Energy Converter Research Articles

Analysis of Implication of Phase Change Material Enclosed Design on Thermal Performance of Solar Collector

Abstract The energy, which is converted from the sun rays, was called solar energy. This is very essential renewable energy converting methods that had a higher influence for water distilling system. Here, the implication of the Phase Change Materials (PCM) in that exit was analyzed. This energy from the sun is trapped in paraffin wax for the storing system whiles the greater radioactive effect. This trapped heat power than utilized for increase the fluid temperature during the lesser radioactive times. Here, the Implication of the heat storing units on the exit temperature was analyzed. Furthermore, Thermal solar collector was analyzed for the following years 2021 and 2022. The Concentric PC is placed over the top of the collector of the solar rays. And then, a paraffin wax layer was placed under the solar absorber plate like the back-up to store the LH Energy. The uniform rate of flow was produced a greater exit temperature of water the two years. The efficiency rate increased 11–14% and the collected energy gain rate enhanced 18–19%. The peak water temperature was 61°C & 60°C for the 2 consecutive years for Paraffin wax integrated solar collecting unit. At the same time the efficiency of heat energy is peak at 49% in January 2022. The solar collector efficiency primarily relies on the design and construction of collector itself.

Design and Tank Testing of Reinforcement Learning Control for Wave Energy Converters

Design and Tank Testing of Reinforcement Learning Control for Wave Energy Converters

Enhanced air filtration and ammonia sensing with cellulose nanofibers-based triboelectric nanogenerators under harsh environments

Fire accidents often occur in environments characterized by severe air pollution, toxic gas emissions, and microbial growth, creating significant challenges for developing multifunctional portable healthcare devices. These devices must achieve high filtration efficiency, minimal pressure drop, and the capability to provide early warnings of toxic gas leaks. Triboelectric nanogenerators present a sustainable solution as self-powered energy converters for advanced healthcare applications. In this study, we grafted Ti3C2Tx/MoS2 nanohybrid materials, which form Schottky heterojunctions, onto cellulose diacetate using tetraethyl orthosilicate, followed by electrospinning to produce nanofibrous films. When paired with a negatively charged material, the resulting device achieved an optimal balance with a low-pressure drop (52 Pa) and high filtration efficiency (98.72 % for PM0.3). It also demonstrated exceptional stability under high-temperature and high-humidity conditions. Notably, the device maintained rapid sterilization within 15 min and consistent filtration performance even after multiple washes. Furthermore, the device exhibited precise detection of trace amounts of NH3 (0.1 ppm) and demonstrated a rapid response, achieving an 86 % response rate within 2 s for 100 ppm NH3, providing an early warning 28 s faster than commercial NH₃ monitors. This study introduces a novel approach to the development of multifunctional, self-powered, wearable medical devices that offer high-efficiency air filtration and sterilization, breath monitoring, and rapid toxic gas leakage detection in harsh environments.

Holistic Methodology of Hypersoft in Tandem with Uncertainty-based Triangular Neutrosophic for Wave Energy Converter Optimization

Global warming, environmental degradation, and climate change have recently emerged as compelling arguments against the combustion of fossil fuels. As well Eliminating and forgoing the intake of fossil fuels is also encouraged by the Sustainable Development Agenda's goals. The healthy substitute for fossil fuels, renewable energy is one of the main devoid power sources found in our natural surroundings. An effective proposition for harnessing wave energy with an emphasis on increasing energy and efficiency are wave energy converters, or WEnCos. It contributes to producing a clean, limitless energy source that might drastically lessen our need for fossil fuels. Generally speaking, the selecting of the appropriate converter is an important endeavor that this study takes on. The process of selecting the optimal converter has been conducted based on effective benchmarks or criteria and its attributes. Multiple Criteria Decision Making (MCDM) techniques seem to be effective tools when it comes to handling the complex issue of benchmarking WEnCos. These approaches consider a variety of criteria, allowing for a comprehensive and nuanced examination. Each utilized technique plays vital role in our decision problem. Hence, CRiteria Importance Through Inter-criteria Correlation (CRITIC) method—which determines the weights of criteria and its attributes in decision making problems. These weights are utilized in Weighted Sum Product (WISP) method. Totally, these techniques are implemented under uncertainty theory of Neutrosophic which combined with soft sets notion to generate Triangular Neutrosophic HyperSoft (TrNSHSS). Totally, all these techniques are contributed to constructing soft decision-making model for analyzing and recommending optimal WEnCo.

