Showing papers in "Journal of Power and Energy Engineering in 2018"
TL;DR: An advanced literature review on the design and performance of solar technology for water pumping is presented, exploring also the best perspective of transition for the developing countries energy needs and the Mozambique's perspective on renewable energy technologies.
Abstract: The use of solar photovoltaic (PV) technology for water pumping systems (WPS) has been one of the most popular forms of solar energy application in recent decades in remote and desert areas, as well as in some urban areas. In this article, an advanced literature review on the design and performance of solar technology for water pumping is presented, exploring also the best perspective of transition for the developing countries energy needs. Additionally, this paper intends to analyze the Mozambique’s perspective on renewable energy technologies setting the Mozambican scenario regarding photovoltaic water pumping systems (PVWPS) technology with the aim to identifying the main knowledge of PVWPS design and research gap. The results show that the most commonly used configuration of PVWPS technology is direct coupling systems without battery storage. These systems are simple and reliable, mainly used in small-scale pumping for small irrigations and domestic use. The mainly variables that influence the performance of PVWPS are: total dynamic head, quantity of fluid extracted, variation of solar radiation level, PV and motor pump technology. Yet, the efficiency of the PV and overall system does not exceed 10% and 5%, respectively. Looking at the designing, mathematical models, software-assisted is being predominant. Yet, as research gap, it is possible to understand from different authors that the dynamic nature of the end-use of PVWPS is not explored on methodology design of PVWPS, and the techno-economic optimum system configuration is not always the one that gives the highest annual system efficiency. For the Mozambican’s context, PVWPS for irrigation has been expanding slowly but has gained expression since 2013. In turn, static models based on software of pump manufacturers for PVWPS design are the most widely used in Mozam-bique. In Mozambique, PVWPS match the perspective of different researchers regarding the availability of solar resource, boreholes and amount of water required for irrigation. The adoption of PVWPS is a means of increasing the sustainability of the rural communities.
24 citations
TL;DR: The work shows and explains the stochastic behavior of the regression neural, experiments the effect of number of neurons of the hidden layers, and shows higher performance for larger training dataset size.
Abstract: Recently, regression artificial neural networks are used to model various systems that have high dimensionality with nonlinear relations. The system under study must have enough dataset available to train the neural network. The aim of this work is to apply and experiment various options effects on feed-foreword artificial neural network (ANN) which used to obtain regression model that predicts electrical output power (EP) of combined cycle power plant based on 4 inputs. Dataset is obtained from an open online source. The work shows and explains the stochastic behavior of the regression neural, experiments the effect of number of neurons of the hidden layers. It shows also higher performance for larger training dataset size; at the other hand, it shows different effect of larger number of variables as input. In addition, two different training functions are applied and compared. Lastly, simple statistical study on the error between real values and estimated values using ANN is conducted, which shows the reliability of the model. This paper provides a quick reference to the effects of main parameters of regression neural networks.
23 citations
TL;DR: An enhanced Genetic Algorithm (GA) is used to minimize the total cost of the system over a 20-year period, while satisfying some reliability and operation constraints.
Abstract: This paper presents a method for optimal sizing of an off-grid hybrid microgrid (MG) system in order to achieve a certain load demand. The hybrid MG is made of a solar photovoltaic (PV) system, wind turbine (TW) and energy storage system (ESS). The reliability of the MG system is modeled based on the loss of power supply probability (SPSP). For optimization, an enhanced Genetic Algorithm (GA) is used to minimize the total cost of the system over a 20-year period, while satisfying some reliability and operation constraints. A case study addressing optimal sizing of an off-grid hybrid microgrid in Nigeria is discussed. The result is compared with results obtained from the Brute Force and standard GA methods.
19 citations
TL;DR: This paper proposes, interleaved boost converter with novel switch adaptive control, to maximise efficiency of standalone photovoltaic system under change of solar power levels, due to illadation condition.
Abstract: DC-DC boost power converters play an important role in solar power systems; they step up the input voltage of a solar array for a given set of conditions. This paper presents an overview of the variance boost converter topologies. Each boost converter is evaluated on its capability to operate efficient, size, and cost of implementation. Conventional boost converter and interleaved boost converter are widely used topologies in photovoltaic systems reported; however, they have negative sides of varied efficiency level under changed weather conditions. Therefore, this paper proposes, interleaved boost converter with novel switch adaptive control, to maximise efficiency of standalone photovoltaic system under change of solar power levels, due to illadation condition.
