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Moustafa M Elsayed - One of the best experts on this subject based on the ideXlab platform.
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Solar Flux Density distribution due to partially shaded blocked mirrors using the separation of variables superposition technique with polynomial and gaussian sunshapes
Journal of Solar Energy Engineering-transactions of The Asme, 1996Co-Authors: Moustafa M Elsayed, K A FathalahAbstract:In a previous work (El Sayed et al., 1994), the separation of a variable/superposition technique was used to predict the Flux Density distribution on the receiver surfaces of Solar central receiver plants. In this paper further developments of the technique are given. A numerical technique is derived to carry out the convolution of the sunshape and error Density functions. Also, a simplified numerical procedure is presented to determine the basic Flux Density function on which the technique depends. The technique is used to predict the receiver Solar Flux distribution using two sunshapes, polynomial and Gaussian distributions. The results predicted with the technique are validated by comparison with experimental results from mirrors both with and without partial shading/blocking of their surfaces.
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Solar Flux-Density distribution due to partially shaded/blocked mirrors using the separation of variables/superposition technique with polynomial and Gaussian sunshapes
Journal of Solar Energy Engineering-transactions of The Asme, 1996Co-Authors: Moustafa M Elsayed, K A FathalahAbstract:In a previous work (El Sayed et al., 1994), the separation of a variable/superposition technique was used to predict the Flux Density distribution on the receiver surfaces of Solar central receiver plants. In this paper further developments of the technique are given. A numerical technique is derived to carry out the convolution of the sunshape and error Density functions. Also, a simplified numerical procedure is presented to determine the basic Flux Density function on which the technique depends. The technique is used to predict the receiver Solar Flux distribution using two sunshapes, polynomial and Gaussian distributions. The results predicted with the technique are validated by comparison with experimental results from mirrors both with and without partial shading/blocking of their surfaces.
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measurements of Solar Flux Density distribution on a plane receiver due to a flat heliostat
Solar Energy, 1995Co-Authors: Moustafa M Elsayed, K Fathalah, Omar M AlrabghiAbstract:Abstract An experimental facility is designed and manufactured to measure the Solar Flux Density distribution on a central flat receiver due to a single flat heliostat. The tracking mechanism of the heliostat is controlled by two stepping motors, one for tilt angle control and the other for azimuth angle control. A x-y traversing mechanism is also designed and mounted on a vertical central receiver plane, where the Solar Flux Density is to be measured. A miniature Solar sensor is mounted on the platform of the traversing mechanism, where it is used to measure the Solar Flux Density distribution on the receiver surface. The sensor is connected to a data acquisition card in a host computer. The two stepping motors of the heliostat tracking mechanism and the two stepping motors of the traversing mechanism are all connected to a controller card in the same host computer. A software “TOWER” is prepared to let the heliostat track the sun, move the platform of the traversing mechanism to the points of a preselected grid, and to measure the Solar Flux Density distribution on the receiver plane. Measurements are carried out using rectangular flat mirrors of different dimensions at several distances from the central receiver. Two types of images were identified on the receiver plane—namely, apparent (or visible) and mirror-reflected radiation images. Comparison between measurements and a mathematical model validates the mathematical model.
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Solar Flux Density distribution using a separation of variables superposition technique
Renewable Energy, 1994Co-Authors: Moustafa M Elsayed, K A FathalahAbstract:A separation of variables/superposition technique is used to determine the Flux Density distribution Γ on the receiver plane of a central receiver system. This distribution is determined in terms of the Flux Density distribution F on the image plane. The distribution F is found in terms of the algebraic sum of several Flux distribution functions. Each of these functions Fi is determined in terms of a basic dimensionless Flux Density function φ, transferred to have its origin of coordinates at one corner of the principal image of the heliostat. Using a special coordinate system, φ is found to depend only on the angle θ∗ between the sides of the principal image of the heliostat, for a given Sun shape and error function. Calculations of θ∗ and the lengths of the sides of the principal image are performed for a wide range of parameters, which include Solar zenith and azimuth angles, radial distance of heliostat and its position azimuth angle, tower height, concentration and dimensions of the heliostat. For a given effective Sun shape, the basic dimensionless Flux Density distribution φ is calculated for several values of θ∗. This distribution is stored in a computer and used in an illustrative example to determine the Flux Density distribution on a receiver plane.
