Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition

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Topic Information

Dear Colleagues,

This Topic is a continuation of the previous successful Topic "Numerical Methods and Computer Simulations in Energy Analysis".

The main aim of this Topic is the dissemination of research regarding the current state of numerical methods, models, optimization algorithms and computer simulation techniques in energy analysis. Energy analysis is understood as its harvesting, consumption, storage, accumulation, transformation and also its direct usage for the various energy-based numerical technique formulations and implementations. Modern numerical techniques include the Finite Element Method, Finite Volume Method, Boundary Element Method, as well as Finite Difference Method. Likewise, the Topic covers approaches based on optimization algorithms, machine learning methods, and computer simulation techniques. Works on a variety of meshless or semi-analytical approaches are welcome together with those that address artificial intelligence or cellular automata models.

Interaction in between these two fields includes reliability engineering of (solar, geothermal or wind) energy systems, computer analysis of various coupled phenomena in engineering, numerical solutions of various fluid and heat flow problems, as well as simulations of thermal, mechanical and electro-magnetic energy exchanges in modern engineering systems and structures. Numerical studies of energetic efficiency, optimization and durability of new technical solutions are especially welcome, including hybrid energy harvesting.

All contributions related to numerical sensitivity analysis, as well as analyses of statistical scattering or stochastic phenomena in different forms of energy exchanges, are invited also. Semi-analytical approaches in energy numerical analysis are understood as computer programs written in conjunction with computer algebra systems and their applications to deliver energy and its exchange determination for some specific applications.

Manuscripts from both academia, research and development laboratories, industry and also from small companies are invited to this topic collection.

Prof. Dr. Marcin Kamiński
Dr. Mateus Mendes
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.0	6.2	2008	16.8 Days	CHF 2600
Applied Sciences applsci	2.5	5.3	2011	18.4 Days	CHF 2400
Mathematics mathematics	2.3	4.0	2013	18.3 Days	CHF 2600
Entropy entropy	2.1	4.9	1999	22.3 Days	CHF 2600
Computers computers	2.6	5.4	2012	15.5 Days	CHF 1800

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19 pages, 19180 KiB  

Open AccessArticle

Flow-Induced Strength Analysis of Large Francis Turbine Under Extended Load Range

by Xingping Liu, Xingxing Huang, Weijiang Chen and Zhengwei Wang

Appl. Sci. 2025, 15(5), 2422; https://doi.org/10.3390/app15052422 - 24 Feb 2025

Viewed by 638

Abstract

To meet the load requirements of the power grid, the hydroelectric power plants need to extend the operational load range of the turbine units, which are often operated under off-design operating conditions. This new challenge significantly changes the flow characteristics of the hydro [...] Read more.

To meet the load requirements of the power grid, the hydroelectric power plants need to extend the operational load range of the turbine units, which are often operated under off-design operating conditions. This new challenge significantly changes the flow characteristics of the hydro turbine units. Strong vibrations and high stresses caused by pressure pulsations at various loads directly lead to severe damage to the runner blades, threatening the safe operation of the hydropower unit. In this study, the detailed flow dynamics analysis under three loading conditions of a large-scale Francis turbine, i.e., 33.3%, 66.6%, and 100% of the Francis turbine’s rated power, is investigated with computational fluid dynamics (CFD) calculations. The pressure files at different operating conditions are adopted to carry out the corresponding flow-induced strength analysis of the Francis runner prototype. The pressure distributions and flow velocity distributions at these three typical operating conditions are studied, and the maximum stress of the runner gradually increases with the power output of the turbine, but it is only around one-third of the yield stress of the runner material. It reveals that the runner is safe to operate in the extended operation range from a 33.3% to 100% of the rated power load. The analysis approach in this work can be applied to other hydraulic machinery including Francis turbines, pumps and pump–turbines. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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10 pages, 1681 KiB  

Open AccessArticle

Simulating Water Invasion Dynamics in Fractured Gas Reservoirs

by Yueyang Li, Enli Zhang, Ping Yue, Han Zhao, Zhiwei Xie and Wei Liu

Energies 2024, 17(23), 6055; https://doi.org/10.3390/en17236055 - 2 Dec 2024

Viewed by 613

Abstract

The Longwangmiao Formation gas reservoir in the Moxi block of the Sichuan Basin is a complex carbonate reservoir characterized by a low porosity and permeability, strong heterogeneity, developed natural fractures, and active water bodies. The existence of natural fractures allows water bodies to [...] Read more.

