Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Article Types

Countries / Regions

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Search Results (421)

Search Parameters:
Keywords = thermal energy harvesting

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
28 pages, 15022 KiB  
Review
Development and Core Technologies of Long-Range Underwater Gliders: A Review
by Xu Wang, Changyu Wang, Ke Zhang, Kai Ren and Jiancheng Yu
J. Mar. Sci. Eng. 2025, 13(8), 1509; https://doi.org/10.3390/jmse13081509 - 5 Aug 2025
Abstract
Long-range underwater gliders (LRUGs) have emerged as essential platforms for sustained and autonomous observation in deep and remote marine environments. This paper provides a comprehensive review of their developmental status, performance characteristics, and application progress. Emphasis is placed on two critical enabling technologies [...] Read more.
Long-range underwater gliders (LRUGs) have emerged as essential platforms for sustained and autonomous observation in deep and remote marine environments. This paper provides a comprehensive review of their developmental status, performance characteristics, and application progress. Emphasis is placed on two critical enabling technologies that fundamentally determine endurance: lightweight, pressure-resistant hull structures and high-efficiency buoyancy-driven propulsion systems. First, the role of carbon fiber composite pressure hulls in enhancing energy capacity and structural integrity is examined, with attention to material selection, fabrication methods, compressibility compatibility, and antifouling resistance. Second, the evolution of buoyancy control systems is analyzed, covering the transition to hybrid active–passive architectures, rapid-response actuators based on smart materials, thermohaline energy harvesting, and energy recovery mechanisms. Based on this analysis, the paper identifies four key technical challenges and proposes strategic research directions, including the development of ultralight, high-strength structural materials; integrated multi-mechanism antifouling technologies; energy-optimized coordinated buoyancy systems; and thermally adaptive glider platforms. Achieving a system architecture with ultra-long endurance, enhanced energy efficiency, and robust environmental adaptability is anticipated to be a foundational enabler for future long-duration missions and globally distributed underwater glider networks. Full article
(This article belongs to the Section Ocean Engineering)
Show Figures

Figure 1

19 pages, 5970 KiB  
Article
Interface Material Modification to Enhance the Performance of a Thin-Film Piezoelectric-on-Silicon (TPoS) MEMS Resonator by Localized Annealing Through Joule Heating
by Adnan Zaman, Ugur Guneroglu, Abdulrahman Alsolami, Liguan Li and Jing Wang
Micromachines 2025, 16(8), 885; https://doi.org/10.3390/mi16080885 - 29 Jul 2025
Viewed by 278
Abstract
This paper presents a novel approach employing localized annealing through Joule heating to enhance the performance of Thin-Film Piezoelectric-on-Silicon (TPoS) MEMS resonators that are crucial for applications in sensing, energy harvesting, frequency filtering, and timing control. Despite recent advancements, piezoelectric MEMS resonators still [...] Read more.
This paper presents a novel approach employing localized annealing through Joule heating to enhance the performance of Thin-Film Piezoelectric-on-Silicon (TPoS) MEMS resonators that are crucial for applications in sensing, energy harvesting, frequency filtering, and timing control. Despite recent advancements, piezoelectric MEMS resonators still suffer from anchor-related energy losses and limited quality factors (Qs), posing significant challenges for high-performance applications. This study investigates interface modification to boost the quality factor (Q) and reduce the motional resistance, thus improving the electromechanical coupling coefficient and reducing insertion loss. To balance the trade-off between device miniaturization and performance, this work uniquely applies DC current-induced localized annealing to TPoS MEMS resonators, facilitating metal diffusion at the interface. This process results in the formation of platinum silicide, modifying the resonator’s stiffness and density, consequently enhancing the acoustic velocity and mitigating the side-supporting anchor-related energy dissipations. Experimental results demonstrate a Q-factor enhancement of over 300% (from 916 to 3632) and a reduction in insertion loss by more than 14 dB, underscoring the efficacy of this method for reducing anchor-related dissipations due to the highest annealing temperature at the anchors. The findings not only confirm the feasibility of Joule heating for interface modifications in MEMS resonators but also set a foundation for advancements of this post-fabrication thermal treatment technology. Full article
(This article belongs to the Special Issue MEMS Nano/Micro Fabrication, 2nd Edition)
Show Figures

