High temperature corrosion poses a great threat to boiler water wall safe operation. To investigate the corrosion root cause, a 300 MW level boiler water wall high temperature H2S corrosion case was reported. The typical hydrogen sulfide H2S corrosion feature was large amounts of sulfur which could be found in the cut down sample tube corrosion layer, with a thickness of 482 μm. In addition, huge amounts of lead (Pb) could be found in the corrosion layer, which resulted from the lead sulfide (PbS) deposition when the high temperature flue gas condensed at the water wall tubes. Meanwhile, the sulfur in the corrosion layer was closely related to the H2S concentration in the water wall ambience. The related ambience test showed that the H2S could achieve up to 1000 ppm when the boiler was in operation, far larger than the suggested reference value of 100 ppm. Hence, the overlarge H2S concentration was a vital factor for the tube corrosion. To further investigate the reason why the H2S was... [more]

Chelating agents’ application for EOR and well stimulation is fast growing nowadays. However, reagents of this class have some drawbacks, with high values of interfacial tension (IFT) being among them. IFT may be lowered with the addition of surfactants; however, the simultaneous application of chelating agents and surfactants has not yet been widely studied. This paper focuses on the experimental and theoretical investigation of the interaction between chelating agent (ethylenediaminetetraacetic acid, EDTA) and surfactants of anionic and cationic types (sodium dodecyl sulfate, SDS, and dodecyl trimethynlammonium bromide, DTAB). IFT measurement was performed at ambient conditions, with normal octane being as the reference hydrocarbon to eliminate the temperature and salinity effects and compare surfactant-containing systems. The experimental results show that chelating agents’ addition to the solutions of surfactants leads to a decrease in IFT value. Moreover, surfactants’ critical mic... [more]

As the second-largest contributor to historical global warming, methane emissions must be controlled to slow down temperature increase and achieve climate benefits. Due to a lack of knowledge about the specific sources and processes, a quantitative approach will lead to inaccurate estimation. In this paper, a typical local distribution company with more than 100 years of operation history was chosen. Detailed procedures of pipeline constructions and accidents were investigated, and critical steps leading to methane emissions were clarified. Then emission quantification methodologies for all processes were proposed, including a new pipeline connection, new regulator connection, emergency repair and third-party damages. As a basis for emission estimation, the distribution of parameters, such as diameter, length and pressure, was counted. Then the emission rates of all projects were calculated, and emission factors were established. The average emission rates of the new pipeline connectio... [more]

Cavitation can cause noise in the water-jet pump. If cavitation occurs in the water-jet pump, the hydraulic components in the pump are prone to erosion. The surface erosion reduces energy delivery efficiency and increases maintenance costs. The decline in pump performance will lead to the instability of the entire energy system. In this paper, the cavitation flow structure of the water-jet pump is studied by the method of numerical simulation and experiment, which provides a reference for the prediction and improvement of cavitation. Based on the closed test platform, in order to reveal the physical process of cavitation evolution, high-speed photography is used to capture the complex cavitation flow phenomenon in the pump. After that, the cavitation vortex structure was further explored by numerical simulation. Through the simulation of the impeller blade tip leakage flow and the Tip Leakage Vortex Cavitation (TLVC) characteristics under different cavitation conditions, the flow mecha... [more]

The introduction of digital technologies into the main control room of a nuclear power plant also introduces new human errors. The operator log records the control information of operators on systems and equipment, and provides an important data source for the retrospective investigation of operating events in a nuclear power plant. A traditional operator log review is conducted manually, which has some major problems, such as being time-consuming and inefficient. This paper proposes an automatic detection method for operator logs, which models an operating procedure at three levels, including procedure, step and action. Such a model clarifies the overall logic and basic attributes of the operating procedure, and can be used as a standardized template of a control action sequence to compare with the actual operation actions in the operator log, so as to identify possible human performance deviations. This paper explains the method, and discusses the advantages and limitations of the pr... [more]

As countries scramble for cleaner energy production and to meet carbon reduction targets, natural gas seems to become an increasingly attractive option with liquified natural gas (LNG) as a popular transportation choice. In this paper, we first conduct a literature review and discuss the various factors affecting the global natural gas market, its recent history, current state, and future. Then we look at the possibility of East Asia becoming an alternative market to Europe for Russian LNG. We also bring in the US both as a political force that employs economic sanctions and as a potential LNG supplier. As a case study, we define a 3-player game between Russia, The United States, and Japan which results in relative market stability. In the case of sanctions against Russia, we conclude that it will lose its foothold in the Japanese market in the long term. Finally, we discuss the potential of LNG trading as the first step for East Asia’s energy transition to a low-carbon economy.

