Electric Power Efficiency Research Articles

A Modelling of 500 Kv Long Transmission Line and Fault Detection Using Inverse Definite Minimum Time Over Current (IDMT O/C) relay

As electricity demand increases day by day due to economic growth, the process of transmitting efficient electrical power is vital. Thus, a power simulation study is required to determine the mechanism of the transmission line, and possible faults that occurred in the transmission line system. On a daily basis, single line to ground fault (L-G), double line to ground fault (2L-G), and triple line to ground fault (3L-G) are the faults that normally occur in the long transmission line system. In this project, a model of a 300km/500 kV EHV transmission line consisting of a three-phase source, distribution line, and load is simulated using MATLAB software. When the L – G fault is applied, the voltage is diminished to zero and upon fault clearance, the R – G line produced overvoltage and overcurrent by 518.9 kV and 1889 A, which increased about 46.83% and 15.67% compared to normal lines of Y – G and B – G at 353. kV and 1633 A. Then, for the 2L – G fault, again the voltage is reduced to zero and when fault clearance occurred, the R – G and Y – G lines experienced overvoltage and overcurrent at 570.4 kV and 708.5kV, which showed more than 60% transient compared to normal line B-G at 353.4 kV. In Contrast, the 3L – G fault causes all transmission lines to experience overvoltage and overcurrent at different times and can damage the whole transmission system. Thus, to reduce the severe impact of fault, the Inverse Definite Minimum Time Over Current (IDMT O/C) relay protection is installed in the line model.

Optimal design of unimorph and segmented piezoelectric cantilevers for energy harvesting

Abstract Segmented piezoelectric layers, instead of a single layer covering the entire length of the supporting cantilevers, may optimise the design of PZT harvesters from various perspectives. Indeed, a suitable selection of the length and position of the piezoelectric patch may increase their effectiveness, save piezoelectric material, and reduce costs from the life-cycle perspective of device disposal. A linear reduced-order model (ROM) for unimorph and stepped piezoelectric energy harvesters with a proof mass is developed to evaluate the power output under transversal ground excitation. The electromechanical PDEs derived by Hamilton’s principle are transformed into a system of uncoupled ODEs using the exact bending modes of an equivalent piecewise uniform, multilayered Bernoulli–Euler beam. The model is validated comparing its analytical voltage-to-acceleration transfer function with that experimentally identified for various resistive loads and tip masses under harmonic excitation. Such a validated ROM allows for fast and accurate computation of the sensitivity of frequency transfer functions with respect to patch length and position, highlighting the optimal combinations of parameters to maximize voltage, electrical power, or piezoelectric material efficiency.

Broadband wireless battery-free acoustic identification tags for high data-rate underwater backscatter communication.

Developing persistent and smart underwater markers is critical for improving navigation accuracy and communication capabilities of autonomous underwater vehicles (AUVs). A wireless acoustic identification tag, which uses a piezoelectric transducer tuned in the broadband ultrasonic range (200-500 kHz), was experimentally demonstrated to achieve highly efficient power transfer (source-to-tag electrical power efficiency of >2% at 6 m) and concurrent high data rate and backscatter level communication (>83.3 kbit s-1, >170 dB sound pressure level at 6 m) with potential operating range ≈ 10 m based on analytical extrapolations. Parameter selection considerations dictated by the desired range and data-rate requirements in communication are presented. The transducer piezoelectric element selection, impedance matching approach, and simulation-based circuit optimization for frequency multiplexed operation are also detailed. Experimental tests benchmarking performance sensitivity to source and tag misalignment are introduced and implications for AUV operations are discussed.

Enhancing room temperature thermoelectric efficiency in zigzag phosphorene nanoribbon junctions through Quasi-Flat impurity bands

Abstract In this study, a novel approach has been utilized to Please specify the corresponding author.explore the room temperature thermoelectric properties of zigzag phosphorene nanoribbon-based monolayer-bilayer-monolayer junctions. To achieve thermoelectric properties at room temperature, a quasi-flat energy band with limited width is required. It has been demonstrated, for the first time, that such bands can be observed by considering a junction of the monolayer and bilayer phosphorene nanoribbons. By adjusting the ribbon widths, quasi-flat bands are produced. This geometrical problem is solved using analytical calculations for a general system and applied to phosphorene. We show that the edge states of phosphorene resemble a one-dimensional tight-binding system, with a close agreement between their results. Using the introduced approach, we calculate the electronic energy band structure of the specified system. Initially, we demonstrate that the formation of zigzag monolayer-bilayer-monolayer junctions can lead to the emergence of quasi-flat impurity bands within the energy bandgap. Furthermore, we show that utilizing these structures at room temperature, across a wide range of lead temperature differences, results in significant output electrical power and improved thermoelectric efficiency. The electrical power and thermoelectric efficiency are examined as functions of applied bias voltage and average chemical potential. Additionally, we explore how the output electrical power, thermoelectric efficiency, and efficiency at maximum power vary with the temperature difference between the leads at the ends of the structure.

