Distribution Of Solar Radiation Research Articles

An Analysis of the Influence of Construct Parameters on the Solar Radiation Input in an Insulated Plastic Greenhouse

Insulated plastic greenhouses (IPG) were a new type of facility emerging in production in China. The mechanism of construct parameters on the indoor solar radiation deserves further study. A mathematical model that can well describe the spatial and temporal distribution of solar radiation in the greenhouse was established. Based on this model, the effects of multiple construct parameters, such as insulation blanket shading, height–span ratio, greenhouse azimuth, and geographical latitude, on the indoor solar radiation of IPG were quantitatively specified. The results showed that the spatial and temporal distribution of inside solar radiation was highly variable along the span direction of IPG. And by analyzing the simulation data, it was found that for different heights of greenhouses, the corresponding optimal span is different. Therefore, in the construction of greenhouses, the appropriate height–span ratio should be selected according to the planting demand. And by simulating the inside solar radiation under different greenhouse azimuth angles, it was found that accumulated daily solar radiation in the greenhouse reaches the optimum value when the greenhouse azimuth angle is in the range of 0–20°. This paper can provide theoretical guidance for the design and optimization of structure parameters of IPG in China.

Predicting daily distribution of solar irradiation by neural networks

This work focuses on prediction of solar irradiation during the day. In order to predict half hourly solar irradiation during the day an artificial neural network is applied. The artificial neural network was trained using error backpropagation learning rule. Meteorological data measured during three years were used to form learning patterns. The trained artificial neural network was tested with different patterns. Some of them were new while the others were used in the training procedure. The comparison of measured and by the artificial neural network predicted daily distribution of so

Study and validation of a fast ray tracing method to determine density flux for symmetric solar optical systems

In this research paper, a computational program called MCMRDF-3D, is developed and validated by comparison with a reference software. MCMRDF-3D is formulated on Multi-Ray Monte Carlo Method for the determination of the distribution of solar irradiation along the receiver of any solar- concentrating system that withstand translational or rotational symmetries. This code incorporate an advantageous approach that consist in estimating the overall distribution of irradiation of a large scale solar concentrating systems on the basis of a consistent sample, then saving computation time, processor capacity and storage memory. The paper presents the new approach and applied it to determine the distribution of irradiation provided by three concentrators. We compare the processing time, the irradiation map rendering, and the size of numeric data, to those provided by a Reference software. The obtained irradiation distribution and power harvesting quantities over the receiver matches very well. We conclude that MCMRDF-3D proves to easy, fast, accurate and reliable approach for the simulation of solar concentrator system. Among other implications, this work opens a path for saving time when studying numerous symmetrical imaged and non-imaged optical systems. For future work, this time saving and flexible program will be of a significant help to envision optical errors from real behavior of optical surface in concentrating systems.

A Novel Reverse Combination Configuration to Reduce Mismatch Loss for Stratospheric Airship Photovoltaic Arrays

Enhancing the output power of stratospheric airship photovoltaic arrays during months with weak irradiance is crucial for extending the endurance of airships. Models for predicting the output power of photovoltaic arrays and the phenomenon of mismatch losses have been proposed. However, static reconstruction schemes to reduce or eliminate mismatch losses have not been studied. In this paper, an output power model for stratospheric airship arrays including the solar radiation and irradiance distribution is established. The characteristics of the irradiance distribution for the photovoltaic array (PV) are investigated through simulation. Furthermore, an innovative reverse combination configuration is developed and compared to the SP and TCT configurations in terms of performance, mismatch loss and fill factor. Finally, simulations are conducted for a full-day irradiance period of 4 days in a real wind field. The simulation results demonstrate that the proposed RC configuration significantly reduces mismatch losses and output power fluctuations, thereby enhancing the PV array’s output power. This research provides interesting insights for the design of PV array topologies for stratospheric airships.

Improving solar still productivity via fin optimization: computational and experimental investigations

ABSTRACT Solar desalination offers a promising solution to conserve energy and meet the growing demand for freshwater. To improve the productivity of solar stills, the incorporation of fins on the absorber has been explored. This study aims at investigating the impact of various fin geometric parameters on solar still efficiency using an experimentally validated Computational Fluid Dynamics (CFD) model. The study specifically examines the height, width, and spacing between the fins, with three levels assessed for each parameter. Solar radiation and temperature distributions are measured through an experimental design. The discrete ordinate (DO) model is used to capture the solar radiation, while the k-ε Renormalization-group (RNG) is employed to investigate the effect of the turbulence. To ensure mesh independent results, a grid size independence test is conducted. The CFD results are validated against experiments, demonstrating an error less than 4%. The findings show that fins having a height of 30–50 mm increase basin temperature by 2.6%, boosting freshwater productivity by 0.03 l/m2.h, and improving solar still efficiency by 1.74%. Widening fin width raises water basin temperature by 10.4%, resulting in 4% efficiency enhancement. Reducing fin spacing from 130 mm to 30 mm increases productivity by 0.04 l/m2.h, which corresponds to 2.48% efficiency improvement. These findings suggest a careful consideration of fin design parameters can further enhance this efficiency.