The Longwangmiao Formation gas reservoir in the Moxi block of the Sichuan Basin is a complex carbonate reservoir characterized by a low porosity and permeability, strong heterogeneity, developed natural fractures, and active water bodies. The existence of natural fractures allows water bodies to easily channel along these fractures, resulting in a more complicated mechanism and dynamic law of gas-well water production, which seriously impacts reservoir development. Therefore, a core-based simulation experiment was designed for oil–water two-phase flow. Three main factors influencing the water production of the gas reservoir, namely fracture permeability, fracture penetration, and water volume multiple, were analyzed using the orthogonal test method. The experimental results showed that the influences of the experimental parameters on the recovery factor and average water production can be ranked as water volume multiple > fracture penetration > fracture permeability, with the influence of the water volume multiple being slightly greater than that of the other two parameters. It provides a certain theoretical basis for water control of the gas reservoir. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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22 pages, 12960 KiB  

Open AccessArticle

Aerodynamic Performance and Numerical Validation Study of a Scaled-Down and Full-Scale Wind Turbine Models

by Zahid Mehmood, Zhenyu Wang, Xin Zhang and Guiying Shen

Energies 2024, 17(21), 5449; https://doi.org/10.3390/en17215449 - 31 Oct 2024

Viewed by 3059

Abstract

Understanding the aerodynamic performance of scaled-down models is vital for providing crucial insights into wind energy optimization. In this study, the aerodynamic performance of a scaled-down model (12%) was investigated. This validates the findings of the unsteady aerodynamic experiment (UAE) test sequence H. [...] Read more.

Understanding the aerodynamic performance of scaled-down models is vital for providing crucial insights into wind energy optimization. In this study, the aerodynamic performance of a scaled-down model (12%) was investigated. This validates the findings of the unsteady aerodynamic experiment (UAE) test sequence H. UAE tests provide information on the configuration and conditions of wind tunnel testing to measure the pressure coefficient distribution on the blade surface and the aerodynamic performance of the wind turbine. The computational simulations used shear stress transport and kinetic energy (SST K-Omega) and transitional shear stress transport (SST) turbulence models, with wind speeds ranging from 5 m/s to 25 m/s for the National Renewable Energy Laboratory (NREL) Phase VI and 4 m/s to 14 m/s for the 12% scaled-down model. The aerodynamic performance of both cases was assessed at representative wind speeds of 7 m/s for low, 10 m/s for medium, and 20 m/s for high flow speeds for NREL Phase VI and 7 m/s for low, 9 m/s medium, and 12 m/s for the scaled-down model. The results of the SST K-Omega and transitional SST models were aligned with experimental test measurement data at low wind speeds. However, the SST K-Omega torque values exhibited a slight deviation. The transitional SST and SST K-Omega models yielded aerodynamic properties that were comparable to those of the 12% scaled-down model. The torque values obtained from the simulation for the full-scale NREL Phase VI and the scaled-down model were 1686.5 Nm and 0.8349 Nm, respectively. Both turbulence models reliably predicted torque and pressure coefficient values that were consistent with the experimental data, considering specific flow regimes. The pressure coefficient was maximum at the leading edge of the wind turbine blade on the windward side and minimum on the leeward side. For the 12% scaled-down model, the flow simulation results bordering the low-pressure region of the blade varied slightly. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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12 pages, 8825 KiB  

Open AccessArticle

Study of the Impact of Acquisition Parameters on Fault Feature Identification Based on Magnetotelluric Modeling

by Hui Zhang and Fajian Nie

Appl. Sci. 2024, 14(21), 9720; https://doi.org/10.3390/app14219720 - 24 Oct 2024

Viewed by 873

Abstract

The electromagnetic method is widely used in mineral exploration, geothermal resource exploration, and deep earth structure detection. To improve the resolution and positioning accuracy of magnetotelluric surveys for targets beneath cover, it is essential to utilize forward modeling. This approach allows for a [...] Read more.

