Simulated Solar Energy Research Articles

Experimental analysis of thermal insulation performance in concrete blocks integrated with recycled rubber crumbs

This paper presents an experimental investigation of thermal insulation in rubberized concrete blocks, where the fine aggregate size was replaced by rubber crumbs at varying ratios (0%, 10%, 20%, 30%, 40%, and 50%). The rubber crumbs used in this study ranged in size from 0-1mm, 1-3mm, and 2-4mm. A mixing ratio of 4:2:1 was employed, and simulated solar energy at a rate of 500 W/m2 was applied to the outer surface of the test samples. Heat flux sensors were installed on both the internal and external surfaces to measure transient heat flux through the samples, while K-type sensors were used to measure surface temperatures. The samples were placed in an adiabatic room with an open front side for testing. The results of the study indicate that the addition of rubber crumbs to the concrete mixture improves thermal insulation properties, as evidenced by a decrease in thermal conductivity corresponding to the volumetric substitution ratio of rubber crumbs with the volume of sand in the sample. Particularly, a 50% incorporation of rubber crumbs led to a substantial 76.2% reduction in thermal conductivity, indicating the effective thermal insulation provided by rubberized concrete. These findings hold significant implications for energy conservation within the building sector, where the use of rubberized concrete can contribute to improved energy efficiency and reduced heat transfer.

A simplified evaluation method of rooftop solar energy potential based on image semantic segmentation of urban streetscapes

The evaluation of rooftop solar energy potential in cities has a fundamental role in the development and utilization of solar energy. The irradiance-based approach of evaluation is a repetitive calculation process combined with the complex geometry of urban forms. This research paper proposes a framework that utilizes urban streetscapes to quickly estimate the urban solar energy potential using a simplified solar energy yield model based on two indicators: sky view factor (SVF) and sun coverage factor (SCF). First, 327 Google Street View images were converted into fisheye images, which were semantically segmented based on the deep-learning Full Convolutional Network (FCN). Then, the SVF and SCF were calculated based on the method of pixel statistics. Finally, a model with the simulated solar energy yield was established. Furthermore, a validation study was conducted using rooftop solar production data, which showed that the maximum estimation error of the proposed model was less than 8% and the average relative error was 6.6%. Generally, the proposed model reduced the required computation time while preserving a satisfactory degree of accuracy.

Ti/TiO2 nanotubes sensitized PbS quantum dots as photoelectrodes applied for decomposition of anticancer drugs under simulated solar energy

One of the challenges in research into photoelectrocatalytic (PEC) degradation of pollutants is finding the appropriate photoanode material, which has a significant impact on the process efficiency. Among all others, photoelectrodes based on an ordered TiO2 nanotube arrays are a promising material due to well-developed surface area and efficient charge separation. To increase the PEC activity of this material, the SILAR method was used to decorate Ti/TiO2 nanotubes by PbS quantum dots (QD). The ifosfamide (IF) degradation rate constants was twice as higher for PbS-Ti/TiO2 (0.0148 min−1) than for Ti/TiO2 (0.0072 min−1). Our research showed the highest efficiency of PEC degradation of drugs using IIIPbS-Ti/TiO2 made with 3 SILAR cycles (PbS QD size mainly 2–4 nm). The 4 and 6 of SILAR cycles resulted in the aggregation of PbS nanoparticles on the Ti/TiO2 surface and decreased IF PEC degradation rate to 0.0043 and 0.0033 min−1, respectively. Research on PEC mechanism has shown that the drugs are degraded mainly by the activity of photogenerated holes and hydroxyl radicals. In addition, the identified drug intermediates made possible to propose a degradation pathways of anticancer drugs and the ecotoxicity test show no inhibition of Lemna minor growth of treated solutions.

