Energy security is a main challenge in today’s economies [...]

Supercapacitors (SCs) are widely used as energy storage devices in many practical applications of wireless power transfer. However, the modeling and analysis of a wireless power transfer system are seldom based on SC load; thus, the effects of the charging process on the wireless power transfer system cannot be analyzed clearly. In this paper, a variable-resistance-based method is proposed for the modeling and analysis of the process of constant current charging. First, how to make an SC equivalent in variable resistance is described, and the relationship between SC and variable resistance is considered. Next, the charging process, including charging current, voltage, power and transfer efficiency, is analyzed in detail. Furthermore, the effects of transmitting side voltage and frequency offset on this system are studied, and the optimal design method for an SC-load WPT system is provided on a preliminary basis. Finally, the theoretical derivation and analysis are verified by means of... [more]

The availability of water, energy and food plays a key role in meeting the basic needs of the world population and allowing them to achieve prosperity and supports the UN’s sustainable development goals (SDGs). These three fundamental resources are closely interrelated, with their deep interdependencies reflected in various concepts of the ‘water−energy−food nexus’ (W−E−F). One-third of the total food produced globally results in food loss and waste (FL and FW), which also means the waste of resources used for their production, mainly energy and water. We thus propose a fusion of the W−E−F nexus and the FS−FW−FL nexus to achieve a better correlation between food production and food consumption in order to avoid additional negative effects. We explore the research problem of how the availability of water, energy and food resources can be improved by reducing FW and FL. The objective of this paper is to present an overview of opportunities to reduce the negative effects of FWL. The... [more]

The latest electronically controlled marine engines have a control system that allows the operator to view all the essential parameters of the engine in real conditions during operation. The system is connected to the electronic control system (ECS) through the control network, thus controlling the engine. The operator has various management and monitoring options. The objective of this paper was to become familiar with the specific factors that affect engine operation and optimize engine operation. A model of a large marine engine was developed and calibrated with measured data. Simulations were performed, and the combustion process was analyzed. The parameter study was performed by varying the fuel injection and the gas exchange timing. Fuel consumption decreases by 6 g/kWh, and NOx emissions decrease by 0.5 g/kWh. The research conducted in this work will be used by engineers to understand the potential of new technologies to optimize combustion in real-world conditions during operat... [more]

Based on the model of irreversible single resonance energy-selective electron heat engine established in the previous literature, this paper applies finite-time thermodynamic theory and NSGA-II algorithm to perform multi-objective optimization. Single-, bi-, tri- and quadru-objective optimizations are performed when the energy boundary and the resonance width are taken as the optimization variables, and the power output, thermal efficiency, efficient power and ecological function are taken as the optimization objectives. The deviation indexes of different optimization objective combinations are obtained by using LINMAP, TOPSIS and Shannon entropy approaches. The results show that the values of energy boundary and resonance width can be reasonably selected according to the design requirements of the system. When power output and efficiency are optimized, the minimal deviation index is obtained by TOPSIS approach and the value is 0.0748, which is the most ideal design scheme.

In this work, we develop a hybrid battery thermal management (BTM) system for a 7 × 7 large battery module by coupling an epoxy resin (ER)-enhanced phase change material (PCM) module with internal liquid cooling (LC) tubes. The supporting material of ER greatly enhances the thermal stability and prevents PCM leakage under high-temperature environments. In addition, the other two components of paraffin and expanded graphite contribute a large latent heat of 189 J g−1 and a high thermal conductivity of 2.2 W m−1 K−1 to the PCM module, respectively. The LC tubes can dissipate extra heat under severe operating conditions, demonstrating effective secondary heat dissipation and avoiding heat storage saturation of the module. Consequently, during the charge-discharge tests under a 40 °C ambient temperature, the temperature of the PCM-LC battery module could be maintained below 40.48, 43.56, 45.38 and 47.61 °C with the inlet water temperature of 20, 25, 30 and 35 °C, respectively. During the c... [more]

The effect of positive (adverse) and negative (favorable) longitudinal pressure gradients on the structure and heat transfer of gas-droplet (air and water) flow in axisymmetric duct with sudden expansion are examined. The superimposed pressure gradient has a large influence on the flow structure and heat transfer in a two-phase mist flow in both a confuser and a diffuser. A narrowing of the confuser angle leads to significant suppression of flow turbulence (more than four times that of the gas-drop flow after sudden pipe expansion without a pressure gradient at φ = 0°). Recirculation zone length decreases significantly compared to the gas-droplet flow without a longitudinal pressure gradient (by up to 30%), and the locus of the heat-transfer maximum shifts slightly downstream, and roughly aligns with the reattachment point of the two-phase flow. Growth of the diffuser opening angle leads to additional production of kinetic energy of gas flow turbulence (almost twice as much as gas-drop... [more]

