management Systems (EMS), the correct identification of an equivalence factor (K), which translates electric power in equivalent fuel consumption, is of paramount importance. To guarantee charge sustaining operation, the K factor must be adjusted to different mission profiles. Adaptive ECMS (A-ECMS) techniques have thus been introduced, which automatically determine the optimal equivalence factor based on the vehicle mission. The aim of this research activity is to assess the potential in terms of fuel consumption and charge sustainability of different A-ECMS techniques on a gasoline hybrid-electric passenger car. First, the 0D vehicle and powertrain model was developed in the commercial CAE software GT-SUITE. An ECMS-based EMS was used to contro... [more]

Accurate prediction of an off-normal event in a nuclear reactor is dependent upon the availability of sensory data, reactor core physical condition, and understanding of the underlying phenomenon. This work presents a method to project the data from some discrete sensory locations to the overall reactor domain during conduction cooldown scenarios similar to High Temperature Gas-cooled Reactors (HTGRs). The existing models for conductive cooldown in a heterogeneous multi-body system, such as an assembly of prismatic blocks or pebble beds relies on knowledge of the thermal contact conductance, requiring significant knowledge of local thermal contacts and heat transport possibilities across those contacts. With a priori knowledge of bulk geometry features and some discrete sensors, a machine learning approach was devised. The presented work uses an experimental facility to mimic conduction cooldown with an assembly of 68 cylindrical rods initially heated to 1200 K. High-fidelity temperatu... [more]

In order to study the effect of groove parameters on solid particles’ deposition in mechanical face seal lubrication film, a multi-phase flow calculation model for the sealing micro-gap lubricating film was established based on the Laminar model, mixture multi-phase flow model, Zwart−Gerber−Belamri cavitation model, and DPM model in Fluent, and a numerical simulation of the effect of groove parameters is presented. The results show that, with the increase of groove depth, the circumferential sedimentary zone in the dam area decreases or even disappears, and the groove area becomes the main sedimentary part; the particle deposition rate decreases first and then increases with the increase of groove depth and spiral angle. The influence of groove depth on the deposition rate at low speed is more significant than that at high speed. The increase of deposition rate caused by a spiral angle that is too large is greater than that caused by a spiral angle that is too small. The optimal groove... [more]

Liquefied natural gas (LNG) is regarded as the cleanest among fossil fuels due to its lower environmental impact. In power plants, it emits 50−60% less carbon dioxide into the atmosphere compared to regular oil or coal-fired plants. As the demand for a lower environmental footprint is increasing, fuel cells powered by LNG are starting to appear as a promising technology, especially suitable for off-grid applications, since they can supply both electricity and heating. This article presents a techno-economic assessment for an integrated system consisting of a solid oxide fuel cell (SOFC) stack and a micro gas turbine (MGT) fueled by LNG, that feeds the waste heat to a multi-effect desalination system (MED) on the Greek island of Patmos. The partial or total replacement of the diesel engines on the non-interconnected island of Patmos with SOFC systems is investigated. The optimal system implementation is analyzed through a multi-stage approach that includes dynamic computational analysis... [more]

Addressing the problem of the vibration and noise of a permanent-magnet synchronous motor (PMSM), this paper optimizes the structure of a permanent-magnet motor rotator, introduces the electromagnetic-structure-acoustic coupling calculation model, and optimizes the motor rotator to reduce the vibration and noise of a permanent-magnet motor. Using the theory of Maxwell’s stress equation, the radial electromagnetic force on the stator teeth of the permanent-magnet motor is deduced and analyzed, and the correctness of the analysis calculation is verified by using the finite element multi-physical field coupling method. Based on the deduced analytical expression of the radial electromagnetic force, the sources of the radial electromagnetic force for each order and the frequency of the permanent-magnet motor are summarized. A 12-slot, 8-pole, permanent-magnet motor is taken as an example. A calculation model considering the spatial distribution of the radial electromagnetic force and the el... [more]

Multiple elimination has always been a key, challenge, and hotspot in the field of hydrocarbon exploration. However, each multiple elimination method comes with one or more limitations at present. The efficiency and success of each approach strongly depend on their corresponding prior assumptions, in particular for seismic data acquired from complex geological regions. The multiple elimination approach using deep learning encodes the input seismic data to multiple levels of abstraction and decodes those levels to reconstruct the primaries without multiples. In this study, we employ a classic convolution neural network (CNN) with a U-shaped architecture which uses extremely few seismic data for end-to-end training, strongly increasing the neural network speed. Then, we apply the trained network to predict all seismic data, which solves the problem of difficult elimination of global multiples, avoids the regularization of seismic data, and reduces massive amounts of calculation in tradit... [more]