Charging a vanadium redox battery with a photo(catalytic) fuel cell

A Photo(catalytic) Fuel Cell based on a CdS/TiO2 photoanode and using ethanol as model fuel has been studied as an electric power source to charge a vanadium redox battery. The Photo Fuel Cell was tested under various current production conditions in terms of stability and power output capacity. The cell was functional and produced substantial electric power by consuming an organic fuel under simulated solar energy irradiation. However, it has been found that CdS sensitizer may undergo a self-oxidation process which is relatively fast when the current output is large but is much slower when the current production is low. The conditions for slow self-oxidation have thus been delimited and this allowed determining the conditions for charging the vanadium redox battery using electricity produced by the Photo Fuel Cell. These findings set the basis for production of sustainable electricity and for its storage in a vanadium redox battery.

Efficient photocatalytic removal of orange II by a Mn3O4–FeS2/Fe2O3 heterogeneous catalyst

Elemental doping has been proven to be an effective strategy for increasing the catalytic activity and structural stability of Fenton catalysts. Therefore, this work reports that Mn-doped FeS2/Fe2O3 (Mn3O4–FeS2/Fe2O3) has excellent catalytic performance for the degradation of Orange II under simulated solar energy. Degradation experiment results showed that the sample with a manganese-iron molar ratio of 1:2 exhibited higher activity than others. The degradation rate of 20 mg/L OII reached 99.0% in 18 min under the conditions of 0.3 g/L Mn3O4–FeS2/Fe2O3, 5 mM H2O2 and pH = 2.8. In addition to, the Mn3O4–FeS2/Fe2O3 catalyst shows good reusability for Orange II and high activity for other dyes (MB, MG, Rh B and MO) under optimal conditions. Degradation mechanism study indicated that the heterogeneous Fenton reaction was promoted by retarding the recombination of photogenerated charge carriers and accelerating the cycle between Fe3+/Mn2+ and Fe2+/Mn3+, which improved photo-Fenton-like catalytic performance, resulting in the enhanced degradation of organic pollutant. Finally, a possible degradation pathway was proposed according to the results of liquid chromatography-mass spectrometry (LC-MS). In short, the catalyst has potential application value in wastewater treatment.

Efficiency enhancement of photocatalytic degradation of tetracycline using reduced graphene oxide coordinated titania nanoplatelet

Abstract The compound tetracycline hydrochloride (TCH) is an antibiotic used in the veterinary and medical application, however, it's over usage and accidental release into riverine and estuaries raising up serious threats to the ecology, environment and public health. This study focused on developing a low-cost catalyst to photodegrade TCH. Different formulations of TiO2 photocatalysts scaffolded with reduced graphene (denoted as TiO2-RGO-TiO2) were produced using a cost-effective sol-gel method. The mesoporous structured TiO2-RGO-TiO2 was tuned using citric acid as a complexing agent, Pluronic P-123 as a grafting agent and graphene oxide (GO) as structural “core” to guide the TiO2 growth. Our findings documented that the TiO2-RGO-TiO2 catalysts displayed high degradation efficiency towards TCH. This efficiency was determined to be improved by 22.8% under ultraviolet light and 32.80% under simulated solar energy within 2 h exposure respectively, relative to catalysis by TiO2 alone. It was found that 6 wt percent GO resulted in the highest degradation percentage (˜ 94%) due to the synergistic effects of inhibition of the electron-hole (e− and h+) recombination and improvement of effective reactive sites. The holes were found to the major factor in facilitating the photocatalytic degradation of TCH (75.4%), while the reactive oxygen species (ROS) accounted for the remaining 24.63%. Another factor to contribute to the superior performance of the TiO2-RGO-TiO2 compared to TiO2 alone lies in the decrease of the band gap energy of TiO2 from 3.20 to 2.87 eV upon introduction of reduced GO.