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Solar Flux Density distribution using a separation of variables/superposition technique
Renewable Energy, 1994Co-Authors: Moustafa M Elsayed, K A FathalahAbstract:A separation of variables/superposition technique is used to determine the Flux Density distribution Γ on the receiver plane of a central receiver system. This distribution is determined in terms of the Flux Density distribution F on the image plane. The distribution F is found in terms of the algebraic sum of several Flux distribution functions. Each of these functions Fi is determined in terms of a basic dimensionless Flux Density function φ, transferred to have its origin of coordinates at one corner of the principal image of the heliostat. Using a special coordinate system, φ is found to depend only on the angle θ∗ between the sides of the principal image of the heliostat, for a given Sun shape and error function. Calculations of θ∗ and the lengths of the sides of the principal image are performed for a wide range of parameters, which include Solar zenith and azimuth angles, radial distance of heliostat and its position azimuth angle, tower height, concentration and dimensions of the heliostat. For a given effective Sun shape, the basic dimensionless Flux Density distribution φ is calculated for several values of θ∗. This distribution is stored in a computer and used in an illustrative example to determine the Flux Density distribution on a receiver plane.
K A Fathalah - One of the best experts on this subject based on the ideXlab platform.
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Solar Flux Density distribution due to partially shaded blocked mirrors using the separation of variables superposition technique with polynomial and gaussian sunshapes
Journal of Solar Energy Engineering-transactions of The Asme, 1996Co-Authors: Moustafa M Elsayed, K A FathalahAbstract:In a previous work (El Sayed et al., 1994), the separation of a variable/superposition technique was used to predict the Flux Density distribution on the receiver surfaces of Solar central receiver plants. In this paper further developments of the technique are given. A numerical technique is derived to carry out the convolution of the sunshape and error Density functions. Also, a simplified numerical procedure is presented to determine the basic Flux Density function on which the technique depends. The technique is used to predict the receiver Solar Flux distribution using two sunshapes, polynomial and Gaussian distributions. The results predicted with the technique are validated by comparison with experimental results from mirrors both with and without partial shading/blocking of their surfaces.
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Solar Flux-Density distribution due to partially shaded/blocked mirrors using the separation of variables/superposition technique with polynomial and Gaussian sunshapes
Journal of Solar Energy Engineering-transactions of The Asme, 1996Co-Authors: Moustafa M Elsayed, K A FathalahAbstract:In a previous work (El Sayed et al., 1994), the separation of a variable/superposition technique was used to predict the Flux Density distribution on the receiver surfaces of Solar central receiver plants. In this paper further developments of the technique are given. A numerical technique is derived to carry out the convolution of the sunshape and error Density functions. Also, a simplified numerical procedure is presented to determine the basic Flux Density function on which the technique depends. The technique is used to predict the receiver Solar Flux distribution using two sunshapes, polynomial and Gaussian distributions. The results predicted with the technique are validated by comparison with experimental results from mirrors both with and without partial shading/blocking of their surfaces.
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Solar Flux Density distribution using a separation of variables superposition technique
Renewable Energy, 1994Co-Authors: Moustafa M Elsayed, K A FathalahAbstract:A separation of variables/superposition technique is used to determine the Flux Density distribution Γ on the receiver plane of a central receiver system. This distribution is determined in terms of the Flux Density distribution F on the image plane. The distribution F is found in terms of the algebraic sum of several Flux distribution functions. Each of these functions Fi is determined in terms of a basic dimensionless Flux Density function φ, transferred to have its origin of coordinates at one corner of the principal image of the heliostat. Using a special coordinate system, φ is found to depend only on the angle θ∗ between the sides of the principal image of the heliostat, for a given Sun shape and error function. Calculations of θ∗ and the lengths of the sides of the principal image are performed for a wide range of parameters, which include Solar zenith and azimuth angles, radial distance of heliostat and its position azimuth angle, tower height, concentration and dimensions of the heliostat. For a given effective Sun shape, the basic dimensionless Flux Density distribution φ is calculated for several values of θ∗. This distribution is stored in a computer and used in an illustrative example to determine the Flux Density distribution on a receiver plane.
