High Efficiency Power Generation Research Articles

Stack performance classification and fault diagnosis optimization of solid oxide fuel cell system based on bayesian artificial neural network and feature selection

Solid oxide fuel cell (SOFC) has attracted much attention because of its high efficiency and silent power generation, and can be applied to the field of fuel cell-powered unmanned boats. However, a fuel deficit failure in the system can lead to reduced stack performance, reducing the reliability of SOFC applications in the field of unmanned boats. Therefore, this paper proposes an efficient breakdown diagnosis model for SOFC system fault diagnosis. Firstly, Bayesian artificial neural network is constructed by using the best feature data subset after Relief-F combined with minimum Redundancy Maximum Relevance algorithm feature selecting. Secondly, the correct diagnosis rate under different number of optimal features is calculated, and the best feature combinations are combined to verify. Finally, the particle swarm algorithm selects the optimal hidden neuron count to optimization model. Experimental findings suggest that for correct diagnosis rate, the breakdown diagnosis model based on the optimal number of 3 features can reduce the training time and maintain high accuracy compared with the use of all 34 features. This research result provides a feasible way for the fault diagnosis application of SOFC system power generation in the field of unmanned boats.

Enhanced thermoelectric performance of graphene [formula omitted] junction nanoribbon

We study the thermoelectric transport of the graphene p−n junction under the perpendicular magnetic field. The Seebeck coefficient Sc, the thermoelectrical figure of merit ZT and the power-generation efficiency η are obtained by the Landauer–Büttiker formula combined with the nonequilibrium Green’s function method. Compared to the perfect graphene system, the graphene p−n junction has a zero-transport coefficient plateau (or the transport gap). The sudden jump of the transmission coefficient near the transport gap edge lead to very larger peaks of the Sc and ZT. Especially in the presence of a magnetic field, the perpendicular magnetic field applied to the p−n junction strongly suppresses the conductance, and enhances the Seebeck coefficient Sc and increases the ZT. Moreover, it is found that the Seebeck coefficient Sc and ZT are strongly dependent on the applied perpendicular magnetic field ϕ, the potential drop in the center region of the p−n junction and the center region length M of the p−n junction. This means that the thermoelectric performance of the graphene p−n junction can be easily regulated by changing the magnetic field and the center region lengths of the p−n junction. Finally, the power-generation efficiency η of the graphene p−n junction as a power generator is calculated. It is found that when the Carnot power-generation efficiency is greater than 30%, ZTM can still be greater than 10. The large ZTM value also maintains a high power-generation efficiency, which indicates that the graphene p−n junction has potential applications as thermoelectric devices.

Thermoelectric system investigation with the combination of solar concentration, greenhouse and radiative cooling for all-day power generation

Thermoelectric generator (TEG) can utilize solar heating to generate electricity without any fossil fuel consumption. However, conventional solar driven TEG fails to achieve high efficiency power generation for 24-h, due to the losing of solar concentration at the hot end and additional cooling capability at the cold end. Therefore, a novel TEG system with the combination of solar concentration, greenhouse and radiative cooling is proposed. With the aim to significantly increase the temperature of hot end, a dish-type concentrator is introduced to concentrate solar radiation and a greenhouse seals up heat. Radiative cooling panel is used to decrease the temperature of cold end, which can realize temperature differences of TEG at night. The eight-day outdoor experimental test indicates that the thermoelectric system achieves a maximum temperature difference of 47.5 °C and a voltage output of 1293.8 mV. The system attains the average power outputs of 3.6 W/m2 on sunny and 0.16 W/m2 on cloudy. Moreover, even at the nights of high humidity and low temperature, the system also achieves a maximum power output of 0.08 W/m2, which can enable continuous power generation throughout the day. This innovative TEG system presents a viable strategy for powering small-scale devices in remote areas.