Figure 1

21 pages, 2965 KiB  
Article
Inspection Method Enabled by Lightweight Self-Attention for Multi-Fault Detection in Photovoltaic Modules
by Shufeng Meng and Tianxu Xu
Electronics 2025, 14(15), 3019; https://doi.org/10.3390/electronics14153019 - 29 Jul 2025
Viewed by 298
Abstract
Bird-dropping fouling and hotspot anomalies remain the most prevalent and detrimental defects in utility-scale photovoltaic (PV) plants; their co-occurrence on a single module markedly curbs energy yield and accelerates irreversible cell degradation. However, markedly disparate visual–thermal signatures of the two phenomena impede high-fidelity [...] Read more.
Bird-dropping fouling and hotspot anomalies remain the most prevalent and detrimental defects in utility-scale photovoltaic (PV) plants; their co-occurrence on a single module markedly curbs energy yield and accelerates irreversible cell degradation. However, markedly disparate visual–thermal signatures of the two phenomena impede high-fidelity concurrent detection in existing robotic inspection systems, while stringent onboard compute budgets also preclude the adoption of bulky detectors. To resolve this accuracy–efficiency trade-off for dual-defect detection, we present YOLOv8-SG, a lightweight yet powerful framework engineered for mobile PV inspectors. First, a rigorously curated multi-modal dataset—RGB for stains and long-wave infrared for hotspots—is assembled to enforce robust cross-domain representation learning. Second, the HSV color space is leveraged to disentangle chromatic and luminance cues, thereby stabilizing appearance variations across sensors. Third, a single-head self-attention (SHSA) block is embedded in the backbone to harvest long-range dependencies at negligible parameter cost, while a global context (GC) module is grafted onto the detection head to amplify fine-grained semantic cues. Finally, an auxiliary bounding box refinement term is appended to the loss to hasten convergence and tighten localization. Extensive field experiments demonstrate that YOLOv8-SG attains 86.8% mAP@0.5, surpassing the vanilla YOLOv8 by 2.7 pp while trimming 12.6% of parameters (18.8 MB). Grad-CAM saliency maps corroborate that the model’s attention consistently coincides with defect regions, underscoring its interpretability. The proposed method, therefore, furnishes PV operators with a practical low-latency solution for concurrent bird-dropping and hotspot surveillance. Full article
Show Figures

Figure 1

18 pages, 4169 KiB  
Article
Sustainable Thermoelectric Composites: A Study of Bi2Te3-Filled Biobased Resin
by Luca Ferretti, Pietro Russo, Jessica Passaro, Francesca Nanni, Saverio D’Ascoli, Francesco Fabbrocino and Mario Bragaglia
Materials 2025, 18(15), 3453; https://doi.org/10.3390/ma18153453 - 23 Jul 2025
Viewed by 311
Abstract
In this work, bio-based thermoelectric composites were developed using acrylated epoxidized soybean oil (AESO) as the polymer matrix and bismuth telluride (Bi2Te3) as the thermoelectric filler. The materials were formulated for both UV-curing and thermal-curing processes, with a focus [...] Read more.
In this work, bio-based thermoelectric composites were developed using acrylated epoxidized soybean oil (AESO) as the polymer matrix and bismuth telluride (Bi2Te3) as the thermoelectric filler. The materials were formulated for both UV-curing and thermal-curing processes, with a focus on Digital Light Processing (DLP) 3D printing. Although UV curing proved ineffective at high filler concentrations due to the light opacity of Bi2Te3, thermal curing enabled the fabrication of stable, homogeneously dispersed composites. The samples were thoroughly characterized through rheology, FTIR, TGA, XRD, SEM, and density measurements. Thermoelectric performance was assessed under a 70 °C temperature gradient, with Seebeck coefficients reaching up to 51 µV/K. Accelerated chemical degradation studies in basic media confirmed the degradability of the matrix. The results demonstrate the feasibility of combining additive manufacturing with sustainable materials for low-power thermoelectric energy harvesting applications. Full article
Show Figures

