Incident Sun Research Articles

Design of a nature-inspired sun-tracking device in context of rural India

The efficiency of the photovoltaic system is traditionally being increased with the help of solar concentrators. The concentrators based on biomimetic structures of various flowers have proven to be effective in increasing performance efficiency. The present study proposes the design of a nature-inspired, novel and passive, single-axis solar tracker that operates on the principle of variable coefficients of thermal expansions of different metals in a bimetallic plate. The proposition mimics the heliotropism mechanism of Sunflowers to achieve acceptable results. It involves the use of a solar PV panel mounted on a gear assembly, connected to a bimetallic plate via connecting linkage and a concave mirror to reflect the incident sun rays on the plates during the day. The resultant deflection in the plates rotates the mounted solar PV panel to follow the sun throughout its diurnal course. There were certain conditions that were determined mathematically to ensure correct working of the proposed design. CAD modelling was adopted to better study the functioning of the envisioned contraption as a whole. The proposed design is easy to construct; thereby making it an efficient, promising and economical alternative to other passive and fixed ones.

Photosynthetic performance under adaxial and abaxial illumination in three Mediterranean Quercus species differing in branch architecture and individual leaf area.

Light availability effects on canopy-level carbon balance constitute an especially difficult issue to address, owing to the strong spatial and temporal changes of the light environment within the canopy. One of the least explored aspects in relation to light environment is the interaction between leaf angle and leaf anatomy. The inclination of the leaf may affect the distribution of light between the adaxial and abaxial surface. The purpose of this study is determining the proportions of the leaf area receiving light from the abaxial side in branches of isolated trees in three Mediterranean oaks, as well as the photosynthetic responses to light under adaxial and abaxial illumination. The proportions of the leaf area illuminated from below were low for sun incidence angles near 0° with respect to the main axis of the branch. However, for sun incidence angles about 45°, the proportion of leaves receiving abaxial illumination was considerable. PPFD levels on the sunlit part of the abaxial surface were always lower than those in the upper leaf side, as a consequence of the lower projection efficiency for the leaves facing the sun by the lower side. Light absorptance was also lower on the abaxial side. The differences between both sides of the leaf tended to be stronger for thicker, longer-living leaves. We conclude that mean C assimilation of the canopy is significantly decreased by the presence of leaves facing the sun by the lower side and that this decrease is stronger in evergreen species with thicker leaves.

Multi-tower heliostat field optimization by means of adiabatic quantum computer

In this work, the possible use of quantum annealers for the optimization of multi-tower systems is studied. These systems are constituted by multiple solar towers and a set of mirrors (heliostats) reflecting the incident sun radiation toward a receiver on top of a tower of choice. The optimization consists in choosing on which tower each of the heliostats should focus the reflected radiation in order to optimize the global collected energy and, therefore, is inherently discrete. In this work, we formulated it in Quadratic Unconstrained Binary Optimization (QUBO) form and solved it with the use of quantum annealers. Results are shown for systems ranging from 2 to 9 towers and from tenths to thousands of heliostats. It is demonstrated that quantum annealers, used in hybrid mode, are effective in finding good solutions. The results are compared with the ones obtained with classical annealers showing comparable performances.

Performance prediction and determination of optimum optical property of the nanofluid for energy storage in direct absorption solar collectors

A direct absorption solar collector converts solar energy into thermal energy and stores it directly in the working fluid. Usually, a nanofluid is used as the working fluid. This work aims to study the behavior of the collector with wide variations of constructional and operating conditions, and then to arrive at the optimum mean extinction coefficients of the nanofluid for obtaining maximum energy storage efficiency. Some studies on these issues with limited scopes are available in the literature. A generalized way of choosing an optimized mean extinction coefficient of the nanofluid for applications in a direct absorption solar collector is not available elsewhere.The parametric behavior of a direct absorption solar collector is studied through a transient finite difference model that considers radiation and convection heat losses from the top surface and mirror reflection from the bottom. Node-wise transient energy equations are developed in terms of the mean extinction coefficient of the working fluid. The optimized mean extinction coefficient points, corresponding to the maximum energy storage efficiency under one sun incident illumination, are identified over a large number of parametric computations. These data show that the optimum mean extinction coefficient decreases with fluid height and illumination time. Correlations for optimum mean extinction coefficient as functions of fluid height and illumination time are derived through regression analyses over the maxima points. A simplified time-averaged correlation solely as a function of fluid height is also presented. In addition, an average optical thickness, a product of the fluid height and optimum mean extinction coefficient, of 2.35 is recommended while using a fluid height between 20 and 80 mm. It is expected that this work would enable one not only to understand the parametric behavior of the collector but also to design it optimally.

