Ultra-wideband polarization-incident angle insensitive nano-scale metamaterial absorber for solar energy harvesting and infrared detection

In this paper, we propose a broadband tunable metamaterial absorber in the terahertz (THz) region. The absorber comprises a Dirac semimetal film, a dielectric layer, and a gold ground plane. Numerical results show that the absorptivity remains above 90% in the range from 5.7 THz to 8.4 THz when the Fermi level is 65 meV. By varying the Fermi energy of the Dirac semimetal film from 40 meV to 80 meV, the absorption bandwidth and absorption peaks can be dynamically tuned. To explain the mechanism of high absorption, the magnetic field, surface current, and power loss density distributions at different resonant frequencies were presented. Our work may have potential applications in various fields such as sensors, detectors, and photovoltaic devices in THz regions.

Absorption of solar energy in a room

Ultra-broadband and polarization-insensitive metasurface absorber with behavior prediction using machine learning

This chapter provides a brief background in the various conventional methods (surface-based absorption of solar energy) available for harnessing solar thermal energy at a community level. It describes some of the main differences between the typical non-concentrating as well as concentrating type solar collectors, and highlights some of their main attributes. It also presents in detail the results of a novel technique for harnessing solar energy. In this technique, the solar energy is directly absorbed by the fluid (volumetrically) using nanoparticle-laden fluids (hence, it is categorized as volumetric-based absorption of solar energy). Such a collector is analysed in detail using a numerical model. The results of the numerical model are then discussed, which simulates the requirements of hot water for a typical community consists of about 10 households (40 persons). Two of the main performance evaluation parameters - collector efficiency and the fluid outlet temperature - have been extensively studied, and the influence of various design and operational parameters (particle volume fraction, mass flow rate, solar irradiation, collector height, collector length) on these two have been studied in detail. Moreover, the variation of spectral intensity, energy generation rate and spatial temperature distribution within the collector has been quantified. The calculations also show the dimensions of the desired solar collector in order to meet the daily hot water requirements (100 kg/person) for this community.

A tunable metamaterial absorber (MA) with dual-broadband and high absorption properties at terahertz (THz) frequencies is designed in this work. The MA consists of a periodic array of flower-like monolayer graphene patterns at top, a SiO2 dielectric spacer in middle, and a gold ground plane at the bottom. The simulation results demonstrate that the designed MA has two wide absorption bands with an absorption of over 90% in frequency ranges of 0.68 THz–1.63 THz and 3.34 THz–4.08 THz, and the corresponding relative bandwidths reach 82.3% and 20%, respectively. The peak absorptivity of the absorber can be dynamically controlled from less than 10% to nearly 100% by adjusting the graphene chemical potential from 0 eV to 0.9 eV. Furthermore, the designed absorber is polarization-insensitive and has good robustness to incident angles. Such a high-performance MA has broad application prospects in THz imaging, modulating, filtering, etc.

Spectral changes of hemoproteins in the near ultraviolet region on binding to a ligand and on oxidation-reduction of the heme-iron were studied by computer-controlled spectrophotometry. Near ultraviolet difference spectra between the low spin and high spin forms of ferric hemoproteins were classified into three groups: Those showing two absorption peaks having maxima at around 285 and 295 nm, those showing a peak at around 275 nm, and those showing a peak at around 300 nm. No corresponding absorption peak was observed with model heme complexes of low molecular weight. The intensity of the peak in cyanide difference spectra of catalase and horseradish peroxidase in the near ultraviolet region was dependent on the concentration of added cyanide and paralleled the intensity of the spectral changes in the Soret region. The spectral changes in both the near ultraviolet and Soret regions developed within 6 ms after the addition of cyanide. Difference spectra between the reduced and oxidized forms of cytochrome c, cytochrome oxidase-cyanide complex, hemoglobin, and lactoperoxidase-cyanide complex showed a characteristic peak at around 285-290 nm. Various difference spectra of hemoglobin in the near ultraviolet region were also measured. The observed positions, shapes, combinations, and relative intensities of the peaks were compared with those of solvent perturbation difference spectra and pH difference spectra of proteins and aromatic amino acids and also with the diacetylchitobiose-induced difference spectrum of lysozyme. The kinds of aromatic amino acid residues possibly responsible for the observed difference peaks were discussed on the basis of the results of the comparison. Based on the results obtained, the common occurrence of a heme-linked functional response of the hemoprotein conformation was suggested.

