High Intensity Of Solar Radiation Research Articles

The influence of high intensity solar radiation on the temperature and reduction of an oxygen carrier particle in hybrid chemical looping combustion

The temperature variations during the conversion of an oxygen carrier particle exposed to high intensity solar heat flux are assessed as a function of time with an unsteady-state model. The conservation equations of energy and mass are solved simultaneously using an appropriate numerical technique, whose reliability was assessed by comparison with the available experimental and numerical data from the literature. This model was used to study the effect on the particle conversion and maximum temperature of various operating parameters i.e. particle size, external heat and mass transfer, radiation heat flux intensity, CH4 mole fraction and surrounding temperature. The numerical results show that exposing the particle to high flux solar radiation decreases the conversion time and increases the particle temperature. The calculations indicate that a higher Nusselt number results in a lower temperature rise of the particle and a lower conversion time. The calculations also show that, convection is the dominant mechanism of particle cooling, despite the high temperature of the particle surface.

The influence of climate change on stomatal ozone flux to a mountain Norway spruce forest

Daily stomatal ozone flux to a mountain Norway spruce forest stand at the Bily Kriz experimental site in the Beskydy Mts. (Czech Republic) was modelled using a multiplicative model during the 2009 growing season. The multiplicative model was run with meteorological data for the growing season 2009 and ALADIN-CLIMATE/CZ model data for the 2030 growing season. The exceedance of the flux-based critical level of O3 (Phytotoxic Ozone Dose) might be lower for Norway spruce at the Bily Kriz experimental site in a future climate (around 2030), due to increased stomatal closure induced by climate change, even when taking into account increased tropospheric background O3 concentration. In contrast, exceedance of the concentration-based critical level (AOT40) of O3 will increase with the projected increase in background O3 concentration. Ozone concentration and stomatal flux of ozone significantly decreased NEP under both present and future climatic conditions, especially under high intensities of solar radiation.

Comparison of PV Cell Temperature Estimation by Different Thermal Power Exchange Calculation Methods

A steady-state thermal model for calculate the temperature of a photovoltaic (PV) module has been developed for outdoor installation such as ground-mounted systems. The PV temperature is influenced by environmental variables such as: irradiance ambient temperature, intensity and direction of the wind, module design, orientation and mounting structure. As well as it is influenced by electrical parameters. In literature some single layer thermal balance consider only an overall heat transfer coefficient as a function of wind speed, neglecting the radiative thermal flux. In this paper, five thermal balance are compared and it is shown that the radiative term cannot be neglected, otherwise the PV temperature could be overestimated for low solar radiation intensity and it could be underestimated for high solar radiation intensity. For this reason, the percentage contribution of the heat exchanges, normalized as function of normal incoming solar radiation, are evaluated for wind speed within 1 m/s (natural convection).

Physical and rheological properties of asphalt binders containing various antiaging agents

Laboratory methods to simulate the short-term and long-term aging occurring during the service life of asphalt binder in a pavement are standardized, and the influence of ultraviolet (UV) radiations is ignored. The thermal and UV aging of asphalt binders must be considered in the study of the performance of asphalt pavement, especially in geographical regions where high solar radiation intensity occurs. The effects of antioxidants and UV absorbers on the properties of asphalt binders were studied in this study. Experimental results indicated that the improvement of the antiaging resistance of asphalt binder is noticeable when compound antiaging agents containing antioxidants and UV absorbers, at which the physical properties of asphalt is not change remarkably. The results of aging indicated that the asphalt/antioxidants blend has good heat aging resistance, and asphalt/UV absorbers blends have good photostability. However, to prepare asphalt binders with better physical and antiaging resistance, the compound antiaging agents containing antioxidants and UV absorbers must be selected. The results also indicated that the effects of antiaging agents on storage stability of asphalt/antiaging agents blend are little and can be used in pavement after long time storage at high temperature.