Breeding Population and Nesting Habitat of Skuas in the Harmony Point Antarctic Specially Protected Area

Regular monitoring of breeding population abundance and environmental factors related to the nesting habitat has proven fundamental for seabird conservation. Harmony Point (Nelson Island) is an Antarctic Specially Protected Area (ASPA) designated to manage and protect the high biological value of seabirds’ richness and abundance. However, due to the remote location of their breeding sites, many species lack updated population counts. Skuas (Catharacta sp.) exhibited a two-decade gap since the last census was conducted in Harmony Point. The abundance and spatial distribution of the nests of skuas were studied during the austral summer of 2019/2020. Through an exhaustive search, we counted and mapped active nests. Nesting habitat was assessed by the use of an unmanned aerial vehicle to take aerial pictures and build an orthomosaic image to determine vegetation in the area. Additionally, a digital elevation model was built to calculate a series of geomorphological-related variables. Suitability models were used to estimate the importance of variables to the nesting of skuas. A total of 71 brown skua (Catharacta antarctica) and 3 south polar skua (C. maccormicki) nests were counted. Two of the seven variables (terrain slope and vegetation cover) accounted for 57.5% ± 14.1% of the models’ variability; sun radiation incidence, and wind shielding were of secondary importance. Water flow accumulation, distance from penguin colonies, and terrain elevation were the least important variables. Skuas selected for nesting flat terrains (slope < 10°) with a vegetation cover of above 20%, slightly higher sun incidence (270 to 280 kW/h), and intermediary windshielding (45% to 55% of exposition). Considering previous estimates, the skua species at Harmony Point has kept an apparently stable population size over the last 25 years. However, expected changes in nesting habitat availability, i.e., increased snow-free area, increased wind intensity, changes in vegetation cover, and reduction of penguin populations, might change population size in the mid to long term.

Unique New Cooling Technology for Energy Savings in Refineries and Data Centers: Technology and Two Case Studies

Cooling is a major energy use in both refineries and data centers. An invention <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> developed by researchers at Stanford University may alleviate both energy consumption and water usage in numerous applications. This cooling technology uses a band in the atmosphere infrared spectrum that has minimal attenuation of this wavelength. This technology can significantly cool fluid below ambient during the day with incident sun on a panel. The atmosphere is basically “transparent” to radiation from 8 to 13 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m. This allows light in this wavelength band to escape our atmosphere to outer space, which can be modelled as a blackbody at approximately 2 K. This is done using a “nano-photonic radiative cooling” surface made on a film that can be economically fabricated in square meter sizes. Currently, the system can radiate about 100–400 W/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> depending on ambient temperatures. Current photovoltaic solar can produce about 200 W/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with an input of about 1000 W/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The current prototype systems have the same form factor as solar panels; so much of the “rest of plant” is already designed. This article examines the technology and then two case studies: refinery water and energy usage, and energy use for cooling in computer data centers. This article is a revision of the original article presented at the 2021 IEEE PCIC Conference in San Antonio, Texas in September 2021 <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> .