The electromagnetic method is widely used in mineral exploration, geothermal resource exploration, and deep earth structure detection. To improve the resolution and positioning accuracy of magnetotelluric surveys for targets beneath cover, it is essential to utilize forward modeling. This approach allows for a better understanding of the capabilities and limitations of MT in resolving features of different scales. In this paper, we employ forward modeling using the finite element method to simulate a series of continuous fault zones ranging from 100 m to 400 m in width, with varying lengths and dips. These fault zones represent conductive fluid pathways that could be associated with different scales and depths. The forward modeling provides the necessary data and method testing to assess the effectiveness of MT surveys in identifying and resolving such features. Our findings demonstrate that a station spacing of 400 m is optimal for resolving fault zones of various widths. For narrower faults (approximately 100 m), extending the survey line to 12 km or more significantly improves the deep structural inversion of the bounding faults, while an 8 km survey line suffices for wider faults (400 m). However, the vertical extent of these features is less well constrained, with deeper faults appearing broader and inversion depths being notably shallower than actual depths. These results highlight the need for careful interpretation of inversion anomalies, especially when supplementary data from other geophysical methods are lacking. Misinterpretation can lead to inaccurate resource assessments and exploration potential. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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19 pages, 3060 KiB  

Open AccessArticle

Study of a Numerical Integral Interpolation Method for Electromagnetic Transient Simulations

by Kaiyuan Sun, Kun Chen, Haifeng Cen, Fucheng Tan and Xiaohui Ye

Energies 2024, 17(15), 3837; https://doi.org/10.3390/en17153837 - 3 Aug 2024

Viewed by 1251

Abstract

In the fixed time-step electromagnetic transient (EMT)-type program, an interpolation process is applied to deal with switching events. The interpolation method frequently reduces the algorithm’s accuracy when dealing with power electronics. In this study, we use the Butcher tableau to analyze the defects [...] Read more.

In the fixed time-step electromagnetic transient (EMT)-type program, an interpolation process is applied to deal with switching events. The interpolation method frequently reduces the algorithm’s accuracy when dealing with power electronics. In this study, we use the Butcher tableau to analyze the defects of linear interpolation. Then, based on the theories of Runge–Kutta integration, we propose two three-stage diagonally implicit Runge–Kutta (3S-DIRK) algorithms combined with the trapezoidal rule (TR) and backward Euler (BE), respectively, with TR-3S-DIRK and BE2-3S-DIRK for the interpolation and synchronization processes. The proposed numerical integral interpolation scheme has second-order accuracy and does not produce spurious oscillations due to the size change in the time step. The proposed method is compared with the critical damping adjustment method (CDA) and the trapezoidal method, showing that it does not produce spurious numerical oscillations or first-order errors. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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17 pages, 2327 KiB  

Open AccessArticle

Observer-Based Suboptimal Controller Design for Permanent Magnet Synchronous Motors: State-Dependent Riccati Equation Controller and Impulsive Observer Approaches

by Nasrin Kalamian, Masoud Soltani, Fariba Bouzari Liavoli and Mona Faraji Niri

Computers 2024, 13(6), 142; https://doi.org/10.3390/computers13060142 - 4 Jun 2024

Cited by 1 | Viewed by 1360

Abstract

Permanent Magnet Synchronous Motors (PMSMs) with high energy efficiency, reliable performance, and a relatively simple structure are widely utilised in various applications. In this paper, a suboptimal controller is proposed for PMSMs without sensors based on the state-dependent Riccati equation (SDRE) technique combined [...] Read more.

Permanent Magnet Synchronous Motors (PMSMs) with high energy efficiency, reliable performance, and a relatively simple structure are widely utilised in various applications. In this paper, a suboptimal controller is proposed for PMSMs without sensors based on the state-dependent Riccati equation (SDRE) technique combined with customised impulsive observers (IOs). Here, the SDRE technique facilitates a pseudo-linearised display of the motor with state-dependent coefficients (SDCs) while preserving all its nonlinear features. Considering the risk of non-available/non-measurable states in the motor due to sensor and instrumentation costs, the SDRE is combined with IOs to estimate the PMSM speed and position states. Customised IOs are proven to be capable of obtaining quality, continuous estimates of the motor states despite the discrete format of the output signals. The simulation results in this work illustrate an accurate state estimation and control mechanism for the speed of the PMSM in the presence of load torque disturbances and reference speed changes. It is clearly shown that the SDRE-IO design is superior compared to the most popular existing regulators in the literature for sensorless speed control. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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20 pages, 9314 KiB  

Open AccessArticle

Electrodynamic Forces in Main Three-Phase Busbar System of Low-Voltage Switchgear—FEA Simulation

by Sebastian Łapczyński, Michał Szulborski, Łukasz Kolimas, Przemysław Sul, Maciej Owsiński, Przemysław Berowski, Tomasz Żelaziński and Andrzej Lange

Energies 2024, 17(8), 1891; https://doi.org/10.3390/en17081891 - 16 Apr 2024

Cited by 2 | Viewed by 2232

Abstract

This paper concerns the effects of electrodynamic forces that act on current paths that are part of high-grade industrial distribution switchgear. This work is composed of experimental and simulation sections. In the experimental section, the short-circuit tests are presented and the occurrence of [...] Read more.