Novel design of centralized square array of pin-fins in microchannels heat sink for thermal management of high concentrator photovoltaic systems

High concentrations of direct normal irradiation on photovoltaic cells can cause a substantial rise in the cell’s temperature, leading to a decline in performance and potential damage to the cell. Therefore, maintaining low and uniform temperatures in solar cells is crucial for enhancing reliability and optimizing the performance of high concentrator photovoltaic systems. By placing the solar cell layer centrally and integrating a centralized square array of pin-fins within rectangular microchannels, cooling performance can be greatly improved. This study proposes a novel heat sink design incorporating a centralized square array of pin-fins in rectangular microchannels, specifically aimed at efficient active cooling of high concentrator photovoltaic systems. The investigation was conducted under a concentration ratio of 1000 suns and mass flow rates of water coolant ranging from 15 to 1000 g/min with the inlet temperature of 25 °C. The number of centralized square array of pin-fins were varied with the aim of obtaining the best design of square array of pin-fins that provides efficient cooling of solar cell with minimum temperature non-uniformity distribution. The results revealed that the number of square arrays of pin-fins have significant effect on the cell temperature, temperature uniformity, cell efficiency, net electrical power, thermal and exergy efficiency. For all design cases, the non-uniformity temperature of the cell declines with increase in mass flow rates, and the minimum value of 9.50 K for a design case 4 with 7-square array of pin-fins was achieved at the mass flow rate of 1000 g/min. The net electrical power peaks at 35.825 W for the design case 8 as the mass flow rate increases from 15 to 200 g/min. However, as the mass flow rate further increases from 200 to 1000 g/min, the net power decreases due to increased pumping power with design case 1 and 8 experiencing the minimum and maximum percentage reduction of 0.231 % and 6.606 % respectively. CFD code was utilized for the computations and validated with the available data in an open literature.

Efficient Hybrid Electric Vehicle Power Management: Dual Battery Energy Storage Empowered by Bidirectional DC–DC Converter

ABSTRACTThis work offers a fuel cell power system with the ability to distribute power to the load from the electrical source and charge an auxiliary battery utilizing regenerative power flows created by the load. The approach is established on a bidirectional closed‐loop DC converter. A bidirectional DC–DC converter is presented as a means of achieving extremely high voltage energy storage systems (ESSs) for a DC bus or supply of electricity in power applications. This paper presents a novel dual‐active‐bridge (DAB) bidirectional DC–DC converter power management system for hybrid electric vehicles (HEVs). The proposed system makes it possible to charge an additional battery with regenerative power flows and distributes power from the electrical source to the load efficiently. The two main stages of the DAB converter, which are the focus of this work, are an interleaved buck/boost converter on the battery and a three‐phase wye‐wye series resonating converter on the DC bus. Each switch's current stress is greatly reduced by this design, which lowers transmission losses and enhances thermal performance. The interleaved buck conversion on the battery allows for lesser current stress in each switch, resulting in lower transmission loss. The increasing complexity and power of automotive embedded electronic systems have made the use of more potent power electronic converters in automobiles necessary. In recent years, many dual volt (42 V/14 V) bidirectional inverter topologies for automotive systems have been presented. However, the majority of them are either inefficient or use a huge number of transistors and magnetic devices in both parallel and series arrangements. As a result, in this study, a bidirectional high‐efficiency inverter with fewer components is provided. The design, modes of operation, and performance metrics of the DAB converter are examined, emphasizing its ability to achieve zero‐voltage switching (ZVS) and zero current switching (ZCS) throughout its operating range. The suggested system seeks to maximize EV power management, guaranteeing high dependability and efficiency. To test all of the aforementioned qualities, an evaluation version was created, with an average efficiency of 97.5%. This research could have a substantial impact on the advancement of power electronic converters for automotive applications, leading to better EV power management, increased system reliability, and increased overall efficiency.

