Intensity Of Incoming Solar Radiation Research Articles

Poređenje teorijskih i izotropnih modela dolaznog solarnog zračenja za nagnuti, fiksni, ravni solarni prijemnik orijentisan ka jugu

Knowing the intensity of incoming solar radiation is the starting point for any further analysis of the thermal performance of (all) solar collectors. A large number of existing theoretical models (both isotropic and anisotropic) can be justified by the complexity of determining its components, because the total solar radiation for an arbitrarily oriented surface of the solar collector consists of: direct, diffuse and reflected solar radiation. In the first part of the paper, three theoretical and isotropic models of incoming solar radiation are presented in detail, for the tilted, fixed, flat-plate solar collector oriented to the south, presented in the works of the following authors: LUKIĆ-BABIĆ, WIDÉN-MUNKHAMMAR and DESPOTOVIĆ. In the second part of the paper, using the mentioned methods, the incoming solar radiation was calculated by comparing the obtained results, all with the aim of facilitating (by pointing out the advantages and disadvantages of their use) other researchers to select the appropriate solar model in theoretical calculations of the solar collectors.

An Experimental Study of Greenhouse Gas Concentration on the Maximum Power Point of Solar PV Panels

The energy demand increases along with demographic and development growth. India is the second-most populous country in the world and most of its population needs more energy as its human and energy development indices are rather low. So, the country depends on cheaper sources of energy which have ample effects on the environment. Many energy sources are polluting, but solar energy is pollution-free and its availability is abundant with zero cost. Solar Photo Voltaic (PV) technology is the best technology to harness electricity. The effect of varying environmental factors regulates the performance factors of this technology. Its efficiency mainly depends on the concentration of greenhouse gases (GHGs), ambient temperature, module temperature, incoming solar radiation intensity, and PV material composition. To understand the behavior of solar panels on maximum power point under various GHGs concentrations, three experiments were conducted. One in normal atmospheric CO2 concentration and two in higher CO2 concentration chambers.

Interview

Shamsodin Taheri Shamsodin Taheri, from the University of Quebec Outaouais, Canada, talks to us about his group's submission “Analysis of electrical behaviour of PV arrays covered with nonuniform snow” page 192. I am an Associate Professor of Electrical Engineering in the Department of Computer Science and Engineering at the Université du Québec en Outaouais (UQO). The expertise of my research group in the field of power energy has advanced our understanding of the performance of photovoltaic (PV) sources in cold-climate conditions. This research was inspired by the issues that PV plants in Canada experience during cold months. In recent years, we have collaborated with several industry partners, who own utility-scale PV plants, to evaluate the performance of their facilities. This ongoing research helps mitigate the technical challenges facing the integration of renewable energy sources into power grids in cold regions. PV systems have found different applications in cold areas for a long time, such as remote research facilities in the South and North Poles and space travelling. The majority of PV energy plants are presently installed in geographical cold locations with a considerable amount of snowfall every year. Furthermore, the solar energy industry is expanding competitively in cold climate regions. For example, in Canada, the installed capacity of solar PV grew from 95 MW to more than 2500 MW during 2009–2016. PV panel efficiency is not only influenced by PV technology, but environmental conditions can also influence their energy production. Accumulation of snow/ice decreases solar radiation reaching the PV panels, which results in a significant loss of power generation. Non-uniform snow accretion on PV panels often occurs due to ambient conditions such as wind, temperature variation, partial snow shedding and ground interference. This leads to power loss that is dependent on the configuration of the PV system. Owing to the increasing deployment of PV systems, there is a significant interest in optimal utilisation of PV potential in cold climate regions. A fundamental need for knowledge of the impact of nonuniform snow accretion on PV systems is therefore essential. This research has shown that the snow-covered PV panels can still produce a significant amount of energy depending on the pattern and depth of the snow accumulation. The portion of this energy that could be collected is decided by configuration of the PV array as well as the maximum power point tracking (MPPT) technique. Investigations concerning the effect of bypass diodes have shown that the PV string without bypass diodes generally experiences more power loss. In addition, the vertical and horizontal PV array layouts were tested to determine power loss due to nonuniform snow accretion. The horizontal PV array layout would be more effective in snowy climates. This work is helpful for PV system performance assessment, MPPT development and testing, power generation prediction, and proper arrangement of panels in cold regions. The accumulation of snow on PV modules weakens the intensity of incoming solar radiation and hence limits their ability to generate electricity during cold months. However, the true extent of such impact on the energy production of PV modules cannot be specified in a straightforward way, since it is not proportional to the snow-covered area. In some instances, snow covering only one cell can reduce the efficiency of a whole module by a noticeable amount. Snow is a complex phenomenon, and a quantitative characterisation of radiation transmittance through snow coverage requires knowledge of the physical properties of snow. In fact, the interaction of sunlight with snow to determine the influence of snow coverage on the PV modules is a challenge. This leads to changing the electrical characteristics of the PV array and producing multiple, local peaks on PV characteristics. Accurate modelling of the electric behaviour of PV modules and systems is a key element in improving system operation and efficiency. Hence, proper modelling approaches of the operation of PV generators under varying environmental conditions that improve their performance control and assist the design of PV converters and their MPPT controller have been achieved. Moreover, an appropriate tool has been proposed to determine the efficiency of PV farms under cold conditions. Furthermore, a high performance MPPT technique has been proposed to harvest the maximum energy of a PV array with multipeak characteristic under partial shading condition. Major progress must be made on the proper design and arrangement of PV arrays and power electronic interfaces, minimising the effects of snow on large-scale PV farms and the increasing the use of bifacial PV modules as a candidate for cold regions over the next ten years.