High-resolution assessment of solar energy resources over the Arabian Peninsula

This study presents a high-resolution spatial and temporal assessment of the solar energy resources over the Arabian Peninsula (AP) from 38 years (1980–2017) reanalysis data generated using an assimilative Weather Research and Forecasting Solar model. The simulations are performed based on two, two-way nested domains with 15 km and 5 km resolutions using the European Centre for Medium-Range Weather Forecasts as initial and boundary conditions and assimilating most of available observations in the region. Simulated solar energy resources, such as the Global Horizontal Irradiance (GHI), Direct Normal Irradiance (DNI), and the Diffusive Horizontal Irradiance (DHI), are first validated with daily observations collected at 46 in-situ radiometer stations over Saudi Arabia for a period of four years (2013–2016). Observed and modelled data are in good agreement with high correlation coefficients, index of agreements, and low normalized biases.The total mean annual GHI (DNI) over the AP ranges from 6000 to 8500 Wh m−2 (3000 to 6500 Wh m−2) with significant seasonal variations. The diffuse fraction (the ratio of the DHI to the GHI) is high (low) over the northern (southern) AP in winter whereas it is high (low) over the central to southern (northern) AP during summer, indicating a significant modulation of the sky clearness over the region. Clouds over the northern AP in winter and the aerosol loading due to desert dust over the central and southern AP in summer are the major factors driving the variability of the DHI. The effects of dust and clouds are more pronounced in the diurnal variability of the solar radiation parameters. Our analysis of various solar radiation parameters and the aerosol properties suggest a significant potential for solar energy harvesting in the AP. In particular, the southeastern to northwestern Saudi Arabia are identified as the most suitable areas to exploit solar energy with a minimum cloud coverage over the region.

Synergistic effect in MMT-dispersed Au/TiO2 monolithic nanocatalyst for plasmon-absorption and metallic interband transitions dynamic CO2 photo-reduction to CO

Structured montmorillonite (MMT) dispersed Au/TiO2 nanocomposite has been designed and synthesized through a facile sol-gel method. Cordierite monolithic support was employed in order to load the catalyst for improved photo-activity and reusability in CO2 utilization process. The samples were characterized by XRD, Raman, SEM, TEM, FTIR, XPS, N2 adsorption-desorption, UV–vis and PL spectroscopy. The synergistic effect of MMT-dispersed Au/TiO2 nanocatalyst was evaluated in a gas-phase dynamic monolith photoreactor system using UV and visible light irradiations. The maximum CO yield over 0.5wt.% Au–10wt.% MMT-loaded TiO2 catalyst reached to 1223μmole g-catal.−1h−1, a 24 fold higher than the amount of CO produced over the 10wt.% MMT/TiO2 and 68 times the amount of CO produced over the bare TiO2 catalyst. The other products observed with considerable amounts were CH4 and C2H6. This enactment under UV-light was due to interband transition of Au in catalyst composite. Enhanced photo-activity under simulated solar energy for CO2-to-CO reduction was due to LSPR effect of Au in the MMT/TiO2 sample. More importantly, the performance of Au-MM/TiO2 catalyst for CO evolution under UV-light was 6 folds higher than using visible light. The synergistic effect between MMT transition metals and Au ions and faster adsorption-desorption process contributed to remarkably enhance dynamic CO2 reduction to CO. The present design of catalyst provides prolonged stability to catalyst while CO evolution sustained even after 44h of operation time. The reaction mechanism developed to understand the role of Au/MMT and monolithic support on the photo-activity and reusability of catalyst for CO2 photo-reduction to fuels.

Photo-induced CO2 reduction by CH4/H2O to fuels over Cu-modified g-C3N4 nanorods under simulated solar energy