Thermal management enhancement of building-integrated photovoltaic systems using coupled heat pipe and evaporative porous clay cooler

The building-integrated photovoltaic (BIPV) panel systems often lead to a notable decline in PV panels efficiency and lifetime due to their temperature rise because of inadequate cooling. This study investigates the performance of innovative cooling strategy of using a coupled heat pipes and porous clay cooler and compare it with other related three BIPV cooling systems configurations including a conventional BIPV cooling with and without air gap and a pure evaporative porous clay cooling. The aim is to improve the PV panel cooling, ultimately reduce the PV temperature and enhance the overall performance of the BIPV system as well as reducing the building indoor temperature and boosting energy efficiency within the building. The system model, comprising sets of transient equations for the different system configurations, was solved using MATLAB and confirmed with previous experimental findings. The results indicate that comparing with the traditional BIPV system, using BIPV/Clay cooling systems and the hybrid BIPV/Clay-heat pipe cooling systems achieved peak PV temperature reductions of up to 14 °C and 14.7 °C, respectively. Additionally, these cooling methods led to a maximum interior room temperature reduction of approximately 14 °C and an average decrease of 8 °C. Moreover, the hybrid BIPV/Clay-heat pipe cooling system demonstrates superior performance compared to traditional BIPV system, achieving the highest improvements in PV electrical efficiency, output power, and exergy efficiency, with gains of 7.8 %, 6.4 %, and 8.4 %, respectively. Further, when the hybrid BIPV/Clay-heat pipe cooling system was employed, the clay cooling efficiency and clay exergy efficiency values improved on average by 30.2 % and 29.7 %, respectively, compared to the BIPV/Clay cooling system in addition to the increase of the lifetime of the PV panels due to isolating it from the contact with the water/water vapor of the clay cooling system. However, this hybrid approach resulted in a rise in electricity production costs from 0.077 $/kWh to roughly 0.138 $/kWh and extended the payback time from 7.38 years to 13.6 years. But, despite its initial economic drawbacks, the hybrid BIPV/Clay-HP cooling system demonstrates considerable effectiveness and long lifetime compared to other cooling configurations.

Optimization and Structural Analysis of Automotive Battery Packs Using ANSYS

The development of new energy vehicles, particularly electric vehicles, is robust, with the power battery pack being a core component of the battery system, playing a vital role in the vehicle’s range and safety. This study takes the battery pack of an electric vehicle as a subject, employing advanced three-dimensional modeling technology to conduct static and dynamic analyses. Through weight reduction and structural optimization, an innovative power battery pack design scheme is proposed, aiming to achieve a more efficient and lighter electric vehicle power system. The main research tasks are as follows: Firstly, we designed the main load-bearing components of a certain electric vehicle’s power battery pack and established a three-dimensional (3D) model. Then, the model was simplified according to the actual stress conditions of the power battery pack of the electric vehicle and imported into finite element analysis (FEA) software. Next, based on the fundamental principles of the finite element method (FEM), we conducted static analyses under three conditions: bumpy road sharp left turn, bumpy road sharp right turn, and bumpy road emergency braking. The analysis results indicate that the strength of the battery pack meets the allowable requirements, suggesting that the lower housing design has significant redundancy, providing guidance for subsequent optimization. Finally, through modal analysis, we extracted the first six modes of the power battery box, with the first mode frequency being 33.69 Hz. This suggests that the battery pack may experience resonance during actual operation. Based on the static and modal analysis results, we proposed a structural optimization and lightweight design solution for a certain electric vehicle battery pack and compared it with the pre-optimization data.

Design and performance evaluation of a multi-load and multi-source DC-DC converter for efficient electric vehicle power systems

This paper introduces the design and comprehensive performance evaluation of a novel Multi-Load and Multi-Source DC-DC converter tailored for electric vehicle (EV) power systems. The proposed converter integrates a primary battery power source with a secondary renewable energy source—specifically, solar energy—to enhance overall energy efficiency and reliability in EV applications. Unlike conventional multi-port converters that often suffer from cross-regulation issues and limited scalability, this converter ensures stable power distribution to various EV subsystems, including the motor, air conditioning unit, audio systems, and lighting. A key feature of the design is its ability to independently manage multiple power loads while maintaining isolated outputs, thus eliminating the inductor current imbalance that is common in traditional systems. Experimental validation using a 100 W prototype demonstrated the converter’s ability to deliver stable 24 V and 48 V outputs from a 12 V input, with output voltage deviations kept within ± 1%, significantly improving upon the ± 5% deviations typically seen in existing converters. Furthermore, the system achieved an impressive 93% efficiency under variable load conditions. The modular nature of the converter makes it not only suitable for EV applications but also for a broader range of industries, including renewable energy systems and industrial power supplies. This paper concludes by discussing optimization strategies for future improvements and potential scaling of the technology for commercial use in sustainable energy applications.

