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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Finite element analysis of cooling mechanism by flat heat-sinks in ultra-high CPV systems
摘要： The potential cost reduction of Concentrator photovoltaic (CPV) systems is closely related to the concentration factor because higher light concentrations imply lower amount of semiconductor material required for the solar cells. However, the thermal management at such ultra-high light fluxes is difficult. The use of small-sized solar cells is beneficial for improving the thermal management. Among the possible cooling strategies, the use of flat-plate heat-sinks for passive cooling, if feasible, would be the simplest way to dissipate heat and would accelerate the development of ultra-high CPV prototypes. In this work, a thermal 3D finite-element model is used to investigate the possibilities of flat-plate heat-sinks for passive cooling at concentration ratios within 2,000-10,000 suns. Results show that a micro solar cells of 1mm x 1mm area can be thermally handled with conventional Aluminium flat plate heat-sinks up to 10,000 suns.
关键词： ultra-high concentration,passive cooling,Concentrator photovoltaic (CPV),thermal management,flat-plate heat-sinks
更新于2025-09-11 14:15:04
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Proton Irradiation on Cesium‐Fluoride‐Free and Cesium‐Fluoride‐Treated Cu(In,Ga)Se <sub/>2</sub> Solar Cells and Annealing Effects under Illumination
摘要： Several studies have been performed on proton irradiation onto alkali-metal untreated Cu(In,Ga)Se2 (CIGS) solar cells. However, there are almost no studies describing similar effects on alkali-treated CIGS solar cells. With this motivation, this work investigates proton irradiation and annealing effects under illumination on cesium-?uoride-free (CsF-free) and CsF-treated CIGS solar cells. Both CsF-free and CsF-treated CIGS solar cells degrade under proton irradiation. External quantum ef?ciency measurements show degradation in long wavelengths after the treatment. The experimental data are ?tted with a simulation, which show that proton-irradiated degradation is more severe at high ?uence. Capacitance–voltage measurements show a broadening of the depletion region after proton irradiation, which is due to the decreased net carrier concentration. It is proposed that proton irradiation at low ?uence generates shallow-type defects, whereas high-?uence protons generate deep defects. However, it is observed that room-temperature storage of the proton-irradiated solar cells causes partial recovery. Thermal annealing under illumination treatments is found to be bene?cial to the drastic recovery of the performance of solar cells irradiated at low ?uence. High-?uence proton-irradiated solar cells undergo minor recovery.
关键词： Cu(In,Ga)Se2 solar cells,cesium-?uoride,heat-light soaking,proton irradiation,annealing
更新于2025-09-11 14:15:04
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Characteristics analysis of the photovoltaic thermal heat pump system on refrigeration mode: An experimental investigation
摘要： Photovoltaic thermal heat pump technology stands for the combination of solar heat pump technology and a photovoltaic system, which has the characteristics of tri-generation (heating, cooling, and electricity) to meet the building's energy requirement. In this paper, the dual-use photovoltaic thermal heat pump system was used and investigated experimentally with an emphasis on the refrigeration mode, which with the feature of the novel roll-bond photovoltaic thermal unit working as condenser directly. Moreover, renewable energy such as solar radiation and long-wave radiation are the main energy source of this system. The experimental investigation of the system comprising; 4 roll-bond photovoltaic thermal units, 1 horsepower heat pump unit and 600 L ice storage tank was carried out. The performance evaluation method and uncertainty analysis of the system was proposed and implemented along with the examination on the refrigeration performance and operating characteristics of the system. The results indicate that the proposed photovoltaic thermal heat pump system can achieve the refrigeration for building space cooling demand in summer with high performance and long-term stable operation. This study could provide a valuable reference for the photovoltaic thermal heat pump multi-generation system design and large-scale practical application in northern China.
