It is extremely dangerous for a turbocharged boiler to have a leakage fault in its vaporization tube. However, early detection and fault diagnosis of micro-leakage faults are very difficult. On the one hand, there are few fault samples that lead to a difficult and intelligent diagnosis. On the other hand, the system fault response characteristics of the characterization parameters in the process are complex and easily confused with the load-changing characteristics. In order to obtain fault samples and identify fault characteristics, a fault simulation model for the micro-leakage of the boiler evaporation tube is established based on the dynamic mathematical model of all working conditions. The model’s effectiveness is verified by typical fault experiments. The dynamic simulation experiments of three kinds of micro-leakage and four kinds of load changing were carried out. Through the analysis of combustion equilibrium and vapor-liquid equilibrium of 14 groups of characterization parame... [more]

Energy management in power systems is influenced by such factors as economic and ecological aspects. Increasing the use of electricity produced at a given time from renewable energy sources (RES) by employing the elastic energy management algorithm will allow for an increase in “green energy“ in the energy sector. At the same time, it can reduce the production of electricity from fossil fuels, which is a positive economic aspect. In addition, it will reduce the volume of energy from RES that have to be stored using expensive energy storage or sent to other parts of the grid. The model parameters proposed in the elastic energy management algorithm are discussed. In particular, attention is paid to the time shift, which allows for the acceleration or the delay in the start-up of smart appliances. The actions taken by the algorithm are aimed at maintaining a compromise between the user’s comfort and the requirements of distribution network operators. Establishing the value of the time shi... [more]

A complex method developed to assess quality within a proposed framework and at a certain scope of measurement for circular economy (CE) quality indicators is presented. This was used to compare three different scenarios for municipal waste management systems: 1—incineration; 2—recycling and reuse of separated municipal waste and the transformation of the organic fraction into biodiesel and bio-coal; and 3—an upgraded Scenario 2 including decreased recycling of waste streams and the bioprocessing of paper/cardboard and processing the non-recycled fraction into bio-diesel, bio-coal, and second-generation biofuel. For the evaluation of the CE quality indicator, a set of technical, environmental, economic, and social elements was selected by a panel of experts, who also assigned them a qualitative assessment and weighting on the basis of the factors identified. The calculated Relative Increase in the CE indicator for the scenarios analyzed showed that Scenarios 3 and 2 are much more benef... [more]

The objective of this work is the integration of a linear cavity receiver in an asymmetric compound parabolic collector. Two different numerical models were developed; one for the conventional geometry and one for the cavity configuration. Both models were examined for inlet temperatures from 20 °C up to 80 °C, considering water as the operating fluid with a typical volume flow rate of 15 lt/h. Emphasis was given to the comparison of the thermal and optical performance between the designs, as well as in the temperature levels of the fluids and the receiver. The geometry of the integrated cavity receiver was optimized according to two independent parameters and two possible optimum designs were finally revealed. The optimization took place regarding the optical performance of the collector with the cavity receiver. The simulation results indicated that the cavity design leads to enhancements of up to 4.40% and 4.00% in the optical and thermal efficiency respectively, while the minimum p... [more]

Heat transport in rotating processes finds a wide range of application in which academic issues in the fluid mechanics and heat transfer areas are here reported. This paper discusses successive works from the seminal paper of Taylor (1923) to recent numerical results established from a broad range of methods such as DNS, LES, RANS or LB methods. The flow regimes identification is thus reported in Taylor−Couette geometry. The role of the axial flow rates in the apparition, stabilization and destruction of the large-scale of the turbulent structures is depicted in the case of Taylor−Couette−Poiseuille geometry. In a non-isothermal condition, a discussion is held on the various exponent values found in the scaling relationships relying on the Nusselt number as a function of the Rayleigh or Reynolds numbers according to the regimes of thermal convection.