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Solar Flux Density distribution using a separation of variables/superposition technique
Renewable Energy, 1994Co-Authors: Moustafa M Elsayed, K A FathalahAbstract:A separation of variables/superposition technique is used to determine the Flux Density distribution Γ on the receiver plane of a central receiver system. This distribution is determined in terms of the Flux Density distribution F on the image plane. The distribution F is found in terms of the algebraic sum of several Flux distribution functions. Each of these functions Fi is determined in terms of a basic dimensionless Flux Density function φ, transferred to have its origin of coordinates at one corner of the principal image of the heliostat. Using a special coordinate system, φ is found to depend only on the angle θ∗ between the sides of the principal image of the heliostat, for a given Sun shape and error function. Calculations of θ∗ and the lengths of the sides of the principal image are performed for a wide range of parameters, which include Solar zenith and azimuth angles, radial distance of heliostat and its position azimuth angle, tower height, concentration and dimensions of the heliostat. For a given effective Sun shape, the basic dimensionless Flux Density distribution φ is calculated for several values of θ∗. This distribution is stored in a computer and used in an illustrative example to determine the Flux Density distribution on a receiver plane.
Marc Roger - One of the best experts on this subject based on the ideXlab platform.
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Efficiency determination of tubular Solar receivers in central receiver systems
Solar Energy, 2016Co-Authors: Miriam Ebert, Marc Roger, Daniel Benitez, Roman Korzynietz, José Antonio BriosoAbstract:Abstract This paper describes a method for the efficiency determination of a cavity receiver using the example of the Solar hybrid gas turbine system SOLUGAS. Major focus is given on the improvement of a new approach of the Solar Flux Density determination based on a measurement-supported simulation technique where an acceptable uncertainty of the Solar input power of −1.3%…+6.3% is achieved. For the thermal evaluation an uncertainty of 2.4% is determined that leads to an overall uncertainty of the thermal receiver efficiency of −2.8%…+7.7%. Detailed uncertainty propagation is presented and conclusions discussed.
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Durability of Solar reflector materials for secondary concentrators used in CSP systems
Solar Energy Materials and Solar Cells, 2014Co-Authors: Aránzazu Fernández-garcía, Marc Roger, Maria Elena Cantos-soto, Christian Hutter, Christian Wieckert, Lucía Martínez-arcosAbstract:Abstract Secondary concentrators are used in Solar concentrating systems to redirect Solar beams reflected by the primary concentrators to the focal point or line. These components allow to increase the concentrated Solar Flux Density and hence to lower thermal radiation losses. Solar reflectors for secondary concentrators are permanently exposed to environmental conditions, high radiation Fluxes and elevated temperatures that potentially cause stress and degradation throughout the time. Therefore, analyzing Solar reflectors of secondary concentrators by simulating these conditions is crucial. No previous research works about the durability of Solar reflector materials for secondary concentrators have been reported. The present work is focused on studying the degradation of the reflector materials by simulating accelerated aging, caused by several ambient parameters and the effect of concentrated radiation. Both cooled and uncooled systems for secondary concentrators are included in this study. According to results obtained, aluminum reflectors and thin silvered-glass reflectors glued to an aluminum structure showed minimum reflectance losses and structural degradation under the operation conditions of cooled 3D secondary concentrators (tower systems). Following critical aspects to avoid reflector degradation were identified: to select a suitable adhesive material to glue the thin silvered-glass reflector to the support aluminum structure, to properly protect reflectors edges, to design a suitable cooling system and to avoid the combination of high radiation Fluxes with mechanical stress. In addition, laminated silvered-glass reflectors have shown to be suitable for uncooled 2D secondary concentrators (Fresnel collectors). Furthermore, a comparison with naturally aged secondary concentrators using silvered-glass reflectors glued to an aluminum structure revealed that the simulated degradation under accelerated conditions performed in this work did reproduce the most frequent degradation patterns suffered in real operating conditions.
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techniques to measure Solar Flux Density distribution on large scale receivers
Journal of Solar Energy Engineering-transactions of The Asme, 2014Co-Authors: Marc Roger, Patrik Herrmann, Steffen Ulmer, Miriam Ebert, Christoph Prahl, Felix GohringAbstract:Flux Density measurement applied to central receiver ystems delivers the spatial distribution of the concentrated Solar radiation on the receiver aperture, measures receiver input power, and monitors and might control heliostat aimpoints. Commercial Solar tower plants have much larger aperture surfaces than the receiver prototypes tested in earlier research and development (R&D) projects. Existing methods to measure the Solar Flux Density in the receiver aperture face new challenges regarding the receiver size. Also, the requirements regarding costs, accuracy, spatial resolution, and measuring speed are different. This paper summarizes existent concepts, presents recent research results for techniques that can be applied to large-scale receivers and assesses them against a catalog of requirements. Direct and indirect moving bar techniques offer high measurement accuracy, but also have the disadvantage of large moving parts on a Solar tower. In the case of external receivers, measuring directly on receiver surfaces avoids moving parts and allows continuous measurement but may be not as precise. This promising technique requires proper scientific evaluation due to specific reflectance properties of current receiver materials. Measurement-supported simulation techniques can also be applied to cavity receivers without installing moving parts. They have reasonable uncertainties under ideal conditions and require comparatively low effort.