The increasing use of photovoltaics (PVs) in distribution systems owing to the low-carbon policy has given rise to the need for various technological changes. In particular, the operation of on-load tap changers (OLTCs) has attracted attention. In traditional distribution systems, the OLTC operates via a line-drop compensator (LDC), which focuses on the load to solve the low-voltage problem; however, the problem of over-voltage caused by PVs persists. Currently, a method for operating an OLTC using the measured voltage is being researched; however, solving the voltage problem for several feeders connected to a main transformer (MT) is not viable. Therefore, this study proposes an OLTC operation method to address the feeder with the largest voltage problem depending on the direction of power flow. The proposed method selects a point where the OLTC operates using the difference between the measured and reference voltages. Setting the reference voltage can solve the problem that occurs du... [more]

The main aim of this study was to develop a method for assessing the level of robustness of timetabled transport performance in rail transport. When the railway lines are supplied by DC networks, lower voltages are observed, and consequently, current values are often ten times higher than in AC networks. This is an operational problem, as high currents make it easier to overload the supply network. Based on a literature review, the authors show that the problem of running railway traffic when the capacity of the power supply network is limited (by the size of the permitted currents) is not well studied. The authors propose a method based on the Markov approach supplemented by classical theoretical vehicle traffic dynamics to improve the operational robustness of the rail transport system using DC power supply system. Each train run was parameterised in such a way that it is possible to determine the state that the train is in during the run, the transitions between states, and the dete... [more]

In this paper, we present the results of dispersion of thermodynamically immiscible polypropylene (PP) and ethylene-propylene triple synthetic rubber (EPTSR) polymer blends using the Solution-Enhanced Dispersion by Supercritical Fluid (SEDS) technique at operation conditions in the pressure range of (8 to 25) MPa and at temperatures t = 40 °C and 60 °C. The kinetics of crystallization and phase transformation in polymer blends obtained by conventional method (melt blending) and by mixing in the SEDS process have been studied using the DSC technique. The effects of the SEDS operation process on the physical—chemical (melting temperature, heat of fusion) and mechanical (microparticle size) characteristics of the SEDS-produced polymer blends were studied.

Low-voltage grid-connected microgrids rely on the exploitation of inverter-interfaced distributed energy resources (DERs) in order to feed loads and to achieve bidirectional power flow controllability at their point of common coupling (PCC) with the upstream grid. However, adverse operational conditions, such as the existence of DERs of different operation natures, DERs of non-equal power ratings, as well as the occurrence of non-steady and non-sinusoidal grid voltage scenarios, bring complications to microgrid energy management. Consequently, control strategies employed to coordinate DERs in dispatchable microgrids need to be resilient to such non-ideal conditions. Hence, this paper demonstrates that a multi-purpose strategy, so-called the Generalized Current-Based Control (GCBC) approach, is capable of steering DERs under such adverse operational scenarios, ensuring proportional current sharing among them while also regulating the microgrid power dispatchability at the PCC. The discu... [more]

Shallow geothermal energy is a clean and effective form of energy that can overcome the problems associated with the depletion of carbon-based energy carbon emissions. Due to the special hydrogeological conditions in karst regions, the heat transfer between heat exchange boreholes and the ground formation is a complicated, multi-physical process. The abundant groundwater flow plays an important role in the heat transfer process, and even presents an opportunity to mitigate the heat imbalance during the long term operation of ground-coupled heat pumps (GCHP). In this study, both laboratorial experiments and numerical simulations were performed to analyze the mechanism that shows how fracture water impacts on heat capacity and the thermal imbalance of the energy storage rock mass. The results showed that the overall temperature fluctuation of the rock mass was reduced by the fracture water, and the temperature curve with time became gentler, which means in practice that the heat imbalanc... [more]

This paper describes a system for the automatic determination of rock-breaking target poses for impact hammers used in underground mines. The rock-breaking target pose is defined as the position and angle at which the impact hammer must strike a rock in order to break it. The automatic determination of this pose is essential for the autonomous operation of an impact hammer. The proposed system takes as input sensor data composed of point clouds and images, and automatically determines a rock-breaking target pose. The system consists of a rock segmentation subsystem that receives the sensor data and identifies and individualizes the rocks/boulders present above the grizzly, and a rock-breaking target pose generation and evaluation subsystem that receives the rock information produced by the rock segmentation subsystem, and generates a list of rock-breaking target pose candidates, it evaluates them, and it selects the best candidate as the rock-breaking target pose. The system is evaluat... [more]

Universal power converters (UPCs) have aroused significant attention in performing multiple operations in a single power converter. Furthermore, they contribute to economic operation and improved system performance. In this work, a new configuration of the universal power converter (UPC) was proposed by using a simple switching arrangement. It can perform different modes of operations, such as AC−DC, DC−DC, DC−AC, AC−AC, and cyclo-converter operations. In DC−DC conversion, the proposed configuration can perform buck mode, boost mode, and buck−boost mode of operations. Moreover, in DC−AC conversion, it gives better total harmonic distortion (THD). The effectiveness of the proposed configuration was verified by an extensive simulation, using MATLAB/Simulink environment. A low-power prototype circuit was designed to test the viability of the proposed circuit configuration and validated with simulation results.