The Curie point depth (CPD) has been established to enhance the determination of magnetic sources average bottom depth. In this study, the CPD and heat flow regime of the Eratosthenes Seamount in the Eastern Mediterranean were investigated in order to understand the relationship between them. When CPD and heat flow values are determined together, we can understand the types and processes of geothermal resources formation. CPD and heat flow were obtained by applying the spectral analysis method to magnetic data, which was obtained from the Earth Magnetic Anomaly Grid (EMAG2). The result shows that CPD is approximately 22 km across the Seamount and is approximately 9 km in the northern part of the Eratosthenes Seamount near Cyprus. The heat flow regime manifested from CPD is about 95 mW/m2 in the investigated region, where the average thermal conductivity value (k) is considered to be 2.5 W/m °C. The heat flow regime is characterized by an increase in the northward part of the Eratosthen... [more]

A simplified model that calculates the deflagration pressure−time curves of a hydrogen explosion was proposed. The deflagration parameters (pressure peak, duration, deflagration index, and impulse) of hydrogen−air mixtures with different hydrogen concentrations were experimentally investigated. The results show that the pressure curves calculated by the model are consistent with experimental data pertaining to a methane and hydrogen explosion. By comparison, the pressure peak and deflagration index are found to be influenced by the aspect ratio and surface area of vessels. The impulse and explosion times at fuel-lean hydrogen concentrations are greater than those at fuel-rich concentrations. When the hydrogen concentration is between 34 vol.% and 18 vol.%, the greatest explosion damage effect is formed by both the overpressure and the impulse, which should be considered for hydrogen explosion safety design in industrial production.

The European Union’s energy and climate policies are geared on reducing carbon dioxide emissions and advancing sustainable energy, focusing on a faster propagation of renewable energy sources to decarbonize the energy sector. The management of locally produced energy, which can be implemented by a microgrid capable of either being linked to the main grid or operating independently, is equally crucial. Additionally, it seems that electricity storage is the only practical way to manage energy effectively within a microgrid. Energy storage is hence one of the main technological parameters upon which future energy management has to be based. Especially during crisis periods (such as the COVID-19 pandemic or the ongoing energy crisis), storage is a valuable tool to optimize energy management, particularly from renewables, in order to successfully cover demand fluctuation, hence achieving resilience, while at the same time reducing overall energy costs. The purpose of the paper is to analyze... [more]

This is an experimental work performed to identify the influence of direct contact condensation inside an eductor. The fluid used in the experiments is water in two different phases: liquid and vapor, for primary and secondary flows, respectively. This study was conducted in an attempt to establish the suitability of an eductor as a combined vacuum generator and condenser for membrane desalination applications. The pressure and temperature measurements at critical points in the flow paths have been summarized to identify the influence of primary flow on secondary fluid saturation and condensation. In addition, the mechanism of phase change has been explained through the photography of fluid flow in a two-dimensional eductor. A consistent oscillation of the gas-liquid interface was observed during steady-state operations of the eductor. This work also contributes to the validation of future computational research. It will provide a baseline for computational thermal fluid analysis relat... [more]

A new method of high-speed flow control using permanently operating thermally stratified energy deposition is presented. The paper focuses on the analysis of the dependence of the characteristics of a steady supersonic flow and an aerodynamic (AD) body on the temperature values in the layers of a stratified source and the possibility of making the transition from one steady flow mode to another by changing the temperature in the layers. A detailed visualization of the dynamics of the fields of density, pressure, temperature, and local Mach number is presented during the controlled establishment of steady flow modes. Multiple generation of the Richtmyer−Meshkov instability is shown. The sharp peaks accompanying the development of the Richtmyer−Meshkov instabilities were obtained, which remain in the steady flow mode established under the action of a stratified energy source. Basic approaches for controlling the bow shock wave, drag and lift (pitch) forces (at zero angle of attack), and... [more]

This paper is designed to determine whether producing oil and gas via shale has an economically significant effect on population migration dynamics and on the labor market in terms of the number of employed individuals, the number of establishments, total wages, and average annual pay per person in twenty-six counties in Ohio and Pennsylvania, USA. The analysis incorporates migration inflow and outflow between producing and nonproducing counties. The results of the analysis show that the counties that engage in shale gas extraction saw a negative impact on net migration but a much larger positive impact on labor market outcomes. Specifically, the number of jobs is higher by 2.4%, the number of establishments is higher by 1.1%, total wages are 3% more and the average annual pay is 1.5% more in producing counties after shale. The analysis reveals a small but statistically significant negative impact on migration, as shale regions experienced some migration outflows.