With a focus on the shock oscillation phenomenon of a supersonic inlet at a high Mach number, the influence of isolator overflow on shock oscillation is studied in this paper. The shock wave dynamic model with overflow was established by the theoretical method, and the integrated numerical model of internal flow and external flow in the inlet was established too. The theoretical analysis of rate of overflow and overflow position on the flow field is carried out, and the changes of flow field parameters are studied by numerical simulation under different overflow positions. The results showed that both increasing the rate of overflow and setting the overflow gap close to the shock front were beneficial to reducing the flow parameters’ oscillation. In the viscous flow field, the overflow gap restricted the forward development of the local separation region of the shock train system, thus constraining the shock wave movement process, which could significantly reduce the parameter oscillat... [more]

Gasification has played an important role in the sustainable use of waste biomass, providing useful combustible gases in the process. Gasification has an important role in waste management and promotes energy independence for many oil-deficit countries. The gasification process has been studied by various researchers, and improvements have been achieved in its sub-processes such as devolatilization, feed input methods, and so on. We examined the influence of gasifier operation parameters, such as oxidizer content, moisture content in the feedstock, and solar flux input inside the gasifier, on the temperature distribution, velocity distribution, and product gas yields of the gasifier. The results indicate that inducing solar energy at different stages of the gasifier leads to different yields of product gas composition (CO and H2).

A series of PFDPP copolymers based on fluorene (F) and diketopyrrolopyrrole (DPP) monomers were synthesized via direct arylation polycondensation using Fagnou conditions which involved palladium acetate as catalyst (a gradual catalyst addition of three different percentages were used), potassium carbonate as the base, and neodecanoic acid in N, N-dimethylacetamide. This synthesis provides a low cost compared with traditional methods of transition-metal-catalyzed polymerization. Among the different amounts of catalyst used in the present work, 12% was optimal because it gave the highest reaction yield (81.5%) and one of the highest molecular weights (Mn = 13.8 KDa). Copolymers’ chemical structures, molecular weight distributions, and optical and thermal properties were analyzed. The linear optical properties of PFDPP copolymers resulted very similarly independently to the catalyst amounts used in the synthesis of the PFDPP copolymers: two absorptions bands distinctive of donor−acceptor... [more]

This paper proposes and demonstrates, in full scale, a novel type of energy geostructure (“the Climate Road”) that combines a ground-source heat pump (GSHP) with a sustainable urban drainage system (SUDS) by utilizing the gravel roadbed simultaneously as an energy source and a rainwater retarding basin. The Climate Road measures 50 m × 8 m × 1 m (length, width, depth, respectively) and has 800 m of geothermal piping embedded in the roadbed, serving as the heat collector for a GSHP that supplies a nearby kindergarten with domestic hot water and space heating. Model analysis of operational data from 2018−2021 indicates sustainable annual heat production levels of around 0.6 MWh per meter road, with a COP of 2.9−3.1. The continued infiltration of rainwater into the roadbed increases the amount of extractable heat by an estimated 17% compared to the case of zero infiltration. Using the developed model for scenario analysis, we find that draining rainwater from three single-family houses an... [more]

Nowadays, there are significant issues in the classification of lithofacies and the identification of rock types in particular. Zamzama gas field demonstrates the complex nature of lithofacies due to the heterogeneous nature of the reservoir formation, while it is quite challenging to identify the lithofacies. Using our machine learning approach and cluster analysis, we can not only resolve these difficulties, but also minimize their time-consuming aspects and provide an accurate result even when the user is inexperienced. To constrain accurate reservoir models, rock type identification is a critical step in reservoir characterization. Many empirical and statistical methodologies have been established based on the effect of rock type on reservoir performance. Only well-logged data are provided, and no cores are sampled. Given these circumstances, and the fact that traditional methods such as regression are intractable, we have chosen to apply three strategies: (1) using a self-organizi... [more]

Digital twins (DTs) and building information modelling (BIM) are proving to be valuable tools for managing the entire life cycle of a building (LCB), from the early design stages to management and maintenance over time. On the other hand, BIM platforms cannot manage the geometric complexities of existing buildings and the large amount of information that sensors can collect. For this reason, this research proposes a scan-to-BIM process capable of managing high levels of detail (LODs) and information (LOIs) during the design, construction site management, and construction phases. Specific grades of generation (GOGs) were applied to create as-found, as-designed, and as-built models that interact with and support the rehabilitation project of a multi-level residential building. Furthermore, thanks to the sharing of specific APIs (Revit and Autodesk Forge APIs), it was possible to switch from static representations to novel levels of interoperability and interactivity for the user and more... [more]