As energy consumption constantly gains importance, it has become one of the major issues in managing logistics systems. However, it is ranked against other company priorities, and the rationalization for investing in energy needs to be justified by the savings achieved. A solution for reducing energy consumption via electric forklifts for performing docking operations at distribution centers, which requires no investments in infrastructure or equipment, is outlined in this paper. The solution is based on optimizing inbound dock door allocation, and the energy savings are quantified using a simulation model. A case study of a local FMCG distributor’s logistics center was conducted to collect the data and information needed for modeling inbound docking operations and performing simulation experiments. The optimal dock door allocation was obtained using a linear programming method using an MS Excel spreadsheet optimizer (Solver), while the simulation of the docking operations was carried... [more]

Worldwide practices have proven that gas-assisted gravity drainage can obviously enhance oil recovery, and this technology can be especially effective for reservoirs with a thick formation and large inclination angle. For the successful implementation of this process, a key technology is the stable control of gas−oil interface during gas injection. For a detailed exploration of this technique, a three-stage permeable visual model was designed and manufactured, with permeability decreasing from top to bottom, thus, a reverse rhythm reservoir was effectively modeled. Then the experiment concerning CO2-assisted gravity drainage was carried out with the adoption of a self-developed micro visual displacement device. This study mainly focused on the micro migration law of gas−oil interface and the development effects of CO2-assisted gravity drainage. According to the experiments, CO2 fingering somewhat happens in the same permeable layer from the beginning of gas injection. However, phenomen... [more]

This paper assesses the profitability of battery storage systems (BSS) by focusing on the internal rate of return (IRR) as a profitability measure which offers advantages over other frequently used measures, most notably the net present value (NPV). Furthermore, this study proposes a multi-objective optimisation (MOO) approach to IRR estimation instead of relying on the simple linear optimisation and compares the results to the popular linear optimisation with battery cycle-cost penalty. The analysis is conducted under perfect foresight conditions by considering multiple revenue streams: arbitrage trading in the day-ahead and intraday markets, peak shaving, participating in the primary reserves market, and from photovoltaic (PV) power-generation unit. Data are collected for the German power market for 2017 and 2021. The results show that MOO approach yields similar IRR estimates to the cycle-cost model in 2017. However, higher market volatility and increased electricity prices in 2021... [more]

Maintaining stability and control over the electric system requires increasing information about the consumers’ profiling due to changes in the form of electricity generation and consumption. To overcome this trouble, short-term load forecasting (STLF) on individual consumers gained importance in the last years. Nonetheless, predicting the profile of an individual consumer is a difficult task. The main challenge lies in the uncertainty related to the individual consumption profile, which increases forecasting errors. Thus, this paper aims to implement a load predictive model focused on individual consumers taking into account its randomness. For this purpose, a methodology is proposed to determine and select predictive features for individual STLF. The load forecasting of an individual consumer is simulated based on the four main machine learning techniques used in the literature. A 2.73% reduction in the forecast error is obtained after the correct selection of the predictive features... [more]

The research is aimed at comparing residential building windows’ thermal performance with and without thermal shutters, and at examining thermal shutters’ performance upon being insulated with various types of insulation, glares, outside temperatures, and solar radiation. As an example, one case study based out of the UAE is chosen, covering the status of the housing typology and traits of building energy consumption. The study uses the primary tool of computer simulation software “DesignBuilder” to examine the impact of window shutters design on energy consumption and environmental impact. It was found that the usage of conventional insulating materials within the shutters is sufficient for the house to attain a reduction in heat gain of up to 50%. Furthermore, the application of the rolling shutters with analyzed control strategies recorded a potential reduction in equivalent CO2 emissions level, up to 15%, which would decrease the environmental burden on a national level. The simula... [more]

Energy generation using dielectric elastomers (DE) has received a great deal of attention due to their light weight, low cost, and high efficiency. This method is an environmentally friendly system that generates electricity without emitting carbon dioxide and without using rare earths, and can contribute to the reduction of global warming. However, this DE system is expected to be used for wearables, such as shoe power generation, because it is not yet possible to make an energy generation element of a very large size. The problem is that this small DE generator can only generate a small amount of energy at one time. Therefore, in order to increase energy generation efficiency, it is necessary to use a material with higher conductivity for the DE electrode. Moreover, since DE energy generation is output at a high voltage, a circuit capable of stepping down with high efficiency is required in order to use this power for ordinary electric appliances. In addition to this, a circuit that... [more]