The impact of spectral distribution on photovoltaic power generation and its quantitative evaluation model

With the implementation of energy saving and carbon reduction, the quantitative analysis of solar energy spectral characteristics has been paid more and more attention. Currently, the international test standards provide a spectral distribution with a large span between different wavebands, which makes it difficult to meet the needs of special spectral wavebands. In this paper, based on the principle of spectral splitting, the spectral distribution of solar radiation models (SDSR models) is proposed, and the differences in the spectral distributions of natural outdoor and artificial indoor light sources are evaluated. Firstly, the differences in PV module output power between the outdoor light sources and indoor artificial light sources are assessed in terms of inclination angle and solar radiation, respectively. Secondly, based on that difference, the influencing factors of the spectral distribution of solar radiation are investigated, and the SDSR models of different wavelengths is established based on spectral analysis results. Finally, based on the established SDSR models, the spectral distribution modified models (SDM models) for different inclination angles under artificial light sources is proposed. By comparing the calculated values of the SDM models with the measured data, the calculated values of the model are close to the measured data at different incidence angles. The SDM models proposed in this paper shortens the gap between the spectral distribution of the artificial light source and the outdoor natural light source, and reveal the influence mechanism of the difference in the output power of indoor and outdoor PV modules from the perspective of the spectral distribution. The results can provide guidance for the spectral distribution of solar radiation and the quantitative modification of the artificial light source.

Forecasting the Climate Change through the Distributions of Solar Radiation and Maximum Temperature

Forecasting the Climate Change through the Distributions of Solar Radiation and Maximum Temperature

Analysis and determination of the optimal collector array orientation characteristics in solar systems

This paper presents results analysis for the distribution of direct and diffuse solar radiation for a specific climatic zone in Bulgaria. The influence of the slope angle of the collector array over monthly solar radiation incident is studied and regression dependencies regarding incident total, direct and diffuse specific annual solar radiation are derived. Based on the obtained dependencies, the optimal value of the solar collectors slope angle, that guarantees maximum value of the annual solar radiation, is determined. The ratio of direct radiation on an inclined to that on a horizontal surface depending on the azimuth of collector arrays with different slope angle is investigated using a dynamic simulation software. Graphical dependencies, allowing the determination of the total annual solar radiation at different values of the azimuth and the slope angle of the collector array are obtained.

Mathematical modelling and technical analysis of an auxiliary system to reflect solar radiations for PV panels: Effect of mirror height on the system performance

The present study represents the design of a new auxiliary system to reflect solar radiations for PV panels. The goal is to choose the best mirror height for the proposed system, in which, despite the increase in the power production, the construction costs of the reflective system remain reasonable. Using a maximum PowerPoint Tracker System (MPPT), the sun is tracked to optimize solar radiation on the PV module. To analyze the energy aspects of the proposed system, an energy balance model with zero-dimensional characteristics was developed, owing to the uniform distribution of solar radiation and the thinness of the PV layers. In this model, the temperature distribution along the thickness of the panel layers is considered constant. Our simulation results indicate that the proposed system enables the production of approximately 2.9 times more electrical energy in comparison to conventional PVs without the concentrator, thereby demonstrating the energetic viability of the proposed system.

Seasonal Fluctuations and Vertical Heterogeneity of Biochemical-Structural Parameters in Wetland Emergent Aquatic Vegetation.

Accurate understanding of vertical patterns of canopy structure characteristics and solar radiation distribution patterns of aquatic vegetation is pivotal in formulating a bidirectional reflection model and comprehending the ecological dynamics of wetlands. Further, physiological and biochemical stratified structural properties of aquatic vegetation in wetlands remain unexplored due to more inherent investigation challenges than terrestrial vegetation. This study evaluated the structural characteristics of vegetation communities and the regulation of direct solar radiation variations within the canopy across seasons of Phragmites australis (P. australis) and Typha orientalis (T. orientalis), 2 typical emergent aquatic vegetations (EAVs), based on radiative transfer theory. Observations revealed that physiological and biochemical metrics varied at different growth stages with canopy height, the stratified leaf area index in the middle being higher than at the top and bottom of the P. australis cluster. Moreover, the vertical profiles of direct solar radiation decrease with depth, showing a bowl-shaped and V-shaped curve in the P. australis and T. orientalis clusters, respectively. Interestingly, the sensitivity of layered solar direct radiation transmittance to canopy structural parameters is obviously higher than that of canopy pigments, suggesting considerable potential for estimating layered structural parameters. The transmittance of direct solar radiation decreases with increasing leaf area index at different heights, and stratified transmittance in the cluster can be accurately described by a negative binomial function with a deviation of less than 2%.