关键词： Photovoltaic thermal heat pump,Experimental study,Refrigeration performance,PVT,Operation characteristics
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Periodic Amplification of Radiative Heat Transfer
摘要： The thermal excitation of materials with a periodic heat flux or temperature modulated in time is a reliable and accurate tool usually applied to determine thermal properties, through techniques such as thermoreflectance, photothermal radiometry, 3ω, photoacoustics, thermal-wave resonant cavity, etc. Moreover, over the past years, the control of heat flux has been improved by means of phase-change materials (PCMs), whose internal structures are strongly driven by their temperature, which results in significant variations of their thermal, optical, and electrical properties. Thermochromic materials (VO2, nitinol) or superconductors are examples of such PCMs, where the material can be either in an insulator phase, with low thermal/electrical conductivity and high emissivity, or in a metallic one characterized by a high thermal/electrical conductivity and low emissivity. This metal-insulator transition (MIT) occurs at the critical temperature of each PCM and can therefore be used to tune the heat currents that the PCM exchanges with the environment, which paves the wave for novel applications.
关键词： radiative heat transfer,metal-insulator transition,thermochromic materials,thermal excitation,phase-change materials
更新于2025-09-11 14:15:04
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A Review of Advances in Thermophotovoltaics for Power Generation and Waste Heat Harvesting
摘要： The vast majority of power generation in the United States today is produced through the same processes as it was in the late-1800s: heat is applied to water to generate steam, which turns a turbine, which turns a generator, generating electrical power. Researchers today are developing solid-state power generation processes that are more befitting the 21st-century. Thermophotovoltaic (TPV) cells directly convert radiated thermal energy into electrical power, through a process similar to how traditional photovoltaics work. These TPV generators, however, include additional system components that solar cells do not incorporate. These components, selective-emitters and filters, shape the way the radiated heat is transferred into the TPV cell for conversion and are critical for its efficiency. Here, we present a review of work performed to improve the components in these systems. These improvements will help enable TPV generators to be used with nearly any thermal source for both primary power generation and waste heat harvesting.
关键词： Power Generation,Thermophotovoltaics,Waste Heat Harvesting,Selective-emitters,Filters
更新于2025-09-11 14:15:04
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Radiative Heat Transfer in Two-Dimensional Cylindrical Medium Coupled with BRDF Surface
摘要： For radiative heat transfer analysis and temperature measurements, the surface is usually assumed to be blackbody, diffuse, or specular, which may cause obvious errors under actual working conditions. The bidirectional reflectance distribution function (BRDF), which is considered as a relatively strict approach for characterizing a real surface, has been adopted in heat transfer analysis. In this study, two BRDF models—the Minnaert model and the Torrance and Sparrow model—are applied to investigate the effects of different boundary conditions on the radiative heat transfer. Additionally, the distribution of ratios of energy scattered by the medium or reflected by the boundary surface method is extended to solve the radiative transfer in a two-dimensional graded-index medium coupled with BRDF surfaces in a cylindrical coordinate system. The results show that greater deviation of the BRDF surface from the diffuse characteristics yields a larger difference of the radiative heat flux and intensity distributions between the BRDF and the diffuse surface. The radiative heat flux deviation reaches 12.78%, and more significant differences exist in the radiative intensity along some directions under different boundary conditions. The specular reflection plays a leading role at high reflection angles. However, the increased scattering ability can weaken the influence of the reflection of the BRDF on the radiative intensity distributions.
关键词： radiative heat transfer,graded-index medium,Torrance and Sparrow model,Minnaert model,BRDF surface,cylindrical medium
更新于2025-09-11 14:15:04
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[IEEE 2019 10th International Workshop on the Analysis of Multitemporal Remote Sensing Images (MultiTemp) - Shanghai, China (2019.8.5-2019.8.7)] 2019 10th International Workshop on the Analysis of Multitemporal Remote Sensing Images (MultiTemp) - Comparison between Field-Measured and Multitemporal Modeled Temperature for Firn Compaction Modelling in Taishan Station, Antarctica
摘要： In Antarctic ice sheet, firn compaction corrections should be applied to the elevation changes estimated from multi-year satellite altimetry to reduce components without mass change contribution. Firn compaction rate is mainly affected by firn temperature and density in the vertical column during the yearly and decadal scale compaction processes and it’s essential to account for these two parameters in the firn compaction modelling. In this paper, we solved the temperature along depth and time given initial and boundary conditions based on published physical principles and both our experimental software and an open-source package. We have performed a comparison analysis between the modeled and field temporal temperature profiles at the Taishan Station, East Antarctica. The mean temperature differences of the results with the 12-hour and 1-month time steps are -0.36 K and -0.45 K, and the standard deviations are 1.7 K and 3.2 K, respectively. The temperature modelling process is a part of the firn compaction correction estimation modeling.