Figure 1

22 pages, 3505 KiB  
Review
Solar Energy Solutions for Healthcare in Rural Areas of Developing Countries: Technologies, Challenges, and Opportunities
by Surafel Kifle Teklemariam, Rachele Schiasselloni, Luca Cattani and Fabio Bozzoli
Energies 2025, 18(15), 3908; https://doi.org/10.3390/en18153908 - 22 Jul 2025
Viewed by 481
Abstract
Recently, solar energy technologies are a cornerstone of the global effort to transition towards cleaner and more sustainable energy systems. However, in many rural areas of developing countries, unreliable electricity severely impacts healthcare delivery, resulting in reduced medical efficiency and increased risks to [...] Read more.
Recently, solar energy technologies are a cornerstone of the global effort to transition towards cleaner and more sustainable energy systems. However, in many rural areas of developing countries, unreliable electricity severely impacts healthcare delivery, resulting in reduced medical efficiency and increased risks to patient safety. This review explores the transformative potential of solar energy as a sustainable solution for powering healthcare facilities, reducing dependence on fossil fuels, and improving health outcomes. Consequently, energy harvesting is a vital renewable energy source that captures abundant solar and thermal energy, which can sustain medical centers by ensuring the continuous operation of life-saving equipment, lighting, vaccine refrigeration, sanitation, and waste management. Beyond healthcare, it reduces greenhouse gas emissions, lowers operational costs, and enhances community resilience. To address this issue, the paper reviews critical solar energy technologies, energy storage systems, challenges of energy access, and successful solar energy implementations in rural healthcare systems, providing strategic recommendations to overcome adoption challenges. To fulfill the aims of this study, a focused literature review was conducted, covering publications from 2005 to 2025 in the Scopus, ScienceDirect, MDPI, and Google Scholar databases. With targeted investments, policy support, and community engagement, solar energy can significantly improve healthcare access in underserved regions and contribute to sustainable development. Full article
Show Figures

Figure 1

15 pages, 3898 KiB  
Article
Wireless Temperature Monitoring of a Shaft Based on Piezoelectric Energy Harvesting
by Piotr Micek and Dariusz Grzybek
Energies 2025, 18(14), 3620; https://doi.org/10.3390/en18143620 - 9 Jul 2025
Viewed by 246
Abstract
Wireless structural health monitoring is needed for machine elements of which the working motions prevent wired monitoring. Rotating machine shafts are such elements. Wired monitoring of the rotating shaft requires making significant changes to the shaft structure, primarily drilling a hole in the [...] Read more.
Wireless structural health monitoring is needed for machine elements of which the working motions prevent wired monitoring. Rotating machine shafts are such elements. Wired monitoring of the rotating shaft requires making significant changes to the shaft structure, primarily drilling a hole in the longitudinal axis of the shaft and installing a slip ring assembly at the end of the shaft. Such changes to the shaft structure are not always possible. This paper proposes the use of piezoelectric energy harvesting from a rotating shaft to power wireless temperature monitoring of the shaft surface. The main components of presented wireless temperature monitoring are three piezoelectric composite patches, three thermal fuses, a system for storing and distributing the harvested energy, and a radio transmitter. This article contains the results of experimental research of such wireless monitoring on a dedicated laboratory stand. This research included four connections of piezoelectric composite patches: delta, star, parallel, and series for different capacities of a storage capacitor. Based on experimental results, three parameters that influence the frequency of sending data packets by the presented wireless temperature monitoring are identified: amplitude of stress in the rotating shaft, rotation speed of the shaft, and the capacity of a storage capacitor. Full article
(This article belongs to the Special Issue Innovations and Applications in Piezoelectric Energy Harvesting)
Show Figures

Figure 1

12 pages, 13780 KiB  
Article
Additive Manufacturing of Composite Structures with Transverse Thermoelectricity
by Weixiao Gao, Shuai Yu, Buntong Tan and Fei Ren
J. Compos. Sci. 2025, 9(7), 344; https://doi.org/10.3390/jcs9070344 - 2 Jul 2025
Viewed by 353
Abstract
This study investigates the application of additive manufacturing (AM) in fabricating transverse thermoelectric (TTE) composites, demonstrating the feasibility of this methodology for TTE material synthesis. Zinc oxide (ZnO), a wide-bandgap semiconductor with moderate thermoelectric performance, and copper (Cu), a highly conductive metal, were [...] Read more.
This study investigates the application of additive manufacturing (AM) in fabricating transverse thermoelectric (TTE) composites, demonstrating the feasibility of this methodology for TTE material synthesis. Zinc oxide (ZnO), a wide-bandgap semiconductor with moderate thermoelectric performance, and copper (Cu), a highly conductive metal, were selected as base materials. These were formulated into stable paste-like feedstocks for direct ink writing (DIW). A custom dual-nozzle 3D printer was developed to precisely deposit these materials in pre-designed architectures. The resulting structures exhibited measurable transverse Seebeck effects. Unlike prior TE research primarily focused on longitudinal configurations, this work demonstrates a novel AM-enabled strategy that integrates directional compositional anisotropy, embedded metal–semiconductor interfaces, and scalable multi-material printing to realize TTE behavior. The approach offers a cost-effective and programmable pathway toward next-generation energy harvesting and thermal management systems. Full article
(This article belongs to the Special Issue 3D Printing and Additive Manufacturing of Composites)
Show Figures