15 citations
TL;DR: In this research work, a controllable Pitch Propeller (CPP) was considered whereby the pitch was varied, but only the extreme pitch set the limit of operation and matching was done with theextreme pitch condition.
Abstract: The optimal matching of a propeller to the hull and the diesel engine of the combine diesel or gas (CODOG) system is a critical design analysis in ship building. In this research work, a controllable Pitch Propeller (CPP) was considered whereby the pitch was varied, but only the extreme pitch set the limit of operation and matching was done with the extreme pitch condition. It considers the performance analysis of the propeller, the hull and the engine both in design and off design conditions. Without propulsion a vessel built cannot move and so choosing the right propeller to match the hull and engine is very vital. The various processes involved in the matching of the propeller to the diesel engine and hull of the vessel are considered, in order to achieve optimal performance of the vessel. A Java program (prop-matching) was developed to facilitate the matching process. The graphs obtained are used to determine the matching point at corresponding speed and power. The thrust and torque developed under different conditions as well as their significance, considering the fact that the propeller is a CPP. The engine response in transient conditions in reaction to the turbo charger was considered, the matching graph of the turbo charger compressor was discussed, and the calculated mass flow rate with various engine speeds and boost pressure were also discussed. This program was further used in matching the propeller to the hull and diesel or gas engines of a F90 frigate. The corresponding propeller rpm and engine power with pitch ratios from the program were similar to those from the design of the frigates. The various thrust and torque coefficients and open water efficiency all correspond to the simulated results of those of the naval frigate.
11 citations
TL;DR: A complete and inclusive study of power quality events, such as automatic classification and signal processing via creative techniques and the noises effect on the detection and classification of powerquality disturbances are revealed.
Abstract: Around the globe, the necessity of green supply with a dedicated standard quality thrust of consumers is increasing day by day. The advancement in technology urges the electrical power system to deliver a high-quality rated undistorted sinusoidal current, the voltage at a constant desired standard frequency to its consumers. The present paper reveals a complete and inclusive study of power quality events, such as automatic classification and signal processing via creative techniques and the noises effect on the detection and classification of power quality disturbances. It’s planned to make a possible list for quick reference to obtain an extensive variety on the condition & status of available research for detection and classification for young engineers, designers and researchers who enter in the power quality field. The current extensive study is supported by a critical review of more than 200 publications on detection and classification techniques of power quality disturbances.
11 citations
TL;DR: In this article, the estimation of methane emissions from the waste can be an economic and useful way for more accurate control and management of waste disposal in Kossihouen, Ivory Coast.
Abstract: In order to solve the problem of the management of municipal solid waste in Abidjan (Cote d’Ivoire), a sanitary landfill has been designed in Kossihouen. Despite the adverse greenhouse effects of the methane, this gas has a potential of electrical energy. The estimation of methane emissions from the waste can be an economic and useful way for more accurate control and management of waste disposal in Kossihouen. Therefore, conducting this study is essential. Methane emissions were estimated based on the methane generation constant K and the methane generation potential L0 using LandGEM 3.02. The results show that the quantity of methane emissions was 7.97E+07 m3/year. Based on this result, the methane content can generate 10% of total electricity consumed in Abidjan in 2026. This paper could serve as a source of scientific information for decision making on environmental sustainability in waste-to-energy projects in Cote d’Ivoire.
11 citations
TL;DR: In this paper, the authors show that piezoelectric materials are capable of producing nonlocal forces of induction in external objects and conclude that the nature of the forces generated is not originated from traditional interactions.
Abstract: We describe the phenomenon of generation of an external field of forces from piezoelectric materials subjected to the application of electric fields or mechanical stress. We show that piezoelectric materials are capable of producing nonlocal forces of induction in external objects and we conclude that the nature of the forces generated is not originated from traditional interactions. Further we specifically assert that the generation of forces by the piezoelectric materials is ruled by the hypothesis of preexisting condition of generalized quantum entanglement between the molecular structure of the material bulk and the surrounding environment. In addition, the widely spread coupling of the molecules with the environment can be manifested from the so-called direct effect or the converse effect in piezoelectric materials and this coupling is not intermediated by acoustic waves or electromagnetic fields. We show that the novel effect has a theoretical explanation consistent with the generalized quantum entanglement framework and the direction of the induced forces depends on either the direction of the mechanical force or the electric field applied in these materials.