关键词： firn compaction modelling,multitemporal modeled temperature,heat transfer,Taishan Station
更新于2025-09-11 14:15:04
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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - The role of pulse to pulse interactions during usp-laser ablation with high average power and repetition rates
摘要： Ultrafast lasers are a versatile tool for micro processing for a wide range of materials. One common field of application is e.g. the surface structuring for mold and embossing tools. While the extremely short pulse durations < 10 ps and interaction times enable highly precise processing quality, the productivity is one major issue and much too small for many industrial applications. To improve the productivity and throughput, increasing the applied average power is a key parameter. Therefore, ultrafast lasers with high average power have the potential to scale up the productivity and reduce the processing times significantly. We present investigations on the processing of metals with a multi-100 W ultrafast laser system with pulse repetition rates of up to 20 MHz. For such power levels and high repetition rates effects like heat accumulation and shielding by pulse-plume interactions occur and have to be taken into account. We describe the relevance and impact of process parameters like spatial pulse separation, repetition rate and pulse duration on the productivity of the ablation process. A theoretical model is presented to distinguish between the influences of the aforementioned effects on the experimental results. Moreover, the fabrication of surface structures utilizing multi-100 W average power is presented.
关键词： ultrafast lasers,repetition rates,heat accumulation,pulse-plume interactions,high average power,micro processing
更新于2025-09-11 14:15:04
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Imaging and micro-structural characterization of moisture induced degradation in crystalline silicon photovoltaic modules
摘要： Moisture induced degradation in photovoltaic (PV) modules operate via multiple chemical mechanisms commonly identi?ed by the sole use of destructive techniques. However, in such cases, e?ective use of spatial imaging techniques can aid identi?cation of certain operating mechanisms on the basis of degradation pattern characteristics. This paper presents an approach of imaging the e?ects of moisture induced degradation in crystalline silicon PV modules under damp heat (DH) test conditions using electroluminescence (EL) and dark lock-in-thermography (DLIT) imaging techniques. The a?ected regions were extracted for identi?cation of degradation products using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) micro-structural characterization technique. Consequently, combination of both imaging and micro-structural characterization techniques were used to propose the mechanism of degradation. The presented approach was instrumental in identi?cation of the e?ects of moisture induced degradation through imaging techniques, moreover the investigation also provided insights in this ?eld of work. The results present signature image patterns for identi?cation and di?erentiation of dominant chemical mechanisms under moisture induced conditions viz. tin migration at the ?nger-wafer interface and formation of silver oxide at cell cracks and edges. The ribbon interconnects was identi?ed as an active site for deposition of oxides from solder material, and aluminium electrode in presence of water as an electrolyte. Moreover, loss in interfacial adhesion between wafer, encapsulant and ?nger. In addition, material quality, manufacturing distinctions, and module design parameters seem to be responsible for observing di?erent operating mechanisms. Also, the obtained insights were applied for investigation of a 20-year-old aged PV module.
关键词： Chemical degradation,Damp heat test,Photovoltaic modules,Electroluminescence imaging,Dark lock-in thermography imaging,Moisture induced degradation
更新于2025-09-11 14:15:04
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Continuous-wave laser diodes based on epitaxially integrated InGaAs/AlGaAs/GaAs heterostructures
摘要： We report the results of the development and investigation of the main characteristics of integrated laser emitters for the spectral range from 1040 to 1080 nm. These devices are fabricated using epitaxially integrated InGaAs/AlGaAs/GaAs heterostructures with one or two emitting regions, and measurements are performed in pulsed, quasi-continuous, and continuous-wave pump regimes. It is found that along with the obvious advantage of integrated emitters – an increase in the output optical power, they also have a significant limitation, which consists in increasing the amount of released heat. Despite this, it is shown that such integrated double laser diodes operate efficiently in the continuous-wave generation regime (Pmax ~ 6 W), demonstrating a 1.7-fold increase in the differential quantum efficiency as compared to single laser diodes.
关键词： continuous-wave regime,laser diode,epitaxially integrated heterostructure,heat release
更新于2025-09-11 14:15:04