This paper provides computer analysis and experiential investigation of the permanent magnet machines with neodymium and ferrite permanent magnets to discuss the feasibility of utilizing induction machines-oriented equipment for PM machine production. For this purpose, the machines are obtained by replacing the squirrel-cage rotor of the induction motor with the flux-focusing (tangential) and surface-mounted (radial) permanent magnet rotors. Electromechanical parameters of the machines as electromagnetic torque and output power are discussed and compared. The temperatures of the neodymium and ferrite magnets are also calculated at rated current, and short circuit scenarios and the performance of two different cooling systems in minimizing the temperature effect on the machines are investigated. Furthermore, the demagnetization of permanent magnets at various load conditions is also studied. Finally, the results of the computer modeling are validated by the physical prototypes of the ma... [more]

The aim of the article is to present a new idea of limiting the bearing voltage in electric machines with permanent magnets through the use of a shielding winding placed in stator slot wedges. The first part of the article is dedicated to the mechanisms of generating bearing voltages when the machine is supplied from the mains and from a power electronic converter. Additionally, some methods of counteracting these phenomena were described. Next, multivariant simulation tests were carried out based on the two-dimensional field model of a synchronous machine with permanent magnets. The tests were run in order to determine the internal capacitances of the machine, on which the level of bearing voltages depends. Based on these results, the optimal variant of the design solution ensuring the limitation of the bearing voltage to a safe level was selected. Using the model of a two-level converter and based on the equivalent diagram of the internal capacitances of the machine, the influence of... [more]

The internal heat transfer performance and flow structures of a sweeping jet and film composite cooling on a flat plate were numerically studied. Sweeping jet and film composite cooling consists of a fluidic oscillator and 20 cylindrical film holes; the direct jet is formed by removing the feedback from the fluidic oscillator, which is different from the traditional cylindrical nozzle. Four different mass flow rates of coolant were considered, and the inclination angle of the film hole was 30°. The Conjugate Heat Transfer method (CHT) and Unsteady Reynolds Averaged Navier Stokes equation (URANS) were employed. The results indicated that the flow resistance coefficients of the sweeping jet were larger than those of the direct jet, and the Nusselt number monotonously increased with the increase in the mass flow rate. Compared to the direct jet, the sweeping jet had a more spatially uniform heat removal rate, and the area-averaged Nusselt number was slightly lower. Therefore, the sweeping... [more]

This study examines the heat and mass transfer coefficient, thermal effusivity, and other thermal properties of solar-dried cocoyam chips, as well as the drying kinetics. The research also assessed the economics of the solar dryer. For these reasons, a solar dryer with a partitioned collector was developed that creates a double airflow travel distance to delay the airflow inside the collector. The partitioning of the collector delays the airflow and helps to create more turbulence for the airflow with increased energy. The solar dryer was locally developed at the Michael Okpara University of Agriculture and tested during the humid crop harvesting period of September for the worst-case scenario. The obtained drying curves and kinetics for cocoyam drying are subjected to the vagaries of weather conditions. The drying rate showed declining sinusoidal characteristics and took about 25 h to attain equilibrium. Analysis of the airflow velocity showed gravitation between laminar and turbulent... [more]

A constant worldwide growing load stress over a power system compelled the practice of a reactive power injection to ensure an efficient power network. For this purpose, multiple technologies exist in the knowledge market out of which this paper emphasizes the usage of the flexible alternating current transmission system (FACTS) and presents a comparative study of the static var compensator (SVC) with the static synchronous compensator (STATCOM), inducted in a real electric substation. The aim is to improve the power factor (PF) and power quality and to encounter reliably extreme conditions. A 220 kV electric substation was opted for the analysis, and both the static and dynamic conditions were observed with the help of a power system analysis tool termed PowerFactory-DIgSILENT. Multiple aspects were investigated via software simulations to assess the performance of the aforementioned FACTS devices, such as the voltage profile evaluation via the load flow analysis method (LFA), the har... [more]

Hyper compressors are key facilities for producing the low-density polyethylene with discharge pressure up to 350 MPa. Such high pressure brings great challenges to the design of the hyper compressor in many aspects. In this paper, a 3D transient computational fluid dynamics (CFD) model with inlet and outlet pipelines is built to investigate the thermodynamic performance of a hyper compressor. To realize the interaction between the thermodynamic processes and the pressure pulsation through valve dynamics, the pressures across the valve surfaces were monitored to the dynamic equation of the poppet valve. Then, structured grids were generated for the flow domain inside the valve, and the entire numerical model was solved by a commercial code: ANSYS Fluent. Consequently, the p-V diagram, the valve motion and pressure pulsation could be acquired simultaneously. The results of the numerical model showed that the exponents of the expansion and compression processes were 5.12 and 13.22, which... [more]