Improving Electric Power Stability and Efficiency Using an Integrated Control System for Refrigerated Containers

In this study, a method is proposed to minimize electrical load fluctuations and improve the efficiency of engine generator operation by managing refrigerated ship containers through an integrated control system. The proposed system actively controls the electrical load by assigning operational priorities based on cargo temperature deviations to existing independently operated refrigerated containers, ensuring that they operate only within the available power of the engine generator. As a result, the average specific fuel oil consumption can be reduced. A 70 h simulation of the refrigerated containers, a power system, and an integrated control system demonstrated in MATLAB/Simulink 2021b that the magnitude of electrical load fluctuations decreases from 37.6% to 9.6% of the engine generator’s rated power compared with the conventional operation of refrigerated containers. In addition, a 1.88% fuel saving is realized.

Design and performance estimation of a novel solar multiplate mirror concentration PVT system based on nanofluid spectral filter

This paper presents the design and performance evaluation of a novel solar multiplate mirror concentration photovoltaic and thermal (MPVT) system using ethylene glycol/indium tin oxide liquid spectral filter (LSF). The LSF is prepared, and the test results show that its average spectral transmissivity and average spectral absorptivity are 69.2 % and 30.8 %. Optical characteristics and operation performance of the MPVT system are evaluated, and parametric interaction analysis is also carried out to reveal the relationships of optical and structural parameters of the MPVT system. The results indicate that the MPVT system is technically feasible and has acceptable adaptability on solar tracking error. The decrease in LSF flow channel width and increase in LSF flow channel installation height can increase the concentration ratio. The electric power and photoelectric efficiency of the photovoltaic module are 818.2 W and 29.07 %. The thermal and exergy efficiencies of the MPVT system are 23.88 % and 32.81 %. By increasing the inlet LSF flow velocity and ambient temperature or decreasing the inlet LSF temperature properly, the thermal performance of the MPVT system can be improved. But the effects of the three parameters on the exergy efficiency of the MPVT system are all relatively small.

Novel design and performance analysis of a selectively filtered nanofluid spectrum semi-trough solar concentrated photovoltaic/thermal system

ABSTRACT In this paper, the main novelty is the proposal and performance analysis of a novel selectively filtered nanofluid spectrum semi-trough solar concentrated photovoltaic-thermal (SPVT) system. Experimental preparation and optical tests of Ag-CoSO4/water nanofluid are conducted. The selected nanofluid for the SPVT system has an average absorptance of 53.5% and an average transmittance of 46.5% in 250.0 ~ 2500.0 nm. The optical analysis results show that the optical efficiency of the SPVT system is 94.3% under the optical filtering condition. When the solar tracking error increases to 0.3°, the optical efficiency of the SPVT system can still be kept at 84.8%. This means that the SPVT system has relatively good adaptability on solar tracking error. The operation performance analysis results indicate that under the optical filtering condition, the electric power and photo-electric efficiency of the PV subsystem are 392.1 W and 30.9%, and the thermal efficiency of the SPVT system is 40.7%. Effects of four factors on the thermal performance of the SPVT system are evaluated, which are the inlet nanofluid flow velocity and temperature, environmental temperature and convection heat transfer coefficient between the nanofluid flow channel and air. The results show that the thermal performance of the SPVT system can be improved by properly increasing the inlet nanofluid flow velocity and environmental temperature or by reducing the inlet nanofluid temperature and convection heat transfer coefficient between the nanofluid flow channel and air. When the inlet nanofluid flow velocity increases from 0.002 m/s to 0.004 m/s, the thermal efficiency of the SPVT system increases from 40.9% to 50.7%, and with the inlet nanofluid temperature increased from 6.0°C to 14.0°C, the thermal efficiency decreases from 48.6% to 45.6%. The results of this paper can provide certain reference for research and development works of solar PVT systems in the future.

Novel glassbox based explainable boosting machine for fault detection in electrical power transmission system.