An Estimation of Solar Radiation using Robust Linear Regression Method

The air temperature data is the most important component to estimate the solar radiation in photovoltaic systems. From the Malaysia Meteorological Department, the data of air temperature and solar radiation can be found the hourly, daily, monthly and also the annually. Based on solar radiation data for the past 26 years, the average monthly solar radiation was 5009.56 Wh/m2. It was greater than the normal solar radiation (3 kWh/m2), which indicates that the sky in Perlis was clear and very high solar radiation intensity for the months in the past 26 years. This paper presents an investigation of a relationship between solar radiation and temperature in Perlis, Northern Malaysia for the year of 2006. The Least Trimmed Squares (LTS) robust regression model was selected to estimate the solar radiation since the robust method is do not breakdown easily and are not much influenced by outliers.

Performance investigation of a salt gradient solar pond coupled with desalination facility near the Dead Sea

Abstract Solar ponds provide the most convenient and least expensive option for heat storage for daily and seasonal cycles. This is particularly important for a desalination facility, if steady and constant water production is required. If, in addition to high storage capacity, other favorable conditions exist, the salt gradient solar ponds (SGSPs) are expected to be able to carry the entire load of a large-scale flash desalination plants without dependence upon supplementary sources. This paper presents a performance investigation of a SGSP coupled with desalination plant under Jordanian climatic conditions. This is particularly convenient in the Dead Sea region characterized by high solar radiation intensities, high ambient temperature most of the year, and by the availability of high concentration brine. It was found that a 3000 m 2 solar pond installed near the Dead Sea is able to provide an annual average production rate of 4.3 L min −1 distilled water compared with 3.3 L min −1 that would be produced by El Paso solar pond, which has the same surface area. Based on this study, solar ponds appear to be a feasible and an appropriate technology for water desalination near the Dead Sea in Jordan.

Ozone flux over a Norway spruce forest and correlation with net ecosystem production

Daily ozone deposition flux to a Norway spruce forest in Czech Republic was measured using the gradient method in July and August 2008. Results were in good agreement with a deposition flux model. The mean daily stomatal uptake of ozone was around 47% of total deposition. Average deposition velocity was 0.39 cm s −1 and 0.36 cm s −1 by the gradient method and the deposition model, respectively. Measured and modelled non-stomatal uptake was around 0.2 cm s −1. In addition, net ecosystem production (NEP) was measured by using Eddy Covariance and correlations with O 3 concentrations at 15 m a.g.l., total deposition and stomatal uptake were tested. Total deposition and stomatal uptake of ozone significantly decreased NEP, especially by high intensities of solar radiation.

Shilajit: A panacea for high-altitude problems.

High altitude problems like hypoxia, acute mountain sickness, high altitude cerebral edema, pulmonary edema, insomnia, tiredness, lethargy, lack of appetite, body pain, dementia, and depression may occur when a person or a soldier residing in a lower altitude ascends to high-altitude areas. These problems arise due to low atmospheric pressure, severe cold, high intensity of solar radiation, high wind velocity, and very high fluctuation of day and night temperatures in these regions. These problems may escalate rapidly and may sometimes become life-threatening. Shilajit is a herbomineral drug which is pale-brown to blackish-brown, is composed of a gummy exudate that oozes from the rocks of the Himalayas in the summer months. It contains humus, organic plant materials, and fulvic acid as the main carrier molecules. It actively takes part in the transportation of nutrients into deep tissues and helps to overcome tiredness, lethargy, and chronic fatigue. Shilajit improves the ability to handle high altitudinal stresses and stimulates the immune system. Thus, Shilajit can be given as a supplement to people ascending to high-altitude areas so that it can act as a “health rejuvenator” and help to overcome high-altitude related problems.

Sublethal stress: Impact of solar UV radiation on protein synthesis in the copepod Acartia tonsa

Aquatic organisms respond to environmental challenges such as thermal stress with the rapid induction of highly conserved polypeptides known as stress proteins or heat shock proteins (Hsps). Solar ultraviolet radiation (UVR, 280–400 nm) is an important environmental stressor in marine ecosystems. Here, we present results of experiments conducted with the marine copepod Acartia tonsa to follow the de novo protein synthesis and measure the level of constitutive and inducible isoforms of the Hsp70 gene family of stress proteins after UV exposure. Animals were collected from Tampa Bay, Florida (USA), and exposed to solar radiation (full spectrum), UV-A (320–400 nm) and PAR (400–700 nm), or PAR only, for periods of 0.5–4 h. Controls were kept in the dark. Protein synthesis was robust under all treatments when the copepods were exposed to low solar radiation intensities. Conversely, high solar radiation intensities (both UV-B and UV-A) caused an overall suppression in the protein synthesis of the copepods with no detectable induction of stress-inducible isoforms of Hsps. Immunochemical assays (western blotting) showed that UVR increased levels (3.5–4-fold increase compared to the dark control) of the constitutively expressed 70 kDa heat-shock (Hsc70) protein in A. tonsa, without indication of inducible isoform upregulation.