Layout Optimization of Wave Energy Park Based on Multi-Objective Optimization Algorithm

Abstract In this paper, both semi-analytical method and numerical simulation is applied to investigate the hydrodynamic behavior of large arrays of point-absorber wave energy converters (WECs). To analyze wave interactions among multiple WECs within an array, a semi-analytical model is developed based on the potential flow theory and the matched eigen-function expansions method. The fluid domain is divided into two kinds of regions: interior regions underneath the cylinders and an exterior region surrounding all the cylinders. The matched eigenfunction expansions method is employed to solve the radiation potential problem in each domain, and the hydrodynamic coefficients and motion response of the cylinders in the array are evaluated. To validate the accuracy of the semi-analytical method, WAMIT is adopted to simulate the wave energy park numerically and compared with the results by the semi-analytical model. The hydrodynamic characteristics and power absorption performance of the WECs within the wave energy park are analyzed. The power performance of a wave energy park is studied as functions of layout geometry, incident wave direction and separation distance between WECs respectively. Finally, MOPSO based on a surrogate model is used to optimize the layout of wave energy array.

Hydrodynamic analysis of a semi-submersible fish farming cage platform integrated with an oscillating water column wave energy converter

Abstract This research article describes an investigation into integrating semi-submersible farm cages with oscillating water column (OWC) wave energy converters. The objective is to optimize the structural parameters of the platform through an examination of the impacts of three float structures. The AQWA hydrodynamic simulation software is employed to develop a numerical model to analyze the hydrodynamic properties of the semi-submersible farming platform. The findings suggest that the response to the heavy degree of freedom is positively correlated with the size of the floating structure. In contrast, the response of the roll degree of freedom is negatively correlated within a specific range. The results of this study establish a theoretical framework that can be utilized to optimize the design of semi-submersible farming platforms that integrate OWC technology.

Dispatch of Decentralized Energy Systems using Artificial Neural Networks: A Comparative Analysis with Emphasis on Training Methods

Due to the availability of flexibility, Decentralized Energy Systems (DES) play a central role in integrating renewable energies. To efficiently utilize renewable energy, dispatchable components must be operated to bridge the time gap between inflexible supply and energy demand. Due to the large number of energy converters, energy storage systems, and flexible consumers, there are many ways to achieve this. Conventional rule-based dispatch strategies often reach their limits here, and optimized dispatch strategies (e.g., model predictive control or the optimal dispatch) are usually based on very good forecasts. Reinforcement learning, particularly the application of Artificial Neural Networks (ANN), offers the possibility to learn complex decision-making processes. Since long training times are required for this, an efficient training framework is needed. The present paper proposes different training methods to learn an ANN-based dispatch strategy. In Method I, the ANN attempts to learn the solution to the corresponding optimal dispatch problem. In method II, the energy system model is simulated during the training to compute the observation state and operating costs resulting from the ANN-based dispatch. Method III uses the fast executable Method I solution as a warm-up solution for the computationally expensive training with Method II. In the present paper, a model-based analysis compares the different ANN-based dispatch strategies with rule-based dispatch strategies, model predictive dispatch (MPC), and optimal dispatch regarding their computational efficiency and the resulting operating costs. The dispatch strategies are compared based on three case studies with different system topologies for which training and test data are applied.Training method I proved to be non-competitive. However, training methods II and III significantly outperformed rule-based dispatch strategies across all case studies for both training and test data sets. Notably, methods II and III also surpassed MPC-based dispatch strategies under high and medium uncertainty forecasts for the training data in the first two case studies. In contrast, MPC-based dispatch was superior in the third case study, likely due to the higher system’s complexity and in the test data set due to the methodological advantage of being optimized for each specific data set. The effectiveness of training method III depends on the performance of the warm-up training with method I: warm-up is beneficial only if this results in an already promising dispatch (as seen in case study two). Otherwise, training method II proves more effective, as observed in case studies one and three.

