Efficiency Of Electric Power Generation Research Articles

Improving Efficiency and Power Output of Switched Reluctance Generators through Optimum Operating Parameters

The optimization of energy production in renewable energy systems is crucial to improve energy efficiency. In this context, the aim of this study focuses on maximizing the efficiency of a switched reluctance generator. This paper presents a novel approach to enhance the electrical power and efficiency of a switched reluctance generator by determining the optimal operating parameters based on the mechanical input power of the system. The proposed strategy consists of the following steps: First, an algorithm was developed that provides machine data for different power modes based on control parameters, including electrical and mechanical powers such as speed, torque, and turn-on and turn-off angles. In the next step, the obtained data were analyzed to identify the optimum points corresponding to the states with maximum power and efficiency for various scenarios. An algorithm for maximum power point tracking was also developed to determine the optimal parameters as a function of mechanical energy. Finally, the data and algorithms were integrated into the switched reluctance generator control system. Simulations were conducted to compare the proposed MPPT technique with other techniques. This comparison is essential to validate the effectiveness of the proposed strategy in achieving enhanced electrical power generation efficiency.

Continuous decentralized hydrogen production through alkaline water electrolysis powered by an oxygen-enriched air integrated biomass gasification combined cycle

This research work presents an innovative approach for continuous decentralized production of renewable hydrogen from woody biomass. Alkaline water electrolysis (AWE) is used to produce high-purity hydrogen, while the oxygen by-product is mixed with ambient air and used to fire a biomass-fueled downdraft gasifier in order to produce an upgraded producer gas with a lower heating value (LHV) between 7–8 MJ/Nm3. This fuel gas is then subjected to a conditioning stage and eventually fed to a combined cycle consisting of a recuperative gas turbine as topping unit and a regenerative subcritical organic Rankine cycle as bottoming unit, which together allow for a combined electric power generation efficiency close to 40%. Most of the net AC power from the integrated gasification combined cycle (IGCC) is rectified to DC power and ultimately used to power an alkaline electrolyzer, with a minor share allocated to all the required utilities and ancillary equipment, including hydrogen compression to 200 bar. The results from simulation of the hybrid IGCC-AWE plant under steady-state operating conditions in Aspen Plus V.11 indicate an optimal efficiency of 17.6% based on the LHV of hydrogen. Thus, if sized for a biomass consumption of 1 t/h, the proposed plant is capable of providing around 26 kg/h of compressed hydrogen at 200 bar.

An electric power generation improvement for small Savonius wind turbines under low-speed wind

<p>Savonius wind turbines have advantages of self-rotating at low speed wind, high starting torque, and less noise generation. However, they have low electric power generation capacity. This paper presents electric power generation improvement for small Savonius wind turbines when operating at low-speed wind of 1-6 m/s by using optimal Bach-type blades, twist blades and a wind tunnel. The turbine prototypes with the optimum diameter and height of 32 cm were developed with 3 different blade types: conventional semicircular blades, Bach-type blades and twisted 15° blades and a wind tunnel. The experimental results showed that the Savonius wind turbine with Bach-type generated highest electric voltage, which was 19.3% and 7.6% higher compared to conventional blades and twisted 15° blades. The additional wind tunnel could improve electric power generation efficiency by approximately 21.4% compared to the turbines without the tunnels.</p>

A novel liquid metal MHD enhanced Closed-Brayton-Cycle power generation system for hypersonic vehicles: Thermodynamic analysis and performance evaluation with finite cold source