Copper modified polymeric graphitic carbon nitride (Cu/g-C3N4) nanorods for photo-induced CO2 conversion with methane (CH4) and water (H2O) as reducing system under simulated solar energy has been investigated. The nanocatalysts, synthesized by pyrolysis and sonication, were characterized by XRD, FTIR, Raman analysis, XPS, SEM, N2 adsorption-desorption and PL spectroscopy. The presence of Cu2+ ions over the g-C3N4 structure inhibited charge carriers recombination process. The results indicated that photo-activity and selectivity of Cu/g-C3N4 photo-catalyst for CO2 reduction greatly dependent on the type of CO2-reduction system. CO2 was efficiently converted to CH4 and CH3OH with traces of C2H4 and C2H6 hydrocarbons in the CO2-water system. The yield of the main product, CH4 over 3wt.% Cu/g-C3N4 was 109μmoleg-cata.−1h−1 under visible light irradiation, significantly higher than the pure g-C3N4 catalyst (60μmole/g.cat). In photo-induced CO2-CH4 reaction, CO and H2 were detected as the main products with smaller amount of hydrocarbons. The highest efficiency was detected over 3wt.%Cu-loading of g-C3N4 and at optimal CH4/CO2 feed ratio of 1.0. The maximum yield of CO and H2 detected were 142 and 76μmoleg-catal.−1h−1, respectively at selectivity 66.6% and 32.5%, respectively. Significantly enhanced CO2/CH4 reduction over Cu/g-C3N4 was attributed to its polymeric structure with efficient charge transfer property and inhibited charges recombination rate. A proposed photo-induced reaction mechanism, corroborated with the experimental data, was also deliberated.

Solar thermophotovoltaic system using nanostructures.

This paper presents results on a highly efficient experimental solar thermophotovoltaic (STPV) system using simulated solar energy. An overall power conversion efficiency of 6.2% was recorded under solar simulation. This was matched with a thermodynamic model, and the losses within the system, as well as a path forward to mitigate these losses, have been investigated. The system consists of a planar, tungsten absorbing/emitting structure with an anti-reflection layer coated laser-microtextured absorbing surface and single-layer dielectric coated emitting surface. A GaSb PV cell was used to capture the emitted radiation and convert it into electrical energy. This simple structure is both easy to fabricate and temperature stable, and contains no moving parts or heat exchange fluids.

Chimney Effect of Solar Hybrid-double Wall with Different Thickness PCM of Na2CO3•10H2O

The experiment of the chimney effect of the solar hybrid-double wall with various thicknesses Na2CO3•10H2O was carried out by the simulated solar energy resulted from the adaptable voltage heater. The effect of the various thicknesses on the temperature distribution of the both sides of PCM, the air gap and on the velocity distribution of the air gap were discussed and analyzed. The nature ventilation air volume induced by the chimney effect and the heat gained by the air were also discussed. The results show that the temperature of PCM initially began to rise gradually from ambient temperature, after having absorbed radiation. When the heat storage materials melt completely, the temperature continues to rise until the maximum value at about 10 hour's point. The thicker the PCM, the higher the peak temperature is. At the beginning of heating, the values of average air velocity, air mass flow and the heat gained by the air in the gap increase rapidly to a certain value, and then tends to be stable, which reach a maximum peak at the PCM thickness of 20mm.

Enhanced visible-light photocatalytic activity of multi-elements-doped ZrO2 for degradation of indigo carmine

In this study, C,N,S-doped ZrO2 and a series of Eu doped C,N,S-ZrO2 photocatalysts were synthesized by a coprecipitation method using thiourea as the source of C, N and S and Eu(NO3)·6H2O as source of Eu. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-visible diffuse reflectance spectroscopy, scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). Indigo carmine (IC) was chosen as a model for organic pollutants and used to evaluate the photocatalytic performance of the photocatalysts under simulated solar light. Commercial ZrO2 was used as a reference material. XRD and Raman results indicated the formation of both tetragonal and monoclinic phase ZrO2 with particle size ranging from 8-30 nm. Multi-element doping had a great influence on the optical responses manifested as red shift in the absorption edge. The highest photocatalytic activity towards IC was observed for the Eu,C,N,S-doped ZrO2 (0.6 mol.% Eu) sample (k=1.09×10−2 min−1). The commercial ZrO2 showed the lowest photodegradation activity (k=5.83×10−4 min−1). The results showed that the control of Eu doping in the C,N,S-ZrO2 was very important in reducing electron-hole recombination. The synergistic effect of Eu, C, N, and S in the ZrO2 matrix led to enhanced utilization of simulated solar energy for the degradation of IC through narrowing of bandgaps.