Variability of VTEC Gradient and TEC Rate Index Over Kisumu, Kenya During Selected Quiet and Storm Days of 2013 and 2014

Vertical Total electron content (VTEC) gradient or rate of change of TEC (ROT) and total electron content (TEC) rate index or rate of change of TEC index (ROTI) can directly be estimated from receiver independent exchange (RINEX) data and can be used to estimate presence and intensity of ionospheric irregularities. In this paper we present results of the variation of ROT and ROTI over Kisumu, Kenya (Geomagnetic coordinates: 9.64°S, 108.59°E; Geographic coordinates: 0.02°S, 34.6°E) for both selected quiet and disturbed conditions between 1^st January 2013 and 31^st December 2014 using data derived from NovAtel GSV4004B SCINDA-GPS receiver at Kisumu as a step in establishing ionospheric irregularities over Kisumu, Kenya during a high solar activity period of solar cycle 24. ROT was calculated from filtered average daily VTEC data within intervals of 120 seconds while ROTI was computed over 4 minutes window from ROT. ROT and corresponding ROTI for the selected quiet and storm days were plotted against universal time (UT). The presence and intensity of irregularities on the selected quiet and storm days of the years 2013 and 2014 were determined by checking ROT fluctuations and the corresponding ROTI values from the plots. The obtained results showed increased fluctuation of ROT corresponding with large ROTI values after sunset. The selected storm days of the years 2013 and 2014 had higher ROTI values than the selected quiet days of the years 2013 and 2014. The higher ROTI values during the selected storm days may be attributed to the impact of geomagnetic storms brought about by several competing dynamics including Prompt penetration electric field (PPEF), disturbance dynamo electric field (DDEF) and reduction in electron density due to increased recombination rates. The high ROTI values after sunset were a manifestation of post-sunset plasma irregularities. The obtained results also showed a diurnal trend for ROT and ROTI where ROT increased steadily from 0.00UT to around 12:00UT before falling and having an increased fluctuation between 18:00UT and 20:00UT. This corresponded well with low ROTI values between 0:00UT and 16:00UT followed by high ROTI values between 18:00UT and 20:00UT. The diurnal variability of ROT might have resulted from variation of TEC and which was attributed to changes in the intensity of incoming solar radiation.