Closed-Brayton-cycle (CBC) is a potential thermodynamic cycle for high-power dynamic electricity generation on hypersonic vehicles, but finite cold source onboard limits its power level. This study presents a liquid metal MHD (LMMHD) enhanced CBC power generation system and exhibits its theoretical advantages through thermodynamic analysis. The influence of cold source temperature rise, turbine inlet temperature and LMMHD conversion efficiency on system performance is investigated by a zero-dimensional power optimization model, and the electric power and power generation efficiency between LMMHD enhanced CBC and standalone CBC are compared. Results indicate that LMMHD enhanced CBC can theoretically meet the demand for megawatt-class power generation on hypersonic vehicles, the electric power per unit fuel mass flowrate of which can reach 637.84 kW. High-temperature liquid metal and well-designed LMMHD generator are extremely essential to improve the turbine inlet temperature and LMMHD conversion efficiency. Compared with standalone CBC, the electric power increased percentage of LMMHD enhanced CBC is as high as 92.44 %. This paper provides primary performance evaluation for LMMHD enhanced CBC, the key technical issues of which, including the LMMHD generator structure design, mixing and separation process optimization, will be the focus in our next work.

On the efficient topology of the exhaust heat exchangers equipped with thermoelectric generators for an internal combustion engine

The increasing energy demand and simultaneously growing concerns about pollution and climate change can clarify the importance of energy recovery, especially in the transportation section where a huge amount of fossil fuels is still consumed. Thermoelectric modules (TEMs) are one of the most stable means to extract energy from flue gases. However, the heat recovery by TEMs require a precise thermo-hydrodynamic design for heat exchangers to transfer more energy, owing to the low efficiency of the modules. Therefore, the current numerical study follows the ideas that can increase the efficiency of electrical power generation in vehicles. Three various simple or dimpled geometries, called Dual Flat, C-shaped, and U-shaped models, are introduced involving the ideas of chaotic flows, extending heat transferring surfaces, and intensifying turbulence levels. The number of TEMs is kept constant for all geometries and a trial procedure is performed to specify the thermo-physical properties of TEMs, directly connected to their hot and cold side temperature. The results are compared to the traditional Flat geometry, in terms of power generation, efficiency, and thermo-hydrodynamic evaluations. Dual Flat and Flat geometry are respectively labeled as the most and least power generating models by 45% relative difference. Despite the highest pressure drop, the chaotic flow in a C-shaped geometry provides the most efficient case if the pressure drop is freely provided by the engine exhaust inertia, while dimpled Dual Flat geometry is ranked the first for best efficiency when pressure drop compensation needs additional cost. The latter geometry can produce nearly 700 W power, as the maximum value.

Considering the effect of dustiness of a photovoltaic module surfaces on solar power generation by matlab software

Purpose. Improving the simulation model of a solar power plant by creating a block model for accounting for dustiness of the surface of photovoltaic modules when calculating the efficiency of electric power generation by a solar power plant. 
 Methodology. Use of statistical data processing methods and modeling in the structure of Matlab tools.
 Findings. A mathematical model was created, which made it possible to take into account the influence of dustiness of the surface of photovoltaic modules on the efficiency of electric power generation by a solar power station. The model was tested on the real object and the accuracy of modeling was proved. 
 Originality. The scientific novelty is to create mathematical models that describe the effect of dust on the surface of photovoltaic modules on the efficiency of solar station generation based on the Bouguer-Lambert-Behr law, the blocks of precipitation influence on dust were developed, and the rate of dust accumulation was corrected by taking into account the air humidity. 
 Practical value. The obtained results will help to improve the accuracy of modeling of all types of photovoltaic systems. These models can be used as the formation of commercial proposals with more accurate schedules of electric power generation, which can significantly increase the accuracy of the choice of rated capacity of equipment.

Electrical Power Generation System: Optimal Design for Medium-Load Industries with High-Rated Generators