High efficient ultra-broadband nanoscale solar energy absorber based on stacked bilayer nano-arrays structure

Nowadays we use many types of bicycle in the world for daily commute. Like we have normal bicycle which needs paddling for moving it, we also have motorized bicycle option which uses fuel for its prime power and next is the electric bicycle which we can use only for an hour. Because we find some weaknesses in the existing systems, the idea of making the solar powered electric bicycle came in to mind. The main concept is to make the bicycle cover longer distance in terms of electric power and it can be automatically recharge by solar power or energy when the bicycle is parked or not in use. In this concept we are putting the high torque motor on the bicycle which will be run by battery and that battery can be charged by solar energy. For generation of power using solar cells the absorption of solar energy is done by portable solar panels. If the power absorbed by solar panel can match the power requirement of battery or the motor then that power is directly used for charging the battery or driving the motor. If direct use is not possible then, the motor will use the power from battery. When the bicycle is not in use during day time, solar panels will charge the battery. Because of this system the bicycle will work more efficiently. Keywords: Bicycle, DC motor, solar panels, conversion of energy, battery Cite this Article Aniket J. Borawane, Vivek P. Chaudhari, Pratik P. Devne et al . Design and Manufacturing of Solar Powered Electric Bicycle. Journal of Instrumentation Technology & Innovations . 2018; 8(2): 36–41p.

Solar energy harvesting is among the best solutions for a global transition toward carbon-neutral energy technologies. The existing solar energy harvesting technologies like photovoltaics (PV) and emerging molecular concepts such as solar fuels and molecular solar thermal energy storage (MOST) are rapidly developing. However, to realize their full potential, fundamental solar energy loss channels like photon transmission, recombination, and thermalization need to be addressed. Triplet–triplet annihilation mediated photon upconversion (TTA-UC) is emerging as a way to overcome losses due to the transmission of photons below the PV/chromophore band gap. However, there are several challenges related to the integration of efficient solid-state TTA-UC systems into efficient devices such as: wide band absorption, materials sustainability, and device architecture. In this article, we review existing work, identify and discuss challenges as well as present our perspective toward possible future directions.

Perfect metamaterial absorbers have attracted researchers’ attention in solar energy harvesting and utilization. An ideal solar absorber should provide high absorption, be ultra-wideband, and be insensitive to polarization and incident angles, which brings challenges to research. In this paper, we proposed and optimized an ultra-wideband solar absorber based on Ti-Al2O3 cross elliptical disk arrays to obtain the ultra-wideband absorption of solar energy. The addition of a cavity greatly improves the energy-absorbing effect in the operating band, which has research value. The absorption spectrum and field distribution were analyzed by the finite difference time domain method. For the physical mechanism, the electric and magnetic field distribution indicates that ultra-wideband absorption is caused by propagation surface plasmon resonance (SPR), localized SPR and Fabry–Perot (F-P) resonance excited between Ti and Al2O3 disks. The results demonstrate that the absorption bandwidth with the absorption rate beyond 90% reaches 1380 nm (385–1765 nm), and the average absorption reaches an astonishing 98.78%. The absorption bandwidth matches the main radiation bandwidth of the solar energy, which is approximately 295–2500 nm according to the data from the literature, and the total thickness of the structure is only 445 nm. Moreover, the ultra-wideband solar absorber is insensitive to the polarization angle and oblique incidence angle. The proposed ultra-wideband solar absorber has research and application value in solar energy harvesting, photothermal conversion and utilization.

Based on the tunable conductivity of silicon as a function of incident pump power, a photoexcited switchable dual-function metamaterial absorber for sensing and wideband absorption at the THz band is designed in this paper. The absorber has an absorption peak at 2.08 THz with the absorption up to 99.6% when the conductivity of silicon is 150 Sm−1, which can be used for sensing. The refractive index sensitivity of the absorption peak is up to 456 GHz/RIU. A wideband absorption is generated from 3.4 THz to 4.5 THz with the bandwidth of 1.1 THz as the conductivity σsi = 12,000 Sm−1. The generation mechanism of the sensing absorption peak and wideband absorption is explained by monitoring the surface current, electric, and magnetic field distribution at some absorption frequencies. It has the advantages of being simple and having a high sensitivity, and wideband absorption with wide application prospects on terahertz communication, electromagnetic stealth, and biochemical detection.

