Intensity Of Incident Solar Radiation Research Articles

Energy- and exergy-based economical and environmental (4E) evaluation of the influence of natural pollutants on PV array performance

In the present investigation, thermodynamic/eco/environmental analysis of the relationship between time-dependent particle deposition and thermal-based losses and incident solar radiation intensity on the PV front cover glass during the months with the least precipitation in the city of Samsun (Turkey) was performed. To evaluate the effect of dust accumulation, controlled experiments were carried out where the surface of one set of PV panels was periodically cleaned with water and the other one was left to natural contamination. The results showed that over three months, the difference in energy loss rates between cleaned and uncleaned PV arrays ranged from 2.53% to 8.1%, with the exergy efficiency difference measured at 1.3%–2.44%. According to the energy-based analyzes, August was the most effective month, with cleaned PV arrays reducing CO2 emissions by 401.5 kg and saving $6.02, compared to uncleaned PV arrays which reduced emissions by 362.21 kg and cost $5.43, respectively. Similarly, in the exergy-based evaluation, August was the most efficient month, with cleaned PV arrays decreasing CO2 emissions by 401.5 kg and saving $6.02, compared to uncleaned PV arrays, which dropped CO2 emissions by 362.21 kg and costing $5.43, respectively. While the cleaned surfaces were initially positive, a decrease was observed over time. However, the efficiency of PV decreased with increasing panel temperature. The study concludes that PV surfaces need to be cleaned at certain intervals, depending on the location’s weather conditions.

Effects of Human Activities on Climate Change: A Narrative Review

The sun supplies the energy which runs the earth’s climate system. Changes and modifications in the configuration and intensity of incident solar radiation which hits the Earth may produce changes in global and regional Climate. Since 1950, most of the warming has been caused by human activities, human activities which create the emissions of greenhouse gases. The energy balance of the climate system has been significantly disturbed by Human activities not only by burning fuels but also by the usage of various components of carbon. Greenhouse gas concentrations increase and global temperatures rise, the total amount of water vapor in the atmosphere also increases, further amplifying the warming effect. Therefore, this paper aims to explore the effects of human activities on climate change.

Importance of the silvipastoral system on the animal health and welfare of dairy cattle

Brazil stands out for having one of the largest cattle herds in the world, being the first place in the commercial herd in the whole planet. Within bovine farming, dairy cattle raising stands out for its importance within the national economy because of the representativeness of small family farms, which develop a large part of the national milk production. However, despite the extensive area available for agricultural production, a large part of Brazil is located in the tropical area of the planet. This region is distinguished by high temperatures and high intensity of incident solar radiation. This condition tends to lead the animals to heat stress, thus leading to a decrease in the production of meat, but mainly milk, especially in properties that make use of european breeds. One of the alternatives to overcome the impact of heat stress in tropical regions is to cross european breeds with zebu dairy breeds, as well as seeking measures to reduce the incidence of solar radiation of these animals through integrated systems, such as silvipastoral systems. Thus, this review aims to show that the silvipastoral system is necessary to improve the animal welfare of dairy cattle.

Thermal modeling, characterization, and enviro-economic investigations on inclined felt sheet solar distiller for seawater desalination.

Sustainable desalination can be achieved by adopting renewable energy-based low-cost and low-impact desalting techniques. In this investigation, capability of inclined felt sheet solar distiller in desalting seawater is assessed by evaluating its performance, distillate water quality, economics, and environmental impacts. The distiller with 1.18-m2 aperture area produced around 4.60L/day of distillate for a cumulative incident solar radiation intensity of about 20.52MJ/m2day. Its pollutant removal efficiency is very much superior to other available solar stills reported in literatures. Thermal model developed for estimating distiller's performance is able to predict its productivity with reasonable accuracy (only 8.0% deviation from experimental values) and was used for estimating distiller's performance in various seashore locations in India with varying clear days (191 to 246). Yearly mean distillate production and thermal and exergy efficiencies of the proposed distiller range between 3.60 to 4.50L/day, 36.45 to 42.39%, and 2.85 to 3.65%, respectively, in east seashore locations of India. Moreover, 18.46tons of CO2, 132.72kg of SO2, and 54.20kg of NO emission can be mitigated by adopting the distiller for potable water production. Distillate production cost of inclined felt sheet solar distiller is in the range of 1.15 to 2.29 INR/L and highly depends on the interest rate at which the distiller is financed. Generation of reasonable quantity of high-quality potable water at low cost with huge environmental benefits makes proposed inclined felt sheet solar distiller a suitable option for quenching thirst in coastal and remote locations.