To support the grid system with high power quality from photovoltaics (PVs) and reduce the partial shading condition (PSC) effect of the PV system, as well as the mismatch power issue, in this study, we present a simple single-phase, nine-level cascade inverter architecture for photovoltaic (PV) systems with a minimum number of power components and passive parts. This reduction in the number of switches decreases the switching losses and the number of driving circuits, which causes a reduction in the complexity of the control circuit and hence reduces the cost and size. The suggested inverter shows a lower output voltage total harmonic distortion (THD) and unity power factor. In addition, this inverter’s control and switching techniques are far simpler than those of recently published designs. To evaluate the performance of the proposed inverter, we performed a comparison of the cascaded multilevel inverter (CMLI) topology, which required recent cascade topologies with the same nine vo... [more]

At present, the treatment of landfill leachate is an unavoidable challenge facing environmental problems. Incineration is one of the effective methods to treat landfill leachate which meets the 3T+E principle and can avoid the production of dioxin in the process of treatment. Based on the 3T+E principle, this paper studied the influence of burner arrangement on the treatment of landfill leachate through the numerical simulation method. The research showed that the symmetrical arrangement of reverse swirl and same direction flow were more conducive to the combustion of landfill leachate concentrations in the incinerator so that the residence time of the flue gas in the second combustion chamber can also exceed 2 s. When the nozzle arrangement height is 0.9 m−0.8 m, the wall collision rate of concentrated liquid droplets can be reduced, and the burnout rate of landfill leachate was the highest, reaching more than 92%.

This study investigates whether natural gas exploitation is a blessing or a curse for provincial and prefecture economic growth. This study employs regression models and synthetic control methods (SCM) to investigate the research question based on hybrid panel and time-series data from 1993 to 2015 from 14 prefecture cities in Sichuan province in China. Based on the provincial data of Sichuan, the regression results show that natural gas exploitation is a curse for the provincial economic development of Sichuan because of the negative associations between gas resources and economic performance, for which the increasing rent-seeking in the province may partially account. However, the SCM results find that the local economy of Dazhou city may benefit from its sufficient natural gas resources in the short run, but it is not sustainable. Meanwhile, the gas resource has no significant contributions to the regional economic growth of Sichuan overall, which is partially attributed to the fact... [more]

This paper reviews and assesses India’s energy policy in the context of its commitment to achieve the target of net-zero carbon emissions by 2070. It emphasizes the central role of green electrification, particularly through the expansion of solar power capacity. It discusses policies outside the energy sector that need to be part of a strategy of achieving this target, including the use of information technology, infrastructure development, and transportation. Furthermore, it examines possible policy options for accelerating the target date to 2050, especially with the use of carbon capture to manage the transition from the current heavy use of coal. The paper also discusses the possible financial and growth implications of various strategy options, arguing that feasible external financing commitments can allow India to achieve net-zero goals without sacrificing economic growth.

MIL-53(Fe) was prepared and modified with benzoic acid to prepare MIL-53(Fe)-BA additive, which was used to improve the catalytic oxidation rate of sulfite, prevent the scaling of the desulfurization tower, and improve the desulfurization efficiency during the wet flue gas desulfurization (WFGD) process of power plants. MIL-53(Fe)-BA exhibits abundant Lewis acid sites because of the appearance of coordination unsaturated Fe atoms. Due to the excellent sorption capacity, Ca(OH)2 was used as the main SO2 desulfurizer. The composite desulfurizers were prepared by mixing MIL-53(Fe)-based additives and Ca(OH)2, and were characterized by SEM, XRD, and FT-IR. A desulfurization unit was set up at laboratory scale to study the effect of catalytic oxidation additives on sulfite oxidation and desulfurization efficiency. The results showed that the addition of MIL-53(Fe)-BA can increase the oxidation capacity of sulfite by 159%, and greatly improve the desulfurization efficiency. These composite d... [more]

A run for increasing the integration of renewable energy sources in the electricity network has been seen in recent years because of the big concern about environmental issues and pollution from controllable power units. This paper aims to give a general overview of the concept of ramp rate limitation and its principal applications in the literature regarding the field of control strategies, which deal with smoothing the wind power output. Wind power is one of the most-used renewable energy sources, and the objective of limiting the ramp rate of the power output is to produce more stable power. The studies of ramp rate limitation applied in wind power production deal with the definition and detection of this phenomenon in the real data, the methodologies used to forecast it, its application for managing grids and microgrids, the different actions aimed at physically implementing the restriction, and some of the grid code requirements used in different nations.

