scholarly journals Effect of the Orientation Schemes of the Energy Collection Element on the Optical Performance of a Parabolic Trough Concentrating Collector

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 128 ◽  
Author(s):  
Majedul Islam ◽  
Prasad Yarlagadda ◽  
Azharul Karim
Keyword(s):  
Monte Carlo ◽  
State Of The Art ◽  
Tracking Error ◽  
Surface Group ◽  
Energy Performance ◽  
Optical Performance ◽  
Extended Version ◽  
Parabolic Trough ◽  
Tracking Errors ◽  
Optical Efficiency

While the circular shape is currently the proven optimum design of the energy collection element (ECE) of a parabolic trough collector, that is yet to be confirmed for parabolic trough concentrating collectors (PTCCs) like trough concentrating photovoltaic collectors and hybrid photovoltaic/thermal collectors. Orientation scheme of the ECE is expected to have significant effect on the optical performance including the irradiance distribution around the ECE and the optical efficiency, and therefore, on the overall energy performance of the PTCC. However, little progress addressing this issue has been reported in the literature. In this study, a thorough investigation has been conducted to determine the effect of the orientation schemes of ECE on the optical performance of a PTCC applying a state-of-the-art Monte Carlo ray tracing (MCRT) technique. The orientation schemes considered are a flat rectangular target and a hollow circular, semi-circular, triangular, inverted triangular, rectangular and rectangle on semi-circle (RSc). The effect of ECE defocus, Sun tracking error and trough rim angle on the optical performance is also investigated. The MCRT study reveals that the ECE orientation schemes with a curved surface at the trough end showed much higher optical efficiency than those with a linear surface under ideal conditions. ECEs among the linear surface group, the inverted triangular orientation exhibited the highest optical efficiency, whereas the flat and triangular ones exhibited the lowest optical efficiency, and the rectangular one was in between them. In the event of defocus and tracking errors, a significant portion of the concentrated light was observed to be intercepted by the surfaces of the rectangular and RSc ECEs that are perpendicular to the trough aperture. This is an extended version of a published work by the current authors, which will help to design an optically efficient ECE for a parabolic trough concentrating collector.

scholarly journals Investigation on the Optical Design and Performance of a Single-Axis-Tracking Solar Parabolic trough Collector with a Secondary Reflector

2021 ◽  
Vol 13 (17) ◽  
pp. 9918
Author(s):  
Chinnasamy Subramaniyan ◽  
Jothirathinam Subramani ◽  
Balasubramanian Kalidasan ◽  
Natarajan Anbuselvan ◽  
Thangaraj Yuvaraj ◽  
...  
Keyword(s):  
Incidence Angle ◽  
Optical Design ◽  
Operating Conditions ◽  
Optical Performance ◽  
Ambient Conditions ◽  
Parabolic Trough ◽  
Tracking Errors ◽  
Optical Efficiency ◽  
Collector System ◽  
And Performance

The design of solar concentrating collectors for the effective utilization of solar energy is a challenging condition due to tracking errors leading to different divergences of the solar incidence angle. To enhance the optical performance of solar parabolic trough collectors (SPTC) under a diverged solar incidence angle, an additional compound parabolic concentrator (CPC) is introduced as a secondary reflector. SPTC with CPC is designed and modeled for a single axis-tracking concentrating collector based on the local ambient conditions. In this work, the optical performance of the novel SPTC system with and without a secondary reflector is investigated using MATLAB and TRACEPRO software simulations for various tracking errors. The significance parameters such as the solar incidence angle, aperture length, receiver tube diameter, rim angle, concentration ratio, solar radiation, and absorbed flux are analyzed. The simulation results show that the rate of the absorbed flux on the receiver tube is significantly improved by providing the secondary reflector, which enhances the optical efficiency of the collector. It is found that the optical efficiency of the SPTC with a secondary reflector is 20% higher than the conventional collector system for a solar incidence angle of 2°. This work can effectively direct the choice of optimal secondary reflectors for SPTC under different design and operating conditions.

Comparison-Based Optical Assessment of Hyperboloid and Ellipsoid Reflectors in a Beam-Down Solar Tower System With Linear Fresnel Heliostats

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Xian Li ◽  
Meng Lin ◽  
Yanjun Dai ◽  
Chi-Hwa Wang
Keyword(s):  
Large Scale ◽  
Power Transmission ◽  
Tracking Error ◽  
Tracking Errors ◽  
Optical Efficiency ◽  
System A ◽  
Point Line ◽  
Line Coupling ◽  
Efficiency Gap ◽  
Tower System