Enhance of the absorption and bandwidth based on a ultra-thin tungsten structure metamaterial absorber in 400–1500 nm range

In this paper, the effect of the form and the shape of the exhibition on the performance of the absorption of solar energy in both cold & mountainous and hot & dry climates has been investigated. The form as the most prominent design feature in buildings has a significant impact on energy efficiency and can be expressed in different ways in a building. In order to evaluate the energy performance of various geometries as an exhibition, the absorption of solar energy in several geometries with different shapes, such as: hexagonal / pyramid / prism / incomplete prism / rectangular cube / cube / hemisphere / cylinder / cylinder combination and the rectangle cube combination, have been numerically simulated. For all geometries, the total area and other simulation conditions are assumed to be the same. The results show that in both types of climate, the most absorbed solar energy is obtained for pyramidal geometry and the least absorption is obtained by hemispherical geometry. The hemisphere form in the hot and dry climate has the best form-to-type ratio in order to provide thermal comfort and reduce energy consumption during the exhibition. In the cold and mountainous climate, pyramidal geometry has the highest energy absorption and is the best option among all investigated geometries. The absorption of solar energy in hemispherical geometry for hot & dry and cold & mountain climate is 66% and 54% compared to pyramidal, respectively.

As a kind of clean and renewable energy, solar energy has been widely used in photovoltaic power generation, photothermal utilization, photocatalysis and other fields. According to its working temperature range, photothermal utilization can be divided into three areas: Low-temperature heat utilization ( medium-temperature heat utilization (80−250°C) and high-temperature heat utilization (>250°C). At present, the technologies of low-temperature heat utilization and high-temperature heat utilization have been relatively mature, while the development of medium-temperature heat utilization technology is relatively slow. Furthermore, the medium-temperature heat utilization is one of the effective technologies to solve the current energy shortage, environmental pollution and other problems. The key problem in solar energy heat utilization is how to improve the efficiency of solar collector. Nanofluids-based direct absorption of solar radiation energy can effectively improve the collection efficiency of solar collectors. However, nanofluids are easy to settle in the long-term cold-hot alternating process, which will deposit on the pipe wall of heat exchanger and even cause blockage, resulting in the increase of thermal resistance and serious heat loss in the process of heat exchange. In this paper, a way of magnetic nanofluid-based direct absorption system for medium-temperature heat utilization is proposed. Firstly, a heat-conducting oil-based nanofluid with magnetic Co@NC is prepared by “two-step” method, and high temperature fluids are obtained under high-power simulated solar irradiation by its excellent optical absorption performance. Secondly, based on magnetic separation technology, Co@NC nanoparticles are separated from the heat conducting oil matrix to obtain pure base liquids with high temperature. Under five solar radiations, the highest temperature of the nanofluids could reach to 120.37°C. Moreover, various liquids with higher temperature can be obtained by the process of heat exchange. Finally, the effects of illumination on the photothermal conversion properties of nanofluids are studied, and the mechanism is explained. This method achieves high photothermal conversion efficiency, and can effectively solve the problem of sedimentation caused by the instability of nanofluids. In addition, it provides a scheme for promoting new development of nanofluids in the use of solar energy at medium temperature. The results show that the photothermal conversion efficiency of magnetic nanofluids is significantly higher than that of base fluids. When the illumination intensity is 5000 W/m2 and the concentration is 100 ppm, the highest temperature can reach to 120.37°C, which is higher than that of pure thermal conductive oil (90.7°C). In addition, the highest photothermal conversion efficiency is 65.23% when the illumination intensity is 1000 W/m2 and the concentration is 100 ppm. With the increase of illumination intensity at the same concentration, the final temperature of the nanofluids increases, but the photothermal conversion efficiency decreases significantly. When the illumination intensity is 5000 W/m2 and the concentration is 100 ppm, the highest photothermal conversion efficiency is only 33.84%. The main reason for this phenomenon is that part of the sunlight can’t be absorbed. With the increase of light intensity, the absorptivity of nanoparticles in nanofluids quickly reaches saturation. Moreover, the stronger the illumination is, the stronger the penetration ability is. The colorimetric dish with a thickness of 1 cm is used, and the maximum concentration of nanofluids is 100 ppm , which is relatively low. Some light passes through the whole nanofluidic layer and can’t be fully absorbed. Therefore, the results show that the photothermal conversion efficiency decreases with the increase of light intensity.

The use of the MPPT algorithm in harvesting solar cell energy has been developed by various methods and has been used in the market. The use of this system has high efficiency and is stable in harvesting and storing electrical energy. However, the use of solar cell energy has the problem of controlling excessive energy consumption by electrical equipment, causing problems in the system and shortening the life of the system. For this reason, a study was conducted to control the optimization of the MPPT system and the use of energy from solar energy storage. The method used is optimization of the MPPT system using microcontroller control and integrated with current limiting control for the output load. From the results of these studies, it is found that the power harvested from solar cells is at the maximum point and a balance between the stored power from absorption from solar cells with power consumption by electronic equipment. These results can increase the efficiency and effectiveness of the absorption and use of solar energy based on solar cells. With this balance, it will reduce the factors that cause system failure and ensure a long battery life