디지털성범죄 예방을 위한 제도적 검토

Our society is being grown a risk factor in a new form available for violating the the benefit and protection of the law in virtual reality by utilizing the information and communication technology that has developed in recent years owing to the transformation into a non-face-to-face society caused by the COVID-19 era.BR The whole nation was in great shock and confusion through a series of incidents, which have occurred in the meantime, such as the Burning Sun incident, the distribution of child pornography on the dark web, and the Nth Room incident, recognized the seriousness of fast- evolving digital sex crimes, and sympathized with the need for countermeasures. Accordingly, various legal and institutional strategies have been prepared such as raising the legal penalty along with adding the constituent requirements of a crime by reflecting the people

In orbit calibration of the non-orthogonality of the two fluxgate sensors onboard CSES

With the accumulation of data, it is possible to study the long-term variation of Fluxgate Magnetometers (FGM) of High Precision Magnetometer (HPM) onboard the China Seismo-Electromagnetic Satellite (CSES). The calibration method of HPM depends on an assumption that the linear parameters of FGM, including the gain factors, the offsets, and non-orthogonal angles are stable. However, HPM exhibits some unexpected trends in the scalar residuals when processed according to the assumption. Study on the residual finds out that under changing space thermal conditions, the non-orthogonal angles of FGM change periodically, suggesting that the data calibration method we used before should be modified. A multi-dimensional polynomial model is established for defining the change of non-orthogonal angles of FGM as a function of the sun incidence angles, geographic latitude and sensor temperature. Apply the polynomial model to data from August 2018 to May 2021, the standard deviation of the scalar residuals is reduced to around 0.5 nT and tends to be more random and in line with the normal distribution. Meanwhile, the variation trend in gain factors and offset factors are eliminated. Results show that the model can correctly reflect the period variation of the non-orthogonal angles of FGM with the space thermal conditions.Graphical

A stochastic cellular automaton model to describe the evolution of the snow-covered area across a high-elevation mountain catchment.

Variations in the extent and duration of snow cover impinge on surface albedo and snowmelt rate, influencing the energy and water budgets. Monitoring snow coverage is therefore crucial for both optimising the supply of snowpack-derived water and understanding how climate change could impact on this source, vital for sustaining human activities and the natural environment during the dry season. Mountainous sites can be characterised by complex morphologies, cloud cover and forests that can introduce errors into the estimates of snow cover obtained from remote sensing. Consequently, there is a need to develop simulation models capable of predicting how snow coverage evolves across a season. Cellular Automata models have previously been used to simulate snowmelt dynamics, but at a coarser scale that limits insight into the precise factors driving snowmelt at different stages. To address this information gap, we formulate a novel, fine-scale stochastic Cellular Automaton model that describes snow coverage across a high-elevation catchment. Exploiting its refinement, the model is used to explore the interplay between three factors proposed to play a critical role: terrain elevation, sun incidence angle, and the extent of nearby snow. We calibrate the model via a randomised parameter search, fitting simulation data against snow cover masks estimated from Sentinel-2 satellite images. Our analysis shows that.

Investigation of annealing effects on physical properties of chemically prepared copper oxide thin films

Copper Oxide (CuO) thin films, a candidate for PSC and p-n junction SCs, were deposited on glass substrates by chemical bath deposition (CBD) and effects of annealing at 300, 350, 400, 450, and 500 °C for 1 h in a muffle furnace on different physical properties were studied. XRD spectra matched well with monoclinic nature of CuO. XRD results revealed that with increasing annealing temperature, crystallite size increased. Raman spectroscopy confirmed development of CuO phase. UV–vis spectroscopy showed excellent photo absorption in the visible region of incident sun light and absorption coefficient remained high. Optical bandgap energy decreased in the range of 1.45 to 1.52 eV with increasing annealing temperatures. Conductivity type observed by thermoelectric/hot probe confirmed the p-type conductivity. The obtained results suggest that CuO thin films with excellent optical properties and p-type nature could be reliably companioned with n-type layer in both n-i-p PSC and p-n junction solar cell structures.

Use of spacecraft solar panels and Sun sensors for estimation of the Sun-pointing direction in the UPMSat-2 mission

Solar panels are a key component for most spacecraft as they provide energy to the vehicle. However, their possible use is not limited only to power generation, as they can also be used as solar sensors for attitude determination. To calculate the direction of the Sun, photovoltaic models (two of them explicit, and the well-known 1-D/2-R equivalent circuit) that simulate the performance of the solar panel (including environmental conditions such as temperature, irradiance and Earth’s albedo, to obtain accurate results) are described in this paper. These models are used to estimate the Sun incidence angle in relation to a spacecraft based on solar panel generation data. This methodology is checked with data from the UPMSat-2 mission and compared with independent measurements derived from this satellite magnetometer data. The Sun direction results are finally compared to the results obtained from the low-cost solar sensors on board the UPMSat-2. The results included in this paper hint at the possibility of using spacecraft solar panels as an additional attitude determination instrument to improve the accuracy of the estimation of the sun direction.