Sizing and configuring community-shared energy storage according to the actual demand of community users is important for the development of user-side energy storage. To solve this problem, this paper first proposes a community energy storage cooperative sharing mode containing multiple transaction types and then establishes a sizing and configuration model of community-shared energy storage based on a cooperative game among community users and energy storage operators, in which the loss caused by the capacity decay of energy storage is quantified by a dynamic power loss cost factor. To improve the solving efficiency, a distributed and cooperating solving method based on ADMM is used to solve the sizing and configuration model. On this basis, the bilateral Shapley method is used to allocate the total annual cost according to the marginal expected cost brought by each user. Compared with existing strategies, this paper calculates the economic benefits of community-shared energy storage... [more]

Electric vehicle grid integration (EVGI) is one of the most important parts of transportation electrification. However, large-scale EV charging/discharging can have an adverse effect on the distribution grid, due to a large amount of load being drawn from or fed back to the power grid. Additionally, the power electronics used in the grid interaction may impose additional complications, such as voltage and frequency deviation, harmonic distortion, etc. With proper control scheme designs for the grid-connected inverters, such complications can be mitigated, and several grid ancillary services, such as voltage and frequency support, reactive power support, and harmonic mitigation, can be facilitated from large-scale EVGI. In this study, a large-scale EVGI system is developed where the vector control implementation of a grid-connected inverter in the d-q reference frame is presented for providing different grid ancillary services using the EVGI system. The EVGI system is operated in differ... [more]

The energy sector is one of the most important sectors as it is the producer and supplier of fuel to run other industries and economies. This research aims to present an intertwined structure of risk exposure measuring the performance of the S&P Bombay Stock Exchange (BSE) Energy Index and selected companies from the constituents while taking into account two scenarios of risk, namely the COVID-19 pandemic and the Russia−Ukraine conflict, in a manner appropriate for energy stock investors, energy companies, and the economy through hedging against investment risk, diversification in operations securing the continuation of energy production, and the risk of fluctuating prices in the energy market, respectively. The research problem is observed as the requirement to choose the representative stocks of the S&P (BSE) Energy Index to evaluate their situations during the period of the two crisis scenarios and to provide the current risk exposure to India’s energy sector. The methodological ap... [more]

The present study provides an energy, exergy and economic analysis of a seawater regasification system (open loop) combining stages of simple organic Rankine cycles (ORCs) arranged in series with an open organic Rankine cycle (OC) in order to exploit the cold energy of liquefied natural gas (LNG). The proposed system, termed ORC-OC, is implemented in a Floating Storage Regasification Unit (FSRU) to achieve the objective of zero greenhouse emissions during the regasification process. Configurations of up to three stages of ORCs and the use of zeotropic mixtures of ethane/propane and n-butane/propane as working fluids are considered in the study of the novel regasification system. Only the two-stage ORC-OC (2ORC-OC) and three-stage (3ORC-OC) configurations accomplish the objective of zero emissions, attaining exergy efficiencies of 61.80% and 62.04%, respectively. The overall cost rate of the latter, however, is 20.85% greater, so the 2ORC-OC results as being more cost-effective. A compa... [more]