11 citations
TL;DR: A novel topology of Integrated Boost-SEPIC (IBS) AC-DC converter using common part sharing method (CPSM) has been proposed in this paper and eliminates the requirement of bridge rectifier achieving high efficiency, improved power factor and lower THD.
Abstract: A novel topology of Integrated Boost-SEPIC (IBS) AC-DC converter using common part sharing method (CPSM) has been proposed in this paper. Conventional boost converters with bridge rectifier configuration are inefficient due to limited voltage step-up ratio which may not be applicable for high step-up applications as in the case of micro generators. The proposed IBS topology is based on the common part sharing method capable of operating both for positive and negative half cycle of the input signal. Result and simulation were conducted using PSIM environment. The proposed AC-DC IBS topology eliminates the requirement of bridge rectifier achieving high efficiency (about 99%), improved power factor (0.75, leading) and lower THD (about 38.8%) which is within IEEE standard.
11 citations
TL;DR: Critical node (bus) identification based on power system network structure is proposed and a comparative analysis with other bus voltage stability indices is presented to test the suitability of the proposed approach using the IEEE 14, 30, 57 and 118 bus test systems.
Abstract: Voltage security assessment of power system is an important and all-inclusive aspect of power system operation and preventive control actions. Fast and accurate detection of critical components of the power system is one essential approach for preventing the occurrence of voltage collapse phenomenon. Over the years, several approaches for voltage collapse point identification and prevention have been widely studied using the continuous power flow approach, minimum singular value of eigenvalues, Jacobian matrices, and power transfer concept. In this work, critical node (bus) identification based on power system network structure is proposed. In this approach, the power system is treated as a multidimensional graph with several nodes (buses) linked together by the transmission lines. An improved line voltage stability margin estimator which is based on active and reactive power changes in a power system is used as the weight of each transmission line and an adaptation of the degree of centrality approach is used to determine the criticality of the system buses. A comparative analysis with other bus voltage stability indices is presented to test the suitability of the proposed approach using the IEEE 14, 30, 57 and 118 bus test systems.
11 citations
TL;DR: A new performance indicator which considers PV panel slope and orientation is proposed and is used to develop a friendly user calculator of PV system output that can be used by, energy providers and PV system installers to evaluate the output of the PV grid connect network.
Abstract: The energy assessment of the PV power systems is carried out by using different types of performance indicators that benchmark the output of these systems against the PV panel maximum output at hypothetical operation conditions. In this paper, a comparative analysis of six types of performance indicators is conducted and a new performance indicator which considers PV panel slope and orientation is proposed. The proposed indicator is benchmarking the PV system actual output against the maximum output of the same system if it would operate in two axis tracking mode. The proposed performance indicator is used to develop a friendly user calculator of PV system output that can be used by, energy providers and PV system installers to evaluate the output of the PV grid connect network. The advantage of the developed calculator is high-lighted by a case study that estimates energy capacity of different residential rooftop PV systems installed in a residential suburb in Sydney.
TL;DR: In this paper, an experimental analysis for comparisons of conventional flat plate solar collectors and collectors integrated with different numbers of baffles was presented, which showed that integrating solar collector with baffles significantly increased the efficiency of the system.
Abstract: This paper presents an experimental analysis for comparisons of conventional flat plate solar collectors and collectors integrated with different numbers of baffles. Heat transfer between absorber plate and drying fluid (air) has been one of the major challenges in the design and operations of the indirect solar dryer systems. In this experiment, efficiency of air flat plate solar collector integrated with 2, 3, 4 and 8 baffles was studied and compared with the ordinary collector. The results showed that integrating solar collector with baffles significantly increased the efficiency of the system. It was noted that collector with 2, 3, 4 and 8 baffles had a mean efficiency of 29.2%, 31.3%, 33.1% and 33.7% respectively while with no baffles was 28.9%. The analysis showed that when there were less than four baffles in the collector, heat transfer was dominant over pressure drop and hence high efficiency. However, when the number of baffles exceeded four, the effect associated with an increase in pressure drop highly observed compared to heat transfer coefficient, thus resulted to insignificant increase in efficiency. Therefore, the optimum number of four baffles was commended for the designed model for optimum efficiency.