Figure 1

49 pages, 9659 KiB  
Article
Machine Learning Approach to Nonlinear Fluid-Induced Vibration of Pronged Nanotubes in a Thermal–Magnetic Environment
by Ahmed Yinusa, Ridwan Amokun, John Eke, Gbeminiyi Sobamowo, George Oguntala, Adegboyega Ehinmowo, Faruq Salami, Oluwatosin Osigwe, Adekunle Adelaja, Sunday Ojolo and Mohammed Usman
Vibration 2025, 8(3), 35; https://doi.org/10.3390/vibration8030035 - 27 Jun 2025
Viewed by 443
Abstract
Exploring the dynamics of nonlinear nanofluidic flow-induced vibrations, this work focuses on single-walled branched carbon nanotubes (SWCNTs) operating in a thermal–magnetic environment. Carbon nanotubes (CNTs), renowned for their exceptional strength, conductivity, and flexibility, are modeled using Euler–Bernoulli beam theory alongside Eringen’s nonlocal elasticity [...] Read more.
Exploring the dynamics of nonlinear nanofluidic flow-induced vibrations, this work focuses on single-walled branched carbon nanotubes (SWCNTs) operating in a thermal–magnetic environment. Carbon nanotubes (CNTs), renowned for their exceptional strength, conductivity, and flexibility, are modeled using Euler–Bernoulli beam theory alongside Eringen’s nonlocal elasticity to capture nanoscale effects for varying downstream angles. The intricate interactions between nanofluids and SWCNTs are analyzed using the Differential Transform Method (DTM) and validated through ANSYS simulations, where modal analysis reveals the vibrational characteristics of various geometries. To enhance predictive accuracy and system stability, machine learning algorithms, including XGBoost, CATBoost, Random Forest, and Artificial Neural Networks, are employed, offering a robust comparison for optimizing vibrational and thermo-magnetic performance. Key parameters such as nanotube geometry, magnetic flux density, and fluid flow dynamics are identified as critical to minimizing vibrational noise and improving structural stability. These insights advance applications in energy harvesting, biomedical devices like artificial muscles and nanosensors, and nanoscale fluid control systems. Overall, the study demonstrates the significant advantages of integrating machine learning with physics-based simulations for next-generation nanotechnology solutions. Full article
(This article belongs to the Special Issue Nonlinear Vibration of Mechanical Systems)
Show Figures

Figure 1

19 pages, 2403 KiB  
Article
Magnetic Frequency Tuning of a Shape Memory Alloy Thermoelectric Vibration Energy Harvester
by Ivo Yotov, Georgi Todorov, Todor Gavrilov and Todor Todorov
Energies 2025, 18(13), 3341; https://doi.org/10.3390/en18133341 - 25 Jun 2025
Viewed by 262
Abstract
This study examines how the frequency of an innovative energy harvester is tuned and how it behaves. This harvester transforms thermal energy into mechanical oscillations of two polyvinylidene fluoride (PVDF) piezoelectric beams, which produce electrical energy via a shape memory alloy (SMA) thread. [...] Read more.
This study examines how the frequency of an innovative energy harvester is tuned and how it behaves. This harvester transforms thermal energy into mechanical oscillations of two polyvinylidene fluoride (PVDF) piezoelectric beams, which produce electrical energy via a shape memory alloy (SMA) thread. The oscillation frequency is modified by two magnetic weights that are positioned symmetrically on the SMA thread and interact with stationary NdFeB permanent magnets. The SMA thread shifts laterally due to longitudinal thermal contraction and expansion induced by a constant-temperature heater. Temperature gradients above the heater trigger cyclical variations in the length of the SMA thread, leading to autonomous vibrations of the masses in both the vertical and horizontal planes. An experimental apparatus was constructed to analyze the harvester by tracking the motions of the masses and the voltages produced by the piezoelectric beams. Information was gathered regarding the correlation between output voltage and power with the consumer’s load resistance. These outcomes were confirmed using a multiphysics dynamic simulation that incorporated the interconnections among mechanical, thermal, magnetic, and electrical systems. The findings indicate that the use of permanent magnets increases the bending vibration frequency from 8.3 Hz to 9.2 Hz. For a heater maintained at 70 °C, this boosts the output power from 1.9 µW to 8.18 µW. A notable property of the considered energy harvester configuration is its ability to operate at cryogenic temperatures. Full article
Show Figures