The demand for electrical power is rapidly increasing due to the rise of industries in developing countries. Power generation stations are having troubles to strike a balance between demand and generation. In this situation, it is urged that appropriate remedial action be taken. Rising power demand can be met by designing an efficient electric power generation system which will also help lowering the generation cost. It is shown that while high rated electric power generators are connected in parallel the value of neutral current is rising and the cooling temperature is also increased. Here, the goal of this experimental work is to present a new model for designing an efficient power production system for average-load (ranging up to 8000 Amp, 440 V) industries to minimize the demand on centralized interconnected grid. A scheme is proposed with four generators (2500 kVA, 2000 kVA, 2000 kVA and 1250 KVA) in parallel and enough cooling arrangement is provided with minimal cost. The coolant temperature is maintained 61 °C to 61.5 °C and at that time diesel temperature is not more than 38.5 °C. The amount of neutral-current is also optimized (up to 8.5 Amp.) which was more than 12 Amp. At the morning and afternoon, the neutral current is almost constant, but it is bit fluctuating between 7.5 Amp to 8.2 Amp at mid-day. The final outcome shows, the suggested system is efficiently stable with the change of load and generates optimal electricity.

Electrical Power Generation System: Optimal Design for Medium-Load Industries with High-Rated Generators

The demand for electrical power is rapidly increasing due to the rise of industries in developing countries. Power generation stations are having troubles to strike a balance between demand and generation. In this situation, it is urged that appropriate remedial action be taken. Rising power demand can be met by designing an efficient electric power generation system which will also help lowering the generation cost. It is shown that while high rated electric power generators are connected in parallel the value of neutral current is rising and the cooling temperature is also increased. Here, the goal of this experimental work is to present a new model for designing an efficient power production system for average-load (ranging up to 8000 Amp, 440 V) industries to minimize the demand on centralized interconnected grid. A scheme is proposed with four generators (2500 kVA, 2000 kVA, 2000 kVA and 1250 KVA) in parallel and enough cooling arrangement is provided with minimal cost. The coolant temperature is maintained 61 °C to 61.5 °C and at that time diesel temperature is not more than 38.5 °C. The amount of neutral-current is also optimized (up to 8.5 Amp.) which was more than 12 Amp. At the morning and afternoon, the neutral current is almost constant, but it is bit fluctuating between 7.5 Amp to 8.2 Amp at mid-day. The final outcome shows, the suggested system is efficiently stable with the change of load and generates optimal electricity.

Verification of Carrier Concentration-Dependent Behavior in Water-Infiltration-Induced Electricity Generation by Ionovoltaic Effect.

Water-infiltration-induced power generation has the renewable characteristic of generating electrical energy from ambient water. Importantly, it is found that the carrier concentration in semiconductor constituting the energy generator seriously affect the electricity generation. Nevertheless, few studies are conducted on the influence of semiconductor carrier concentration, a crucial factor on electricity generation. Due to this, understanding of the energy harvesting mechanism is still insufficient. Herein, the semiconductor carrier concentration-dependent behavior in water-infiltration-induced electricity generation and the energy harvesting mechanism by ionovoltaic effect are comprehensively verified. A clue to enhance the electric power generation efficiency is also proposed. When 20 µL of water (NaCl, 0.1 m) infiltrates into a porous CuO nanowires film (PCNF), electric power of ≈0.5V and ≈1 µA are produced for 25 min. Moreover, the PCNF shows good practicability by generating electricity using various ambient water, turning on LEDs, and being fabricated as a curved one.

Techno-Economic Analysis and Environmental Impact of Electric Buses

Electric vehicles are a leading candidate in the clean energy market. This paper aims to analyse the feasibility of the deployment of electric buses (EB) based on the existing bus routes in Brunei, by the use of life cycle cost analysis and the analysis of the parameters that influence the overall life cycle cost. The findings from the study revealed that EB are significantly more expensive than diesel buses (DB), with their acquisition and maintenance costs contributing substantially to their overall life cycle cost. In order to promote EB deployment, the government needs to look simultaneously into providing subsidies for EB and imposing taxes on DB, the provision of charging infrastructure, and ensuring maintenance capability, as well as increasing the current subsidised diesel price. It was also shown that increasing the cost of diesel to the average US diesel price of USD$3.101/L, an initial subsidy of USD$67,586 towards the purchase of EB, and a tax of USD$67,586 for the purchase of DB would allow EB to compete in the market, with the amount of tax and subsidy being gradually reducible over time, as EB and battery technology becomes more mature. From an environmental perspective, the emissions from EB come out higher than the emissions from DB. The efficiency of electric power generation needs to be enhanced, and renewable energy sources and the adoption of carbon capture technology need to be explored in order to exploit the full benefit of EB and ensure more environmentally sustainable bus operation.