The reliable operation of electrical power transmission systems is crucial for ensuring consumer's stable and uninterrupted electricity supply. Faults in electrical power transmission systems can lead to significant disruptions, economic losses, and potential safety hazards. A protective approach is essential for transmission lines to guard against faults caused by natural disturbances, short circuits, and open circuit issues. This study employs an advanced artificial neural network methodology for fault detection and classification, specifically distinguishing between single-phase fault and fault between all three phases and three-phase symmetrical fault. For fault data creation and analysis, we utilized a collection of line currents and voltages for different fault conditions, modelled in the MATLAB environment. Different fault scenarios with varied parameters are simulated to assess the applied method's detection ability. We analyzed the signal data time series analysis based on phase line current and phase line voltage. We employed SMOTE-based data oversampling to balance the dataset. Subsequently, we developed four advanced machine-learning models and one deep-learning model using signal data from line currents and voltage faults. We have proposed an optimized novel glassbox Explainable Boosting (EB) approach for fault detection. The proposed EB method incorporates the strengths of boosting and interpretable tree models. Simulation results affirm the high-efficiency scores of 99% in detecting and categorizing faults on transmission lines compared to traditional fault detection state-of-the-art methods. We conducted hyperparameter optimization and k-fold validations to enhance fault detection performance and validate our approach. We evaluated the computational complexity of fault detection models and augmented it with eXplainable Artificial Intelligence (XAI) analysis to illuminate the decision-making process of the proposed model for fault detection. Our proposed research presents a scalable and adaptable method for advancing smart grid technology, paving the way for more secure and efficient electrical power transmission systems.

Optimal Values of Power Equipment Parameters when Degassing of Solid Municipal Waste Polygons

The possibility of using the energy values of landfill gas to generate electrical and thermal energy based on a contact cogeneration gas turbine installation has been studied. The optimal values degree of increase pressure in the cycle are determined, which make it possible to determine the maximum specific electrical power and thermodynamic efficiency of a cogeneration gas turbine installation with steam injection, in which landfill gas from solid waste landfills is used as an energy carrier. It is concluded that using the proposed engineering solution, landfill gas from municipal solid waste can be usefully implemented in a cogeneration contact gas turbine installation, which will save the country's national wealth and at the same time solve pressing problems of modern cities associated with the disposal of municipal solid waste.

Enhanced performance of a hybrid adsorption desalination system integrated with solar PV/T collectors: Experimental investigation and machine learning modeling coupled with manta ray foraging algorithm

This study explores the performance augmentation of a solar adsorption desalination system (SADS) powered by a hybrid solar thermal system with evacuated tubes and photovoltaic thermal (PV/T) collectors, both numerically and experimentally. The system concurrently generates both electrical power via the PV/T system and desalinated water through the SADS. The cooling of photovoltaic cells is achieved through the utilization of chilled water produced during the desalination process of the SADS, which aims to enhance the electrical efficiency of photovoltaic cells and optimize the overall utilization of the adsorption distillation cycle. The SADS is examined under different operational scenarios and thoroughly assessed in terms of specific cooling power, specific daily freshwater product, and the coefficient of performance (COP). More so, a hybrid machine learning framework integrating an adaptive network-based fuzzy inference system (ANFIS) fine-tuned through the utilization of a manta ray foraging optimization algorithm (MRFOA) is also developed to predict the performance parameters of the SADS. The experiments indicated that the modified PV/T system improved the PV efficiency by 18 % at peak time, where the yielded electrical power and electrical efficiency reached 112 W/m2 and 11.13 %, respectively. The specific freshwater product (SWP), specific cooling power (SCP), and COP of the SADS are estimated as 53.3 L/ton-cycle (6.30 m3/ton-day), 153 W/kg, and 0.25, respectively. Furthermore, Furthermore, the simulated findings showed that the deterministic coefficient and RMSE of the predictive SWP are 0.989 and 1.314 for ANFIS-MRFOA and 0.965 and 2.323 for typical ANFIS, respectively. Hence, the ANFIS-MRFOA exhibited the highest prediction accuracy and can be deemed a potent optimization tool for forecasting the energetic performance of adsorption distillation systems.

