The high-quality operation of a superheated steam temperature (SST) system is a core fact of the safety, economy, and stability of thermal power units. How to improve the control performance of an SST system under large-varying operating conditions is becoming a research hotspot. To solve this challenge, this paper proposes a proportional integral derivative (PID) control strategy based on integral gain scheduling. Based on the introduction of the SST system and classical model under typical operating conditions, the control difficulties of the SST system are analyzed theoretically. Then, a PID control strategy, based on integral gain scheduling, is introduced for the cascade control structure, and the stability of the proposed control strategy is analyzed by calculating the PID stability region. Finally, the effectiveness of the proposed method is verified under nominal and uncertain conditions, where the proposed method could obtain satisfactory tracking and disturbance rejection con... [more]

In order to solve the poor flow performance issues of selective catalytic reduction (SCR) denitration systems, the effect of the static mixer on the flow field was studied using computational fluid dynamics (CFD) numerical simulations. Based on the analysis of the original SCR denitration system, two static mixers were selected to explore their influence on system performance. The results show that both static mixers can effectively improve the denitration performance under different conditions. The static mixer with a rotating arrangement showed a better performance in the uniformity of concentration. The pressure loss without a static mixer is 834 Pa, and the pressure loss increases by 94 Pa and 73 Pa for rotating and X-arranged static mixers, respectively. Meanwhile, a static mixer will increase energy loss. Therefore, power plants can choose the layout of their static mixers according to the actual situation to achieve the optimal performance.

Oil, coal, and natural gas are traditional fossil energy sources and the main components of primary energy consumption globally [...]

This paper presents the development of a neural inverse optimal control (NIOC) for a regenerative braking system installed in electric vehicles (EVs), which is composed of a main energy system (MES) including a storage system and an auxiliary energy system (AES). This last one is composed of a supercapacitor and a buck−boost converter. The AES aims to recover the energy generated during braking that the MES is incapable of saving and using later during the speed increase. To build up the NIOC, a neural identifier has been trained with an extended Kalman filter (EKF) to estimate the real dynamics of the buck−boost converter. The NIOC is implemented to regulate the voltage and current dynamics in the AES. For testing the drive system of the EV, a DC motor is considered where the speed is controlled using a PID controller to regulate the tracking source in the regenerative braking. Simulation results illustrate the efficiency of the proposed control scheme to track time-varying references... [more]

In this paper, a low-order approximation (LOA) of fractional order PID (FOPID) for an automatic voltage regulator (AVR) based on the modified artificial bee colony (ABC) is proposed. The improved artificial bee colony (IABC) high-order approximation (HOA)-based fractional order PID (IABC/HOA-FOPID) controller, which is distinguished by a significant order approximation and by an integer order transfer function, requires the use of a large number of parameters. To improve the AVR system’s performance in terms of transient and frequency response analysis, the memory capacity of the IABC/HOA-FOPID controller was lowered so that it could fit better in the corrective loop. The new robust controller is named the improved artificial bee colony (IABC) low-order approximation (LOA)-based fractional order PID (IABC/LOA-FOPID). The performance of the proposed IABC/LOA-FOPID controller was compared not only to the original ABC algorithm-tuned PID controller, but also to other controllers tuned by... [more]

Over 5.5 million tons of plastic waste are generated globally from the research sectors. A university laboratory, e.g., pathology, can generate 250 tons of clinical plastic waste annually. The UK National Health Service (NHS) generates 133 kilotons (kt) of clinical plastic waste annually. Healthcare facilities in the US generate 1.7 million tons of clinical plastic waste annually. In addition, 95% of the clinical plastics are single-use plastics derived from fossil resources, i.e., crude oils. These single-use clinical plastic wastes are incinerated, contributing to global warming, or go to the landfill, contributing to resource depletion. Plastic leakage is a major threat to the environment. This linear plastics economy model, take-make-dispose, must be replaced by a circular plastics economy, i.e., sort plastic wastes, wash, decontaminate, recover materials, blend with bio-based compounds as necessary and circulate recyclate plastics, for holistic systemic sustainability. While there... [more]

In this paper, the effect of the swirler scheme on combustion instability is studied. Through the proper orthogonal decomposition (POD) of flame images, Abel inverse transform and other methods, the influence of swirl intensity on the characteristic frequency of combustion instability was emphatically studied. Based on the low order thermoacoustic network (LOTAN) of the combustor, the flame transfer function (FTF) under different swirl schemes was obtained by the optimization method. The experimental results show that the stable combustion equivalence ratio boundary of the system decreases monotonously with the decrease in swirl intensity, while the characteristic frequency of unstable combustion is not monotonous with the swirl intensity (the oscillating frequency of swirler A with the largest swirl intensity is approximately 319 Hz, swirler B is approximately 280 Hz, swirler C with the smallest swirl intensity is approximately 290 Hz). The optimization results of FTF can easily intro... [more]