Passive/active photovoltaic-thermal (PVT) system implementing infiltrated phase change material (PCM) in PS-CNT foam

Power efficiency of Photovoltaic (PV) cell reduce due to the warm up under solar irradiation. Several passive and active cooling experimental investigations are implemented on a PV cell in this study to find out their impacts on the electrical and thermal performance of a PVT system. All experiments are performed in a solar simulator under a wide range (regular-concentrated) of solar radiation power (800–1700 W m−2). PCM is used as passive coolant system, whereas to overcome the malfunction of PCM, due its low thermal conductivity, PCM is infiltered in a special heat conductive foam (PS-CNT foam). Results revealed that PCM-composite can diminish the PV-cell temperature up to 6.8% and increase electrical effciciency up to 14.%. Separately, active cooling are examined by passing water with the range of 0.3–1 lit.min−1 through a cooling block mounted undre the PVT system. In the active cooling system, due to the efficient electrical power generation as well as harvesting thermal energy, the system performance is much higher than passive PVT systems. The best PVT system examined in this study is the PV-PCM-composite system which its energy efficiencies in the active cooling is 66.8–82.6%.

Анализ показателей эффективности двухтопливных парогазовых установок с параллельной схемой работы

The paper examines the effectiveness of dual-fuel combined-cycle plants that operate with different initial steam parameters. It presents analysis results of the plant`s technical and economic parameters, capital expenses evaluation, and the possibility of the examined technology be implemented in the discussed region. The calculation results have shown that the use of a dual-fuel combined-cycle plant with the parallel scheme of operation allows to increase electrical power generation efficiency by an average of 22% in comparison to a coal power plant mode of operation. Besides, the transition to the combined-cycle plant mode allows to cut back on specific equivalent fuel consumption by 21%. Transition to the supercritical steam parameters increases the efficiency parameters of the power generating unit by an average of 2%.

Additive Manufacturing of Solid Oxide Fuel Cell (AM-SOFC) Stacks

The Solid oxide fuel cell (SOFC) is an electrochemical energy-conversion device which offers tremendous promise for delivering high electrical efficiency and significant environmental benefits in terms of fuel flexibility, as well as clean and efficient electric power generation. However, the state-of-the-art SOFC cell currently involves expensive and time-consuming multi-step manufacturing processes including tape casting, screen printing, shaping, lamination, sintering, etc. In addition, SOFC stacks are usually assembled with pre-fabricated cells, metal interconnects, and glass-ceramic sealing. These indispensable components add extra layers of complexity to the stack structure’s fabrication and maintenance, significantly increasing the size and weight of the final product. These intrinsic limitations on the current planar stack cannot be easily removed by traditional manufacturing processes. However, as additive manufacturing (AM) technologies start to mature and show increasing market penetration, it lends itself admirably to breaking the limits on high-power-density SOFC stack manufacturing. Storagenergy’s SOFC project is developing an all-ceramic AM-SOFC by a high-speed AM process of multiple materials. The developed technology allows the fabrication of robust and compact AM-SOFC stacks with unique features such as monolithic architecture with embedded novel micro flow channels and thinner elements (anode, cathode, electrolyte, and interconnect) by only three production steps (3D printing, sintering, and catalyst infiltration) without the need for subsequent assembly of individual layers and indispensable components. This simplification of the fabrication process is expected to reduce the cost of the SOFC and increase SOFC design flexibility and manufacturing reliability.