Comparison of electrochromic devices with V- and Sn/Mo-oxide counter electrodes and (3-glycidoxypropyl)trimethoxysilane-based ormolytes with three different lithium salts

Electrochromic (EC) devices represent an effective way to modulate the intensity of incoming solar radiation in buildings or through the sun roofs of cars, but can also be used in helmets, sunglasses and home appliances. Herein we report on the development of all sol–gel WO3-based EC devices of a battery type, in which all three internal layers were prepared via sol–gel processes. A comparison of the performance of EC devices assembled with two different counter electrode films, i.e. V-oxide (150°C) and Sn/Mo-oxide (500°C) films deposited on fluorine dopped tin oxide (FTO) glass, is presented. The applicability of both types of counter electrodes for flexible polymeric substrates is also demonstrated. The sol–gel electrolyte (ormolyte) based on (3-glycidoxypropyl)trimethoxysilane was applied in EC devices; additionally, three different lithium salts were introduced, i.e. lithium perclorate (LiClO4), lithium trifluoromethanesulfonate (LiCF3SO3) and lithium bis(oxalato)borate (LiBOB). The spectroelectrochemical characterisation of the EC devices revealed that the optical modulation at 634nm increased when electrolytes with LiClO4<LiCF3SO3<LiBOB were used.

Regional climate forcing of aerosol estimated by a box model for a rural site in Central Europe during summer

In the present work, a box model is applied to estimate the direct climate forcing of aerosol particles for rural air in Central Europe during summertime. In the model, the input parameters reflect regional character: data from satellite observations and other surface measurements are used referring to the selected area, Hungary. In the calculation of direct climate forcing of aerosol particles satellite observations serve as the source of incoming solar radiation intensity data and cloudiness, while different aerosol parameters of the model (mass extinction coefficient, chemical composition, scale height, hygroscopic growth factor, etc.) are based on local measurements. Finally, surface albedo of the area studied was determined on the basis of vegetation cover and precipitation amount. As the summary of our calculations, in Central Europe direct climate forcing of ammonium sulfate is equal to –2.4 W m −2. The climate forcing of total carbon is composed of two terms. The forcings due to scattering and absorption are –1.0 and +0.2 W m −2, respectively. In spite of the fact that the mass concentrations of ammonium sulfate and total carbon are similar, their contribution to the aerosol direct forcing is different. We conclude that ammonium sulfate plays the major role in this process and organics have an additional impact.

EVAPOTRANSPIRATION AND CANOPY RESISTANCE AT AN UNDEVELOPED PRAIRIE IN A HUMID SUBTROPICAL CLIMATE1

ABSTRACT: Reliable estimates of evapotranspiration from areas of wildland vegetation are needed for many types of water‐resource investigations. However, little is known about surface fluxes from many areally important vegetation types, and relatively few comparisons have been made to examine how well evapotranspiration models can predict evapotranspiration for soil‐, climate‐, or vegetation‐types that differ from those under which the models have been calibrated. In this investigation at a prairie site in west‐central Florida, latent heat flux (λE) computed from the energy balance and alternatively by eddy covariance during a 15‐month period differed by 4 percent and 7 percent on hourly and daily time scales, respectively. Annual evapotranspiration computed from the energy balance and by eddy covariance were 978 and 944 mm, respectively. An hourly Penman‐Monteith (PM) evapotranspiration model with stomatal control predicated on water‐vapor‐pressure deficit at canopy level, incoming solar radiation intensity, and soil water deficit was developed and calibrated using surface fluxes from eddy covariance. Model‐predicted λE agreed closely with λE computed from the energy balance except when moisture from dew or precipitation covered vegetation surfaces. Finally, an hourly PM model developed for an Amazonian pasture predicted λE for the Florida prairie with unexpected reliability. Additional comparisons of PM‐type models that have been developed for differing types of short vegetation could aid in assessing interchangeability of such models.

Comparative studies of “all sol–gel” electrochromic windows employing various counter-electrodes

Electrochromic (EC) “smart” windows for buildings represent an effective way to modulate the intensity of incoming solar radiation. While it is accepted that WO 3 films represent the best option for the working electrode, the choice of the best counter-electrode is still debatable. Optical properties of counter-electrodes such as Ce, Fe, V and Sn oxides are presented. Electrochromic windows were made with a sol–gel WO 3 active colouring film (150°C), Ce, Fe, V oxide counter-electrodes and a sol–gel organic–inorganic hybrid (Li +ormolyte) ion conductor. The electrochromic responses of these devices predicted from the charge capacities, photopic transmittances and coloration efficiencies of individual films are compared with measured values.