Process system simulation of coupled pyrolysis disposal of domestic waste in coal-fired boiler and pilot study on dioxin emission

The disposal of domestic waste has become a critical and costly problem. Incineration for power generation is currently the primary domestic waste treatment method. Due to its small capacity and low parameters, domestic waste incineration is generally uneconomical and associated with significant risks to public health and environmental safety. The coal-fired power plants are generally characterized with huge capacity and high parameters, consequently resulting in much higher power generation efficiency with lower cost emission control. This indicates that co-disposal of domestic waste using existing coal-fired units may significantly reduce its treatment costs associated with the improvement of utilization efficiency and environmental risks. Base on this, a highly-flexible coupling of pyrolysis-pretreated solid waste in pulverized coal furnace is proposed in this paper, and field tests and numerical simulations have been carried out separately according to the process route. The results show that after coupling with pulverized coal boiler, domestic waste pyrolysis pretreatment unit can operate self-sustainably without external energy supply and the process route is feasible. Furthermore, the coupled co-combustion of domestic waste pyrolysis products and pulverized coal was simulated by fluent software. Compared with pure pulverized coal combustion, mixing domestic waste pyrolysis products can promote pulverized coal combustion in the furnace and help the pulverized coal boiler to burn stably at low load. The emission concentrations of NOx at the outlet of the furnace are 530 ppm, 545 ppm and 478 ppm respectively when pulverized coal is burned purely and mixed with 100 t/d and 200 t/d domestic waste. the NOx emissions could be reduced to a certain extent by mixing domestic waste. On the basis of previous research, the field test of coupling disposal of domestic waste by pulverized coal boiler was carried out, and the dioxin concentration in flue gas and fly ash was tested emphatically. The results show that when the amount of waste is less than 4 %, the concentration of dioxin in flue gas is 0.0107 ng TEQ/m3, which meets the latest emission standard of air pollutants in Shanghai coal-fired sludge power plant of 0.02 ng TEQ/m3. Low proportion of domestic waste will not increase the production and emission of dioxins. These studies show that it is feasible and promising to treat municipal solid waste with low coupling ratio by using existing coal-fired units.

Synergistic Bulk and Surface Engineering for Expeditious and Durable Reversible Protonic Ceramic Electrochemical Cells Air Electrode.

Reversible protonic ceramic electrochemical cells (R-PCECs) offer the potential for high-efficiency power generation and green hydrogen production at intermediate temperatures. However, the commercial viability of R-PCECs is hampered by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) within conventional air electrodes operating at reduced temperatures. To address this challenge, this work introduces a novel approach based on the simultaneous optimization of bulk-phase metal-oxygen bonds and in-situ formation of a metal oxide nano-catalyst surface modification. This strategy is designed to expedite the ORR/OER electrocatalytic activity of air electrodes exhibiting triple (O2-, H+, e-) conductivity. Specifically, this engineered air electrode nanocomposite-Ba(Co0.4Fe0.4Zr0.1Y0.1)0.95Ni0.05F0.1O2.9-δ demonstrates remarkable ORR/OER catalytic activity and exceptional durability in R-PCECs. This is evidenced by significantly improved peak power density from 626 to 996mW cm-2 and highly stable reversibility over a 100-h cycling period. This research offers a rational design strategy to achieve high-performance R-PCEC air electrodes with superior operational activity and stability for efficient and sustainable energy conversion and storage.

Design and Control Strategy of an Integrated Floating Photovoltaic Energy Storage System

Floating photovoltaic (FPV) power generation technology has gained widespread attention due to its advantages, which include the lack of the need to occupy land resources, low risk of power limitations, high power generation efficiency, reduced water evaporation, and the conservation of water resources. However, FPV systems also face challenges, such as a significant impact from aquatic environments on the system’s stability and safety and high operational and maintenance costs, leading to large fluctuations in the grid-connected power output. Therefore, it is necessary to integrate energy storage devices with FPV systems to form an integrated floating photovoltaic energy storage system that facilitates the secure supply of power. This study investigates the theoretical and practical issues of integrated floating photovoltaic energy storage systems. A novel integrated floating photovoltaic energy storage system was designed with a photovoltaic power generation capacity of 14 kW and an energy storage capacity of 18.8 kW/100 kWh. The control methods for photovoltaic cells and energy storage batteries were analyzed. The coordinated control of photovoltaic cells was achieved through MPPT control and improved droop control, while the coordinated control of energy storage batteries involved a droop charge–discharge mode, a constant-voltage charging mode, and a standby mode. The simulations were realized in MATLAB/Simulink and the results validated the effectiveness of the coordinated control strategy proposed in this study. The strategy achieved operational stability and efficiency of the integrated photovoltaic energy storage system.