Investigation of the Degradation of Thermal Control Materials by Thermal Analysis

Thermal analysis is the name of a collection of techniques that investigates material properties as a function of temperature. Four main techniques which all look at specific material properties are differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechnical analysis (TMA) and dynamic mechanical analysis (DMA). The commercially available polyimide foils Kapton HN and Upilex S are often used as external thermal control material on spacecraft. For missions to the inner part of the solar system, these materials need to withstand an elevated service temperature in combination with high intensity solar radiation, such as UV and protons. The thermal stability of Kapton and Upilex has been investigated at around 2503 C for a mission to Venus and at 3503C for a mission to Mercury. Samples were aged at representative temperature levels, also in combination with high intensity UV and proton radiation. It was found that TMA and DMA revealed, in good detail, the environmental effects of the behavior of the materials. Both foils are known to be thermally stable materials. Assessment by TGA and kinetic modeling indicates a better stability of Upilex at 350 3C. The DMA experiments of foils aged at 3503C for up to 3580 h prove that the glass transition of Kapton is largely affected and almost completely disappears. Upilex is also affected but remains more stable. The TMA assessment revealed annealing of residual stresses at elevated temperature that cause (partial) shrinking of the foils. Ageing at around 2503C causes such annealing besides other more subtle changes. The added irradiation to high intensity UV and protons does not cause significant changes compared to thermal ageing alone. The DMA results are in good agreement with the TMA. The behavior of Upilex is deemed to be somewhat less affected by the environmental testing than Kapton.

Photodegradation of hot-mix asphalt

Photodegradation of asphalts must be considered in the study of the performance of asphalt pavement, especially in geographical regions where a high solar radiation intensity occurs. The aim of this work is to study asphalt ageing caused by the effect of xenon radiation, by using environmental tests. The spectral profile of a xenon arc is very similar to the solar radiation spectrum. Hot-mix asphalt samples were submitted to a weathering test, with cycles of exposure to a xenon radiation and humidity, and the sample degradation was evaluated using thermal analysis, Fourier transform infrared spectroscopy, and gel permeation chromatography. After the weathering test, the thermal stability of asphalt binder decreased. The qualitative analysis by using gel permeation chromatography indicated a decrease of the molecular weight of the asphalt binder after the weathering test. The results of the Fourier transform infrared spectroscopy analysis indicate an oxidation process of material, which occurred during the weathering test. The normalized absorbance of the peak associated to the C O group and OH group increased in relation to the total area of peaks for the hot-mix asphalt samples, after exposure to xenon radiation.

Opportunities and challenges for the development of an integrated seaweed-based aquaculture activity in Chile: determining the physiological capabilities of Macrocystis and Gracilaria as biofilters

Seaweed production is a reality in Chile. More than ten species are commercially used to produce phycocolloids, fertilizers, plant growth control products, human food or animal fodder and feed additives. These multiple uses of algae offer a number of possibilities for coupling this activity to salmon, abalone and filter-feeder farming. In this context, different experiments carried out in Chile have demonstrated that Gracilaria chilensis and Macrocystis pyrifera have great potential in the development of an integrated aquaculture strategy. The present Integrated Multi-Trophic Aquaculture (IMTA) approach study showed that Gracilaria can be cultured best at 1 m depth whereas Macrocystis has an especially good growth response at 3 m depth. Both species use available nitrogen efficiently. On the other hand, high intensities of solar radiation (UV and PAR) can be critical at low depths of cultivation, and our results indicate that both species show photosynthetic susceptibility mainly at noon during the summer. The demand of Macrocystis for abalone feeding is increasing, thus improving the opportunity for developing an integrated nutrient waste recycling activity in Chile. Although Gracilaria shows a higher nitrogen uptake capacity than Macrocystis, its market value does not yet allow a massive commercial scaling.