TL;DR: In this article, the anomalous forces in rotating superconductor rings seem to be nonlocal in its nature, according to same theoretical framework in our previous analysis concerning to superconducting disks and toroids.
Abstract: In this work, we show that anomalous forces in rotating superconductor rings seem to be nonlocal in its nature, according to same theoretical framework in our previous analysis concerning to superconducting disks and toroids. Here we discuss an experiment involving rotating and angularly accelerated superconducting rings and show that the concept of generalized quantum entanglement can explain the anomaly accordingly. In fact, the hypothesis of momentum variation exchanged between Cooper pairs and outer particles regarding a hypothesis of preexisting state of generalized quantum entanglement which is also valid in this system because classical macroscopic quantities are performed in the calculation and indicate good agreement between experimental and theoretical results. We also analyze the possible reason for the discrepance between positive and null results in case of some high voltage discharge experiments involving superconducting discs in terms of nonlocal force induction aiming to reinforce that the anomalous effect can really exist in all of those superconducting systems. The experiments indicate that the anomalous forces are still weak, but our study can provide some possible physical conditions in order to increase the magnitude of the forces and provide future viable technological applications from that phenomenon.
TL;DR: In this article, the development of a vertical axis hydrokinetic twin turbine for harvesting energy from flowing water in man-made channels is described and the technology readiness level (TRL) assessment procedure, developed by NASA and modified by the US Department of Energy, is followed and it is shown that the turbine successfully reaches TRL 7, which is a full scale, similar (prototypical) system demonstrated in a relevant environment.
Abstract: In this paper, the development of a vertical axis hydrokinetic twin turbine for harvesting energy from flowing water in man-made channels is described The Technology Readiness Level (TRL) assessment procedure, developed by NASA and modified by the US Department of Energy, is followed and it is shown that the hydrokinetic turbine successfully reaches TRL 7, which is a full-scale, similar (prototypical) system demonstrated in a relevant environment The concept of the twin turbine (TRL 1 - 3) is first validated and tested using a 1:10 scale laboratory model at Cardiff University and efficiencies of up to 75% are achieved (TRL 4 - 5) In order to justify system functionality and performance in a relevant environment as well as up-scalability, a 1:3 scale model of the twin turbine is implemented and tested in a discharge channel of a water treatment plant in Atlanta, thereby achieving TRL6 This paved the way for an application in the form of an array of ten full-scale twin turbine prototypes, including all relevant components such as housing, drive-train, gear-box and generator Successful deployment and testing in the South Boulder Canal near Denver means that the hydrokinetic twin turbine system reached TRL7
TL;DR: An autonomous and distributive demand-side management based on Bayesian game theory is developed and applied among users in a grid connected micro-grid with storage, evidence its efficacy when employed to manage the charging of electric vehicles.
Abstract: In this paper, an autonomous and distributive demand-side management based on Bayesian game theory is developed and applied among users in a grid connected micro-grid with storage. To derive that strategy, an energy consumption of shiftable loads belonging to a given user is modelled as a noncooperative three-player game of incomplete information, in which each user plays against the storage unit and an opponent gathering all the other users in the micro-grid. Each player is assumed to be endowed with statistical information about its behavior and that of its opponents so that he can take actions maximizing his expected utility. Results of the proposed strategy evaluated by simulating, under MATLAB environment, a connected micro-grid with storage device evidence its efficacy when employed to manage the charging of electric vehicles.
TL;DR: In this paper, the Soave-Redlich-Kwong (SRK) equation of state was used to calculate exergy-based analyses in order to calculate its exergy efficiency and evaluate its environmental impact under standard conditions.