High‐Performance Self‐Powered Flexible Thermoelectric Device for Accelerated Wound Healing

AbstractElectric signal accelerates full‐thickness wound healing in the clinic, which is usually generated by a large power generation system and requires delicate control by authorized personnel. Here, a self‐powered flexible and biocompatible thermoelectric device with exceptionally high power generation efficiency is developed. It generates 10 mV voltage at a temperature gradient of 10 K, outperforming all reported flexible thermoelectric devices. Accordingly, it can directly and efficiently convert the omnipresent heat in the skin to electricity at the microvolt level. The output electricity activates and upregulates the expression of Piezo1‐mediated pathways that are associated with tissue regeneration, accelerating the cell migration and proliferation in vitro and healing the wound 4 days faster in vivo. Importantly, the thermoelectric device fast‐heals the wound without involving any additional electric circuit such as an amplifier. These advantages will revolutionize the designing of self‐powered wearable bioelectronics for diagnosing, monitoring, and treating various pathological conditions employing the skin heat.

High-Performance Reversible Solid Oxide Cells for Powering Electric Vehicles, Long-Term Energy Storage, and CO2 Conversion.

The rapid population growth coupled with rising global energy demand underscores the crucial importance of advancing intermittent renewable energy technologies and low-emission vehicles, which will be pivotal toward carbon neutralization. Reversible solid oxide cells (RSOCs) hold significant promise as a technology for high-efficiency power generation, long-term chemical energy storage, and CO2 conversion. Herein, RSOCs were, for the first time, studied to power electric vehicles. Based on our experimental results, an ideal RSOC stack was established with reasonable assumptions. Subsequently, through analysis and comparison of important merits, such as power densities, energy densities, charging/refueling time, and fuel economy of RSOC-based electric vehicles (RSOCEVs), conventional internal combustor vehicles (ICEVs), and battery-based electric vehicles (BEVs), the advantages and prospects of RSOCEVs were highlighted. Our H2-H2O RSOCs exhibit high electrochemical performances in both fuel cell (peak power density = 1.6 W cm-2 at 750 °C) and electrolysis modes (current density = 2.0 A cm-2 at 1.3 V and 750 °C), along with durable reversible operation under a wide range of conditions. In CO-CO2, our RSOCs achieved excellent performance in fuel cell mode (peak power density = 0.68 cm-2 at 700 °C). Furthermore, a world record current density of 3.4 A cm-2 at 1.5 V and 750 °C was achieved in the CO2 electrolysis mode. Moreover, an assessment of the CO2 electrolysis efficiency was conducted, offering insights for establishing energy storage strategies and mitigating CO2 emissions. Therefore, the RSOC technology has the potential to assume a central role in a future energy system with abundant renewable power generation while mitigating the CO2 released from fossil fuels.

Phase-Transition-Promoted Thermoelectric Textiles Based on Twin Surface-Modified CNT Fibers.

With the fast development of new science and technology, wearable devices are in great demand in modern human daily life. However, the energy problem is a long-lasting issue to achieve real smart, wearable, and portable devices. Flexible thermoelectric generators (TEGs) based on thermoelectric conversion systems can convert body waste heat into electricity with excellent flexibility and wearability, which shows a new direction to solving this issue. Here in this work, polyethylenimine (PEI) and gold nanoparticles (Au NPs) twin surface-modified carbon nanotube fibers (CNTFs) were designed and prepared to fabricate thermoelectric textiles (TET) with high performance, good air stability, and high-efficiency power generation. To better utilize the heat emitted by the human body, microencapsulated phase change materials (MPCM) were coated on the hot end of the TET to achieve the phase-transition-promoted TET. MPCM-coated TET device could generate 25.7% more energy than the untreated control device, which indicates the great potential of the phase-transition-promoted TET.