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Flux Density measurement for industrial scale Solar power towers
2014Co-Authors: Matthias Offergeld, Marc Roger, Hannes Stadler, Bernhard HoffschmidtAbstract:For separate acceptance tests of a Solar power tower’s heliostat field and receiver, it is necessary to determine the Solar Flux Density distribution over the whole absorber surface. Integrating the Flux Density delivers the receiver input power, which is required for calculating the energy conversion efficiencies of both heliostat field and receiver. Furthermore, Flux Density measurement is valuable for supervision and control during operation of a power tower. Flux Density at small-scale prototype receivers has mostly been measured by using a camera and a moving bar so far. The moving bar is a white diffusely reflecting target which is moved quickly through the radiation’s focus in front of the receiver surface. At the same time, a digital camera cap-tures the radiation reflected off the moving bar, which allows determining the incident Flux Density. At industrial-scale receivers though, the installation of a moving bar is hardly feasible due to difficult construction and high costs. Therefore, the development of a measurement method without any mov-ing parts is aspired. For this purpose, the radiation reflected off the absorber itself can be measured in order to calculate the incident Flux Density [1]. Preliminary work on this method is still immature and has not yet lead to a reliable and satisfying measuring accuracy under all conditions [2]; achieving this is a main aim of the presented thesis. The central challenge with measuring Flux Density by reflection off the absorber is the absorber’s non-diffusive reflectivity, which depends especially on the direction of the incident radiation as well as on the observation angle [1]. Hence, detailed understanding of reflection at the structured surface of open volumetric receivers as well as tube receivers and following software-aided correction of these effects are essential for reducing the measurement uncertainty. The improvements will be imple-mented and tested at the Solar Tower Julich. Finally, the improved Flux Density measurement system is planned to be used in a demonstrational acceptance testing at the Solar Tower Julich, including a comparison of measurements and simulation results.
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Accelerated Ageing of Solar Reflectors for Secondary Concentrators
2012Co-Authors: Aránzazu Fernández-garcía, Marc Roger, Maria Elena Cantos-soto, Christian Hutter, Christian WieckertAbstract:Secondary concentrators are used in Solar concentrating systems to redirect Solar beams reflected by the primary concentrators to the focal point or line. Secondary concentrators allow smaller receiver apertures (and hence lower reradiation losses) and increase the concentrated Solar Flux Density. Solar mirrors for secondary concentrators are permanently exposed to environmental conditions, a high radiation Flux and elevated temperatures that potentially cause stress and degradations throughout the time. For most Solar mirrors, exposures to sunlight during service, particulary ultraviolet wavelenghts, temperature, and moisture can lead to loss in reflectance. Insufficient cooling of mirror surfaces may lead to destruction of the mirror e.g. by melting. Therefore, analyzing Solar reflectors of secondary concetrators by simulating the previouse conditions is crucial. The present work is focused on studying the degradation of the mirrors by simulating accelerated exposure, caused by several ambient paramenters and the effect of concetrated radiation. It has been done under the framwork of the SFERA project. The tests were performed at two installations. The salt spray tests and weathering tests (constant and cycle temperature, damp heat and humidity) were completed at the Solar Reflectors Durability Laboratory of PSA (Plataforma Solar de Almeria, Spain). The high Flux exposure tests of mirrors with their cooling system were performed at the Solar Technology Laboratory (STL) of PSI (Paul Scherrer Institute, Switherland). A total of 9 selected mirror types were exposed to different levels of concentrated radiation and accelerated weathering parameters to simulate and analyze the effects caused by the ambient conditions. According to results obtained, aluminium reflectors and thin-glass silvered reflectors glued to an aluminium structure have demonstrated to be appropriate for cooled 3D secondary concentrators (tower systems). In addition, laminated silvered-glass mirrors have shown to be suitable for non-cooled 2D secondary concentrators (Fresnel and parabolic-trough collectors).