Solar Panel Tracker Using PIC Microcontroller 16F628A

Energy sources are of two types renewable and non-renewable. ‘Renewable’ resources are those that recover their capacity in a time significant by human needs. Examples are sun light or wind power, when natural phenomenon that are the primary source of energy are going and not depleted by human demands. Now days, sometimes we complete our demand of electricity with the help of solar energy. This is done with the help of solar panels. By maintaining the solar panel always perpendicular to the incident sun rays we can receive maximum amount of energy. For this purpose, we have to set the tracker below the solar panel which always sets the panel orientation towards maximum intensity.

Analysis of dynamic louver control with prism redirecting fenestrations for office daylighting optimization

Daylighting with redirecting complex fenestration system (CFS) may improve the indoor luminous environment. This study is to explore the strategies for controlling louver tilts of dynamic micro-prism film louvers corresponding to different solar incident angles, to optimize the work-plane illuminance (WPI) at the middle/back zone of the analyzed large-depth office, based on the simulation results of daylight filtering. To reduce the rotation frequency of the slats, several slat tilt angles were tested to adapt to the changes of different sun incident angles. The study compared the annual daylight performance and glare levels of the three CFSs with dynamic metal louvers, dynamic micro-prism film louvers, and micro-prism film, using the Five-phase method (5-PM). The results showed that the dynamic micro-prism film louvers combined with the proposed control strategy provided a better daylighting luminous environment, regarding the improved useful daylight illuminance (UDI) at inner space, and yielded less glare occurrence rates at space close to windows, compared with dynamic metal louvers and double glazing. Furthermore, the study proposed the combined dynamic louvers that consisted of micro-prism film slats and metal slats to reduce the possible glare on the premise and improve the indoor illuminance at the inner space. The simulation results showed that the combined dynamic louvers could reduce the discomfort glare occurrence rate by 68.9%, compared to the discomfort rate with double glazing at the front zone; UDI300-2000 lx of the combined louvers could be improved by 23%, compared with that of double glazing at the front zone. Compared with the metal louvers with similar low glare occurrence rate, the combined louvers could improve UDI100-300 lx at front/middle/back zones by 7.9%, 29.1%, and 2.9%, respectively, and UDI300-2000 lx by 40.0%, 11.7%, and 5.7% at these zones, respectively.

Development of low-cost reflective plate thermal energy absorber systems for application in South Africa

An innovative solar heat collector system was developed from low-cost materials by applying innovative design technology and using adaptive technologies. The system design entails placing long black polymer pipes connected in series circulation, mounted and positioned in grooves of inverted box rib galvanised steel plating. The grooves reflect and focus the incident rays on the centre piping, concentrating incident sun rays on the black piping and increasing the absorption of thermal energy in the piping filled with circulating water. The circulation of the water is facilitated by a direct-current solar-driven pump powered by a small photovoltaic panel. The thermal energy as collected is stored in a standard household geyser tank. A 3 × 4 m heat absorber of this type collects approximately 10 kWh of energy per day. The estimated cost of the system, considering the capital outlay over an expected ten-year life cycle for the product was estimated at R0.25 per kWh. This pricing competes extremely favourably with the general cost of grid electricity in South Africa for medium-sized households, which is of the order of R2 per kWh up to 1000 kWh per month, including taxes. With an estimated electricity cost escalation of above 5% every year, the ten-year saving for a household using this prototype can be approximately R200 000. The technology and designs developed through the study can create many new business opportunities in South Africa in both urban and rural environments, through manufacturing, installing, repairing, and maintaining the systems.

Experimental study on the electrical performance of a solar photovoltaic panel by water immersion.