Exponential feedback effects in a parametric resonance climate model

The variations in the distribution of solar radiation due to the ~ 105 years Milankovitch cycle, which is connected to the Earth eccentricity variation, cannot explain the sharp drop in temperature of 6 °C ÷ 10 °C that marks the transition from the interglacial to the glacial age registered in the last ~ 5.5 106 years temperature variation behavior. More specifically, neglecting other effects, only a temperature variation of 0.2 °C ÷ 0.3 °C can be attributed to this cycle and, therefore, positive feedback effects should be taken into account to explain the registered effect. In the present work, a comparative Wavelet-Fourier analysis of the Vostok recontructed temperature record, for which different sampling steps are taken into account, is performed. Then, a study of exponential feedback effects within a climate parametric resonance model is dealt and discussed. The obtained findings put into evidence an exponential amplification of the temperature variation from the interglacial to the glacial age supporting the hypothesis that the system energization be connected to periodic variations in the internal solar system parameters. More in details, it is shown that, following the parametric resonance climate model, even small oscillations increase over time proportionally to the system energy itself, i.e. exponentially, and hence, a series of connected resonances is able to energize the climate system.

Experimental investigation of the partitioning of radiation in the melt pond–ice–ocean system

To study the partitioning of solar radiation over the melting Arctic sea ice and address the lack of systematic measurements of the optical properties of melt ponds and the underlying ice, four experiments in non-Arctic regions were designed to explore the distribution of solar irradiance on pond surface, pond bottom, and underlying ice. These experiments also investigated the influence of different pond depths (Hp), underlying ice thicknesses (Hi), and melt pond sidewall conditions (i.e., the black sidewalls, ice sidewalls, and pond horizon size) on the apparent optical properties (AOPs) of melt ponds. The black sidewalls with a small pond radius (barrel experiment) showed the greatest influence on the AOPs, significantly lowering the albedo and transmittance, and increasing the energy absorbed by the pond (Ψp) and underlying ice (Ψi). Different sidewall types, such as the black and ice sidewalls, did not affect the AOPs' trend, but affected their values. The AOPs were also influenced by pond size. The albedo linearly decreased and Ψp linearly increased with the increase of pond radius. The albedo and Ψp were almost independent of pond radius as pond radius larger than 0.58 m and 1.25, respectively. The black sidewalls experiment, in which the pond radius was 2.5 m, and the pond size experiment showed that solar energy was mainly absorbed by the melt pond. Ψp increased from 19% to 62%, which corresponded to Hp increasing from 5 cm to 35 cm in the pond size experiment. The results of the four experiments were consistent with the values obtained from numerical simulations and in situ measurements in the Arctic. The experiments conducted in this study were shown to be effective tools to complement and verify the optical measurements of Arctic melt ponds. They allow us to obtain the key information in Arctic pond measurements, which is difficult to achieve due to the severe weather conditions and marine environment.

Simulation for impact of nanofluid spectral splitter on efficiency of concentrated solar photovoltaic thermal system

Nanofluid filter has been applied in current research to boost the efficiency of a concentrated photovoltaic thermal (CPVT) module. Owing to tunable optical features of nanofluid and its greater thermal characteristics, it was utilized as spectral filter and cooling fluid in the present proposed solar system. The mixture of silver and water has been utilized as working fluid and its concentration within the filter and cooling duct are 0.005 and 0.05, respectively. Three dimensional models have been proposed involving spectral distribution of solar irradiation. Also, transmissivity of nanofluid filter has been derived according to empirical models. Two structures have been applied for cooling duct: 1) straight bottom wall; 2) wall with triangular obstacles (semi-wavy wall). As velocity of nanofluid within the filter (Vf) section enhances, the electrical performance increases about 3.4 %. For case 4, with augment of concentration ratio (CR) from 3 to 30, the electrical performance reduces about 13.57 % while thermal performance augments about 5.68 %. When CR=10, utilizing case 4 makes electrical and thermal performance to enhance about 25.09 % and 22.36 % in comparison to case 1. Also, cell temperature decreases about 47.82 % with applying the filter within the second structure of the cooling duct.