Synchronous flowering linked to changes in solar radiation intensity

Synchronous flowering linked to changes in solar radiation intensity

Synchronous flowering of the rubber tree (Hevea brasiliensis) induced by high solar radiation intensity

How tropical trees flower synchronously near the equator in the absence of significant day length variation or other meteorological cues has long been a puzzle. The rubber tree (Hevea brasiliensis) is used as a model to investigate this phenomenon. The annual cycle of solar radiation intensity is shown to correspond closely with the flowering of the rubber tree planted near the equator and in the subtropics. Unlike in temperate regions, where incoming solar radiation (insolation) is dependent on both day length and radiation intensity, insolation at the equator is due entirely to the latter. Insolation at the upper atmosphere peaks twice a year during the spring and autumn equinoxes, but the actual solar radiation that reaches the ground is attenuated to varying extents in different localities. The rubber tree shows one or two flowering seasons a year (with major and minor seasons in the latter) in accordance with the solar radiation intensity received. High solar radiation intensity, and in particular bright sunshine (as distinct from prolonged diffuse radiation), induces synchronous anthesis and blooming in Hevea around the time of the equinoxes. The same mechanism may be operational in other tropical tree species.

Behavioural responses of moose to thermal conditions in the boreal forest

:Among ungulate species living in boreal regions, moose (Alces alces) are most likely to suffer from heat stress since they have a relatively low upper critical temperature (14 °C in summer and -5 °C in winter). We tested the hypothesis that moose adopt behaviours to reduce thermoregulatory costs. We predicted that moose exposed to high intensities of solar radiation or high air temperatures would 1) seek a type of vegetation association that provides thermal shelter and 2) reduce activity. We also predicted that these behaviours would be most evident in summer. Thermal-shelter use and activity of 30 free-ranging moose were measured over 3 y in a 940-km2 study area of boreal forest using GPS telemetry collars. The effect of solar radiation and air temperature on thermal-shelter use and activity were assessed using logistic and multiple regression analyses. Habitat use and activity rates of moose were related to air temperature but not solar radiation. The probability of finding moose in thermal shelters increased with air temperature in summer and fall. Moose activity did not decrease as air temperature increased, but it increased at night during hot periods. As expected, moose response to thermal conditions was most noted in summer. Our results suggest that moose reduce exposure to thermal stress by using thermal shelters during the day and by increasing nocturnal activity. These behavioural adaptations allow moose to cope with thermal stress on a small temporal scale. Negative effects of heat stress could be important in areas where air temperatures are very high for extended periods of time or where thermal cover is scarce.

A multiple-scattering model analysis of zinc oxide pigment for spacecraft thermal control coatings

Space assets inhabit a harsh thermal environment in which the high intensity of direct solar radiation can potentially raise temperatures to harmful levels. Thermal management is obtained through the use of radiators coated with thermal control coatings (TCCs) that diffusely reflect the sun’s high energy visible (VIS) and near infrared (NIR) radiation, while emitting infrared (IR) energy as a method of radiatively cooling. The current state-of-the-art TCC system utilizes a potassium silicate binder and zinc oxide (ZnO) pigment to maintain solar reflectance over a long exposure time. We are investigating improvements to TCCs that will have greater initial performance and significantly better end-of-life properties. We have utilized modeling techniques based upon Mie scattering to determine the theoretical scattering efficiency limits of the currently used materials. An optimized TCC would attain maximum diffuse solar reflectance at a lower film thickness and reduce the pigment volume concentration (PVC) required. These factors would contribute to a reduction in overall weight and possibly extend the durability of the system to longer time scales. Our results of modeling ZnO pigment embedded in a matrix similar to that of potassium silicate under solar irradiance conditions indicate that a narrow particle size distribution centered at 0.35 μm would provide the highest overall scattering coefficients, ranging from 0.75 μm −1 at 1000 nm to 5.0 μm −1 at 380 nm wavelengths. These results indicated that a significant improvement, 2–10 times dependent upon wavelength, in the scattering efficiency of ZnO-based TCCs can be realized by utilizing an optimized particle size distribution rather than the currently used size distribution.