Electricity supply resiliency evaluation by a hybrid renewable energy system for a petrochemical plant: Frameworks and quantitative assessment methodologies

The escalation of harm inflicted upon energy systems, has spurred the investigation of energy system resilience. In this regard, the measurement of resilience capacity can serve as a valuable metric for assessing the energy system's ability to withstand a variety of events that may result in potential adverse outcomes. For renewable energy systems, the measurement of resilience is imperative due to the inherent unpredictability and unreliability in their nature. Often, resilience studies lack the comprehensiveness required to fully comprehend the intricate interdependencies within integrated hybrid renewable energy systems. This research delineates the essential factors required to facilitate a comprehensive understanding and advancement in the quantification of such integrated systems in small-scale. Pardis Petrochemical Company, located in Asalouyeh city, Iran, has been chosen as case study. Four distinct configurations of hybrid renewable energy systems—comprising Photovoltaic panels, Photovoltaic panels + Wind Turbines, Photovoltaic panels + Wave energy converters, and Photovoltaic panels + Wind Turbines + Wave energy converters— connected to grid, have been developed. These configurations are the result of a multi-objective optimization process, considering the following metrics: the cost of electricity (as an economic metric), CO2 emissions (as an environmental metric), loss of power supply probability (as a reliability metric), and exergy efficiency (as a technical metric). Subsequently, a methodological framework for multicriteria decision support is introduced. This framework is constructed based on primary resilience dimensions, namely: “resist,” “restabilize,” “technology,” and “withstand” serve as a tool for measuring the resiliency of the optimized configurations. The findings indicate that the Photovoltaic panels + Wind Turbines + Wave Energy Converters configuration is as the most resilient system among the studied alternatives.

A review of the harvesting methods for offshore renewable energy – advances and challenges

The present work offers general information about present-day and developments in offshore renewable energy, specially of wind, wave and the solar energy harnessing structures. In the introduction, the authors raise awareness of the despite more untapped potentials that exist in the oceans and the offshore Wind Energy Market that is experiencing a steep rise in the recent past due to technological advancement and the great policies that support this energy source. This mainly focuses on the very huge additionality of offshore wind power and the improvements in floating solar PV systems. Section three outlines an assortment of studies that were done by different writers on the strengths and weaknesses of offshore renewable energy technologies through a meta-analysis of the literature. The method of data extraction revolved around several factors, namely technological admissibility, resource identification, location and environmental and economic factors. The sources used comprised of scholarly articles published within the peer reviewed journals in the period of 2013 to 2024, to ensure that the study offered a comprehensive analysis on the technological advancements. The results and discussion section gives an analysis of the results achieved and demonstrates the developments in Offshore Wind Energy, Wave Energy Conversion, and Floating Solar PV Systems. Thus, offshore wind energy is described as the rapidly evolving segment and particular focus is made on the floating wind farms and their advancements in the aspects of power density and structural stability. Wave energy converters are discussed regarding their applicability to complement hybrid electricity production despite limited data on the devices’ performance. Another key feature is that the FFPV systems are reported to be more efficient and cheaper than the land mounted systems. Thus, the article emphasizes the need to produce the further literature on offshore renewable energy, political support, and cooperation between different sectors. It concludes that an offshore renewable energy has the potential for the future development due to advancement in the technology as well as due to environmental factors.

Future role of ocean thermal energy converters in a 100% renewable energy system on the case of the Maldives

Energy transition on small islands is limited by the scarce availability of land, restricting large-scale implementation of onshore renewable energy technologies such as solar photovoltaics and wind power. Ocean energy technologies provide novel opportunities for land-constrained islands to achieve 100% renewable energy systems. While wave power is increasingly implemented in energy system modelling research, ocean thermal energy converters are not yet a standard technology in renewable energy technology portfolios. This research aims to study the impacts of ocean thermal energy converters on the energy system of the Maldives through a structured sensitivity analysis for the two scenario clusters covering e-fuel import and domestic production. The ocean thermal energy conversion plants are modelled using spatially and temporally resolved resource data and cost assumptions from a global upscaling scenario, considering the technology’s current development stage. Results show that ocean thermal energy converters play a limited role in 'purely' cost-optimised sub-scenarios due to the availability of very low-cost offshore floating photovoltaics, making it difficult for them to compete. Nevertheless, reduced requirement of energy storage technologies due to the stable electricity production of ocean thermal energy converters offers an option to diversify the renewable energy technology portfolio with only a minor increase in cost.

Design and dynamic emulation of hybrid solar-wind-wave energy converter (SWWEC) for efficient power generation.