Figure 1

22 pages, 9227 KiB  
Review
Review: The Application of MXene in Thermal Energy Storage Materials for Efficient Solar Energy Utilization
by Han Sun, Yingai Jin and Firoz Alam
Materials 2025, 18(12), 2839; https://doi.org/10.3390/ma18122839 - 16 Jun 2025
Viewed by 477
Abstract
Two-dimensional transition metal carbides/nitrides (MXenes) have shown potential in biosensors, cancer theranostics, microbiology, electromagnetic interference shielding, photothermal conversion, and thermal energy storage due to their unique electronic structure, ability to absorb a wide range of light, and tunable surface chemistry. In spite of [...] Read more.
Two-dimensional transition metal carbides/nitrides (MXenes) have shown potential in biosensors, cancer theranostics, microbiology, electromagnetic interference shielding, photothermal conversion, and thermal energy storage due to their unique electronic structure, ability to absorb a wide range of light, and tunable surface chemistry. In spite of the growing interest in MXenes, there are relatively few studies on their applications in phase-change materials for enhancing thermal conductivity and weak photo-responsiveness between 0 °C and 150 °C. Thus, this study aims to provide a current overview of recent developments, to examine how MXenes are made, and to outline the combined effects of different processes that can convert light into heat. This study illustrates the mechanisms that include enhanced broadband photon harvesting through localized surface plasmon resonance, electron–phonon coupling-mediated nonradiative relaxation, and interlayer phonon transport that optimizes thermal diffusion pathways. This study emphasizes that MXene-engineered 3D thermal networks can greatly improve energy storage and heat conversion, solving important problems with phase-change materials (PCMs), like poor heat conductivity and low responsiveness to light. This study also highlights the real-world issues of making MXene-based materials on a large scale, and suggests future research directions for using them in smart thermal management systems and solar thermal grid technologies. Full article
Show Figures

Figure 1

15 pages, 3526 KiB  
Article
Simple and Cost-Effective Design of a THz-Metamaterial-Based Hybrid Sensor on a Single Substrate
by Uddipan Nath, Sagnik Banerjee, Carlo Santini, Rocco Citroni, Fabio Mangini and Fabrizio Frezza
Sensors 2025, 25(12), 3660; https://doi.org/10.3390/s25123660 - 11 Jun 2025
Viewed by 429
Abstract
This study presents a cost-effective Hybrid Metamaterial Absorber (HMA) featuring a simple circular-patterned cylindrical design, comprising an indium antimonide (InSb) resonator on a thin copper sheet. Through numerical simulations, we demonstrate that the structure exhibits temperature-tunable properties and refractive index sensitivity. At 300 [...] Read more.
This study presents a cost-effective Hybrid Metamaterial Absorber (HMA) featuring a simple circular-patterned cylindrical design, comprising an indium antimonide (InSb) resonator on a thin copper sheet. Through numerical simulations, we demonstrate that the structure exhibits temperature-tunable properties and refractive index sensitivity. At 300 K (refractive index = 1), a peak absorption of 99.94% is achieved at 1.797 THz. Efficient operation is observed across a 40 K temperature range and a refractive index spectrum of 1.00–1.05, relevant for thermal imaging and spatial bio-sensing. The simulated temperature sensing sensitivity is 13.07 GHz/K, and the refractive index sensitivity is 1146 GHz/RIU. Parametric analyses reveal tunable absorption through adjustments of the InSb resonator design parameters. Owing to its high efficiency and sensitivity demonstrated in simulations, this HMA shows promise for sensing applications in biotechnology, semiconductor fabrication, and energy harvesting. Full article
(This article belongs to the Section Sensor Materials)
Show Figures