Survival of microorganisms in space protected by meteorite material: Results of the experiment ‘EXOBIOLOGIE’ of the PERSEUS mission

During the early evolution of life on Earth, before the formation of a protective ozone layer in the atmosphere, high intensities of solar UV radiation of short wavelengths could reach the surface of the Earth. Today the full spectrum of solar UV radiation is only experienced in space, where other important space parameters influence survival and genetic stability additionly, like vacuum, cosmic radiation, temperature extremes, microgravity. To reach a better understanding of the processes leading to the origin, evolution and distribution of life we have performed space experiments with microorganisms. The ability of resistant life forms like bacterial spores to survive high doses of extraterrestrial solar UV alone or in combination with other space parameters, e.g. vacuum, was investigated. Extraterrestrial solar UV was found to have a thousand times higher biological effectiveness than UV radiation filtered by stratospheric ozone concentrations found today on Earth. The protective effects of anorganic substances like artificial or real meteorites were determined on the MIR station. In the experiment EXOBIOLOGIE of the French PERSEUS mission (1999) it was found that very thin layers of anorganic material did not protect spores against the deleterious effects of energy-rich UV radiation in space to the expected amount, but that layers of UV radiation inactivated spores serve as a UV-shield by themselves, so that a hypothetical interplanetary transfer of life by the transport of microorganisms inside rocks through the solar system cannot be excluded, but requires the shielding of a substantial mass of anorganic substances.

The role of solar UV radiation in the ecology of alpine lakes

Solar ultraviolet radiation (UVR, 290–400 nm) is a crucial environmental factor in alpine lakes because of the natural increase of the UVR flux with elevation and the high water transparency of these ecosystems. The ecological importance of UVR, however, has only recently been recognized. This review, examines the general features of alpine lakes regarding UVR, summarizes what is known about the role of solar UVR in the ecology of alpine lakes, and identifies future research directions. Unlike the pattern observed in most lowland lakes, variability of UV attenuation in alpine lakes is poorly explained by differences in dissolved organic carbon (DOC) concentrations, and depends mainly on optical characteristics (absorption) of the chromophoric dissolved organic matter (CDOM). Within the water column of lakes with low DOC concentrations (0.2–0.4 mg l −1), UV attenuation is influenced by phytoplankton whose development at depth (i.e. the deep chlorophyll maximum) causes important changes in UV attenuation. Alpine aquatic organisms have developed a number of strategies to minimize UV damage. The widespread synthesis or bioaccumulation of different compounds that directly or indirectly absorb UV energy is one such strategy. Although most benthic and planktonic primary producers and crustacean zooplankton are well adapted to high intensities of solar radiation, heterotrophic protists, bacteria, and viruses seem to be particularly sensitive to UVR. Understanding the overall impact of UVR on alpine lakes would need to consider synergistic and antagonistic processes resulting from the pronounced climatic warming, which have the potential to modify the UV underwater climate and consequently the stress on aquatic organisms.

Solar‐powered soil vapor extraction for removal of dense nonaqueous phase organics from soil

Both surface and groundwater are threatened by buried waste at a number of sites because of subsurface plumes containing dense non‐aqueous phase liquids (DNAPLs), hazardous metals, and radionuclides. In this work, a novel process is explored which represents an enhancement to thermal extraction methods as well as a mobile system that is suitable for remediation of remote sites. Solar radiation is collected by modular concentrators which transfer the concentrated solar radiation to an optical waveguide (OW) transmission line consisting of low‐loss optical fibers. The OW line transmits the high intensity solar radiation to the contaminated site where the solar flux is injected into the soil for thermally enhanced soil vapor extraction (SVE). The organic compounds driven out of the soil go through off‐gas treatment. A small prototype was constructed and used to heat soil contaminated with trichloroethylene (TCE). The thermal efficiency of the solar SVE process conducted using the small scale experiment was approximately 50%. The moisture loss in the soil sample correlated to the soil heating time. Short heating times were sufficient to remove TCE from soil samples below detection limits.

Production of carbon nanotubes by the solar route

The high intensity of concentrated solar radiation obtained with the Odeillo (France) solar furnace facilities can be used to produce carbon nanotubes by direct vaporization of carbon bi-metal targets under inert gas atmosphere. Electron microscope pictures and Raman spectra show that the structure of the produced carbon nanotubes is likely to depend on experimental conditions and that the growth of single-wall or multi-walled carbon nanotubes can be favored.