A four power-piston low-temperature differential Stirling engine using simulated solar energy as a heat source

In this paper, the performances of a four power-piston, gamma-configuration, low-temperature differential Stirling engine are presented. The engine is tested with air at atmospheric pressure by using a solar simulator with four different solar intensities as a heat source. Variations in engine torque, shaft power and brake thermal efficiency with engine speed and engine performance at various heat inputs are presented. The Beale number obtained from the testing of the engine is also investigated. The results indicate that at the maximum actual energy input of 1378 W and a heater temperature of 439 K, the engine approximately produces a maximum torque of 2.91 N m, a maximum shaft power of 6.1 W, and a maximum brake thermal efficiency of 0.44% at 20 rpm.

Power options for wireless sensor networks

To combat the security threats of the 21 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> century it is increasingly necessary to protect ever-remote terrain with wireless sensor surveillance. These systems must be self-sustaining to ensure they are constantly operational. Sandia developed a software simulation tool to validate a variety of renewable energy sources for commercial needs. While this software is heavily used in industry it has yet to be fully applied to wireless sensor networks. Based on simulated solar energy yields two different solar energy systems were designed, built, and deployed to the field. In the time since the solar energy power supplies were deployed, zero hours have been spent on maintenance and it was not necessary to replace a single battery

Modified titania nanomaterials for sunscreen applications – reducing free radical generation and DNA damage

Inorganic UV absorbers such as titanium oxide and zinc oxide are in common use in formulations of sunscreens and cosmetics. These materials strongly absorb UV, and show no UV induced degradation over time. However, the dissipation mechanism of the UV energy is not often considered. It is demonstrated that the primary de-excitation mechanism of inorganic sunscreen components is via the surface of the particle and leads to the creation of free radicals. Substantial free radical generation is observed under simulated solar energy with all sunscreen grades of titanium oxide and zinc oxide. Free radicals are implicated in a number of potential health issues such as skin aging. Doping trap centres into titanium oxide and zinc oxide results in the total elimination of free radical generation under simulated solar energy. The trap centres provide sites within the oxide via which it is energetically favourable for photogenerated charge carriers to de-excite. Thus the charge is confined on sites within the host lattice and cannot migrate to the particle surface and create free radicals. The absorbed UV energy is converted to long wavelength light and heat. This effect is demonstrated by electron spin resonance, a primary measure of free radical generation, and by a plasmid nicking assay. The plasmid nicking assay demonstrates the effect of free radicals on supercoiled DNA.

Evaluation of photo contribution to a chemical reaction using concentrated solar energy

Highly concentrated simulated solar energy can be used directly as the energy source to carry out the reaction of 2-propanol to propene and acetone. A focused beam from a 1000 watt xenon lamp is used to simulate concentrated solar energy. The reaction is carried out over 1 % V 2O 5 impregnated on silica. In order to obtain the wavelength dependence of the photoreaction, the reaction is run with UV-visible cutoff filters which successively remove portions of the UV-visible radiation from the xenon lamp. The results demonstrate that the dehydration of 2-propanol to propene is highly dependent on the radiation in the region 300–375 nm, whereas the dehydrogenation to acetone is not dependent on UV radiation.

Calorimetric absorptance measurements of thermal-control coatings between room and cryogenic temperatures.

The simulated solar absorptances of 13 spacecraft thermal-control coatings were determined calorimetrically in vacuum and at nominal temperatures of 173°, 306°, and 463°R. The coatings included white organic paints, white inorganic paints, and anodized aluminum coatings. The purpose of the measurements was to determine the absolute absorptance for simulated solar irradiation of the coatings and to determine the effect of cryogenic temperatures on the absorptance of the coatings. The absorptances were determined by comparing the simulated solar energy absorbed by the coatings from a xenon lamp to the energy incident upon the coatings. The solar absorptances of the coatings also were determined radiometrically in air at room temperature with a Gary spectrophotometer and associated integrating sphere. The results indicate that, within the accuracy of measurement, the absorptance of simulated solar irradiation is essentially independent of or a very weak function of coating temperature between 173° and 463°R. For most of the coatings the solar absorptance values determined calorimetrically and radiometrically at or near room temperature are approximately equal.