As research into wave energy converters progresses and new developers enter the field, there arises a growing requirement for a standardized modelling approach. This article presents a novel design and dynamic emulation for a hybrid solar-wind-wave energy converter (SWWEC) which is the combination of three very well-known renewable energies: solar, wind and wave energy. Photovoltaic (PV) panels and vertical axis wind turbine (VAWT) are installed on top of the floating WEC that harness the energies from the sun and wind respectively. The SWWEC is designed with a point absorber capture system. An electrical motor is used to dynamically emulate the performance of the SWWEC under real world conditions to drive the DC generator. The present paper shows the importance and necessity of the required control schemes for the proper control of generator side converters which is present in the offshore marine substation and the most required grid connected onshore converters. The better switching signal generation for the converter control and generated harmonics elimination techniques are also presented in the paper. Outcomes of the present study are discussed and verified.

Wear of Wave Energy Converters Mooring Lines Belts

Abstract Using a belt as a replacement for a rope on a rotary power take-offs (PTOs) system has become more common for wave energy converters, improving cyclic bend over sheave performance with a smaller bending thickness for belts. However, the service life predictions of PTOs are a major concern in design, because belt performance under harsh underwater environments is largely less studied. In this work, the effect of fleet and twist angles on wear life is being investigated both experimentally and numerically. Two three-dimensional equivalent static finite element models are constructed to evaluate the complex stress state of polyurethane-steel belts around steel drums. The first is to capture the response of the experimental investigation performed on the wear life, and the second to predict the wear life of an existing functional PTO. The results show a significant effect for fleet and twist angles on stress concentrations and estimated service life.

Effect of Multiple Orifices of Wave Energy Converter Air Columns Towards Overall Turbine Output

Effect of Multiple Orifices of Wave Energy Converter Air Columns Towards Overall Turbine Output

Experimental and numerical analysis of the geometry of a laboratory-scale overtopping wave energy converter using constructal design

An experimental study is conducted to investigate the influence of the design of a laboratory-scale onshore overtopping device over the mass of water accumulated in its reservoir, and generate a database to validate computational models. The geometric evaluation is based on the constructal design, being investigated one degree of freedom (ratio between the height and length of the ramp, H1/L1) for various depths of free surface of the water (h1). Four geometric constraints delimit the ramps configurations. The exhaustive search is applied to obtain the ramp geometry that maximizes the amount of water that enters the device reservoir, represented by the water level accumulated in the reservoir (hR). For h1 = 0.392 m cases, a numerical model based on the finite volume method is also used for validation purposes. Results indicated that the lowest H1/L1 ratios of the ramp led to the best performances for all studied magnitudes of h1, which agreed with previous findings of literature for similar wave conditions. The proposed numerical model was validated for predicting wave propagation, instantaneous amount of water discharge, and prediction of the effect of H1/L1 over hR, with a maximum relative error (RE) of 3.92 %.

Modeling and performance estimation for L-shaped OWC wave energy converters with a theoretical correction for spring-like air compressibility

The investigation of Oscillating Water Columns (OWC) has gained significant attention in recent years thanks to their resilient structural design, allowing them to withstand harsh environmental conditions. This study focuses on the L-shaped OWC (L-OWC) due to its excellent energy capture efficiency. It should be noted that air compressibility plays a significant role in the plenum chamber of the OWC, especially at full scale. The present paper proposes a scaling-rematched approach, facilitating the evaluation of hydrodynamic coefficients and the performance estimation with a theoretical correction for the unmatched scaling problem of spring-like air compressibility. The methodology is applied successfully to a model-scale L-OWC design, employing three-dimensional, incompressible-flow simulations combined with an impeller model. The present study reveals the hydrodynamic characteristics (advantages) of the L-OWC: small fluid damping coefficient and large added mass, and hence the possibility that the spring-like air compressibility can be used to raise the efficiency of power capturing. Furthermore, there exists an interval where the air compressibility has a positive effect on the performance, not only having a significantly longer span than that of the conventional OWC but also much more directly matching the period range of high energy potential found in the wave climate of Northeastern Taiwan waters.