Structural design and performance optimization of Co/Bi0.5Sb1.5Te3 artificially tilted multilayer thermoelectric devices

Due to the complex principle of transverse thermoelectric conversion and the specific preparation technique, there are few studies on the three-dimensional structure of artificially tilted multilayer thermoelectric devices (ATMTDs), which also lags the development of ATMTDs for applications. It is necessary to optimize the three-dimensional structure of ATMTDs to satisfy the requirements of practical applications in thermal sensors, power generation, refrigeration, and so on. In this paper, Co/Bi0.5Sb1.5Te3 ATMTDs are selected as the research object. A COMSOL Multiphysics simulation analysis and experimental validation are used to establish the relationship between the structure and its thermal sensing, power generation, and cooling performance. Results indicate that increasing the length significantly improves the thermal response voltage. Increasing the length and width enhances output power while increasing the height of the ATMTD improves the thermoelectric conversion efficiency. The effective cooling temperature improves when the heat transfer area decreases or the height increases. Based on these findings, flexible thin-film thermal sensors, high-efficiency waste heat power generation tubular devices, and high-efficiency refrigeration pyramidal devices are designed. The results will lead to effective optimization and promote the multi-field application of ATMTDs.

Effect of steam reinjection mass flow rate on the SOFC–GT system with steam reinjection

A solid oxide fuel cell (SOFC) is regarded as the first choice of high-efficiency and clean power generation technology in the 21st century due to its characteristics of high power generation efficiency and low pollutant emission. In this paper, hydrogen is used as a fuel for SOFCs using the EBSILON platform. A sensitivity analysis of the solid oxide fuel cell–gas turbine (SOFC–GT) system with steam reinjection is carried out to investigate the effect of the steam reinjection mass flow rate on the improvement of the electrical efficiency of the system and on the values of the other parameters. The results show that the variation in the steam reinjection mass flow rate has an effect on other parameters. Changes in several parameters affect the electrical efficiency of the system, which reaches 74.11% at a pressure ratio of 10, SOFC inlet temperature of 783.15 K, turbine back pressure of 70 kPa, and steam reinjection mass flow rate of 6.16 kg/s. Future research can optimize the overall parameter selection of the system in terms of economy and other aspects.

Improving MFC efficiency in power generation and COD removal by using protic ionic liquid in MWCNT-CS-2-aminothiazole-SO3H nanoparticle-infused sulfonated PES

This study exhibits a novel nanofiller, functionalized multi-walled carbon nanotube (MWCNT)/chitosan (CS) by 2-aminothiazole/SO3H. This synthesized nanofiller was incorporated with a fabricated sulfonated polyethersulfone (SPES) to manufacture a composite proton exchange membrane (PEM), SPES/MWCNT-CS-2-aminothiazole-SO3H. The composite membranes were fabricated by different percentage amounts of nanofiller (0.1 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%). The trait comparison of SPES/MWCNT-CS-2-aminothiazole-SO3H, SPES, and Nafion 117 membrane is performed to investigate their application in the microbial fuel cell (MFC). The fabricated composite membrane SPES/MWCNT-CS-2-aminothiazole-SO3H 0.5 wt% illustrated superior water uptake (WU) of 90.41 %. Moreover, the maximum power density (PD) (66.04 mW.m−2) was produced by SPES/MWCNT-CS-2-aminothiazole-SO3H 0.5 wt%, which demonstrated a considerable increase (approximately 20 times) compared to SPES (3.19 mW.m−2). Furthermore, the power density generated by the Nafion 117 membrane was 15.78 mW.m−2. In addition, the statistics in MFC usage presented that prepared composite membrane combined with MWCNT-CS-2-aminothiazole-SO3H 0.5 wt% had the optimum chemical oxygen demand (COD) removal, and the coulombic efficiency (CE), with 90.46 % and 80.68 %, respectively. Due to the high efficiency and remarkable power generation achieved by the MFC with SPES/MWCNT-CS-2-aminothiazole-SO3H 0.5 wt%, this modified membrane can be considered as a promising cost-effective alternative separator in MFC.