The effect of mesoscale flows on regional atmospheric transport in a complex terrain

Model results simulated over a complex terrain under a synoptically calm condition, using a three-dimensional (3-D) regional-scale meteorological acid deposition model (RMADM), show that thermally induced mesoscale circulations (MCs): sea-and land-breeze circulations and up- and down-slope flow circulations play a fundamental role in determining how the pollutants being dispersed. Analysis showed that under synoptically calm condition, the role played by the MC would dilute the smoke released during the early stage of the emission; the accumulation, however, would become important if the synoptically calm condition lasts long. Since the structure and intensity of the MCs depend on geography and topographical allocation, land surface coverage, incoming solar radiation intensity and so on, it makes the estimates of source-reception relationship and long-range atmospheric dispersion more difficulty. It concluded that it is impossible for a pollution model to correctly simulate smokes transport using only the synoptic station data, since the mesoscale information can not be resolved from these datasets.

Estimation of age of females in field populations ofLucilia cuprina(Wiedemann) (Diptera: Calliphoridae) using ambient temperature and solar radiation

AbstractA previously published method for determining the physiological age of femaleLucilia cuprina(Wied.), based on a linear relationship between their rates of ovarian development and temperature, was tested under field-cage conditions. It was found that ovarian development was more rapid than that predicted by thermal summation based on ambient temperature. A re-examination of the rate of development-ambient temperature relationship, over a wider temperature range that that used previously, showed that the development threshold temperature was 8·2°C rather than 11·3°C. Thermal summation using the revised threshold also fell short of the observed day-degree totals. An effective temperature for ovarian development (ambient temperature plus a temperature excess proportional to the incoming solar radiation intensity) was fitted to the data from the field cage. This relationship gave accurate predictions of ovarian development (±8%) for flies that were released into the field.

An evaluation of total solar reflectance and spectral band ratioing techniques for estimating soil water content

For several days in March of 1975, reflected solar radiation measurements were obtained from smooth and rough surfaces of wet, drying, and continually dry Avondale loam at Phoenix, Arizona, with pyranometers located 50 cm above the ground surface and a multispectral scanner flown at a 300-m height. The simple summation of the different band radiances measured by the multispectral scanner proved equally as good as the pyranometer data for estimating surface soil water content if the multispectral scanner data were standardized with respect to the intensity of incoming solar radiation or the reflected radiance from a reference surface, such as the continually dry soil. Without this means of standardization, multispectral scanner data are most useful in a spectral band ratioing context. Our results indicated that, for the bands used, no significant information on soil water content could be obtained by band ratioing. Thus the variability in soil water content should insignificantly affect soil-type discrimination based on identification of type-specific spectral signatures. Therefore remote sensing, conducted in the 0.4- to 1.0-micron wavelength region of the solar spectrum, would seem to be much More suited to identifying crop and soil types than to estimating of soil water content.

Microclimate and Biomass in Communities of the Bryum Association on Ross Island, Continental Antarctica

Microclimate and Biomass in Communities of the Bryum Association on Ross Island, Continental Antarctica

THE ATMOSPHERIC WATER BALANCE AND THE HYDROLOGY OF LARGE RIVER BASINS1

ABSTRACTThe concept of using the atmospheric water balance technique in the study of the hydrology of large (greater than 105km2) river basins is described. The atmospheric water balance technique consists of determining the spacial and time distributions and fluxes of water vapor through the atmospheric volume overlying the basin. The quantity precipitation minus evaporation at the earth's surface is determined as a residual of the computation. A review of the results of various experiments employing this technique is provided.The incorporation of the technique in a study of the hydrology of a large river basin is demonstrated by showing the results of a study of the hydrometeorology of the Upper Colorado River Basin. The example covers the study of eleven winter seasons, November through April, 1957–1968.The seasonal accumulation of water over the basin as determined by the atmospheric water balance is highly correlated with annual runoff. Correlation coefficient r = .8. The daily evaporation rate during dry days varies by a factor of two over the winter season, and is shown to be related to the incoming solar radiation intensity.