The decreased efficiency of a photovoltaic panel due to temperature rise during high solar radiation is one of the major drawbacks. The efficiency drop is due to hotness, which restricts the conversion of incident sun rays into electricity by the silicon cells. Thus, a photovoltaic panel has a negative temperature coefficient that increases the current but drops the voltage potential. In this work, water immersion cooling of the photovoltaic panel is studied to improve panel performance. The module is studied with and without water immersion in a tank made up of acrylic material. The photovoltaic (PV) efficiency is determined at different depths of water immersion (10 to 40 mm) inside the acrylic tank. The solar radiation and thermal and electrical parameters of PV are observed at an interval of 60 min, and besides, the solar radiation is also measured. The electrical efficiency without immersion is about 14.24% at solar radiation of about 725 W/m2. The photovoltaic panel was observed at a temperature of around 30 °C during the water immersion. The panel efficiency with an immersion depth of 10, 20, 30, and 40 mm is approximately 15.02%, 15.54%, 14.58%, and 13.95%, respectively. The results show that the immersion of PV panels in tap water 20 mm increases the PV efficiency by 9.1% compared to the PV without water immersion. The presented experimental results are beneficial to the solar community to improve the PV performance without external power.

Effect of different reflection directional characteristics of building facades on outdoor thermal environment and indoor heat loads by CFD analysis

Diffuse highly reflective (DHR) and specular reflective (SR) materials are widely used in current building facades for urban heat island (UHI) mitigation. Recently, retro-reflective (RR) materials have been studied to replace DHR and SR materials for possible application of building façades. However, previous experimental studies have shown that general RR materials will produce negative downward reflections to the ground at high sun incidence (above 60-degrees). This study uses a Computational Fluid Dynamics (CFD) analysis method to predict the outdoor thermal environment: air temperature (Ta), mean radiation temperature (MRT), wet bulb globe temperature (WBGT) and new standard effective temperature (SET*) under three different building facades (DHR, SR and RR). Additionally, for detecting the negative downward reflection intensity of three different facades, the solar radiation reflected by facades and the heat flux to nearby ground are evaluated. Finally, to examine the effect of three different facades on the heat load of air-conditioning, the heat flow from building façades to interior are evaluated. The results show that RR and SR building facades are the most effective in decreasing MRT, and have smaller heat flow from façade surfaces to the interior for decreasing the heat load of air-conditioning, however the RR and SR building facades yield more negative solar radiation and heat flux to the ground.

Parametric optimization of Solar Parabolic Collector using metaheuristic Optimization

Estimation of an exceptionally exact model for solar parabolic collector from the experimental data is an important task for the researchers for the recreation, assessment, control and plan. Efficient optimization techniques are fundamental to accomplish this undertaking. In this paper a modified optimization technique is proposed for productive and precise estimation of the parameters of solar parabolic collector. The proposed algorithm is concentrated on the modification of Elephant Swarm Water Search Algorithm. This algorithm tested on parabolic collector parameters, namely reflectivity, Absorptivity &amp; period of sun incidence. Response surface methodology has been used to implement the non linear model between the input &amp; output parameters of the process. In addition, the proposed ESWSA optimization technique has been tested against the manufacture datasheet of solar parabolic reflector. Results show the effectiveness of ESWSA algorithm for modeling of the solar parabolic systems. Keyword : Solar parabolic Collector, Parameters, ESWSA, Optimization

Cu3BiS3/MXenes with Excellent Solar-Thermal Conversion for Continuous and Efficient Seawater Desalination.