This paper concerns the effects of electrodynamic forces that act on current paths that are part of high-grade industrial distribution switchgear. This work is composed of experimental and simulation sections. In the experimental section, the short-circuit tests are presented and the occurrence of electrodynamic forces are shown in a visible way. The formation of electrodynamic forces in the current circuits of electrical energy distribution systems is related to the flow of high currents, but mostly it is related to short-circuit currents. In order to highlight these phenomena, the detailed specification of the parameters during tests is displayed. In the simulation section, the physical phenomenon of electrodynamic forces is being captured by employing a detailed real-scale model of switchgear and current paths. Therefore, the authors proposed employment of the FEM (finite element method) in order to obtain values of electrodynamic forces acting on the current paths by executing the detailed 3D coupled simulation. The analysis of the results and aftermath effects of their interactions provided interesting conclusions that concerned the operation of such power distribution layouts in critical short-circuit conditions. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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23 pages, 2779 KiB  

Open AccessArticle

Determination of 12 Combustion Products, Flame Temperature and Laminar Burning Velocity of Saudi LPG Using Numerical Methods Coded in a MATLAB Application

by Roberto Franco Cisneros and Freddy Jesús Rojas

Energies 2023, 16(12), 4688; https://doi.org/10.3390/en16124688 - 13 Jun 2023

Cited by 3 | Viewed by 3044

Abstract

The characterization of a specific fuel has always been an important point for developing and designing new components or systems with the maximum efficient possible. Studying the laminar burning velocity can lay a necessary prerequisite for the accurate poststudy of the turbulent range [...] Read more.

The characterization of a specific fuel has always been an important point for developing and designing new components or systems with the maximum efficient possible. Studying the laminar burning velocity can lay a necessary prerequisite for the accurate poststudy of the turbulent range and to understand how the combustion process takes place. The study of the combustion products from a specific reaction is a requisite for any system in order to understand the elements that are taken in the process and if it is possible to improve it. In this study, a new open code methodology was developed for the determination of combustion products, flame temperature and laminar burning velocity using numerical methods (Newton–Raphson, Taylor series and Gaussian elimination) in an application codified in MATLAB. The MATLAB application was applied for the study of Saudi LPG setting parameters such as initial temperature, pressure and equivalence ratio that are meaningful because they have a great effect on the results. In addition, simulation in Ansys Chemkin using San Diego and RedSD mechanisms was carried out. The results from the MATLAB application were compared with other experimental research and Ansys Chemkin simulation. These are presented in different plots and it is shown that: (1) For the laminar burning velocity results, the numerical method agrees with the experimental results for ratios (0.6–1.2) by other authors and the simulation in Ansys Chemkin. (2) For the highest studied equivalence ratios (1.3–1.7) the laminar burning velocity results between all the resources have more difference. (3) The combustion products calculated by the MATLAB application agree with those simulated in Ansys Chemkin except N and NO. (4) The MATLAB application gives a maximum value of 40.35 cm/s, that is greater than 35 ± 0.91, the one determined by Bader A. Alfarraj. (5) The flame temperature calculated by the MATLAB application overestimates that simulated in Ansys Chemkin but has the same behavior for all the calculated ratios. (6) The MATLAB application has also been developed for the study and analysis of other fuels. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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21 pages, 9586 KiB  

Open AccessArticle

An Application of Relative Entropy in Structural Safety Analysis of Elastoplastic Beam under Fire Conditions

by Marcin Kamiński and Michał Strąkowski

Energies 2023, 16(1), 207; https://doi.org/10.3390/en16010207 - 25 Dec 2022

Cited by 1 | Viewed by 1857

Abstract

The main aim of this work is to propose a new algorithm of reliability assessment for steel civil engineering structures subjected to fire temperatures. This new algorithm is based upon the relative probabilistic entropy concept elaborated by Bhattacharyya, and this probabilistic distance is [...] Read more.