Harvesting contact-separation-compression vibrations using a flexible and compressible triboelectric generator

Progress in renewable, portable, and sustainable energy sources for harvesting energy from ambient environments is of great importance in the Internet of Things (IoT) society. Recently, triboelectric nanogenerators (TENGs) have been proposed and developed by many research groups to convert mechanical energy, such as pressure, bending, stretching and vibration, into electrical energy at any given location and time. We must make clear relationships between contact-separation-compression process with external loads and electric performance of triboelectric generators, and should carefully clarify effects of separation-distance and separation-velocity on output voltage, and key parameters for the output voltage in more details.Here, we propose and develop a simple polymer-based flexible and compressible generator that employs a tribological process for sustainable energy such as wind, wave, current, and mechanical vibration. The proposed triboelectric nanogenerator, which is called FC-TENG (a flexible and compressible type of triboelectric nanogenerator), consists of laminated dielectric elastomer sheets and copper films. The characteristics of the working mechanism of the FC-TENG in the contact, separation, and compression modes are fundamentally elucidated in the vibration test, and it is found that the output voltage depends not on the separation distance but the separation velocity. The vertical strain rate of the FC-TENG is a key factor that influences efficient electrical power generation. A suitable initial separation distance must be selected to create a triboelectric potential layer and to achieve high electrical performance. Moreover, a theoretical model is proposed as a design tool, and the resulting average, maximum, and minimum output voltages exhibited good agreement with the experimental data. The proposed FC-TENG could act as a useful device for sustainable energy harvesting.

하이브리드 전기추진시스템용 SEIG 및 PMSG의 출력 비교 분석

This paper deals with comparison analysis on output characteristics of two types of generators for a hybrid electric propulsion system (H-EPS) consisted of an engine-driven system and an electric driven system. Main components of H-EPS consists of two parts. One is a power generation system with efficient electric power generation performance even in a variable speed condition of a diesel main engine, and the other is a charging system with efficient storage performance of the electric energy. The generator of power generation system for the H-EPS is required to have the highest reliability and stability, despite isolation at sea and poor engine room environment. In addition, it should be compact structure with high output and lightweight in relation to volume. For the purpose of this study, we selected a self excited induction generator (SEIG) and a permanent magnet synchronous generator (PMSG) for H-EPS, and analyzed their output characteristics through several experiments. By comparing the experimental results, it was clear that PMSG exhibited better performance than SEIG as the generator for H-EPS.

Improving the efficiency and reliability of electric power generation at incineration plants

The article deals with the problem of waste disposal and, accordingly, landfills in the Moscow Region, which have now become the number 1 problem for the environment in Moscow and the Moscow Region. To solve this problem, incineration plants (IP) will be established in the near future. 4 plants will be located in the Moscow Region that will be able to eliminate 2800 thousand tons of waste per year. Burning of waste results in formation of slag making 25% of its volume, which has a very high temperature (1300.1500°C). An arrangement is considered, in which slag is sent to a water bath and heats the water to 50.90°C. This temperature is sufficient to evaporate any low-temperature substance (freons, limiting hydrocarbons, etc.), whereupon the steam of the low-temperature working medium is sent to a turbine, which produces additional electricity. The creation of a low-temperature thermal power plant (TPP) increases the reliability of electricity generation at the IP. The operation of low-temperature TPPs due to the heat of slag is very efficient, their efficiency factor being as high as 40.60%. In addition to the efficiency of TPPs, capital costs for the creation of additional devices at the IP are of great importance. Thermal power plants operating on slag are just such additional devices, so it is necessary to minimize the capital costs of their creation. In addition to equipment for the operation of TPPs, it is necessary to have a working medium in an amount determined by calculations. From the wide variety of working media, which are considered in the article, it is necessary to choose the substance with the lowest cost.