This paper presents a new direct maximum power point tracking (MPPT) with a reference voltage (Vref) based on the metaheuristic earthquake algorithm (EA) where the optimization variable is the Vref for hard-switching converters. The efficiency and performance of EA-MPPT-Vref is compared with the perturb-and-observe (P&O) counterpart technique due to the fact that it is widely used for commercial products. Static and dynamic responses for both MPPT strategies are evaluated, which correspond to steady-state oscillations when they are near the maximum power point (MPP), and the tracking-speed, respectively. The efficiency was evaluated with the EN 50530 standard. The results show that the new MPPT proposed is a competitive method using the EA to obtain the optimal voltage reference. From static results, EA-MPPT VP presented a better efficiency of 5.13% and 3.23% for European and California energy commission (CEC) efficiency, respectively. Whereas, from dynamic results, MPPT-Vref technique... [more]

Cooperation between supply chain partners in the oil industry is essential, especially when oil prices suffer from fluctuations that affect the profitability of each party. An essential task in oil field development projects is to create an optimum agreement between the national oil company and the international oil company to guarantee agreement optimization. In this paper, the national oil company is the first party (FP) and the international oil company is the second party (SP). The paper’s purpose is to investigate the use of game theory to obtain the best agreement between the FP and SP in order to enhance the cooperation and reduce conflict. In this paper, Nash and Maxi-min solutions have been applied for the first time in a special type of petroleum agreement, called exploration and production sharing agreements (EPSA). This is conducted for a case study in Libya. The study considers nine negotiation factors (issues) in the EPSA, which are the share percent, the four “A” factors... [more]

Aqueous zinc-ion batteries (AZIBs) are being intensively developed as potential alternative electrochemical power sources, due to their advantages such as low cost, high safety, abundance of natural zinc resources and appropriate energy density. Among currently investigated prospective cathode materials for AZIBs, vanadium oxide-based composites with intrinsically conducting polymers have shown many advantages, such as high capacity, high power density and long battery life. This review gives a focused view of the design for the boosting of zinc ion storage performance using intrinsically conducting polymers in vanadium oxide-based composites and the mechanism of intercalation processes. The main challenges in interfacial engineering of vanadium oxide-conducting polymers composite structures and the prospects for further development of such cathode materials are summarized and discussed. The review would give rise to a broad interest focusing on the advantageous strategy of the develop... [more]

Coiled tubing (CT) is widely used in drilling, workover, completion, fracturing and stimulation in the field of oil and gas exploration and development. During CT operation, the tubing will present a gas−liquid two-phase flow state. The prediction of frictional pressure drop for fluid in the tube is an important part of hydraulic design, and its accuracy directly affects the success of the CT technique. In this study, we analyzed the effects of the gas void fraction, curvature ratio and fluid inlet velocity on frictional pressure drop in CT, numerically. Experimental data verified simulated results. Flow friction sensitivity analysis shows the frictional pressure drop reaches its peak at a gas void fraction of 0.8. The frictional pressure gradient increases with the increase in curvature ratio. As the strength of secondary flow increases with the increase in inlet velocity, the increased trend of gas−liquid two-phase flow friction is aggravated. The correlation of friction factor for g... [more]

The prediction of gas productivity and reservoir stability of natural gas hydrate (NGH) reservoirs plays a vital role in the exploitation of NGH. In this study, we developed a THMC (thermal-hydrodynamic-mechanical-chemical) numerical model for the simulation of gas production behavior and the reservoir response. The model can describe the phase change, multiphase flow in porous media, heat transfer, and deformation behavior during the exploitation of NGH reservoirs. Two different production scenarios were employed for the simulation: depressurization and depressurization coupled with CO2 exchange. The simulation results suggested that the injection of CO2 promotes the dissociation of NGH between the injection well and the production well compared with depressurization only. The cumulative production of gas and water increased by 27.88% and 2.90%, respectively, based on 2000 days of production simulation. In addition, the subsidence of the NGH reservoir was lower in the CO2 exchange cas... [more]

This paper focuses on the design modification of L-type flange joint geometry in wind towers, aiming to enhance its structural safety. For this aim, current design issues of existing flange joints are discussed. The numerical simulations indicate that the threaded bolt and flange-to-shell junction are critical locations where failure may happen. Further discussion to improve structural safety is applied for an existing 5 MW flange joint. Through parametric studies, the major factors influencing ultimate strength are identified. The results show that the aspect ratio plays an important role in increasing the structural safety of the flange joints, while the width of the flange segment weakens the stiffness of the flange-to-shell junction. The findings in this study are expected to provide a useful reference for designing the L-type flange joints in practical engineering fields.