Two-dimensional materials with unique physical and chemical properties have recently attracted widespread attention in the field of solar thermal conversion. However, affected by the Fresnel effect, traditional two-dimensional materials such as MXenes, graphene, transition metal disulfide often have relatively significant light reflection losses at the solid-liquid or gas interface. So how to improve the light absorption of the two-dimensional material performance has become a new challenge in photothermal conversion. Here, we use an improved thermal-injection method to uniformly grow Tricopper(I) Bismuth Sulfide (Cu3BiS3, CBS) on the surface of Ti3C2 nanosheets in a nonaqueous polar solvent environment. A three-dimensional nanoflower-nanosheet structure CBS-Ti3C2 for photothermal conversion has been constructed successfully. Owing to the excellent photothermal performance of Cu3BiS3 in the near-infrared region, the good thermal conductivity of Ti3C2, and the unique porous structure of the composite material, the composite achieves broadband absorption of light (more than 90% in the visible light region, more than 80% in the near-infrared region), which optical model and finite element simulation have theoretically verified. The composite material has obtained higher solar-to-heat conversion performance than similar material systems, and the steady-state temperature can reach 62.3 °C under 1 sun incident light intensity. CBS-Ti3C2 is expected to become a light-absorbing layer material for solar vapor generation devices due to its excellent light-to-heat conversion performance and good material flexibility. It still guarantees a reasonably high steam generation rate (1.32 kg·m-2·h-1) even with a thinner material thickness (0.48 mg·cm-2) and a comprehensive conversion efficiency higher than 90%. Besides, CBS-Ti3C2 also exhibits the characteristics of resisting surface salt accumulation, which is conducive to maintaining the long-lasting photothermal seawater evaporation process. The material's electronic structure and the charge transfer process of the heterojunction interface have been studied with the first-principles calculation. The high light absorption performance and good thermal conductivity of the composite material are theoretically explained and supported.

An Experimental Study on New Multistage Solar Parabolic Trough Collector

Solar parabolic collector is a clean a promising traditional technique due to the deficiency in energy resources. A new designed multistage solar parabolic trough collector was proposed and its thermal performance was investigated in this study. The collector width and length are 1m with a copper receiver tube outside and inside diameters of 2.54cm, 2.46cm, respectively. Four buses tube receiver were proposed inside the parabolic collector fitted in a thermocouple at the entrance and exit regions of each bus. A solar tracker with a solar sensor for maximum collecting incident sun rays from the sun rise to sun set. The test section is covered with a glass sheet for easy cleaning and to protect the system from losing heat to the surrounding. To evaluate the thermal performance of the new collector, several variables were studied which are: temperature difference between the fluid inlet and outlet regions, heat absorbed by the collector, convective heat transfer rate, and collector thermal efficiency. All the studied variables show that minimum water volumetric flow rates will give max temperature difference between the fluid inlet and outlet regions, heat absorbed by the collector, convective heat transfer rate, and collector thermal efficiency respectively.

Investigation of the performance of a hybrid PV/thermal system using water/silver nanofluid-based optical filter

A specific part of the incident sun light on the PV panel that is responsible for the overheating of the cells might be filtered using nanofluids-based optical filter. The goal of this particular analysis is to, numerically, look into the functionality of the hybrid Photovoltaic/thermal (PV/T) solar system accompanied with an optical filtration channel (PV/OF). This analysis is among the first studies to evaluate the impact of many optical filtration managing parameters on the functionality of the hybrid PV/OF system at different atmospheric conditions and solar concentrations using the water/silver nanofluid as a working fluid. The thermal, optical, and electrical models have been developed to assess the common performance of the hybrid system. The effects of the loading and size of the nanoparticles, the height of the optical nanofluid channel and the rate of flow on the common performance of the system at different atmospheric conditions have been examined. The numerical results were validated with experimental data readily available in the literature. Comparatively to the individual PV system, the hybrid system has declared better general performance. This specific enhancement was pronounced at higher atmospheric temperatures and solar concentrations. At an atmospheric temperature of 45 °C and solar concentration of 5, the hybrid system was able to produce both electrical and thermal energies with efficiencies of 8.4% and 66.7% respectively, at the same time, where the standalone PV system was showing an electrical efficiency of 3.7%. Nevertheless, the electrical performance was not better at atmospheric temperatures lower than 34.1 °C in addition to unity solar concentration. At 25 °C, the hybrid system shows electrical and thermal efficiencies of 10.7% and 57.7%, respectively, compared to an electrical efficiency of 11% for the standalone system. The results of the study reveal that the hybrid PV/OF system can be an excellent replacement for the single PV system and its potential becomes more significant at the high atmospheric temperatures and solar concentrations.