The main aim of this work is to propose a new algorithm of reliability assessment for steel civil engineering structures subjected to fire temperatures. This new algorithm is based upon the relative probabilistic entropy concept elaborated by Bhattacharyya, and this probabilistic distance is sought in-between extreme and admissible deformations of some structural beam subjected to higher temperatures. Similar to the First Order Reliability Method, this approach uses the first two probabilistic characteristics of the structural response, when structural output may be modelled with the use of Gaussian distribution. The probabilistic structural response is found here using hybrid computational technique–the Finite Element Method system ABAQUS with its fully coupled thermo-elastic analysis with 3D solid elements and probabilistic modules implemented in the computer algebra system MAPLE. The probabilistic response is determined via a triple stochastic analysis, which is based on the classical Monte-Carlo simulation, iterative generalized stochastic perturbation technique, and also using semi-analytical probabilistic calculus. Final determination of the relative entropy in the Serviceability Limit State of the given structure and its comparison with the results obtained using the FORM analysis enables to calibrate this new technique to numerical values proposed in the engineering designing codes. Hence, a more accurate probabilistic method may use some experimental-based admissible values included in the existing design of legal provisions. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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17 pages, 5839 KiB  

Open AccessArticle

Power Consumption and Effectiveness of Azimuth Stern-Drive (ASD) Tug While Assisting at Ship’s Bow

by Jarosław Artyszuk and Paweł Zalewski

Energies 2022, 15(24), 9519; https://doi.org/10.3390/en15249519 - 15 Dec 2022

Viewed by 2882

Abstract

The purpose of this article is to present a methodical approach to increasing the efficiency of a tug with an azimuth stern drive (ASD). The difficulties in the bow-to-bow (as a reverse tractor) operations of an azimuth stern-drive tug, while pulling at the [...] Read more.

The purpose of this article is to present a methodical approach to increasing the efficiency of a tug with an azimuth stern drive (ASD). The difficulties in the bow-to-bow (as a reverse tractor) operations of an azimuth stern-drive tug, while pulling at the assisted (towed) ship’s bow, are investigated through a parametric study. The authors’ original generic analytical model of a tug in a steady state is utilised. Various design and operation options are also compared, which cover the escort speed, hawser angle, and relative location of the towing point, among others. The latter also means a shift to stern-to-bow operation. The thruster power required and the remaining surplus for executing new alignment (steering) orders are assessed. The study is, thus, aimed at energy savings for the whole operation and, consequently, at long-term harbour-tug-fleet energy effectiveness. The basic output of the present research is the comparison of the behavioural and control patterns of various tug arrangements at a ship’s bow. The results of the study show a slight advantage for a midship winch tug working through her stern for bow operation (stern-to-bow) over the reverse tractor acting bow-to-bow. Comparing various tug designs or operation options is difficult due to complicated tug dynamics and statics patterns under the hawser action. Both relative and absolute towing forces have to be considered (a high relative force may result in a low absolute force, much less than ordered by the pilot), with some geometrical and safety constraints additionally. The practical implementation of the conducted research should cover the guidance and training rendered to tug masters in the scope of the operational limitations of a particular tug and towards the design or acquisition of the tug that is best-suited for a particular harbour operation. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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22 pages, 10614 KiB  

Open AccessArticle

Numerical Study of the Impact of Fluid–Structure Interaction on Flow Noise over a Rectangular Cavity

by Paweł Łojek, Ireneusz Czajka and Andrzej Gołaś

Energies 2022, 15(21), 8017; https://doi.org/10.3390/en15218017 - 28 Oct 2022

Cited by 4 | Viewed by 2082

Abstract

Fluid–structure interactions (FSI) can significantly affect flow and the acoustic field generated by it. In this article, simulations of the flow over a rectangular cavity are conducted with and without taking FSI into account. The aim of this research is to conduct a [...] Read more.