Calibration of the Ångström–Prescott Model for Accurately Estimating Solar Radiation Spatial Distribution in Areas with Few Global Solar Radiation Stations: A Case Study of the China Tropical Zone

The Ångström–Prescott formula is commonly used in climatological calculation methods of solar radiation simulation. Aiming at the characteristics of a vast area, few meteorological stations, and uneven distribution in the tropical regions of China, in order to obtain the optimal parameters of the global solar radiation calculation model, this study proposes a suitable monthly global solar radiation model based on the single-station approach and the between-groups linkage of the A–P model, which utilizes monthly measured meteorological data from 80 meteorological stations spanning the period from 1996 to 2016 in the tropical zone of China, considering the similarity in changes of monthly sunshine percentage between stations. The applicability and accuracy of the correction parameters (a and b coefficients) were tested and evaluated, and then the modified parameters were extended to conventional meteorological stations through Thiessen polygons. Finally, the spatial distribution of solar radiation in the tropical region of China was simulated by kriging, IDW, and spline interpolation techniques. The results show the following: (1) The single-station model exhibited the highest accuracy in simulating the average annual global solar radiation, followed by the model based on the between-groups linkage. After optimizing the a and b coefficients, the simulation accuracy of the average annual global solar radiation increased by 5.3%, 8.1%, and 4.4% for the whole year, dry season, and wet season, respectively. (2) Through cross-validation, the most suitable spatial interpolation methods for the whole year, dry season, and wet season in the tropical zone of China were IDW, Kriging, and Spline, respectively. This research has positive implications for improving the accuracy of solar radiation prediction and guiding regional agricultural production.

A revised morphing algorithm for creating future weather for building performance evaluation

Climate change is one of the greatest challenges the building industry faces. Engineers and architects require representative future weather data if they would like to see how their buildings and designs will fare under a changing climate. The most common method used to create future weather involves manipulating observations commonly known as morphing, but the most used algorithms can create implausible weather conditions due to their unbounded nature. Here, bounded morphing algorithms will be described and their effectiveness proved mathematically. The improved bounded method applies two additional conditions on the morphed distribution to the maximum and minimum values, in addition to the mean values. The benefits over the standard approach will also be illustrated considering the changes in the distribution of temperature and solar irradiation due to climate change. The improved algorithms outperform the standard morphing procedures in terms of preserving the underlying climate signal while not creating unrealistic or implausible weather conditions. This method should give engineers confidence that the generated future weather series are more robust and representative of potential future weather. Practical application: The use of future weather to inform building design is now commonplace within the industry. Reliable weather files are crucial to support and deliver strategies for decarbonisation and adaptation to climate change in the built environment and the wider industry. This article provides support for the use of revised morphing algorithms which result in improved future weather time series which can be used in building simulation. For example, when applied to the temperature, it can be used to produce more accurate representations of future temperature profiles due to climate change, and for building performance assessment, such as energy consumption and overheating. It plays an important role in producing reliable and realistic weather data for future-proof building design.

Comparison of the variation of solar radiation and atmospheric parameters in Kano before, during and after covid-19 lockdown

This study compared the variation of solar radiation and atmospheric parameters in Kano, Nigeria before, during, and after the COVID-19 (2019, 2020, and 2021) lockdown. Data was obtained from the Nigeria Meteorological Center (NIMET) in Abuja and MINITAB's time series method and procedures were used to analyze the data. Results showed that Kano witnessed an increased amount of solar radiation during COVID-19 (2020) when compared with the values of solar radiation distribution observed before and after COVID-19 (2019 and 2021). Atmospheric ozone increased slightly in Kano during the period of COVID-19 when compared with the periods before and after COVID-19 in the same area. Relative humidity variations were observed to be lower before and during COVID-19 when compared with the values after COVID-19, whereas temperature and pressure variation distributions were maintained approximately within the same range in the years of study (2019, 2020, and 2021). These findings provide an insight into the effects of the COVID-19 lockdown on solar radiation and atmospheric parameters in Kano.

Assessment of the Applicability of PV/T Electric Heating System for the Storage of Crude Oil

There are still some doubts about whether the solar photovoltaic/thermal (PV/T) system is applicable for the practical heating system of crude oil storage although there has been a lot of research work on PV/T and heating technology in the oil field. Due to the uneven distribution of solar radiation and uncertain thermal property of crude oil, the amount of energy provided and demanded is hard to evaluate. In this study, an electric heating system based on PV/T is proposed to be applied for the storage of crude oil. By establishing the mathematical model of the system, the energy supply capacity of PV/T and the heat demand of stored crude oil in typical seasons in Xinjiang are predicted by numerical method. The applicable scheme is discussed. This study may promote the application of PV/T heating systems in oil fields.