A predictive model for airflow in a typical solar chimney based on solar radiation

A solar chimney is an important green architectural element that aides the ventilation, heating and cooling of buildings. The proper design of a solar chimney requires a reliable model to estimate the airflow rate generated by solar radiation. Previous analytical models are based on inputs such as temperature, density or heat supply, which are difficult to predict the ventilation performance of a solar chimney at the preliminary design stage. This paper presents a new predictive model for the airflow rate in a typical solar chimney based on inputs such as incident solar radiation intensity and the emissivity of the glass cover considering both room and chimney cavity configurations. This model is developed after obtaining the predictive model of heat gain ratio of air in the gap. In the new predictive model, the airflow rate is expressed explicitly as a function of incident solar radiation intensity, internal heat source intensity, the emissivity of the glass cover and geometrical parameters. This model is verified by using experimental data in the literature. Simple in form, the predictive model has the potential to improve upon existing engineering designs. It is very convenient to estimate the ventilation performance of a solar chimney according to incident solar radiation intensity.

Application of the Double Diode Model of Photovoltaic Cells for Simulation Studies on the Impact of Partial Shading of Silicon Photovoltaic Modules on the Waveforms of Their Current–Voltage Characteristic

Photovoltaics (PV) is the phenomenon of converting sun energy into electric energy by using photovoltaic cells. Furthermore, solar energy is the major renewable energy source. PV modules are systematically more efficient and manufacturing costs decrease at the same time. The PV module performance is affected by ambient temperature, humidity, wind speed, rainfall, incident solar radiation intensity and spectrum, dust deposition, pollution, and shading, which are environmental factors. The problem of partial shading of the generator often arises when designing photovoltaic installations. If it is not possible to avoid this phenomenon, its impact on the operation of the photovoltaic system should be estimated. The classical method is to measure the current–voltage characteristics, but it requires switching off the installation for the duration of the measurements. Therefore, this paper proposes a method using a computer simulation in the Matlab package with the implemented component “Solar Cell” for this purpose. Three cases of partial shading of photovoltaic modules with different degrees of shading were analyzed. The obtained results of the computer simulation were verified for two types of silicon PV modules: Mono- and polycrystalline.

Experimental and numerical study of a PV/Thermal collector equipped with a PV-assisted air circulation system: Configuration suitable for building integration

In this paper, the energy performance of a photovoltaic/thermal collector equipped with a direct PV air circulation device is studied experimentally and numerically. In this system, the air circulation through the collector duct is ensured by a low input power DC fan that is directly connected to a PV module of small power capacity. In fact, depending on which period of the year the PV/thermal collector is being employed, a 4 Wp or 12 Wp PV panel is used to supply the electrical power to run the DC fan respectively for cold/winter or hot/summer periods. Therefore, the air flow rate under which the present hybrid collector operates is variable and highly affected by the incident solar radiation intensity. A theoretical model for the present hybrid system, in which air flow rate is introduced as a simple empirical correlation relating flow rate to solar radiation, was developed and obtained numerical results have been validated by experimental ones. Simulation and experimental results have been found in reasonably good agreement in terms of PV cell temperature, outlet air temperature, and electric PV peak power. Moreover, the obtained results revealed that low flow rate PV-assisted air circulation systems, if properly sized, would be very attractive for cold periods and winter conditions because of the high air temperature difference they could produce which is a key parameter for space heating applications. On the other hand, the high flow rate system seems to be very suitable for summer conditions where priority is given for the ventilation of PV modules to lower their cells temperature. The suggested PV/T collector design offers the advantage to be self-energy dependent and seems to have a great potential in remote areas.

Energy and Environment control to Box type Solar Cooker and Nanoparticles mixed bar plate coating with Effect of Thermal Image cooking pot

Abstract In this paper studies the thermal performance of an exclusive box type solar cooker oven whose five sides are showing to ambient and requirements are also delivered to install the reflectors to improve the intensity of incident solar radiation on the cooker. Experiments were achieved somewhere temperatures reached inside the box cavity are verified on different days and times of the day agreeing to numerous strengths of available solar radiation. The thermal image has been taken through a cooker (rice) edge detector and applied in segmentation techniques should be considered. The image scrutiny has been done considering two days type of endure disorder for each various month of the year at Avadi, Chennai climate condition. The cooker has been enhanced by adeptness evolving in PCM (C18H36O2) and Nanoparticles (Al2O3). It has been established a thermal act of (45.14%), PCM and Nanoparticles adeptness is (53.10%). As compared to with and without nanoparticles mixed in black paint, selective surface coating results in expressively higher oven temperatures (up to Bar plate 92°C) and good agreement with the experimental statistics is extended.