Fluid–structure interactions (FSI) can significantly affect flow and the acoustic field generated by it. In this article, simulations of the flow over a rectangular cavity are conducted with and without taking FSI into account. The aim of this research is to conduct a numerical study of the flow over a cavity and to verify whether interactions between the flow and the elastic structure can significantly affect the flow itself or the acoustic pressure field. Four cases involving flexible walls with different material parameters and one reference case with rigid walls were analysed. The two-directional fluid–structure coupling between the flow and cavity walls was simulated. The simulations were performed with the volume and finite element methods using OpenFOAM software to solve the fluid field, CalculiX software to solve the displacement of the structure, and the preCICE library to couple the codes and computed fields. The acoustic analogy of Ffowcs-Williams and Hawkings and the libAcoustics library were used to calculate the sound pressure. The simulation results showed that FSI has a significant influence on sound pressure in terms of both pressure amplitudes and levels as well as in terms of noise frequency composition. There was a significant increase in the sound pressure compared to the case with rigid walls, especially for frequencies above 1 kHz. The frequencies at which this occurred are related to the natural frequencies of the cavity walls and the Rossiter frequencies. Overlap of these frequencies may lead to an increase in noise and structural vibrations, which was observed for one of the materials used. This study may provide insight into the flow noise generation mechanism when fluid–structure interactions are taken into account. The conclusions presented here can form a basis for further work on aerodynamic noise in the presence of thin-walled structures. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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18 pages, 6191 KiB  

Open AccessArticle

Investigation of a Negative Step Effect on Stilling Basin by Using CFD

by Lei Jiang, Minjun Diao and Chuan’ai Wang

Entropy 2022, 24(11), 1523; https://doi.org/10.3390/e24111523 - 25 Oct 2022

Cited by 4 | Viewed by 2908

Abstract

The negative-step stilling basin is an efficient and safe energy dissipator for high-head, large-unit discharge high-dam projects. However, studies of the effects of the negative step on the hydraulic performance of a high-dam stilling basin have not been conclusive. In the present study, [...] Read more.

The negative-step stilling basin is an efficient and safe energy dissipator for high-head, large-unit discharge high-dam projects. However, studies of the effects of the negative step on the hydraulic performance of a high-dam stilling basin have not been conclusive. In the present study, a 2D RANS-VOF numerical model was developed to simulate the flow field of a negative-step stilling basin. The numerical model was validated with a physical model and then used to simulate and test the performance of the negative-step stilling basin with different step heights and incident angles. The results showed that the flow pattern, the free-surface profile, the velocity profile, the characteristic lengths are strongly influenced by the step geometry. Increasing the height of the step will increase the relative flow depth and the reattachment length in the basin, but reduce the bottom velocity and the roller length. The incident angle has no significant influence on the flow pattern of the negative-step stilling basin, and increasing the incident angle of the step will reduce the bottom velocity and the reattachment length. Both the step height and the incident angle have no significant influence on the energy dissipation efficiency because of the high submergence conditions in this study. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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17 pages, 2214 KiB  

Open AccessArticle

McCARD Criticality Benchmark Analyses with Various Evaluated Nuclear Data Libraries

by Ho Jin Park, Mohammad Alosaimi, Seong-Ah Yang, Heejeong Jeong and Sung Hoon Choi

Energies 2022, 15(18), 6852; https://doi.org/10.3390/en15186852 - 19 Sep 2022

Cited by 4 | Viewed by 2116

Abstract

International Criticality Safety Benchmark Evaluation Project (ICSBEP) criticality analyses were conducted using the McCARD Monte Carlo code for 85 selected benchmark problems with 7 evaluated nuclear data libraries (ENDLs): ENDF/B-VII.1, ENDF/B-VIII.0, JENDL-4.0, JENDL-5.0, JEFF-3.3, TENDL-2021, and CENDL-3.2. Regarding the analyses, it was confirmed [...] Read more.

International Criticality Safety Benchmark Evaluation Project (ICSBEP) criticality analyses were conducted using the McCARD Monte Carlo code for 85 selected benchmark problems with 7 evaluated nuclear data libraries (ENDLs): ENDF/B-VII.1, ENDF/B-VIII.0, JENDL-4.0, JENDL-5.0, JEFF-3.3, TENDL-2021, and CENDL-3.2. Regarding the analyses, it was confirmed that the k_eff results are sensitive to the ENDL. It is noted that the new-version ENDLs show better performance in the fast benchmark cases, while on the other hand, there are no significant differences in k_eff among the different ENDLs in the thermal benchmark cases. The sensitivity of the k_eff results depending on the ENDL may impact nuclear core design parameters such as the shutdown margin, critical boron concentration, and power defects. This study and k_eff results will be a good reference in the development of new types of nuclear cores or new design codes. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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14 pages, 2254 KiB  

Open AccessArticle

Shannon Entropy in Stochastic Analysis of Some Mems

by Marcin Kamiński and Alberto Corigliano

Energies 2022, 15(15), 5483; https://doi.org/10.3390/en15155483 - 28 Jul 2022

Cited by 1 | Viewed by 1700

Abstract

This work is focused on the numerical determination of Shannon probabilistic entropy for MEMS devices exhibiting some uncertainty in their structural response. This entropy is a universal measure of statistical or stochastic disorder in static deformation or dynamic vibrations of engineering systems and [...] Read more.

