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Performance analysis of a photovoltaic panel integrated with phase change material
摘要： The conversion efficiency of photovoltaic (PV) panels is reduced while the PV temperature rises. It is revealed that that every Celsius degree rise in PV temperature can result in as large as a 0.65% drop in the efficiency. This phenomenon attracts substantial scholar attentions in mitigating and controlling the PV temperature. Among those applied techniques, phase change material (PCM) is considered as a potential candidate to hold the PV temperature at a low degree because of its latent heat storage. The integrated system is therefore named PV-PCM system. In this study, the daily performance and viability of this system was evaluated through simulation, illustrating that the temperature of PV can be reduced by 24.9°C through adding PCM, and hence the electricity output increased by up to 11.02%. This study also demonstrates that the latent heat capacity of PCM and natural convection of melted PCM can control PV temperature and enhance the heat dissipation rate from PV to PCM rate by 4 to 5 times.
关键词： Photovoltaic,Phase change material,PV-PCM,Passive cooling,Thermal management
更新于2025-09-12 10:27:22
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Experimental investigation of a photovoltaic thermal collector with energy storage for power generation, building heating and natural ventilation
摘要： A phase change material (PCM) can be used for thermal management of photovoltaics and thermal energy storage. This paper presents a photovoltaic thermal (PVT) system integrated with a PCM as a thermal storage medium for managing the photovoltaic temperature and together with a ventilation duct for preheating supply air or natural ventilation of a building. The novelty of the integrated PVT/PCM system lies in using the PCM as a passive technique not only for PV cooling but also for building heating and ventilation. Experiments have been carried out on a prototype PVT system for different sizes of PCM. The results show that a 30 mm thick PCM layer with a phase change temperature of 25oC can maintain the PV temperature below 45oC and improve the PV electrical efficiency by 10% for about 210 minutes under 600 W/m2 insolation. Increasing the PCM thickness by 10 mm increases the time for thermal control by 60 to 70 minutes. The PVT/PCM system is able to generate a 15 L/s ventilation rate in a vertical duct of 1100 mm wide, 1200 mm high and 100 mm deep during the melting phase and at least 20 L/s during the solidification phase. Use of metal fins to enhance heat transfer in the PCM can increase the PV electrical efficiency further by 3% and the ventilation rate by 30%.
关键词： energy storage,Photovoltaics,phase change material,natural ventilation,thermal management,solar absorber
更新于2025-09-12 10:27:22
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Building integrated photovoltaic modules and the integration of phase change materials for equatorial applications
摘要： The performance of building integrated photovoltaic (BIPV) system depends on the geographical location and the incident angle of solar radiation. In this paper, a simple mathematical model has been developed to predict the performance of BIPV modules with and without phase change material (PCM). The effect of transmittance of the BIPV glass cover is studied with respect to incident solar radiation. The performance curves, annual energy and exergy gains are analysed for hot and humid climatic conditions of Kovilpatti (9°10'00"N, 77°52'00"E), Tamil Nadu, India. The annual electrical energy gains of the BIPV-PCM for the south orientation is (135 kWh) and the east orientation (110 kWh) obtained the minimum. Similarly, the annual electrical energy of the BIPV-PCM is maximum in the east orientation and minimum in the west orientation. The south orientation BIPV-PCM obtained the maximum energy (190 kWh) and exergy (27.3 kWh). The theoretically calculated results have good agreement with experimental results. Practical application: Integration of photovoltaic modules into the building structure has many benefits and challenges; before integrating into the building structure, the performance and impact of the BIPV module needs to be studied. This study will assist developers and designers to understand the likely performance of the BIPV modules and assess the benefit of integrated phase change materials for application in residential buildings in equatorial climate zones.