Figure 1

16 pages, 2229 KiB  
Article
Investigation of the Effect of Molecules Containing Sulfonamide Moiety Adsorbed on the FAPbI3 Perovskite Surface: A First-Principles Study
by Shiyan Yang, Yu Zhuang, Youbo Dou, Jianjun Wang, Hongwen Zhang, Wenjing Lu, Qiuli Zhang, Xihua Zhang, Yuan Wu and Xianfeng Jiang
Molecules 2025, 30(11), 2463; https://doi.org/10.3390/molecules30112463 - 4 Jun 2025
Viewed by 528
Abstract
First-principles calculations were conducted to examine the impact of three sulfonamide-containing molecules (H4N2O2S, CH8N4O3S, and C2H2N6O4S) adsorbed on the FAPbI3(001) perovskite [...] Read more.
First-principles calculations were conducted to examine the impact of three sulfonamide-containing molecules (H4N2O2S, CH8N4O3S, and C2H2N6O4S) adsorbed on the FAPbI3(001) perovskite surface, aiming to establish a significant positive correlation between the molecular structures and their regulatory effects on the perovskite surface. A systematic comparison was conducted to evaluate the adsorption stability of the three molecules on the two distinct surface terminations. The results show that all three molecules exhibit strong adsorption on the FAPbI3(001) surface, with C2H12N6O4S demonstrating the most favorable binding stability due to its extended frameworks and multiple electron-donating/withdrawing groups. Simpler molecules lacking carbon skeletons exhibit weaker adsorption and less dependence on surface termination. Ab initio molecular dynamics simulations (AIMD) further corroborated the thermal stability of the stable adsorption configurations at elevated temperatures. Electronic structure analysis reveals that molecular adsorption significantly reconstructs the density of states (DOS) on the PbI2-terminated surface, inducing shifts in band-edge states and enhancing energy-level coupling between molecular orbitals and surface states. In contrast, the FAI-terminated surface shows weaker interactions. Charge density difference (CDD) analysis indicates that the molecules form multiple coordination bonds (e.g., Pb–O, Pb–S, and Pb–N) with uncoordinated Pb atoms, facilitated by –SO2–NH2 groups. Bader charge and work function analyses indicate that the PbI2-terminated surface exhibits more pronounced electronic coupling and interfacial charge transfer. The C2H12N6O4S adsorption system demonstrates the most substantial reduction in work function. Optical property calculations show a distinct red-shift in the absorption edge along both the XX and YY directions for all adsorption systems, accompanied by enhanced absorption intensity and broadened spectral range. These findings suggest that sulfonamide-containing molecules, particularly C2H12N6O4S with extended carbon skeletons, can effectively stabilize the perovskite interface, optimize charge transport pathways, and enhance light-harvesting performance. Full article
Show Figures

Figure 1

25 pages, 6292 KiB  
Article
Improving Cocoa Drying Efficiency with a Mixed Forced Convection Solar Dryer in an Equatorial Climate
by Arnaud Nzendjang Mbakouop, Claude Bertin Nzoundja Fapi, André Désire Siéwé, Hyacinthe Tchakounté and Awoh Innocentia Ankungha
Thermo 2025, 5(2), 18; https://doi.org/10.3390/thermo5020018 - 30 May 2025
Viewed by 1566
Abstract
A crucial stage in the post-harvest processing of cocoa beans, drying, has a direct effect on the finished product’s quality and market value. This study investigates the efficiency, quality outcomes, and environmental implications of a mixed forced convection solar dryer designed for drying [...] Read more.
A crucial stage in the post-harvest processing of cocoa beans, drying, has a direct effect on the finished product’s quality and market value. This study investigates the efficiency, quality outcomes, and environmental implications of a mixed forced convection solar dryer designed for drying cocoa beans in Ntui, Cameroon, compared to traditional open-air drying methods. The solar dryer’s design, incorporating a solar collector, forced ventilation, and thermal storage, leverages local materials and renewable energy, offering an environmentally sustainable alternative by reducing fossil fuel reliance and post-harvest losses. Experimental trials were conducted to assess key drying parameters, including the temperature, relative humidity, water removal rate, pH, and free fatty acid (FFA) content, under the equatorial climate conditions of high solar irradiation and humidity. Results demonstrate that the solar dryer significantly reduces drying time from an average of 4.83 days in open-air drying to 2.5 days, a 50% improvement, while maintaining optimal conditions for bean quality preservation. The solar-dried beans exhibited a stable pH (5.7–5.9), a low FFA content (0.282% oleic acid equivalent, well below the EU standard of 1.75%), and superior uniformity in texture and color, meeting international quality standards. In contrast, open-air drying showed greater variability in quality due to weather dependencies and contamination risks. The study highlights the dryer’s adaptability to equatorial climates and its potential to enhance cocoa yields and quality for small-scale producers. These findings underscore the viability of solar drying as a high-performance, eco-friendly solution, paving the way for its optimization and broader adoption in cocoa-producing regions. This research contributes to the growing body of knowledge on sustainable drying technologies, addressing both economic and environmental challenges in tropical agriculture. Full article
Show Figures