Hypersonic aircraft design is an enabling technology. However, many problems are encountered, including the design of the hood. The aircraft optical dome can become heated due to aerodynamic effects. Since the optical dome of a hypersonic aircraft should satisfy optical imaging requirements, a conventional ablative coating cannot be adopted. The aerodynamic heating characteristics during the whole flight must be studied. In this study, a numerical simulation method for the aerodynamic heat of hypersonic aircraft under long-term variable working conditions is proposed. In addition, the numerical simulation of the external flow field and structure coupling of the aerodynamic heat problem is performed. The dynamic parameters of temperature and pressure are obtained, and the thermal protection basis of the internal equipment is obtained. Numerical results indicate that the average temperature and maximum temperature of the optical dome for inner and outer walls exhibit an “M” shape with ti... [more]

With an expected annual increase of 1.2%, the industrial sector already consumes over 54% of all the energy generated globally. The majority of industrial sectors presently relies on fossil fuels to fulfil their needs for heat energy, but renewable sources, especially solar energy, can be substituted for them. For an underdeveloped country such as Pakistan, its industrial sector is important for the country’s economic development and long-term growth. The use of solar thermal energy potentially offers a significant and cheap alternative to fossil fuels. The current study focuses on a process heating system based on flat-plate solar collectors, developed to provide low to moderate temperature process heat. The innovative model’s thermal efficiency and economic feasibility have undergone a thorough investigation and analysis through TRNSYS simulations. The system portrayed a 79% thermal energy efficiency and 4.31% exergy efficiency during peak hours. The optimized system for three differ... [more]

It is important to determine the position of the receiver (Rx) coils in wireless power transfer (WPT) system, and to control the power transmitted to the Rx coil based on this result. In particular, in a situation where there is no feedback between the primary side and the secondary side, it is difficult to control the received power because the information is limited. In this paper, a method for determining the position of the Rx coils and controlling the received power using limited parameters in a feedback-free WPT system is proposed. The proposed method is verified by constructing a 4×2 WPT system, and it is validated that the simulation result and the experimental result are consistent well. Furthermore, arbitrary power can be transmitted to the Rx coil based on the result of the position of the Rx coil. The experiment is conducted by transmitting about 1W to Rx 1 and Rx 2, and the efficiency for Rx 1 is about 32.93%, Rx 2 is 25.03%, and the overall efficiency is confirmed to be 5... [more]

Over the years, anaerobic digestion (AD) has evolved as a competent technology to retrieve energy potential from various organic substrates, including wastewater. However, the energy metabolisms of anaerobic microorganisms, biochemical reactions, and biogas production are affected by various parameters, including heavy metals. It is important to understand the interaction of heavy metals with anaerobes and their potential influence on the process to enhance energy potential. This review methodically outlines the occurrence and role of heavy metals in the AD process. Additionally, the repercussions of the most common heavy metals (i.e., Cu, Zn, Cd, Fe, and Ni) on each stage of AD (i.e., hydrolysis, acidogenesis, and methanogenesis) have been discussed. We found that traces of heavy metals can endorse anaerobic digestion, but inhibition increases with increasing concentration. Methanogenic archaea are more susceptible to heavy metal inhibition than hydrolytic and acidogenic archaea. An i... [more]

Fixed-wing aircraft with vertical takeoff and landing capabilities need a lower speed and a higher lift during transition. To meet these needs, a tandem-channel wing layout has been developed, including a FLR (front wing lower than rear wing) configuration and a FUR (front wing upper than rear wing) configuration, which differ in height differences between the front and rear wings. Numerical simulations have been performed to investigate the aerodynamic characteristics of the two configurations. The results show that a significant increase in lift coefficient occurs when the propeller rotational speed and the angle of attack increase. The lift at a small angle of attack increases by more than 50% at a high propeller rotational speed, and the stall angle of attack increases by more than 10 degrees. For the FLR configuration, the downwash effect of the front wing impacts the rear wing, decreasing the local angle of attack and delaying airflow separation on the top surface. For the FUR co... [more]