Design and development of a Building Façade Integrated Asymmetric Compound Parabolic Photovoltaic concentrator (BFI-ACP-PV)

Building Integrated PV and Concentrating PV can generate electricity onsite and provide savings in materials and electricity costs, as well as protecting buildings from weather. In this paper, a novel truncated stationary asymmetric compound parabolic photovoltaic concentrator with a geometric concentration ratio of 2.0 has been designed and experimental characterised. The designed system is suitable for building façade application, especially for vertical façade. It has wide acceptance half angles of 0° and 55°, this acceptance angle range enables the concentrator to operate year-round at its geometric gain in most of the UK and EU climatic condition. A comprehensive indoor test was carried out to evaluate the electrical and thermal characterisation of the developed Building Façade Integrated Asymmetric Compound Parabolic Photovoltaic concentrator (BFI-ACP-PV) system, and also the factors that affect the power output of the developed system. The experimental results showed that the developed BFI-ACP-PV system has the potential to increase the power output per unit solar cell area by a factor of 2, when compared with a non-concentrating PV system. Subsequently, a Phase Change Material (PCM) system was integrated to the rear of the BFI-ACP-PV system to moderate the PV temperature rise and maintain good solar to electrical conversion efficiency. It was found out that the electrical conversion efficiency for the BFI-ACP-PV coupled PCM system was increased by over 5% compared with a similar system with no PCM integrated at the rear, when the incident solar radiation intensity was 280 W/m2, this value increased by over 10% for an incident solar radiation intensity of 670 W/m2.

A Hybrid Electric and Thermal Solar Receiver

Summary Solar energy offers a promising renewable energy source; however, it is expensive to store electricity from photovoltaics (PV), the most widely deployed solar electricity technology. Solar thermal energy technologies can be paired with inexpensive thermal storage, but are more expensive overall. We have developed a solar receiver that combines PV and solar thermal systems to efficiently convert solar radiation to electricity (to be used immediately) and thermal energy (to be stored and converted to electricity on demand). This paper describes the Hybrid Electric And Thermal Solar (HEATS) receiver and models its performance. An idealized model predicts high solar-to-electricity efficiency (35.2%) with high dispatchability (44.2% of electricity from thermal energy) at an operating temperature of 775 K. Modeling using measured performance values for HEATS subcomponents predicts 26.8% efficiency and 81% dispatchability with silicon PV and 28.5% efficiency and 76% dispatchability with gallium arsenide PV, both operating at 700 K.

The Thermal Radiation of the Atmosphere and Its Role in the So-Called Greenhouse Effect

Knowledge about thermal radiation of the atmosphere is rich in hypotheses and theories but poor in empiric evidence. Thereby, the Stefan-Boltzmann relation is of central importance in atmosphere physics, and holds the status of a natural law. However, its empirical foundation is little, tracing back to experiments made by Dulong and Petit two hundred years ago. Originated by Stefan at the end of the 19th century, and theoretically founded afterwards by Boltzmann, it delivers the absolute temperature of a blackbody—or rather of a solid opaque body (SOB)—as a result of the incident solar radiation intensity, the emitted thermal radiation of this body, and the counter-radiation of the atmosphere. Thereby, a similar character of the blackbody radiation—describable by the expression σ·T4—and the atmospheric counter-radiation was assumed. But this appears quite abstruse and must be questioned, not least since no pressure-dependency is provided. Thanks to the author’s recently published work—proposing novel measuring methods—, the possibility was opened-up not only to find an alternative approach for the counter-radiation of the atmosphere, but also to verify it by measurements. This approach was ensued from the observation that the IR-radiative emission of gases is proportional to the pressure and to the square root of the absolute temperature, which could be bolstered by applying the kinetic gas theory. The here presented verification of the modified counter-radiation term A·p·T0.5 in the Stefan-Boltzmann relation was feasible using a direct caloric method for determining the solar absorption coefficients of coloured aluminium-plates and the respective limiting temperatures under direct solar irradiation. For studying the pressure dependency, the experiments were carried out at locations with different altitudes. For the so-called atmospheric emission constant A an approximate value of 22 Wm-2 bar-1 K-0.5 was found. In the non-steady-state, the total thermal emission power of the soil is given by the difference between its blackbody radiation and the counter-radiation of the atmosphere. This relation explains to a considerable part the fact that on mountains the atmospheric temperature is lower than on lowlands, in spite of the enhanced sunlight intensity. Thereto, the so-called greenhouse gases such as carbon-dioxide do not have any influence.