This work is focused on the numerical determination of Shannon probabilistic entropy for MEMS devices exhibiting some uncertainty in their structural response. This entropy is a universal measure of statistical or stochastic disorder in static deformation or dynamic vibrations of engineering systems and is available for both continuous and discrete distributions functions of structural parameters. An interval algorithm using Monte Carlo simulation and polynomial structural response recovery has been implemented to demonstrate an uncertainty propagation of the forced vibrations in some small MEMS devices. A computational example includes stochastic nonlinear vibrations described by the Duffing equation calibrated for some micro-resonators, whose damping is adopted as a Gaussian, uniformly and triangularly distributed input uncertainty source. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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27 pages, 3516 KiB  

Open AccessFeature PaperArticle

A New Perspective on Cooking Stove Loss Coefficient Assessment by Means of the Second Law Analysis

by Lomena Mulenda Augustin, Sumuna Temo Vertomene, Ndaye Nkanka Bernard, Amsini Sadiki and Mbuyi Katshiatshia Haddy

Entropy 2022, 24(8), 1019; https://doi.org/10.3390/e24081019 - 23 Jul 2022

Cited by 1 | Viewed by 4068

Abstract

The chimney effect taking place in biomass cooking stoves results from a conversion process between thermal and mechanical energy. The efficiency of this conversion is assessed with the stove loss coefficient. The derivation of this quantity in cooking stove modelling is still uncertain. [...] Read more.

The chimney effect taking place in biomass cooking stoves results from a conversion process between thermal and mechanical energy. The efficiency of this conversion is assessed with the stove loss coefficient. The derivation of this quantity in cooking stove modelling is still uncertain. Following fluid mechanics, this loss coefficient refers to an overall pressure drop through stove geometry by performing an energy balance according to the first law of thermodynamics. From this approach, heat-transfer processes are quite ignored yet they are important sources of irreversibilities. The present work takes a fresh look at stove loss coefficient assessment relying on the second law of thermodynamics. The purpose in this paper is to identify the influence of operating firepower level on flow dynamics in biomass natural convection-driven cooking stoves. To achieve that, a simplified analytical model of the entropy-generation rate in the flow field is developed. To validate the model, experiments are conducted first on a woodburning stove without cooking pot to better isolate physical processes governing the intrinsic behaviour of the stove. Then, for the practical case of a stove operating with a cooking pot in place, data from published literature have served for validation. In particular, mass-flow rate and flue gas temperature at different firepower levels have been monitored. It turns out that losses due to viscous dissipations are negligible compared to the global process dissipation. Exergy analysis reveals that the loss coefficient should rather be regarded from now as the availability to generate flow work primarily associated with the heat-transfer Carnot factor. In addition, the energy flux applied as flow work has to be considered as pure exergy that is lost through consecutive energy-transfer components comprising the convective heat transfer to the cooking pot. Finally, this paper reports a satisfactory agreement that emerged between the exergy Carnot factor and the experimental loss coefficient at different fuel-burning rates. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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19 pages, 3129 KiB  

Open AccessArticle

Rockburst Intensity Level Prediction Method Based on FA-SSA-PNN Model

by Gang Xu, Kegang Li, Mingliang Li, Qingci Qin and Rui Yue

Energies 2022, 15(14), 5016; https://doi.org/10.3390/en15145016 - 8 Jul 2022

Cited by 16 | Viewed by 1969

Abstract

To accurately and reliably predict the occurrence of rockburst disasters, a rockburst intensity level prediction model based on FA-SSA-PNN is proposed. Crding to the internal and external factors of rockburst occurrence, six rockburst influencing factors (σ_θ, σ_t, σ [...] Read more.