With the expansion of wind power grid integration, the challenges of sharp fluctuations and high uncertainty in preparing the power grid day-ahead plan and short-term dispatching are magnified. These challenges can be overcome through accurate short-term wind power process prediction based on mining historical operation data and taking full advantage of meteorological forecast information. In this paper, adopting the ERA5 reanalysis dataset as input, a short-term wind power prediction framework is proposed, combining light gradient boosting machine (LightGBM), mutual information coefficient (MIC) and nonparametric regression. Primarily, the reanalysis data of ERA5 provide more meteorological information for the framework, which can help improve the model input features. Furthermore, MIC can identify effective feature subsets from massive feature sets that significantly affect the output, enabling concise understanding of the output. Moreover, LightGBM is a prediction method with a stro... [more]

A deep review of the state of the electromobility in urban public transport by bus was conducted from all different charging strategies, types of chargers, and e-buses with a general overview and SWOT analysis. A review of five case studies worldwide was also conducted and a real case study with real data was shown in depth: EMT Madrid, where all chargers and charging systems were developed in a single operation center. Total Cost of Ownership (TCO) from the literature and from the case study for e-buses were shown as compared with different bus technologies.

This paper presents a dedicated system for de-icing trolley wires. The proposed issue is appropriately under the protection of intellectual property for solving as described in patent no.B1 230665 PL in the Patent Office of the Republic of Poland. In the solution presented herein, de-icing is achieved mainly by electrodynamic force excitation and secondarily as a result of heating. Because ice is removed primarily through vibrations, it avoids a large consumption of electricity associated with the high specific heat of water. More importantly, operation is nearly simultaneously applied to the total distance of the trolley power grid between two substations. For this reason, it requires less electricity consumption and less time to apply than in heating, mechanical, or chemical methods.

Insular power systems are a special case of infrastructure for power production due to their particular land morphology with extensive hills and ridges. For a higher renewable energy share in the power production, a dedicated design according to local constraints is required. The high wind and solar resources of such cases can be utilized with offshore wind turbines and concentrating solar power, respectively. In addition, pumped-hydro storage is a mature and suitable technology for such terrain. A case study is presented in the island of Rhodes to obtain a renewable energy penetration higher than 70%. The technical and financial requirements for this implementation support the design of this system, while the introduction of concentrating solar power enables significant energy savings during the periods of peak demand of the island. An annual RES penetration close to 80% can be achieved with the combined operation of both plants. The economic viability of the required investment can b... [more]

For the multi-energy power system composed of thermal power, wind power, and a pumped-storage power station aiming at minimizing coal consumption of the power grid, an optimal dispatch model is established in this paper. Its advantage is to allow the power grid to accept a high proportion of new energy while ensuring power demand. The dynamic programming method is used to solve the problem. In the solution process, the traditional dynamic programming method is improved by introducing the penalty function and the dynamic value of the state variable, which can ensure the reliability of the power supply while achieving the optimization goal, as well as realize the full utilization of energy. Using the example of a high proportion of wind power systems with a pumped-storage power station as the energy storage mode and considering the relevant constraints after the heating transformation of the thermal power plant, our built model solves these challenges. The results show that when the maxi... [more]

Sprinkler skipping is an important issue in fire spread. In general, two sprinklers are installed in air conditioner rooms at the ceiling and 30 cm below to avoid spray failure by energy recovery ventilator in the ceiling. However, there is a problem in that sprinkler skipping occurs in the air conditioner room. In this study, the sprinkler skipping phenomenon was analyzed through numerical analysis and the applicability of the open type of sprinkler operation method was reviewed. As a result, when the upper sprinkler works, sprinkler skipping occurred in all cases. The lower sprinkler shall not rise above the operating temperature of 68.3 °C with a maximum temperature of 65 °C. In particular, the spray failure caused by the energy recovery ventilator reduces the sprinkler head temperature by more than 8 °C by concentrating the spray droplets. As an open type, simultaneous operation of two sprinklers is capable of obtaining an appropriate fire extinguishing effect by covering the fire... [more]