Wave energy extraction from rigid rectangular compound floating plates

We present a theoretical model to analyse the hydrodynamics of wave energy converters (WECs) comprised of three-dimensional, rigid, floating, compound rectangular plates in the open sea. The hydrodynamic problem is solved by means of Green’s theorem and a free-surface Green’s function. Plate motion is predicted through decomposition into rigid natural modes. We first analyse the case of a single rectangular plate and validate our model against experimental results from physical model tests undertaken in the COAST laboratory at the University of Plymouth. Then we extend our theory to complex shapes and arrays of plates and examine how the geometry, incident wave direction and power take-off (PTO) coefficient affect the response of the platform and the consequent absorbed energy.

GWECS: An indicator to describe the energy absorption characteristics of wave energy converter arrays in real sea states

Grouping wave energy converters (WECs) into an array has become a trend to improve power production and achieve economies of scale. Therefore, the performance of a WEC array in real sea states is of vital importance. To intuitively reflect an array's frequency-based energy absorption characteristics instead of only the total extractable power in given irregular wave conditions, a new indicator of group wave energy capture spectrum (GWECS) is proposed by extending the concept of wave energy capture spectrum (WECS) to an array. A practical method to measure the indicator by estimating the absorbed wave surface from the array's power signal is also given. Simulations in two-dimensional conditions with a 2-cuboid WEC array and in three-dimensional conditions with a 2-cylinder WEC array are conducted to study the concept. The results examine the consistency in capture efficiency between the newly proposed indicator and conventional ones, and present the effect of various parameters, including linear power take-off (PTO) damping, buoy permutation, separation distance, and incident wave angle on the GWECS.

AI-enhanced backpack with double frequency-up conversion vibration energy converter for motion recognition and extended battery life

With growing interest in physical activities, wearable device sales have been increasing each year due to their help in tracking movement. However, keeping these devices running for a long time is still a key challenge. This paper presents an AI-enhanced backpack equipped with a hybrid vibration energy converter that integrates piezoelectric (PE) and electromagnetic (EM) technologies, featuring a double frequency-up conversion (FUC) mechanism. The PE unit enables efficient motion recognition, while the EM unit extends battery life via kinetic energy harvesting. The double FUC mechanism boosts human motion signal strength and resolution by converting sub-Hertz frequencies to hundreds of Hertz. This makes the device particularly effective in environments with performance constraints and interference. By adopting deep learning techniques, the system maintains a high motion recognition accuracy of 97.33 % even under low data sampling rates and significant noise interference. The EM unit effectively harvests kinetic energy, generating an average output power of 4.5 mW during activities such as running at 4.5 Hz, despite of the device’s compact size. Additionally, a power management circuit with human motion-stimulated switch optimizes battery life by managing the system’s sleep and active states. This innovative energy management approach ensures that during human activity, the system conserves energy by remaining in sleep state for at least 30 % of the time, significantly extending battery life and enhancing the backpack’s suitability for outdoor applications.

Mechanical interactions modeling of inertial wave energy converters

Numerous technological solutions for wave energy converters (WECs), referred as inertial reaction mass (IRM) systems, incorporate a reacting mass within the floater, coupled with a power take-off (PTO) system, to shelter all electronic components from the hostile sea environment. While the overall complexity of the system increases, the current modeling procedures persist in considering only a limited number of modes of motion, neglecting relevant dynamical effects. In this context, this paper proposes a systematic procedure for defining the kinematic characteristics and overall analytical model for the dynamics of IRM WECs. The significance of the proposed procedure lies in the statement of the reaction mass-related dynamic equation, considering the floater’s parametric excitation in six degrees of freedom (DoF). Additionally, it introduces the procedure for defining the reaction forces that the inertial mass exerts on the floater, which are often neglected in the literature for the full simulation of such systems. Furthermore, the proposed analytical modeling procedure allows the definition of approximated models in more simplified nonlinear forms for dynamic analysis and ultimately in fully linear approximations. This enables the application of methodologies and techniques commonly used in the literature for linear systems. The development of the framework is kept generic, in order to introduce a versatile mathematical procedure, that can be easily adjusted, with minor modifications, to accurately capture and represent the mechanical interaction for a wide family of IRM WEC devices. Subsequently, a case study on a vertical-hinged pendulum WEC is analyzed, to showcase the effectiveness of the proposed methodology. Moreover, to test the reliability of the analytical framework, a comparison with the output of a commercial software is conducted.

Exploiting a novel magnetoelastic tunable bi-stable energy converter for vibration energy mitigation

Exploiting a novel magnetoelastic tunable bi-stable energy converter for vibration energy mitigation