Decentralized Retrofit Model Predictive Control of Inverter-Interfaced Small-Scale Microgrids

In recent years, small-scale microgrids have become popular in the power system industry because they provide an efficient electrical power generation platform to guarantee autonomy and independence from the power grid, which is a critical feature in cases of catastrophic events or remote areas. On the other hand, due to the short distances among multiple distribution generation systems in small-scale microgrids, the interconnection couplings among them increase significantly, which jeopardizes the stability of the entire system. Therefore, this work proposes a novel method to design decentralized robust controllers based on a retrofit model predictive control scheme to tackle the issue of instability due to the short distances among generation systems. In this approach, the retrofit model predictive controller receives the measured feedback signal from the interconnection current and generates a control command signal to limit the interconnection current to prevent instability. To design a retrofit controller, only the model of a robust closed-loop system, as well as an interconnection line, is required. The model predictive control signal is added in parallel to the control signal from the existing robust voltage source inverter controller. Simulation results demonstrate the superior performance of the proposed technique as compared with the virtual impedance and retrofit linear quadratic regulator techniques (benchmarks) with respect to peak-load demand, plug-and-play capability, nonlinear load, and inverter efficiency.

A digital twin framework for efficient electric power restoration and resilient recovery in the aftermath of hurricanes considering the interdependencies with road network and essential facilities

The community's resilience in the face of natural hazards relies heavily on the rapid and efficient restoration of electric power networks, which plays a critical role in emergency response, economic recovery, and the functionality of essential lifeline and social infrastructure systems. Leveraging the recent data revolution, the digital twin (DT) concept emerges as a promising tool to enhance the effectiveness of post-disaster recovery efforts. This paper introduces a novel framework for post-hurricane electric power restoration using a hybrid DT approach that combines physics-based and data-driven models by utilizing a dynamic Bayesian network. By capturing the complexities of power system dynamics and incorporating the road network's influence, the framework offers a comprehensive methodology to guide real-time power restoration efforts in post-disaster scenarios. A discrete event simulation is conducted to demonstrate the proposed framework's efficacy. The study showcases how the electric power restoration DT can be monitored and updated in real-time, reflecting changing conditions and facilitating adaptive decision-making. Furthermore, it demonstrates the framework's flexibility to allow decision-makers to prioritize essential, residential, and business facilities and compare different restoration plans and their potential effect on the community.

The piezoelectric properties of three-phase electrospun PVDF/PZT/Multiwalled Carbone Nanotube composites for energy harvesting applications

In this study, the piezoelectric nanogenerators (PENs) based on the PVDF (polyvinylidene fluoride)/PZT (lead zirconate titanate, the particle size of <1 µm) incorporated with MWCNT (Multiwalled Carbone Nanotube, Outer diameter: 10 nm, Inner diameter: 4.5 nm, and Length: 3–6 µm) were produced using the electrospinning method. An β-phase content of 96.56 % in PVDF electrospun composites was arrived at due to the synergistic effect of the PZT ceramics and the MWCNT nanoparticles. The experimental results showed that a PVDF/PZT/0.7 wt%MWCNT composite with a thickness of 145 μm based on the PEN had an electrical power efficiency (0.16 μW) approximately 1.3 times higher at a vibrational frequency of 20 Hz under a resistive load of 46 KΩ as compared to that of the PEN based on the PVDF/PZT composite (0.12 μW). The PVDF/PZT/MWCNT-based PENs have promising potential for flexible energy transmission and structural health monitoring.

Thermodynamic performance evaluation and optimization of a hybrid system integrating vacuum graphene-anode thermionic converters with direct carbon fuel cells

An efficient hybrid system integrating a direct carbon fuel cell (DCFC) with a vacuum graphene-anode thermionic converter (VGTC) is proposed for cogeneration. The VGTC efficiently recycles waste heat released from the DCFC and generate additional electricity, significantly improving energy utilization efficiency and economic performance. A comprehensive mathematical model is developed to quantitatively assess the thermodynamic performance of the hybrid system, taking into account the overpotential losses of the DCFC and the irreversible energy losses occurring within the system. The results show that at an operating temperature of 923 K, the hybrid system can achieve a maximum power density of 466 W/m2, which is approximately 1.34 times that of a single DCFC, indicating a significant improvement in output performance. Besides, the optimal operating region and parameter selection criteria for the hybrid system are determined using finite-time thermodynamic optimization theory. Furthermore, the effects of essential parameters on the output performance of the hybrid system, such as the operating temperature of the DCFC, the heat transfer coefficient, the Fermi level of graphene, the work function of the cathode, the thermal emissivity, and the reflectivity of the back mirror, are investigated. Finally, the comparative study shows that the proposed hybrid system outperforms other previously reported hybrid systems regarding output electric power and conversion efficiency due to the efficient high-grade waste heat recovery and energy conversion by the VGTC.

Efficient Electrical Power for ICT in TVET Curriculum Development and Delivery

Efficient Electrical Power for ICT in TVET Curriculum Development and Delivery