Experimental study of a solar wall collector with PCM towards the natural ventilation of model house

This paper presents the results of the experimental performance of a solar wall collector with PCM (SC-PCM) towards the natural ventilation of experiment houses. The system is composed of a solar wall collector with PCM panel, an air gap, and an inner wall made of concrete material. The SC-PCM is 1.40 m high and 0.80 m width. The external solar wall collector with PCM and internal concrete wall has a similar thickness of about 15 cm. The opening areas are located at the bottom (indoor) and on the top (outdoor), to release hot air into the atmosphere for improving ventilation. Additionally, the top opening area is covered with anti-insects net. The solar wall collector with PCM system under examination in this paper was installed into the south façade of a small house made of 10 cm thick concrete walls with an interior volume of 4.05 m3. Performances are compared to similar house of the same dimensions made by single concrete walls (SW). The experiment revealed that the indoor temperature of the solar wall collector with PCM room was considerably lower than that of the single concrete. Solar wall collector with PCM can induce ventilation rate proportional to the incident solar radiation intensity. Therefore, it can reduce heat accumulation and improve indoor conditions.

Solar energy contribution to the energy demand for air conditioning system in an office building under Tripoli climate conditions

The feasibility of solar assisted air conditioning in an office building under Tripoli weather conditions is investigated in this paper. A single-effect lithium bromide absorption cycle powered by means of flat-plate solar collectors was modeled in order to predict the potential of the solar energy share. The cooling load profile was generated by using an detailed hourly based program and Typical meteorological year for Tripoli. System performance and solar energy fraction were calculated by varying two major parameters (collector?s slope angle and collector area). The maximum solar fraction of 48% was obtained by means of 1400 m2 of collector surface area. Analysis of results showed that, besides the collector surface area, the main factors affecting the solar fraction were the local weather conditions (intensity of incident solar radiation) and the time of day when the plant was operated.

Numerical Simulation of a Novel Solar-Powered Hybrid Energy System with Cooling and Heating

A novel solar-powered hybrid energy system with cooling and heating is presented, which consists of an adsorption ice maker subsystem and water heater subsystem. It can be used as an ice maker and water heater hybrid system or a single water heater respectively according to incident solar radiation intensity. A numerical model is developed to predict the performances of the hybrid energy system. Performance simulation and analysis on the hybrid energy system have been made. Simulation results show that, under the climatic conditions of daily solar radiation being about 12-20MJ/m2, the hybrid energy system can be used as an ice maker and a water heater effectively, its daily solar cooling COP (coefficient of performance) is about 0.173 - 0.181, the daily heating coefficient of performance is about 0.294-0.327.

Butyronitrile-Based Electrolyte for Dye-Sensitized Solar Cells

We elaborated a new electrolyte composition, based on butyronitrile solvent, that exhibits low volatility for use in dye-sensitized solar cells. The strong point of this new class of electrolyte is that it combines high efficiency and excellent stability properties, while having all the physical characteristics needed to pass the IEC 61646 stability test protocol. In this work, we also reveal a successful approach to control, in a sub-Nernstian way, the energetics of the distribution of the trap states without harming cell stability by means of incorporating NaI in the electrolyte, which shows good compatibility with butyronitrile. These excellent features, in conjunction with the recently developed thiophene-based C106 sensitizer, have enabled us to achieve a champion cell exhibiting 10.0% and even 10.2% power conversion efficiency (PCE) under 100 and 51.2 mW·cm(-2) incident solar radiation intensity, respectively. We reached >95% retention of PCE while displaying as high as 9.1% PCE after 1000 h of 100 mW·cm(-2) light-soaking exposure at 60 °C.

Spectral investigations of the solar radiation during the total solar eclipse on March 29, 2006

We present results from examination of the dynamics and spectral distribution of the solar radiation reaching the Earth's surface during the total solar eclipse on March 29, 2006. The solar spectra were recorded using a multichannel spectrometer OCEAN USB2000 in 2048 spectral channels in the spectral range 350–1000 nm at a spectral resolution (halfwidth) of 1.5 nm. The spectral measurements were carried out between the 1st and 2nd and the 3rd and 4th contacts of the total solar eclipse from an observation point situated on the Mediterranean Sea coast, Antalya region, Turkey. The spectral data were evaluated using statistical methods such as the Student's t-criterion and others. The changes in dynamics of incident solar radiation intensity before and after eclipse totality were found to correlate ( R≈0.998) with the changes during the total Sun's eclipse on August 11, 1999, observed from an observation post on the line of totality situated on the Black Sea coast on Bulgarian territory. The changes in solar radiation measured before and after totality, within the absorption bands of water and oxygen, as well as along the spectra envelope, show statistically significant differences, which point to an unstable terrestrial atmosphere. Images from concurrent videometric observations proved that fine cloudy structures have appeared after totality in front of the solar disk.