Energy analysis and exergy analysis study of a novel high-efficiency wind-hydrogen storage and power generation polygeneration system

This study proposes a novel wind-hydrogen coupled poly generation system. The system consists of alkaline electrolyzers, fuel cells (FC), organic Rankine cycle (ORC), hydrogen compressors, hydrogen turbines, pumps and storage tanks. By the multistage utilization of the waste heat, more electricity, hydrogen and heat energy are provided to the user, and improve the operating conditions of the equipment. The effects of multiple parameters on the system's exergy efficiency and destruction are discussed. The economic and environmental of the system are evaluated. The results show that rising the electrolyzer operating temperatures and ambient temperatures can slightly improve the system's exergy efficiency. Increasing FC operating temperature, the exergy efficiency of FC-ORC and the system rapidly increased to 51.91 % and 58.83 %, respectively. By increasing the hydrogen storage pressure, the system exergy efficiency increases by 6.87 %. The static payback period of the poly generation system is 7.3 years.

Data–Driven Adaptive Fault–Tolerant Control for Floating Offshore Wind Turbines

Floating offshore wind turbines have increased in popularity owing to their adaptability for deep-water applications and high power generation efficiency. The control of floating offshore wind turbines, on the other hand, is very complex. The main challenges are the difficulty in precisely modelling floating offshore wind turbines and the higher failure rate of components. As a consequence, this study proposes a model-free adaptive fault-tolerant control system for blade root moment sensor failures. A model-free adaptive control approach is used to construct an individual pitch controller and a fault compensation to avoid mathematical modelling of floating offshore wind turbines. The proposed fault-tolerant control technique removes the need for fault detection and isolation by converting the fault dynamic compensation process into a real-time control issue for nonlinear systems. The fatigue, aerodynamics, structures, and turbulence code simulates and tests the proposed control strategy, and the results show that the proposed strategy can not only keep the wheel bearing load balanced but also reduce the movement of the floating platform and significantly reduce the bearing load of the floating offshore wind turbines. Furthermore, the output power is closer to the rated power, proving the strategy’s high fault tolerance in the face of repeated blade root moment sensor faults.

Characterization of Ca-doped YCoO3 Perovskite-type oxide as cathode for solid oxide fuel cells

Solid oxide fuel cell (SOFC) uses solid oxide as an electrolyte and has a high-power generation efficiency. One of the major problems in the development of SOFC is the side reaction that occurs at the interface between the electrode and the electrolyte. (Y, Ca)CoO[Formula: see text] materials were evaluated as a new air electrode material to replace the conventional (La, Sr)CoO3 materials. Y[Formula: see text]Ca[Formula: see text]CoO[Formula: see text] has good compatibility with Y-stabilized ZrO2 (YSZ) electrolyte. In addition, the power generation performance was equal to or better than the conventional SOFC cells.

Energy and exergy analysis of a thermoelectric generator system for automotive exhaust waste heat recovery

Thermoelectric generators are a viable solution for recovering and producing energy utilizing wasted energy in automotive exhaust. Exergy analysis can help identify irreversible losses that occur during the transfer of exhaust energy, which is essential for comprehending and developing exhaust thermoelectric generator systems. In this study, we proposed a model based on thermodynamic of the exhaust thermoelectric generator and conducted energy and exergy analyses. The results indicate that convective heat transfer exergy loss and PN junction thermal conductivity exergy loss are the primary exergy losses of the exhaust thermoelectric generator, accounting for more than 52.0 % of the total. Increasing the temperature of exhaust can boost the performance of systems, but it may also reduce the proportion of available energy obtained by the cooling water. When the exhaust heat transfer coefficient is increased to 300, the convective exergy losses of the exhaust can be reduced to 17.6 %, resulting in an overall exergy efficiency of 38.8 %. Furthermore, by increasing the exhaust flow rate from 10 g/s to 50 g/s, the power generation capacity has increased by a factor of 6.87, with little change in exergy losses. These findings are valuable for developing high-efficiency exhaust power generators.