Wearable technology represents a new technological paradigm for promoting physical activity, enabling monitoring of performances and athletic gestures. In addition, they can be employed for remote health monitoring applications, allowing continuous acquisition of users’ vital signs directly at home, emergency alerting, and computer-assisted rehabilitation. Commonly, these devices depend on batteries which are not the better option since researchers aim for dispositive who need minimal human intervention. Energy harvesting devices can be useful to extract energy from the human body, especially by integrating them into the garments, giving health monitoring devices enough energy for their independent operation. This review work focuses on the main new wearable technologies and devices to scavenge energy from the human body. First, the most suitable energy sources exploitable for wearable applications are investigated. Afterward, an overview of the main harvesting technologies (piezoelect... [more]

The objective of this paper is to investigate the future evolution of port systems considering the development of major and minor ports, inter-port competition, and feasible cargo shifts resulting from improved capacity or congestion faced by ports. The literature review on port system dynamics indicates that the relationships that emerge between major and minor ports located in the range stem from competition and cooperation. However, we argue that there are essential ports that play a predominant role in shaping these relationships, while inter-port relations in the system are based on competition. With the use of transshipment forecasts, existing and emerging interdependencies among major and minor ports in the system, and capacity development and/or changes in the level of capacity utilisation, the ex-ante dynamics of the port system are evaluated. The subject of research is two port systems, namely, the Polish port system and the Rhine−Scheldt Delta port system. We investigate the... [more]

Oil mist adversely affects the health of workplace workers, and for this reason, regulations on the limitation of the oil-mist exposure of workers are becoming stricter. In order to reduce the amount of the exposure of workers to oil mist, it is important to effectively remove oil mist from machine tools. In this study, the collection efficiency according to the geometry of the oil-mist-collection cyclone consisting of several disks and the output power and rotation speed of the motor were evaluated. Most of the generated oil mists were less than 10 μm, and the mist removal was assessed using an optical particle counter. The cyclone airflow rate increased linearly with the rotational speed, and the rate was affected more by the cyclone geometry than by the power consumption. The mist-removal performance was significantly enhanced when plate- and cone-type disks were added to the rotating blades. The removal efficiencies of PM10 and PM2.5 under the maximum operational conditions of 5000... [more]

Smart meters (SMs) can play a key role in monitoring vital aspects of different applications such as smart grids (SG), alternative currents (AC) optimal power flows, adversarial training, time series data, etc. Several practical privacy implementations of SM have been made in the literature, but more studies and testing may be able to further improve efficiency and lower implementation costs. The major objectives of cyberattacks are the loss of data privacy on SM-based SG/power grid (PG) networks and threatening human life. As a result, losing data privacy is very expensive and gradually hurts the national economy. Consequently, employing an efficient trust model against cyberattacks is strictly desired. This paper presents a research pivot for researchers who are interested in security and privacy and shade light on the importance of the SM. We highlight the involved SMs’ features in several applications. Afterward, we focus on the SMs’ vulnerabilities. Then, we consider eleven trust... [more]

This article aims to analyze agents’ behavior in a competitive hydrothermal energy market. The idea is to investigate how much the day-to-day behavior of the market can be different from the predictions presented by cost-based models because of the risk perception of each agent (hydroelectric energy producer, in this case) as a participant of the market. The main contribution is in determining the impact on the agents’ revenue in the short-term market due to the variation in the amount of energy generated and the market price, which other methodologies may not be able to capture. For this reason, a case study was made using daily simulations in a given month, observing the strategy and bids of eight hydroelectric agents for a central market operator emulated by an energy price offer simulator called SOPEE. The study reflected qualitative and quantitative examples of how the risk perception and the behavior of each agent can influence market behavior due to the variation in their percep... [more]

As a retailer between the energy suppliers and end users, the integrated energy service provider (IESP) can effectively coordinate the energy supply end and the energy use end by setting energy prices and energy management. Because most of the current research focuses on the pricing of electricity retailers, there are few studies on IESP energy pricing and management, which are still at the initial stage. At the same time, the existing research often does not consider the impact of demand response (DR) and uncertainties, such as natural gas and electricity wholesale prices, on the pricing of IESP. It is necessary to model the DR and uncertainties in the integrated energy system. Aiming at the inadequacy of the existing research and to address the energy pricing and management of IESP, this paper develops a two-stage stochastic hierarchical framework, which comprehensively considers the DR strategy of the user end, characteristics of the electricity/gas/heat storage and the uncertaintie... [more]