When an axial-flow pump is running, there is a very complex flow inside the runner. Based on the two-way fluid−structure coupling method, this paper simulated the forward and reverse operating conditions of an axial-flow pump and calculated the dynamic stress distribution on the blade surface. The stress load spectrum was loaded onto the blade, and fatigue characteristic analysis was carried out to obtain the fatigue life and damage of the blade. This research shows the following: under different working conditions, the dynamic stress is concentrated at the root of the blade, and its amplitude decreases with the increase in the flow rate; at the same time, the change in stress with time shows a periodic change law. Under the working conditions of the turbine, the main frequency is the rotational frequency, and the secondary frequency is composed of multipliers of the rotational frequency, which is obviously affected by the number of blades; the fatigue damage and stress distribution ar... [more]

The treatment and disposal of sewage sludge is one of the most important and critical issues of wastewater treatment plants. One option for sludge liquidation is the production of fuel in the form of pellets from mixed sewage and paper mill sludge. This study presents the results of the combustion of pelletized fuels, namely sewage and paper mill sludge, and their 2:1 and 4:1 blends in a fluidized bed combustor. The flue gas was analysed after reaching a steady state at bed temperatures of 700−800 °C. Commonly used flue gas cleaning is still necessary, especially for SO2; therefore, it is worth mentioning that the addition of paper mill sludge reduced the mercury concentration in the flue gas to limits acceptable in most EU countries. The analysis of ash after combustion showed that magnesium, potassium, calcium, chromium, copper, zinc, arsenic, and lead remained mostly in the ash after combustion, while all cadmium from all fuels used was transferred into the flue gas together with a... [more]

Historic buildings constitute a specific group of buildings where the possibilities of improving energy efficiency and comfort are significantly limited because of the existing construction features and heritage values. Each building has a different history so the scope of renovation and/or retrofitting must be determined individually for each building. This article presents the methodology of measurement and diagnosis of features of particular importance for energy performance and comfort improvements, based on the example of a historic masonry building located in southern Poland. The first research question was which of the comfort conditions have been exceeded according to measurements. The second issue concerned the necessary extension of the basic determinants of comfort, beyond measurable qualities. A multi-faceted approach to the comfort assessment is proposed, including qualitative research that applies the additional criterion of aesthetic comfort. During the case study diagno... [more]

Smart grid operations require accurate information on network topology and electrical equipment parameters. This paper proposes estimating such information with data from the smart grid. Assuming that the availability of bus voltage data is restricted to their magnitude, a linear model of the relationship between these data and the parameters of the admittance matrix is derived in a way that does not involve bus voltage angles. A regression optimizer is then proposed to minimize the deviation between data and values estimated by the linear model. Results on the IEEE 33 bus system are presented to illustrate the model accuracy and efficiency when used to estimate parameters of medium-voltage, three-phase balanced grids.

This article presents a simple and low-cost green synthesized single-layer NiO selective solar absorber nanocoating prepared by spin coating on a Cu substrate at different rotational speeds (RS). The effects of substrate RS on the structural, morphological, chemical, and optical properties of the NiO nanocoatings were thoroughly investigated. The XRD results reveal the formation of pure diffraction peaks indexed to face-centered cubic NiO nanocoatings. SEM confirmed the uniform distribution of the NiO thin films with a nanosphere-like structure and the influence of RS variation on the formation of NiO nanostructures. EDS and XPS confirmed the presence of Ni and O in the green synthesized NiO coatings. AFM showed homogeneous nanopillar-like NiO thin films with the average surface roughness decreasing from 13.6 to 9.06 nm as the RS increased from 700 to 1300 RPM. Raman spectroscopy of the nanocoatings showed normal modes related to longitudinal optical and transverse optical phonons, and... [more]

Electric vehicles (EVs) are emerging as an alternative transportation system owing to a reduction in depleting lubricates usage and greenhouse gas emissions. This paper presents a technical review of each and every sub-system and its feasible control of battery EV (BEV) propulsion units. The study includes the possible combination of electrical machines (EMs), storage system, and power electronic converters and their associated control strategies. The primary unit, i.e., EM, is the heart of the EV, which is used to drive the vehicle at the desired speed as well as to restore the regenerative braking (RB) energy that is generated to enhance the overall system reliability. To electrify the transportation sector, it is necessary to include new options of power electronic converter topologies and their associated control strategies for numerous reasons, which include extracting maximum power from sources in case the EV is powered from renewable energy resources, boosting the energy storage... [more]