Biomass-derived multifunctional nanoscale carbon fibers toward fire warning sensors, supercapacitors and moist-electric generators

Nowadays, great effort has been devoted to designing biomass-derived nanoscale carbon fibers with controllable fibrous morphology, high conductivity, big specific surface area and multifunctional characteristics. Herein, a green and renewable strategy is performed to prepare the biomass-based nanoscale carbon fibers for fire warning sensor, supercapacitor and moist-electric generator. This preparation strategy thoroughly gets over the dependence of petroleum-based polymeride, and effectually improves the energy storage capacity, sensing sensitivity, humidity power generation efficiency of the obtaining biomass-based carbon nanofibers. Without the introduction of any active components or pseudocapacitive materials, the specific capacitance and energy density for biomass-based nanoscale carbon fibers achieve 143.58 F/g and 19.9 Wh/kg, severally. The biomass-based fire sensor displays excellent fire resistance, stability, and flame sensitivity with a response time of 2 s. Furthermore, the biomass-based moist-electric generator shows high power generation efficiency. The output voltage and current of five series connected and parallel-connected biomass-based moist-electric generators reaches 4.30 V and 43 μA, respectively. Notably, as the number of biomass-based moist-electric generators in series or parallel increases, the overall output voltage and current of the device system have a linear relationship. This work proposes a self-powered fire prediction system based on nanoscale carbon fibers that integrates sensing, power generation, and energy storage functions.

A novel high-efficient continuous power generation device employing thermally regenerative electrochemical cycle

The significant attention garnered by thermally regenerative electrochemical cycles (TRECs) is due to their remarkable heat to electricity efficiency in harnessing low-grade heat from energy conversion systems, by addressing the prominent energy challenges associated with waste heat recovery and refrigeration. For a single unit, TREC undergoes four distinct working processes, discharging, heating, charging, and cooling to complete a closed-loop thermodynamic cycle for energy conversion. However, this single unit cannot produce electricity continuously, leading to intermittent power output and significant heat consumption during the heating phase. To address this limitation, current research introduces a novel concept by employing two rotating layers of TREC units, aimed at overcoming the associated problems of discontinuous power output. This system can notably improve energy conversion efficiency by realizing uninterrupted power output and curtails heat absorption. In this work, high-performance TREC device's structure design, working principle, operational processes, and mathematical models are described in detail. Moreover, based on numerical calculations, impact of various key factors including the number, height, and radius of units were thoroughly examined and it was observed that the number and height of units have a substantial impact on the performance of the TREC device. The findings show that, under specific conditions, the device is capable of generating 12.876 mJ of net work at a current density of 124 mA/g. Furthermore, the TREC device achieves an impressive heat-to-electricity efficiency of 10.32 %, equivalent to 68.78 % of the Carnot cycle efficiency. This innovative rotating concept offers a promising solution for achieving continuous and highly efficient energy output from the TREC device, further enhancing its practical application viability.

High-efficiency segmented thermoelectric power generation modules constructed from all skutterudites

High-efficiency segmented thermoelectric power generation modules constructed from all skutterudites

Nonlinear control of permanent magnet synchronous generators (PMSG) using feedback linearization

This paper presents nonlinear control of permanent magnet synchronous generators using feedback linearization. Permanent-magnet synchronous generators (PMSGs) are commonly used for small variable-speed wind turbines to produce highefficiency, high-reliability, and low-cost wind power generation. To eliminate the effects of nonlinearity caused by magnetic saturation, an input–output feedback linearization technique is applied to design the high-performance nonlinear current controllers. With this nonlinear control scheme, output voltage responses become faster than those in cascade control structures. Thus, the size of the output filter capacitor can be much reduced since fast voltage control is feasible. As with usual PWM power converters, in addition, the input current is regulated in a sinusoidal waveform. The proposed control scheme provides the wind generation system with the maximum efficiency and high dynamic performance.