The performance of sodium-ion batteries largely depends on the presence and properties of passive films formed on the electrode/electrolyte interfaces. Passive films on negative electrodes inevitably result from the reduction in electrolyte components (solvent and salt anion). They have the properties of a solid electrolyte with sodium ion conductivity and are insulators in terms of electronic conductivity. Usually, they are called SEI—solid electrolyte interphase. The formation of SEI is associated with the consumption of a certain charge, which is an irreversible capacity. Passive films on the surface of positive electrodes (CEI—cathode electrolyte interphase) arise as a result of electrolyte oxidation. The present review summarizes the literature of the recent 15 years concerning the effects of electrode nature (hard carbon, other carbon materials, various metals, oxides, chalcogenides, etc.), electrolyte composition, and other factors on composition and properties of SEIs in sodium... [more]

The production of biopellets from agricultural residues is an effective method to overcome the expected shortage in the supply of fuel pellets in the future. This work focused on the new potential applications of fuel pellets to produce liquid and gas fuels through thermochemical and hydrothermal biomass-to-gas technologies. The outcomes also provide a basis to compare the effects of steam and hydrothermal gasification techniques on the properties of product and byproduct, as well as their potentials. For steam gasification, the syngas yield increased from 10.7 to 27.8 mmol/g (on a dry and ash-free basis) by a rise in the gasification temperature at a constant steam-to-biomass ratio. In the case of hydrothermal gasification, there was no carbon monoxide, and hydrogen was the main gas product, and with an increase in the temperature, the hydrogen yield rose from 0.4 mmol/g to 3.17 mmol/g with temperatures from 350 to 650 °C. CO had the largest share in the gas product from steam gasific... [more]

Due to high electricity prices and possible shortages of gas and other energy commodities, various fluctuations in electricity generation will need to be regulated. Given the increasing expansion of wind power plants in Europe and worldwide. It is necessary and essential to put power regulation into practice, as mandated by regulation 2016/631 EU. A significant power balance problem may arise on the grid, which may lead to cyclical and recurring blackouts in the future. The motivation for this paper is to raise awareness of the controllability of wind turbines and to highlight the gentle pace of research in this area for pitch angle control. Therefore, the chief idea of the paper is to develop a proposal for wind power plant power control by changing the rotor blade rotation, following previous research in this area, and determining the shortcomings and possibilities. The paper provides a numerical method for controlling the power output of a wind power plant, for which an algorithm ha... [more]

Energy harnessing from renewable energy sources has become more flexible with power electronic technologies. Recent advancements in power electronic technologies achieve converter efficiency higher than 98%. Today, reliable power electronic devices are needed to design a PV-based energy converter (inverter) to reduce the risk of failure and maintenance costs during operation. Wide-bandgap SiC devices are becoming more common in power electronic converters. These devices are designed to reduce switching loss and improve the efficiency of the system. Nevertheless, the cost of SiC devices is a major concern. Hence, to improve the reliability of the PV inverter while considering the economic aspects, this paper develops a highly reliable PV inverter with a hybrid Si/SiC power module that consists of a Si-IGBT with a SiC anti-parallel diode. A test case of a 3 kW PV inverter is considered for reliability analysis. The loading of the PV inverter is done under uncertain environmental conditio... [more]

The catalytic conversion of lignin model compounds was performed using Ru/C catalysts and an autoclave reactor. The Ru/C catalysts were prepared by the impregnation method using highly porous homemade activated carbon and characterized by XRD, SEM, and specific surface area. The catalytic reactions were performed in a high pressure/temperature reactor at different temperatures and with different solvents. The results showed that the novel Ru/C catalysts prepared from carbon supports activated by the KOH agent showed higher catalytic activity than the commercial catalyst. Ethanol and 2-propanol were suitable solvents for the cleavage of the β−O−4 ether bond of 2-phenoxy-1-phenyl ethanol (~65−70% conversion) over a Ru/C-KOH-2 catalyst at 220 °C in comparison to tert-butanol and 1-propanol solvents (~43−47% conversion of 2-phenoxy-1-phenyl ethanol). Also, the increase in reaction temperature from 200 °C to 240 °C enhanced the cleavage of the ether bond with an increase in phenol selectivi... [more]