关键词： Glauber salt,Facade,building integrated photovoltaic phase change material,Building integrated photovoltaic
更新于2025-09-11 14:15:04
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A Novel Temperature Controlled Broadband Metamaterial Absorber for THz Applications
摘要： A broadband switchable metamaterial absorber is investigated in this paper. The switchable response is achieved by utilizing the phase transition property of vanadium dioxide (VO2) that is thermally controlled. A novel band extension scheme is presented by introducing capacitive coupling effects among the resonators. By exploiting the coupling effect, near octave bandwidth is achieved when referred to an absorptivity of 90%. Further, by integrating the temperature controlled VO2 film into the dielectric layer, the proposed absorber can be switched between a frequency band from 0.32 THz to 0.56 THz and another band from 0.356 THz to 0.682 THz that is achieved by changing the operation temperature. Due to the symmetrical structure, the studied absorber features polarization insensitive and a wide incident angle of up to 50?. The broadband and switchable properties are discussed based on the resonant structure, surface current distributions, electric field distributions and impedance matching. It is noted the presented method can be scaled to other adjacent THz frequency band.
关键词： phase change material,metamaterial absorber,Broadband,switchable bandwidth
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 3rd Optoelectronics Global Conference (OGC) - Shenzhen, China (2018.9.4-2018.9.7)] 2018 IEEE 3rd Optoelectronics Global Conference (OGC) - Non-volatile Optical Switch Based on a GST-Loaded Directional Coupler
摘要： We present a non-volatile optical switch based on a directional coupler comprising a silicon-Ge2Sb2Te5 (GST) hybrid waveguide. The non-volatility of GST makes it attractive for reducing static power consumption in optical switching. Experimental results show that the optical switch has an extinction ratio of >20 dB in the bar state and >25 dB in the cross state around 1578 nm wavelength. The insertion loss is 2 dB and 7 dB for the bar and cross states, respectively.
关键词： directional coupler,silicon photonics,phase change material
更新于2025-09-10 09:29:36
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[Energy, Environment, and Sustainability] Advances in Solar Energy Research || Shell-and-Tube Latent Heat Thermal Energy Storage (ST-LHTES)
摘要： Thermal energy storage (TES) unit has become an integral part of thermal energy conservation. As the name implies, the device simply stores heat when energy from the source is available in excess, and releases the same when energy from the source falls short of the requirement. By doing so, such devices deliver heat energy across the temporal barrier, making thermal energy available for extended working hours of solar thermal power plants (STPP). High energy density and stable operation for long duration are desirable qualities which may be found in latent heat thermal energy storage (LHTES) system. To exploit the advantage of LHTES, the most common design reported in the literature is shell-and-tube type latent heat thermal energy storage (ST-LHTES) systems with phase change material ?lled in shell side, while (heat transfer ?uid) HTF ?ows in the tubes (or vice versa). The present chapter gives a detailed classi?cation of ST-LHTES systems based on geometry, orientation and relative position of PCM and HTF in heat exchanger along with the classi?cation of phase-change materials. Numerical modelling of heat transfer phenomenon is presented along with some simulated results for enhanced PCM, clearly describing the coupling between PCM and HTF domain. Various heat transfer enhancement techniques and parametric analysis have been discussed with challenges and future scope.
关键词： Latent heat,Thermal energy storage,Coupling,Shell and Tube Heat Exchanger,Heat transfer ?uid,Phase change material
更新于2025-09-10 09:29:36
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Recent Advances in Tunable and Reconfigurable Metamaterials
摘要： Metamaterials are composed of nanostructures, called artificial atoms, which can give metamaterials extraordinary properties that cannot be found in natural materials. The nanostructures themselves and their arrangements determine the metamaterials’ properties. However, a conventional metamaterial has fixed properties in general, which limit their use. Thus, real-world applications of metamaterials require the development of tunability. This paper reviews studies that realized tunable and reconfigurable metamaterials that are categorized by the mechanisms that cause the change: inducing temperature changes, illuminating light, inducing mechanical deformation, and applying electromagnetic fields. We then provide the advantages and disadvantages of each mechanism and explain the results or effects of tuning. We also introduce studies that overcome the disadvantages or strengthen the advantages of each classified tunable metamaterial.