Figure 1

26 pages, 5819 KiB  
Review
Hybrid Energy Harvesting Applications of ZnO Nanorods for Future Implantable and Wearable Devices
by Kathalingam Adaikalam and Hyun-Seok Kim
Micromachines 2025, 16(6), 605; https://doi.org/10.3390/mi16060605 - 22 May 2025
Viewed by 623
Abstract
The currently used electrical energy devices for portable applications are in limited life and need of frequent recharging, it is a big bottleneck for wireless and transportation systems. The scientific community is motivated to find innovative and efficient devices to convert environmental energy [...] Read more.
The currently used electrical energy devices for portable applications are in limited life and need of frequent recharging, it is a big bottleneck for wireless and transportation systems. The scientific community is motivated to find innovative and efficient devices to convert environmental energy into useful forms. Nanogenerator can mitigate this issue by harvesting ambient energy of different forms into useful electrical energy. Particularly flexible nanogenerators can efficiently convert ambient mechanical energy into electrical energy which can be fruitfully used for self-powered sensors and electronic appliances. Zinc oxide is an interesting photosensitive and piezoelectric material that is expected to play a vital role in the synergetic harvesting of environmental thermal, sound, mechanical, and solar energies. As ZnO can be synthesized using easy methods and materials at low cost, the conversion efficiencies of solar and other energy forms can increase considerably. ZnO is a versatile material with interesting semiconducting, optical, and piezoelectric properties; it can be used advantageously to harvest more than one type of ambient energy. The coupled semiconducting and piezoelectric properties of ZnO are attractive for fabricating nanogenerators capable of harvesting both ambient optical and mechanical energies simultaneously. These nanolevel conversion devices are much required to power remote and implantable devices without the need for additional power sources. The present review briefly discusses the principles and mechanisms of different energy harvesting abilities of ZnO nanorods and their composites by consolidating available literature. In addition, the developments taking place in nanogenerators of different kinds—such as photovoltaic, piezoelectric, pyroelectric, and triboelectrics for self-powered technology—and their progress in hybrid energy harvesting application is reviewed. Full article
Show Figures

Figure 1

49 pages, 7115 KiB  
Review
Emerging Trends in Silane-Modified Nanomaterial–Polymer Nanocomposites for Energy Harvesting Applications
by Vadakkaveedu Subramanian Niranjana, Sathiyanathan Ponnan, Arvind Mukundan, Arun Anand Prabu and Hsiang-Chen Wang
Polymers 2025, 17(10), 1416; https://doi.org/10.3390/polym17101416 - 21 May 2025
Cited by 1 | Viewed by 2050
Abstract
Nanomaterials (NMs) have gained tremendous attention in various applications in the modern era. The most significant challenge associated with NMs is their strong propensity to aggregate. The chemical surface modification of NMs has garnered notable attention in managing NM dispersion and aggregation. Among [...] Read more.
Nanomaterials (NMs) have gained tremendous attention in various applications in the modern era. The most significant challenge associated with NMs is their strong propensity to aggregate. The chemical surface modification of NMs has garnered notable attention in managing NM dispersion and aggregation. Among the modification approaches, the silane modification of NMs has generated great interest among researchers as a versatile approach to tailoring the surface characteristics of NMs. This review comprehensively examined the recent advancements in silane modification techniques with a focus on triboelectric nanogenerator (TENG) applications. It provides an overview of silane chemistry and its interaction with diverse NMs, elucidating the underlying mechanisms governing the successful surface functionalization process. This review emphasized the silane modification, such as improved mechanical properties of composites, enhanced electrical and thermal conductivity, functional coatings, water treatment, textile industries, catalysis, membrane applications, and biomedical applications, of various NMs. In particular, the role of silane-modified NMs in advancing energy harvesting technologies was highlighted, showcasing their potential to enhance the performance and stability of next-generation devices. Full article
(This article belongs to the Special Issue Advances in Polymer Composites for Nanogenerator Applications)
Show Figures

Figure 1

Back to TopTop