The influence of heat capacity and its spatial distribution on the transient wall thermal behavior under the effect of harmonically time-varying driving forces

An analysis was developed for the theoretical investigation of heat capacity and of the effects of its spatial distribution on the thermal behavior of structural walls of uniform thermal resistance. The numerical solution of the governing differential equations under the appropriate initial and boundary conditions, allows the prediction of the time-varying heat flux during the transient heating of walls until quasi steady-state conditions are developed asymptotically. It is derived that as far as the fundamental physical behavior of a clear wall section is concerned, although the time depended heat flux is effectively damped and phased out as the wall heat capacity increases, the average quasi steady-state heat flux is constant, irrespectively of wall heat capacity, incident solar radiation intensity, radiation absorption at the exterior wall surface and particular weather conditions defining wall heat loss or gain. However, even though the average quasi steady-state heat flux is constant irrespectively of the wall heat capacity, its time depended value during the development of transient is strongly influenced by the spatial distribution of heat capacity at a direction perpendicular to the wall plane, something which is determined by the wall time constant.

Diurnal Variation of Precipitable Water over a Mountainous Area of Sumatra Island

Diurnal variations in atmospheric water vapor at Koto Tabang, a mountainous area of Sumatra Island, Indonesia, are studied by analyzing the GPS-derived precipitable water, radiosonde data, and surface meteorological observation data. A permanent GPS receiving station was established at Koto Tabang in March of 2001. Radiosonde soundings were carried out at 3-h intervals to study the atmospheric water and energy cycles in the Maritime Continent of Indonesia. A distinct diurnal variation in water vapor is observed. The precipitable water increases during daytime, reaching its maximum in the late afternoon. The results of the radiosonde observations indicate that the increase in water vapor occurs up to an altitude of approximately 3 km. Water vapor is transported by turbulent mixing with the development of the boundary layer in the afternoon. The diurnal cycle of water vapor is affected by the intensity of incident solar radiation. It is suggested that the diurnal variation in water vapor is caused by the horizontal transport of water vapor by local circulation. The diurnal range of the precipitable water on days with heavy rain was larger than that on days without rain. Rainfall often occurs as intensive showers during a short period in the late afternoon and early evening in the Koto Tabang area; daily shortwave radiation is still sufficiently strong to generate the local circulations and to induce large diurnal variation in precipitable water, even on the heavy-rain days.

Efficiency of sunlight utilization: tubular versus flat photobioreactors

The light saturation effect imposes a serious limitation on the efficiency with which solar energy can be utilized in outdoor algal cultures. One solution proposed to reduce the intensity of incident solar radiation and overcome the light saturation effect is "spatial dilution of light" (i.e., distribution of the impinging photon flux on a greater photosynthetic surface area), but consistent experimental data supporting a significant positive influence of spatial light dilution on the productivity and the photosynthetic efficiency of outdoor algal cultures have never been reported. We used a coiled tubular reactor and compared a near-horizontal straight tubular reactor and a near-horizontal flat panel in outdoor cultivation of the cyanobacterium Arthrospira (Spirulina) platensis under defined operating conditions for optimum productivity. The photosynthetic efficiency achieved in the tubular systems was significantly higher because their curved surface "diluted" the impinging solar radiation and thus reduced the light saturation effect. This interpretation was supported by the results of experiments carried out in the laboratory under continuous artificial illumination using both a flat and a curved chamber reactor. The study also showed that, when the effect of light saturation is eliminated or reduced, productivity and solar irradiance are linearly correlated even at very high diurnal irradiance values, and supported findings that outdoor algal cultures are light-limited even during bright summer days. It was also observed that, besides improving the photosynthetic efficiency of the culture, spatial dilution of light also leads to higher growth rates and lowers the cellular content of accessory pigments; that is, it reduces mutual shading in the culture. The inadequacy of using volumetric productivity as the sole criterion for comparing reactors of different surface-to-volume ratio and of the areal productivity for evaluating the performance of elevated photobioreactors operated outdoors is stressed; it is furthermore suggested that the photosynthetic efficiency achieved by the culture also be calculated to provide a suitable parameter for comparison of different algal cultivation systems operated under similar climatic conditions. Copyright 1998 John Wiley & Sons, Inc.