Analysis of the light performance of Chinese solar greenhouse with internal insulation based on a solar radiation model

Chinese solar greenhouses are important agricultural building facilities with highly efficient and sustainable solar energy consumption. A solar greenhouse with an external insulation blanket for heat preservation is the most prevalent type of CSG. However, greenhouse performance degrades as the thermal insulation performance of the external blanket deteriorates over time when the blanket is exposed to harsh environmental conditions. Moreover, the external blanket is usually parked in an inconvenient location on the south roof in the practice, resulting in shading owing to its increasing coverage length. This significantly influences the solar radiation received by the south roof and that projected on the wall, ultimately affecting the light performance of the greenhouse. Therefore, a solar greenhouse with an innovatively applied internal insulation system was proposed in this study. To analyze the light performance of the solar greenhouse, a solar radiation model was established and verified by comparing the measured and calculated values. Based on the calculated model results, the spatial distribution of solar radiation inside the greenhouse and its allocation to the interior surfaces of the greenhouse were simulated. The total captured and transmitted solar radiation accumulations were compared for three different roof shapes. The captured and transmitted radiation accumulation of the greenhouse with internal insulation increased by 3.9–9.5 and 1.8–4.4 MJ compared to the two other greenhouses, respectively. The effect of the position of the parked blanket on the beam solar radiation projected on the wall and ground was considered. The results indicated that the increased blanket coverage length decreased the cumulative radiation on the wall by 25.24%–99.82%, which did not contribute to improving greenhouse energy-saving production. This study provides a new approach to greenhouse design and optimization.

Insights about Modelling Environmental Spatiotemporal Actions in Thermal Analysis of Concrete Dams: A Case Study

In order to conduct thermal analysis of concrete dams, it is necessary to assess and validate the spatiotemporal representations used for modeling the solar radiation and the water temperature boundary conditions. To illustrate this procedure, the thermal analysis of a concrete multiple-arch dam is presented. The article starts by providing an overview of the problem before focusing explicitly on the estimation of solar radiation distribution. Within this section, a comparison between the solar irradiance computed on the downstream face of the dam with or without considering the beam radiation shading at different times of the year is presented. This is followed by an analysis of the seasonal behavior of the water temperature of the dam’s reservoir based on measured data. After calibrating an empirical/statistical law based on temperatures measured at different depths, it is compared with the values estimated by a hydrodynamic model and some temperature profiles measured upstream of the dam. Finally, the article compares the results obtained with the thermal analysis versus the temperature measured by thermometers installed in the concrete.

A Comparative Study on the Distribution Models of Incident Solar Energy in Buildings with Glazing Facades

The accurate distribution of solar energy on indoor walls is the basis of simulating the indoor thermal environment, and its specific distribution changes all the time due to the influence of solar azimuth and altitude angle. By analyzing the assumptions of each model, the existing solar energy distribution models are eight kinds in all and are divided into three categories. The solar radiation models in TRNSYS, EnergyPlus, and Airpak software all use the absorption-weighted area ratio method, which assumes that a single interior surface is a whole, but the detailed assumptions of the models used in the three software are different. In the Radiosity-irradiation method, the indoor surfaces are discretized into small surfaces for calculation. The calculation accuracy of solar radiation distribution indoors can be controlled by the number of discrete small surfaces. The Radiosity-irradiation method is implemented by using Matlab software programming in this paper. Through the numerical calculation and analysis of typical cases, the solar distribution results of the absorption-weighted area ratio method and the Radiosity-irradiation method all show the asymmetry. The asymmetrical ratio of direct solar radiation varies during the time between 7.96–9.89, and the minimum turns up at 11:30 in the summer solstice. The asymmetrical ratio of diffuse solar radiation is 3.23 constantly. The asymmetrical ratio of total solar energy is mainly influenced by the direct and diffuse solar feat gain and its value changes in the range from 3.4 to 4.45 in the summer solstice. Calculation comparison and error analysis on the solar radiation models used in TRNSYS, EnergyPlus, and Airpak software are conducted. There are significant errors in the simulation results of all three software. TRNSYS has the highest error among the three software as its results do not change over time. For EnergyPlus, the distribution ratio of floor 1 is too large. Airpak has the smallest error, but the solar radiation distribution ratios of the indoor surfaces near the south glazing facade are underrated, especially the indoor surfaces that have not been exposed to direct solar radiation.