The article presents the most commonly used multi-criteria analysis methods for choosing the optimal location for future wind parks. The article makes a comparison of the criteria and restrictions of localisation and an overview of the main legal constraints and prospects in the development of renewable energy sources (RES). Financial assistance from the EU to accelerate the achievement of the required indicators was described. Moreover, restrictions considering environmental, social and noise factors that affect the life of the local population and the perception of the landscape visually are important. Additionally, it includes an option for developing wind energy in the absence of the necessary space for construction. In a new approach for the location of the wind farm, to the investors and another researcher related to the topic of wind turbine foundations, we indicate the most important aspects of wind energy control that should be taken into account in wind farm location proceedi... [more]

For wellbore stability issues induced by drilling operations in natural gas hydrate-containing reservoirs, wellbore stability research will focus on the mechanical properties of hydrate reservoirs. According to the content of the research, the response relationship between the hydrate core and the base physical property changes under different engineering parameters is established, and the law of hydrate mechanical property changes with temperature and pressure is studied for various physical properties. According to theoretical research and experimental data, it has been determined that: hydrate core-resolved gas and transverse and longitudinal wave velocity have a positive correlation with saturation and pressure and a negative correlation with temperature; a negative correlation exists between resistivity and saturation. The hydrate core stiffness strength correlates positively with saturation and adversely with temperature. Under the identical strain conditions, when saturation, po... [more]

The energy crisis, the risk of interruptions or irregular supplies of conventional energy carriers, and the need to protect the environment stimulate the search for new solutions to improve the heat balance of buildings with the use of solar energy. In this paper, direct and indirect solar gain systems integrated with the building envelope are discussed. In the context of the identified operational problems, the evolution of the classic Trombe wall was shown in the period 1967−2022. Modifications to the windows and Trombe wall proposed in the reviewed works can significantly reduce the risk of an insufficient supply of heat in the winter season. This review also indicates the impact of climate conditions on the decision-making process involved in the selection of the Trombe wall design with respect to energy−effects optimization. The insufficient thermal insulating capacity of Trombe walls has been diagnosed as the reason why they do not enjoy much popularity in cold and moderate clima... [more]

A heat pipe is an energy-efficient heat transfer device that relies on evaporation and condensation processes for energy transfer. The main purpose of this study is to simulate a two-phase closed thermosyphon, at moderate temperature, that can be used in industrial applications such as steam power plants. After creating a computational network in the Gambit software, the thermosyphon is simulated in Fluent software using the VOF model. Special oil is employed as the working fluid. Based on the CFD results, the efficiency of the system reaches approximately 96%, and the thermal resistance decreases to 0.54 K/W. The contours of the boiling and evaporation process at differing filling ratios, ranging between 30−90%, is visually investigated and the best performance is obtained for 30% of the filling ratio in thermosyphon. At higher filling ratios, more giant bubbles are generated in thermosyphon, which can attach to the inner wall of the system and reduce the thermal performance. The stea... [more]

This study analyzes the conditions for creating the energy density necessary to obtain supercritical fluids of substances with parameters (temperature T > 1 eV, density N > 1022 cm−3, specific energy density ε > 100 kJ/g). The calculations are carried out on the basis of the one-dimensional (1D) two-temperature (2T) magneto hydrodynamic radiation model, which takes into account the physical processes occurring in the energy storage, switching system and the pulsed plasma load-a cylindrical compressible conductive shell. Developing a mathematical model, we assumed that physical processes were self-consistent. The simulation results were presented as time dependences of the main process parameters. Calculations showed that it becomes possible to sharpen the radiation pulse and pressure in the shock wave. As a result, we formulated the requirements for a laboratory energy source to establish the characteristics of a current pulse flowing through a conductive cylindrical shell and its dime... [more]

This paper presents a new topology of an axial flux-switching memory machine with series-type permanent magnets (SPMs) to improve the flux regulation capability. The key idea was to combine low coercive force (LCF) PMs, which can be magnetized and demagnetized readily, with high coercive force (HCF) PMs in series to provide a variable air-gap magnetic flux. The flux regulating principle and the forward magnetization effect of HCF PMs on LCF PMs are presented and discussed. Based on 3D finite element analysis (FEA), the magnetization variation of LCF PMs and the electromagnetic performances of the machine under different magnetization states were investigated. Simulation results showed that the air-gap magnetic flux could be weakened by up to 45% by using a magnetization current impulse, significantly extending the PM motor’s flux-weakening speed range. Finally, a prototype machine was built, and experiments were performed to validate the predictions. The basic experimental validation s... [more]