To accurately and reliably predict the occurrence of rockburst disasters, a rockburst intensity level prediction model based on FA-SSA-PNN is proposed. Crding to the internal and external factors of rockburst occurrence, six rockburst influencing factors (σ_θ, σ_t, σ_c, σ_c/σ_t, σ_θ/σ_c, W_et) were selected to build a rockburst intensity level prediction index system. Seventy-five sets of typical rockburst case data at home and abroad were collected, the original data were preprocessed based on factor analysis (FA), and the comprehensive rockburst prediction indexes, CPI₁, CPI₂, and CPI₃, obtained after dimensionality reduction, were used as the input features of the SSA-PNN model. Sixty sets of rockburst case data were extracted as the training set, and the remaining 15 sets of rockburst case data were used as the test set. After the model training was completed, the model prediction results were analysed and evaluated. The research results show that the proposed rockburst intensity level prediction method based on the FA-SSA-PNN model has the advantages of high prediction accuracy and fast convergence, which can accurately and reliably predict the rockburst intensity level in a short period of time and can be used as a new method for rockburst intensity level prediction, providing better guidance for rockburst prediction problems in deep rock projects. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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28 pages, 11307 KiB  

Open AccessArticle

Systematic Method for Developing Reference Driving Cycles Appropriate to Electric L-Category Vehicles

by David Watling, Patrícia Baptista, Gonçalo Duarte, Jianbing Gao and Haibo Chen

Energies 2022, 15(9), 3466; https://doi.org/10.3390/en15093466 - 9 May 2022

Cited by 1 | Viewed by 2754

Abstract

Increasingly, demanding environmental standards reflect the need for improved energy efficiency and reduced externalities in the transportation sector. Reference driving cycles provide standard speed profiles against which future developments and innovations may be tested. In the paper, we develop such profiles for a [...] Read more.

Increasingly, demanding environmental standards reflect the need for improved energy efficiency and reduced externalities in the transportation sector. Reference driving cycles provide standard speed profiles against which future developments and innovations may be tested. In the paper, we develop such profiles for a class of electric L-category vehicles, which are anticipated to play an increasing future role in urban areas. While such driving cycles exist for regular L-category vehicles, these may not be suitable in the case of electric vehicles, due to their power output limitations. We present a methodology for deriving these new driving cycles, developed from empirically deduced power relationships, before demonstrating their application under different assumptions on the terrain and vehicle characteristics. The applications demonstrate the feasibility of the method in developing appropriate driving patterns for alternative real-world contexts. On flat terrain, the adjustments made to cope with the power limitations of L-EV do not introduce significant differences in energy consumption, suggesting that the certification does not require extensive modification. However, when considering road slope, differences of up to 5% in energy use and up to 10% in regenerated energy were observed, showing the importance of the developed method for assessing vehicle performance in real-world driving. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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13 pages, 15232 KiB  

Open AccessArticle

Distribution Characteristics of High Wetness Loss Area in the Last Two Stages of Steam Turbine under Varying Conditions

by Shuangshuang Fan, Ying Wang, Kun Yao, Jiakui Shi, Jun Han and Jie Wan

Energies 2022, 15(7), 2527; https://doi.org/10.3390/en15072527 - 30 Mar 2022

Cited by 9 | Viewed by 2402

Abstract

Wetness loss of a steam turbine seriously affects the security of the unit when operating in deep peak regulation. To obtain the distribution characteristics of the high wetness loss area under different working conditions, especially low-load conditions, the last two stages of the [...] Read more.

Wetness loss of a steam turbine seriously affects the security of the unit when operating in deep peak regulation. To obtain the distribution characteristics of the high wetness loss area under different working conditions, especially low-load conditions, the last two stages of the low-pressure cylinder (LPC) of a 600 MW steam turbine were simulated using the non-equilibrium condensation model proposed in this study. The nucleation rate distribution, supercooling degree, and steam velocity droplet were analyzed. Consequently, the diameter distribution of coarse water droplets under 100%, 50%, 40%, 30%, and 20% THA conditions and the distribution of the thermodynamic loss and water droplet resistance loss were obtained. Thermodynamic loss mainly occurred at the front end of second-stage stator blades and trailing end of the last-stage stator blades. The water droplet resistance loss mainly occurred at 40% of the blade height and at the tip of the last-stage stator blades. Moreover, with a reduction in the unit load, the thermodynamic loss continued to decrease, but the water droplet resistance loss continued to increase. Full article

(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)

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