Partial discharge (PD) ultrasonic detection is an early sign of the insolation defects of power transformers. The early diagnosis of PD requires the high sensitivity and reliability of ultrasonic sensing systems. For this purpose, a reformative PD ultrasonic sensing system based on phase-shifted FBG (PS-FBG) was demonstrated. By using PS-FBG as the ultrasonic sensing unit, the ultrasonic sensing system improved the response to the ultrasonic signal and overcame the electromagnetic noise. To compensate for the influence of temperature change on the ultrasonic sensing system, an automatic wavelength scanning demodulating method was carried out. The wavelength spanning strategy was optimized based on the principle of cross-correlation, in order to quicken the spanning. A PD detection test in the transformer oil was conducted, and the result shows that PS-FBG was 17.5 times more sensitive than PZT. Because of the better ultrasonic response, the proposed system was able to achieve the early... [more]

This article presents the application of the radioisotope absorption method in the study of two-phase water−air flow in a horizontal pipe. The measurement principle and the test stand are briefly described. The main part of the article presents the signal analysis methods applied to data obtained from scintillation detectors. Because these signals are mostly stochastic waveforms, they were analyzed statistically using the cross-correlation function (CCF), and methods that are a combination of CCF and differential methods: CCF/ASDF and CCF/AMDF, where ASDF is the average square difference function, and AMDF is the average magnitude difference function. Examples of the results of gas phase velocity measurement for four types of flow are presented. It was found that the CCF/ASDF and CCF/AMDF methods allow more accurate results of measurements of the dispersed phase to be obtained than the CCF method.

This paper presents a regenerative braking logic that aims to maximize the recovery of energy during braking without compromising the stability of the vehicle. This model of regenerative braking ensures that the regenerative torque of the electric motor (for front- and rear-wheel drive vehicles) or electric motors (for all-wheel drive vehicles equipped with one motor for each axle) is exploited to the maximum, avoiding the locking of the driving wheels and, subsequently, if necessary, integrating the braking with the traditional braking system. The priority of the logic is that of maximizing energy recovery under braking, followed by the pursuit of optimal braking distribution. This last aspect in particular occurs when there is an integration of braking and, for vehicles with all-wheel drive, also when choosing the distribution of regenerative torque between the two electric motors. The logic was tested via simulation on a front-, rear-, and all-wheel drive compact car, and from the s... [more]

The article presents spectral sensitivity curves of 22 typical luxmeters and 3 smartphones as a result of laboratory measurements. Based on the measurement data, errors in the spectral correction of the considered instruments and devices were calculated. Due to the fact that the value of the measured illuminance is influenced by the spectral characteristics of the radiation, in order to determine the spectral corrections coefficients, 10 light sources with different spectral distributions of radiation were taken into account. Spectral corrections factors were determined using two methods for all luxmeters and smartphones. This paper presents the relationship between the shape of the spectral sensitivity curves of a given luxmeter and the measured values of f′1 errors. Moreover, the limitations related to the use of spectral corrections in environmental measurements with the use of a luxmeter were demonstrated.

In the first months of 2022, there was a sharp turn in the energy policy of the European Union, initially spurred by increasing energy prices and further escalated by Russia’s invasion of the Ukraine. Further transformation of the energy system will likely be accompanied by the gradual abandonment of natural gas from Russia and an increase of renewable and nuclear energy. Such a transition will not only increase energy security, but also accelerate the pace at which greenhouse gas emissions are reduced in Europe. This could be achieved more effectively if some of the new nuclear energy capacity is optimized to play an increased balancing role in the energy system, thus allowing for deeper market penetration of intermittent renewable energy sources with a reduced need for flexible fossil backup power and storage. A double effect of decarbonization can be achieved by investments in nuclear repowering of coal-fired units, with the replacement of coal boiler islands with nuclear reactor sy... [more]

Owing to the shortcomings of blindness and inaccuracy when backfilling in goafs and based on the key stratum theory, we propose the “multi-arch pier-column” backfilling method. This method involves drilling holes at specific locations on the surface to inject filling and slurry materials into the goaf and separation area under the key stratum. This allows the broken gangue to be cemented to form a stone body, to improve its overall strength. This process, along with filling in the separation area under the key stratum, ensures that the key stratum does not break, forming a joint medium of “separation area filling body + backfilled pier-columns + key stratum + coal column”, which prevents new subsidence on the surface layer. Using the Gaojialiang coal mine as an example, the effects of the proposed method on controlling surface subsidence were determined using a numerical simulation based on FLAC3D simulation software. The results indicate that this method can effectively control the ke... [more]