Abstract: In the first part of this investigation, a Natural Gas Combined Cycle (NGCC) producing 620 MW of electricity was simulated using the commercial software Aspen Hysys V90 and the Soave-Redlich-Kwong (SRK) equation of state The aim of this second part is to use exergy-based analyses in order to calculate its exergy efficiency and evaluate its environmental impact under standard conditions For the exergy efficiency, the performance index under investigation is the exergy destruction ratio (yD) The results of the study show that the combustor is the main contributor to the total exergy destruction of the power plant (yD = 2435%) and has the lowest exergy efficiency of 7565% On the other hand, the Heat Recovery Steam Generator (HRSG) has the lowest contribution to the exergy destruction (yD = 563%) of the power plant and the highest exergy efficiency of 9437% For the overall power plant, the exergy efficiency is equal to 5328% For the environmental impact of the power plant, the relative difference of exergy-related environmental impacts (rb) is utilized as the performance index for each equipment of the plant and the environmental impact of a kWh of electricity (EIE) is used to represent the performance index of the overall power plant In agreement with the exergy analysis, the results indicate that the combustor and the HRSG have respectively the highest (rb = 3219%) and the lowest (rb = 596%) contribution to the environmental impact The environmental impact of a kWh of electricity of the power plant is 3426 mPts/kWh (exergy destruction only), and 3442 mPts/kWh (both exergy destruction and exergy loss)
TL;DR: In this article, a novel effect associated with deviations of laser beams when in the surroundings there is a piezoelectric ceramic subjected to high voltages is reported, which can change the laser beam profiles even considering its weakness.
Abstract: We report in the present work a novel effect associated with deviations of laser beams when in the surroundings there is a piezoelectric ceramic subjected to high voltages. In our previous work we presented experimental evidences of the generation of forces at distance by piezoelectric materials. Hence a methodology for remote sensing and metrology which enhanced the weak effects of the property of generalized quantum entanglement was proposed. The preexisting state between all existing particles in physical systems can allow that piezoelectric ceramics induct forces at distance detected by a sensible accelerometer apart without involving any known local interaction such as those of acoustic or electromagnetic nature. Motivated by the results, we proceed and discover that new unprecedented visual effects arise when nonlocal forces generated by a piezoelectric ceramic change the laser beam profiles even considering its weakness. This novel effect seems to be really detected in our experiments and this achievement opens one opportunity more for developing new technological applications.
TL;DR: This paper focused on the modeling and control of variable speed wind turbine that is composed of two-mass drive train, a Squirrel Cage Induction Generator, and voltage source converter control by Space Vector Pulse Width Modulation (SPVWM).
Abstract: Maximizing the power capture is an important issue to the turbines that are installed in low wind speed area In this paper, we focused on the modeling and control of variable speed wind turbine that is composed of two-mass drive train, a Squirrel Cage Induction Generator (SCIG), and voltage source converter control by Space Vector Pulse Width Modulation (SPVWM) To achieve Maximum Power Point Tracking (MPPT), the reference speed to the generator is searched via Extremum Seeking Control (ESC) ESC was designed for wind turbine region II operation based on dither-modulation scheme ESC is a model-free method that has the ability to increase the captured power in real time under turbulent wind without any requirement for wind measurements The controller is designed in two loops In the outer loop, ESC is used to set a desired reference speed to PI controller to regulate the speed of the generator and extract the maximum electrical power The inner control loop is based on Indirect Field Orientation Control (IFOC) to decouple the currents Finally, Particle Swarm Optimization (PSO) is used to obtain the optimal PI parameters Simulation and control of the system have been accomplished using MATLAB/Simulink 2014
TL;DR: A suitable fuzzy logic controller (FLC) is proposed in the cascaded controller of GSC of PMSG in order to increase reactive power injection and thus improve the FRT capability of WF during voltage dip situation due to severe network fault.
Abstract: This paper presents a new operational strategy for a large-scale wind farm (WF) which is composed of both fixed speed wind turbines with squirrel cage induction generators (FSWT-SCIGs) and variable speed wind turbines with permanent magnet synchronous generators (VSWT-PMSGs). FSWT-SCIGs suffer greatly from meeting the requirements of fault ride through (FRT), because they are largely dependent on reactive power. Integration of flexible ac transmission system (FACTS) devices is a solution to overcome that problem, though it definitely increases the overall cost. Therefore, in this paper, a new method is proposed to stabilize FSWT-SCIGs by using VSWT-PMSGs in a WF. This is achieved by injecting the reactive power to the grid during fault condition by controlling the grid side converter (GSC) of PMSG. The conventional proportional-integral (PI)-based cascaded controller is usually used for GSC which can inject small amount of reactive power during fault period. Thus, it cannot stabilize larger rating of SCIG. In this paper, a suitable fuzzy logic controller (FLC) is proposed in the cascaded controller of GSC of PMSG in order to increase reactive power injection and thus improve the FRT capability of WF during voltage dip situation due to severe network fault. To evaluate the proposed controller performance, simulation analyses are performed on a modified IEEE nine-bus system. Simulation results clearly show that the proposed method can be a cost-effective solution which can effectively stabilize the larger rating of SCIG compared to conventional PI based control strategy.