D. P. Charrois - One of the best experts on this subject based on the ideXlab platform.
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Limits to the accuracy of the 10.7 cm Flux
Solar Physics, 1994Co-Authors: K. F. Tapping, D. P. CharroisAbstract:The 10.7 cm Flux data, which are widely used as an index of Solar activity, are actually spot measurements of the Solar Flux Density at 10.7 cm wavelength, made three times each day, usually at 17:00, 20:00, and 23:00 UT. These values, or the 20:00 UT determination alone, are frequently used as the average Flux for that day. Since each spot measurement takes about one hour to make, and the Sun's emissions at that wavelength can vary over time scales shorter than the intervals between the measurements, the data are unavoidably undersampled. Radio emissions from transient events, such as flares, are defined as contaminants of the Flux, and largely-empirical procedures have evolved which are used to filter them from the data.
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Limits to the accuracy of the 10.7 cm Flux
Solar Physics, 1994Co-Authors: K. F. Tapping, D. P. CharroisAbstract:The 10.7 cm Flux data, which are widely used as an index of Solar activity, are actually spot measurements of the Solar Flux Density at 10.7 cm wavelength, made three times each day, usually at 17:00, 20:00, and 23:00 UT. These values, or the 20:00 UT determination alone, are frequently used as the average Flux for that day. Since each spot measurement takes about one hour to make, and the Sun's emissions at that wavelength can vary over time scales shorter than the intervals between the measurements, the data are unavoidably undersampled. Radio emissions from transient events, such as flares, are defined as contaminants of the Flux, and largely-empirical procedures have evolved which are used to filter them from the data. The utility of the F _10.7 index over more than 40 years suggests that the consequences of the under-sampling and the use of largely-empirical data filters are not serious. However, as new applications of the Flux data appear, and existing ones become more quantitative, we need to better understand the accuracy of data as estimates of the 10.7 cm Flux index, and to know how much precision we can reasonably expect to attain. In this paper we describe part of a study aimed at estimating how good the spot measurements are as estimators of the ‘daily-average’ Flux. By a combination of measurement and modelling, the contributions to the Flux monitor output truly due to the Sun are separated from the non-Solar signals. We then derive the daily average 10.7 cm Flux values and compare them with the spot measurements. We find that in general, the spot measurements are usually within a percent or so of the daily-average Fluxes.
Ya-ling He - One of the best experts on this subject based on the ideXlab platform.
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Three-dimensional numerical study on a novel parabolic trough Solar receiver-reactor of a locally-installed Kenics static mixer for efficient hydrogen production
Applied Energy, 2019Co-Authors: Ze-dong Cheng, Ya-ling HeAbstract:Abstract In this paper, a novel parabolic trough Solar receiver-reactor (PTSRR) system of a locally-installed Kenics static mixer (KSM) is proposed for efficient Solar thermal hydrogen production. A three-dimensional comprehensive model was established for PTSRRs of the methanol-steam reforming reaction (MSRR) for hydrogen production, by combining the Finite Volume Method and the Monte Carlo ray-tracing method with a MSRR comprehensive kinetic model. The validated model was preliminarily applied to study the effects and mechanisms of the concentrated Solar Flux nonuniformity and the locally-installed KSM on PTSRR photo-thermal-chemical comprehensive characteristics and performance, taking the methanol flow rate and the catalyst sintering temperature limitation into account. With a preliminary optimization on the concentrated Solar Flux nonuniformity, the optical efficiency and the Solar Flux nonuniformity are improved by 6.58% and 30.42% respectively. It is further revealed that these PTSRRs of better concentrated Solar Flux Density nonuniformity also have better thermal-chemical comprehensive characteristics and performance. Novel PTSRRs of the locally-installed KSM have better comprehensive characteristics and performance than corresponding original PTSRRs or even optimized PTSRRs, with a maximum increase in the methanol conversion rate of 6.92%. It thus will operate more safely and more efficiently, by the cost of a little more pump power to overcome corresponding larger flow resistance caused by the locally-installed KSM. From the mechanism, this kind of novel PTSRR of a locally-installed KSM provides a useful option of high potential for improving uniformities of a series of key field variables in the whole photo-thermal-chemical conversion process, and thus improves the comprehensive characteristics and performance of PTSRRs.