关键词： plasmonics,metasurface,indium tin oxide,wavefront engineering,phase change material,color filter,perfect absorber,graphene
更新于2025-09-09 09:28:46
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Photo-thermal conversion structure by infiltration of paraffin in three dimensionally interconnected porous polystyrene-carbon nanotubes (PS-CNT) polyHIPE foam
摘要： In this research work, a three dimensionally (3D) interconnected porous polystyrene-carbon nanotubes (PS-CNT) polyHIPE foam was developed as a phase change material (PCM) sca?old for photo-to-thermal energy storage applications. Structural and thermal properties of the novel phase change composite were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X–ray di?raction (XRD) spectroscopy, ultraviolet-visible di?used re?ectance spectroscopy, di?erential scanning calorimetry (DSC) analysis, and laser ?ash analysis. The para?n/PS-CNT composite containing 1 wt% CNTs exhibited a thermal conductivity as high as 0.39 Wm-1 K-1, 1.62 fold higher than that of pure para?n. The highly porous structure of the prepared foam led to a high PCM loading of 82.5%, a high latent heat of 119.3 J g-1 and a melting point of 56.88 °C. The prepared composite preserved its stable thermophysical properties after 100 melting/solidi?cation cycles. The enthalpy of para?n increased about 3.5% after in?ltrating into the PS-CNT polyHIPE foam. Further, the composite displayed excellent shape stability, which prevented the leakage of phase change material during phase transitions. Incorporation of carbon nanotubes in the polyHIPE foam led to black color of the composite leading to an increase in the light absorbance e?ciency and especially the light-to-thermal energy conversion e?ciency (90%).
关键词： Phase change material,PS-CNT polyHIPE,Para?n,Thermal energy storage
更新于2025-09-09 09:28:46
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Tunable near-infrared perfect absorber based on the hybridization of phase-change material and nanocross-shaped resonators
摘要： Ge2Sb2Te5 (GST) is a kind of non-volatile chalcogenide phase-change material, which has a significant difference in permittivity between its amorphous and crystalline states in the infrared range. On account of this remarkable property, the combination of GST and metamaterials has great potential in tunable meta-devices. In this paper, a perfect absorber based on a nanocross-resonator array stacked above a GST spacer layer and an Au mirror (i.e., a metal-dielectric-metal configuration) is designed and experimentally demonstrated. A thin indium tin oxide (ITO) protective layer is inserted between the GST spacer and the Au resonator to avoid heat-induced oxidation of the GST layer during phase transition. We found that the ITO layer not only can protect the GST layer from deterioration, but also allows a significant blue shift in the absorption peak from 1.808 lm to 1.559 lm by optimizing the thickness of the two dielectric layers without scaling down the size of the metal structure, which provides a more feasible idea in pushing the absorption peak to higher frequency. The LC circuit model is presented to explain this blue-shift phenomenon, which is mainly attributed to the engineering of the dielectric environment of the parallel plate capacitance. In addition, such good performance in dynamitic modulation makes this perfect absorber a robust candidate for optical switching and modulating in various situations.
关键词： metamaterials,near-infrared,nanocross-shaped resonators,phase-change material,tunable,perfect absorber,GST
更新于2025-09-09 09:28:46
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - W-Band True-Time Delay Phase Shifters Using Paraffin Microactuators
摘要： We report a distributed loaded line phase shifter based on a new class of electro-thermally actuated RF MEMS devices using paraf?n phase-change material (PCM). Paraf?n is a low loss (tan δ = 6.6×10?4) mechanical phase-change material that exhibits a 15% volumetric change through its solid-liquid transition. Due to its unique electrical and mechanical properties, paraf?n PCM variable capacitors exhibit a very low loss which is critical in designing recon?gurable structures. Here, a low-loss paraf?n PCM based true-time delay, continuously-tunable phase shifter is designed and optimized. A ?gure-of merit of 71.8?/dB is achieved while maintaining a return loss more than 12 dB. Designed phase shifter has a maximum insertion loss of 5 dB for a 360? phase shift. Electro-thermo-mechanical performance of the paraf?n PCM device is studied by carrying out a fully coupled multiphysics simulation. Maximum displacement of 0.8 μm is achieved with a 2.6 μm-thick paraf?n ?lm. A new fabrication method for the deposition of the thin paraf?n ?lm is developed and a fabrication process for the device is presented.
关键词： MEMS,phase shifter,phase-change material,DMTL,paraf?n,millimeter wave
更新于2025-09-04 15:30:14