TL;DR: Simulation studies that were carried out on the proposed SGDMS showed its potential for providing solutions through intelligent distribution techniques and how it influences the cost of electricity.
Abstract: This paper presents the use of proposed Smart Grid Distribution Management System (SGDMS) for Singapore contestable and non-contestable consumers. The SGDMS is a distributed management system proposed using Multi-Agent System (MAS) technology. This system can optimise the distribution of renewable energy while minimizing electricity bills for consumers. The entire system was developed using Java with the extension of JADE which is an IEEE FIPA compliant multi-agent system platform. This decentralised platform allows agents to interact and communicate using energy sources from different sectors and control them intelligently to minimise the cost of electricity for the consumers. Simulation studies were carried out on the proposed system to show its potential for providing solutions through intelligent distribution techniques and how it influences the cost of electricity.
TL;DR: In this article, the authors presented the thermos-economic evaluation of a simple gas turbine (SGT) within the Niger Delta, Nigeria, using MATLAB software to model the various thermodynamic performance equations of the plants while net present value (NPV), internal rate of return (IRR), and Payback period (PBP) were used to evaluate the plant performance.
Abstract: This paper presents the thermos-economic evaluation of a simple gas turbine (SGT) within the Niger Delta, Nigeria. Steady-state monitoring and direct collection of data from the 25 MW plant were performed including logged data for a 12 months period. MATLAB software was used to model the various thermodynamic performance equations of the plants while net present value (NPV), internal rate of return (IRR), and Payback period (PBP) were used to model the economic concept of the plant performance. The thermodynamic analysis shows that for every 1℃ rise in the ambient temperature, the percentage power drop increases by 2.07%, thermal efficiency drops by 0.66%, and the specific fuel consumption increases by 0.93%. For every 1% drop in the power output, the percentage thermal efficiency drops by 0.79% for the given consideration. The economic analysis based on the performance reveals that the power shortages represent about 47.9% of the net power generated and the revenue worth of $4198741.60 is lost due to the inability of the plant to perform at its design point. The NPV value of $6434899.97 shows that the plant investment is viable for the period of twenty years of operation and the IRR on investment is determined to be 12.40% by a numerical approximation for the period, with a PBP of 8.5 years. This provides technical and economic details to plant operators and energy systems investors for decision making.
TL;DR: In this article, the authors present the main results of an energy audit in a milk processing industry in southern Brazil, based on an analysis of the energy costs of the past two years to check the consumption of active and reactive energy and power demand contracted.
Abstract: The industrial energy diagnosis presented in this work occurred in a milk product cooperative, from an analysis of energy consumption in the main milk industrialization and a diagnosis of energy end uses of lighting and cooling systems. Almost all stages of milk industrialization are used hot water and steam generated in the boilers. The largest electricity consumption in this sector is by electric motors followed by cooling needed to maintain the quality of milk products. Because energy costs represent a significant portion of the monthly cost of the company, an analysis of the energy costs of the past two years to check the consumption of active and reactive energy and power demand contracted is performed. This paper presents the main results of an energy audit in a milk processing industry in southern Brazil.
TL;DR: In this article, the authors measured the reflectance and transmittance of fly ash particles by FTIR under the wavelength range of 0.55 - 1.65 μm, using the four-flux model to solve the radiative transfer equation and combing with Mie theory, the absorption and scattering efficiency of 22.7 μm fly ash and optical constant (also known as complex refractive index, m = n + ik) of fly Ash were inversely calculated.