Analysis of the compressorless combined cycle gas turbine unit performance efficiency in district heating systems

Nowadays, thermodynamic cycles are actively studied, in which pure oxygen and fuel are fed into a combustion chamber, and a temperature of a working fluid is regulated by the supply of carbon dioxide and/or water vapor. These cycles are called “oxygen-fuel”. They allow easy to separate CO2, resulting from a fuel combustion, from the working fluid and remove it from the cycle in its pure form. In addition, it has already been shown that an efficiency of electric power generation of such cycles is approaching the best known technologies. However, the efficiency of cogeneration of electricity and heat is more important for many energy systems, especially for Russian, in comparison with the efficiency of electricity generation. The main goal of the study was to analyze the thermal efficiency for cogeneration of electricity and heat of one of the options for the implementation of oxygen-fuel cycles - compressorless combined cycle gas turbine (CCGT) units. A mathematical model of the compressorless CCGT units was developed, which allows to study the thermal performance in a wide range of operating modes. It is conventionally accepted that the system requires a maximum power for power supply of 300 MW, and a maximum power for heat supply of 600 MW. It is assumed that 300 MW of electricity is constantly supplied to the network. In addition, the heat load is provided according to the standard schedule depending on the ambient temperature, and at the same time an averaged data on the temperature of atmospheric air for central Russia over a tenyear period is accepted. The comparison is made with a steam turbine CHP plant and a CCGTCHP plant. The results of the comparison showed a significant advantage of the compressorless CCGT unit.

Experimental investigation of evaporative cooling for enhancing photovoltaic panels efficiency

This paper presents the results of an experimental study on the effect of cooling of solar photovoltaic (PV) panels by evaporative cooling. The evaporation latent heat was utilized to absorb the generated heat from the body of a PV module to reduce its temperature. A simple and effective experimental setup was designed, constructed and tested under outdoor conditions. The back surface of a PV panel was wetted and exposed to surrounding. Water was supplied to the back of the PV panel from a tank by gravity. A series of experiments under real conditions of Riyadh city showing the effectiveness of the method were conducted and analyzed. More than 20 °C reduction in PV panel temperature and around 14% increment in electrical power generation efficiency were achieved compared with a referent PV panel. Uncertainty analysis was performed to assess the accuracy of the results.

Bioenergy recovery analysis from various waste substrates by employing a novel industrial scale AD plant

ABSTRACTIn this novel industrial scale case study, the bioenergy recovery based on sole and mixed cow-buffalo (CBM) and potato waste (PW) substrates has been analyzed in real time, i.e., on-site on a full-scale operational anaerobic digestion (AD) plant. The plant employed in this study is a novel design, consisting of tri-digesters connected via an underground upflow anaerobic sludge blanket (UASB) type lagoon allowing it to function as a continuous-flow reactor. The system has been further equipped with CSTR, microwave heating, gas scrubbers, compression, and storage systems. The highest energy recovery readings were 123.9 m3/1,000 kg, 77 m3/1,000 kg, and 151.6 kWh/1,000 kg in terms of biogas, bio-methane, and electricity generated, respectively, with 75:25 ratio of CBM:PW. Operating with 100% CBM, yields of 79.9 m3/1,000 kg, 47 m3/1,000 kg, and 95 kWh/1,000 kg were obtained. The percentage of recovery in bio-methane production increased on using the mixed substrates, but it was the lowest with a 25:75 ratio of CBM:PW. The electrical power generation efficiency was found to be significantly increased, but not distinctively with the plant aggregate power rating that was probably associated with the variable quality of biogas which was fed to the power generator. A linear regression analysis had shown a significant and positive correlation between the rate of VS removal and biogas yield.

Control of ferroelectrics polarization for increasing of alternative energy device’s efficiency coefficient

A plant, developed with the use of ferro-piezoelectric ceramics for generation of electric power, is studied in the article. The use of electrochemical generator in the plant makes it possible to increase the efficiency of electric power generation by means of polarization of ferro-piezoelectric ceramics control. Polarization control is proved by a mathematical model. Consumption of 1 joule electric power, using mechanical power, generates 3,5...5 joule of electric power output. Efficiency factor of the power plant is about 50....55 percent and depends on ceramics modification and electric circuit.