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A comprehensive study on parabolic trough Solar receiver-reactors of methanol-steam reforming reaction for hydrogen production
Energy Conversion and Management, 2019Co-Authors: Ze-dong Cheng, Xue-ru Zhao, Ya-ling HeAbstract:Abstract In this paper, a three-dimensional comprehensive model is firstly proposed for Parabolic Trough Solar Receiver-Reactors (PTSRR) of the Methanol-Steam Reforming Reaction process (MSRR) for hydrogen production. This PTSRR-MSRR comprehensive model is established by combining a comprehensive kinetic model of MSRR, a validated Monte Carlo Ray-Tracing (MCRT) optical model with a Computational Fluid Dynamics (CFD) model based on the Finite Volume Method (FVM), as well as useful comprehensive evaluation indicators. It is capable of comprehensively simulating and evaluating the whole complex photo-thermal-chemical conversion process of the entire PTSRR system, including the concentration, collection and conversion of photon energy, coupled heat transfers, fluid dynamics, multicomponent transports and methanol-steam reforming reactions. After validation, this comprehensive model was successfully used to determine the comprehensive characteristics and performance of different PTSRRs and realistic conditions. The effects and mechanisms of the Solar time, the reflector geometric parameters, the inlet methanol molar flow rate, the reaction temperature limitation and the nonuniformity of the concentrated Solar Flux Density distribution were discussed in detail. It is revealed that the reaction temperature limitation that should be smaller than the sintering temperature of Cu/ZnO/Al2O3 catalyst particles may only appear locally, which is mainly caused by the nonuniformity of the concentrated Solar Flux Density distribution and the corresponding local peak Solar Flux Density. For the mechanism of this kind of temperature limitation, different control strategies and optimizations were examined. Better comprehensive characteristics and performance of PTSRRs can be obtained, by making a reasonable tradeoff between the optical efficiency, the Solar Flux nonuniformity and the reflector surface curvature characteristics.
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A detailed parameter study on the comprehensive characteristics and performance of a parabolic trough Solar collector system
Applied Thermal Engineering, 2014Co-Authors: Ze-dong Cheng, Ya-ling He, Kun Wang, Bao-cun DuAbstract:Abstract This paper presents the theoretical analysis results of the relations between the geometric parameters of the reflector of a parabolic trough collector (PTC) system and the focal shape formed by the defocusing phenomenon of the non-parallel Solar beam firstly. Then the effects of these designed parameters and the defocusing phenomenon on the comprehensive characteristics and performance of the whole process of the photo-thermal conversion in the PTC system were numerically studied and optimized, using a proposed three-dimensional integrated model combined the Finite Volume Method (FVM) with the Monte Carlo Ray-Trace (MCRT) method. It is revealed that the numerical results can be well explained by the theoretical analysis results, proving that the model and method used in the present study is feasible and reliable. It is also found that the comprehensive characteristics and performance are very different from some critical points determined by the defocusing phenomenon of the non-parallel Solar beam. From these critical points, the optional ranges of the geometric parameters of the reflector are determined to collect the entire reflected beam from the reflector, with relative optimized performance. In addition, an improved description for the characteristics of the Solar Flux Density distributions on the absorber tube is further presented.
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Numerical investigations on coupled heat transfer and synthetical performance of a pressurized volumetric receiver with MCRT–FVM method
Applied Thermal Engineering, 2013Co-Authors: Ze-dong Cheng, Ya-ling HeAbstract:Abstract This paper presents an axisymmetric steady-state computational fluid dynamics model and further studies on the complex coupled heat transfer combined radiation–convection–conduction in the pressurized volumetric receiver (PVR), by combining the Finite Volume Method (FVM) and the Monte Carlo Ray-Trace (MCRT) method. Based on this, effects of geometric parameters of the compound parabolic concentrator (CPC) and properties of the porous absorber on synthetical characteristics and performance of the photo-thermal conversion process in the PVR are further analyzed and discussed detailedly. It is found that the Solar Flux Density distributions are always very heterogeneous with large nonuniformities, and the variation trends of the corresponding temperature distributions are very similar to these but with much lower order of magnitude. The CPC shape determined by the CPC exit aperture has much larger effects on synthetical characteristics and performance of the PVR than that of the CPC entry aperture with a constant acceptance angle. And a suitable or optimal thickness of the porous absorber could be determined by examining where the drastic decreasing trends occur at the curves of variations of synthetical characteristics and performance with the porosity.