Abstract: Radiant syngas cooler (RSC) is the key heat recovery equipment in coal gasification system. The syngas from gasifier carries large amount of slags in which the mass fraction of fly ash less than 100 μm is about 20%. Studying the optical properties of fly ash has high significance for the optimization of heat transfer calculation in RSC. A new experimental method was proposed to inversely calculate the radiative parameters of particles—“KBr transmittance-reflectance method”. By measuring the “directional-hemispherical” reflectance and transmittance of fly ash particles by FTIR under the wavelength range of 0.55 - 1.65 μm, using the four-flux model to solve the radiative transfer equation and combing with Mie theory, the absorption and scattering efficiency of 22.7 μm fly ash and optical constant (also known as complex refractive index, m = n + ik) of fly ash were inversely calculated. The results indicated that for fly ash with large size parameter, there was no obvious change of the absorption and scattering efficiency when the mass fraction of Fe2O3 was between 5.65% and 16.53%, which was well explained by Mie theory; The obtained optical constant was close to the results of KBr trans-mittance method.
TL;DR: In this article, a steam turbine for a small scale steam power plant with target of producing electricity was designed and validated using computer packages, and the results showed that the turbine can adequately tolerate change in stress/load, torsion/compression, temperature and speeds.
Abstract: The steam turbine is a prime mover that converts kinetic energy in steam into rotational mechanical energy through the impact or reaction of the steam against the blades. The aim of this study is to design a steam turbine for a small scale steam power plant with target of producing electricity. The turbine is driven by the heat energy from palm kernel shells as a renewable energy source obtained at a lower or no cost. The study was concentrated on design of turbine elements and its validation using computer packages. Specifically, the microturbine design was limited to design, modeling, simulation and analysis of the rotor, blades and nozzle under the palm kernel shell as fuel for the micro power plant. In blade design, stress failures, efficiency and blade angle parameters were considered. In casing volume design, the overall heat transfer and mean temperature, and different concepts were applied. The thermal distribution on stator and rotor was considered in order to determine its level of tolerance. The design software packages used for design validation were Solidworks and Comsol Multiphysics for analysis. Simulation results showed that the designed steam turbine can adequately tolerate change in stress/load, torsion/compression, temperature and speeds.
TL;DR: The numerical studies showed that the proposed methodology was effective and robust enough to find the optimal solution even if the number of offshore wind turbine increases and the suggested approaches are helpful to avoid a time-consuming process of manually planning the scheduling and routing with a presumably suboptimal outcome.
Abstract: Reducing the operation and maintenance (O & M) cost is one of the potential actions that could reduce the cost of energy produced by offshore wind farms. This article attempts to reduce O & M cost by improving the utilization of the maintenance resources, specifically the efficient scheduling and routing of the maintenance fleet. Scheduling and routing of maintenance fleet is a non-linear optimization problem with high complexity and a number of constraints. A heuristic algorithm, Ant Colony Optimization (ACO), was modified as Multi-ACO to be used to find the optimal scheduling and routing of maintenance fleet. The numerical studies showed that the proposed methodology was effective and robust enough to find the optimal solution even if the number of offshore wind turbine increases. The suggested approaches are helpful to avoid a time-consuming process of manually planning the scheduling and routing with a presumably suboptimal outcome.
TL;DR: In this paper, the authors measured the green energy efficiency of thirty provinces of China from 2000 to 2016 by using the Super-SBM, introducing it to the spatial economic model to study the convergence of Green Energy Efficiency.
Abstract: As an important aspect for the survival and development of human society, energy is an important factor that restricts the economic and social development of a country. This paper measured the green energy efficiency of thirty provinces of China from 2000 to 2016 by using the Super-SBM, introducing it to the spatial economic model to study the convergence of green energy efficiency. The results show that: the overall green energy efficiency of China shows a downward trend with time, and it gradually decreases from east to west. The three regions have significant differences. Among them, there is no β absolute convergence trend for the eastern, central, western regions and the country as a whole, but there is β relative convergence. The level of economic development, R & D investment, the level of technology improvement, and foreign direct investment have positive effects on the development of green energy efficiency. The industrial structure has a positive effect in the eastern but a negative effect in the western.
TL;DR: In this paper, a comprehensive understanding on sustainable biomass supply, co-firing ratios and how direct biomass co-combustion under oxy-fuel conditions can be implemented is presented.
Abstract: Coal-fired plants are under pressure to reduce their carbon-intensity. Available options include co-firing CO2-neutral biomass, oxy-fuel-combustion as part of a carbon capture process or a combination of both to give a “CO2-negative” power plant. BioCCS, the combination of CO2 Capture and Storage (CCS) with sustainable biomass conversion, is the only large-scale technology that can achieve net negative emissions. Combining, developing and demonstrating the oxy-combustion of high ratios of sustainable biomass with coal in flexible circulating fluidized bed (CFB) boiler will bring significant advances in the reduction of greenhouse gases (GHG) emissions. Areas addressed include possibilities for: biomass characterization; handling and feeding; co-firing ratios definition; CFB oxy-co-combustion studies; combustion performance; boiler flexibility in fuel and load; main emissions analysis; slaging, fouling and agglomeration; corrosion and erosion; and implications on plant operation and associated costs. The article will detail a comprehensive understanding on sustainable biomass supply, co-firing ratios and how direct biomass co-combustion under oxy-fuel conditions can be implemented. It seeks to push biomass co-combustion in future large-scale oxy-fuel CFB power stations to high thermal shares while enhancing the power plants’ operational flexibility, economic competitiveness and give operational procedures. There will be a need to consider the public acceptance of power production from coal and coal sustainability, by its combination with renewable sources of energy (biomass).
TL;DR: Zhang et al. as discussed by the authors studied the long-term equilibrium and short-term dynamic adjustment relationship between economic growth and water pollution in cities of Jiangxi Province from 1998 to 2016.
Abstract: Identifying the key influencing factors of water pollution in Jiangxi Province is vital for formulating effective environmental protection measures. Jiangxi Province is located in the central of China. It plays a very important role in the “Rise of Central China” strategy. In recent years, water pollution in various regions of Jiangxi Province has become more and more serious. Therefore, exploring the main driving factors of water pollution in Jiangxi Province is of great practical significance. In this paper, the Autoregressive Distributed Lag (ARDL) approach is used to study the long-term equilibrium and short-term dynamic adjustment relationship between economic growth and water pollution in cities of Jiangxi Province from 1998 to 2016. The results show that there is a long-term equilibrium relationship between the water pollution index and the actual GDP of the first type of cities. However, due to the difference in the form and parameters of model, the inverted “U-shaped” relationship of the water pollution index and the actual GDP is not always presented. The regional economic growth of the second type of urban areas leads to increase of pollutants. It is obvious that the deteriorating environment has increased people’s living costs and inhibited economic growth. The contradiction between economic development and environmental pollution in the third type of urban areas is most acute. Therefore, in order to effectively protect the environment, local governments should consider all these factors as well as regional heterogeneity in formulating policies.
TL;DR: In this paper, the authors simulate the behavior of a jet issuing into a two-layer density-stratified fluid in a cylindrical tank and the resulting mixing phenomena when the Reynolds number Re of the jet is 475, 1426, and 2614.
Abstract: This study simulates the behavior of a jet issuing into a two-layer density-stratified fluid in a cylindrical tank and the resulting mixing phenomena. The upper and lower fluids are water and an aqueous solution of sodium chloride (NaCl), respectively, with the lower fluid issuing diagonally upward from a nozzle on the bottom of the tank. The angle between the centerline of the jet and the tank bottom is 60°. The phenomena when the Reynolds number Re of the jet is 475, 1426, and 2614 are simulated. The mass concentration of the aqueous solution of NaCl is 0.02. The simulation successfully grasps the jet behavior and the resulting mixing, which agree with the authors’ experimental results at the corresponding Re value. The secondary flows that appear in the horizontal cross-sections consist of a pair of vortices and flows along the tank wall. The secondary flow at the density interface represents the intrusion of an internal density current, which gives rise to mixing along the interface.
TL;DR: In this paper, the best configuration based on ampacity is achieved for a three-row, five-column ductbank that is buried at a depth of one meter below the earth’s surface.
Abstract: Electrical power companies are using more underground cables rather than overhead lines to distribute power to their customers. In practice, cables are generally installed in some compact ductbanks. Since the cost of underground cables is very expensive, using the entire space of a ductbank is extremely important. But such usage is limited due to the overheating of cables. Overheating is generally caused by overload, which means the carrying current exceeds the ampacity of a cable. The ampacity of a cable depends on not only the material and design of a cable but also the distance between different cables. Thus the configuration of cables determines the total ampacity value and the potential use of a ductbank. In this paper, the best configuration based on ampacity is achieved for a three-row, five-column ductbank that is buried at a depth of one meter below the earth’s surface. Both balanced and unbalanced scenarios are considered, and all cables have two available types to be selected.