Beam-down concentrating solar tower (BCST) is known for its merits in easy installation and maintenance as well as lower convection heat loss of the central receiver (CR) when comparing to a traditional concentrated solar tower system. A point-line-coupling-focus (PLCF) BCST system using linear Fresnel heliostat (LFH) as the first stage concentrator (heliostat) and hyperboloid/ellipsoid reflector as the tower reflector (TR) is proposed and theoretically analyzed and compared in this paper. Theoretical investigation on the ray concentrating mechanism with two commonly used reflector structures, namely, hyperboloid and ellipsoid, is conducted utilizing Monte Carlo ray-tracing (MCRT) method. The objective of this study is to reveal the achievable optical performance of these types of TRs in the PLCF system considering the effect of LFH tracking errors on TR astigmatism as well as the differences of optical efficiency factors and power transmission in a large-scale biomimetic layout. Results indicate that the ellipsoid system is superior in terms of interception efficiency over the hyperboloid system due to smaller astigmatism at the CR aperture, especially at larger facet tracking error. However, the ellipsoid reflector shows significantly lower TR shading efficiency resulting from the larger TR surface area compared to that of the hyperboloid reflector. The total optical efficiency of the hyperboloid system is always better than that of the ellipsoid system, and this efficiency gap decreases as the ratio ε increases. The hyperboloid TR is proved to be more promising and practical for the PLCF system.

Influences of installation and tracking errors on the optical performance of a solar parabolic trough collector

2016 ◽  
Vol 94 ◽  
pp. 197-212 ◽  
Author(s):  
Dongming Zhao ◽  
Ershu Xu ◽  
Zhifeng Wang ◽  
Qiang Yu ◽  
Li Xu ◽  
...  
Keyword(s):  
Optical Performance ◽  
Parabolic Trough ◽  
Tracking Errors ◽  
Parabolic Trough Collector

A Nonimaging Receiver for Parabolic Trough Concentrating Collectors

Solar Energy ◽  
2002 ◽  
Author(s):  
Randy Gee ◽  
Gilbert Cohen ◽  
Roland Winston
Keyword(s):  
Thermal Energy ◽  
High Performance ◽  
Optical Model ◽  
Energy Output ◽  
Optical Performance ◽  
Parabolic Trough ◽  
Optical Efficiency ◽  
Indirect Benefits ◽  
Reduce Heat Loss ◽  
Insight Into

The design of a nonimaging secondary reflector as part of a parabolic trough receiver has been developed and evaluated. A detailed optical model was used for evaluation, which offered insight into the optical performance of the secondary and showed that the design offers about a 1% net increase in optical efficiency. In addition, the secondary was estimated to reduce heat loss from a high-performance evacuated receiver by about 4%. Overall, the net performance advantage of the secondary reflector is calculated to be 1.4%, that is, the entire trough collector field would have a 1.4% greater annual thermal energy output. This performance increase is small, but the non-imaging secondary also achieves other indirect benefits such as better flux uniformity around the absorber tube, and increased tolerance of parabolic trough collectors to optical errors.

scholarly journals An Adaptive Face Tracker with Application in Yawning Detection

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1494
Author(s):  
Aasim Khurshid ◽  
Jacob Scharcanski
Keyword(s):  
State Of The Art ◽  
Tracking Error ◽  
Face Tracking ◽  
Facial Features ◽  
Local Models ◽  
Tracking Errors ◽  
Detection Scheme ◽  
Search Mechanism ◽  
The Face ◽  
Divergence Estimate

In this work, we propose an adaptive face tracking scheme that compensates for possible face tracking errors during its operation. The proposed scheme is equipped with a tracking divergence estimate, which allows to detect early and minimize the face tracking errors, so the tracked face is not missed indefinitely. When the estimated face tracking error increases, a resyncing mechanism based on Constrained Local Models (CLM) is activated to reduce the tracking errors by re-estimating the tracked facial features’ locations (e.g., facial landmarks). To improve the Constrained Local Model (CLM) feature search mechanism, a Weighted-CLM (W-CLM) is proposed and used in resyncing. The performance of the proposed face tracking method is evaluated in the challenging context of driver monitoring using yawning detection and talking video datasets. Furthermore, an improvement in a yawning detection scheme is proposed. Experiments suggest that our proposed face tracking scheme can obtain a better performance than comparable state-of-the-art face tracking methods and can be successfully applied in yawning detection.

scholarly journals Multiple particle filtering for tracking wireless agents via Monte Carlo likelihood approximation

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Stephan Schlupkothen ◽  
Gerd Ascheid
Keyword(s):  
Monte Carlo ◽  
Computational Complexity ◽  
Particle Filtering ◽  
Gaussian Approximation ◽  
State Of The Art ◽  
Approximation Techniques ◽  
Accurate Localization ◽  
Likelihood Approximation ◽  
Current State ◽  
Multiple Particle

Abstract The localization of multiple wireless agents via, for example, distance and/or bearing measurements is challenging, particularly if relying on beacon-to-agent measurements alone is insufficient to guarantee accurate localization. In these cases, agent-to-agent measurements also need to be considered to improve the localization quality. In the context of particle filtering, the computational complexity of tracking many wireless agents is high when relying on conventional schemes. This is because in such schemes, all agents’ states are estimated simultaneously using a single filter. To overcome this problem, the concept of multiple particle filtering (MPF), in which an individual filter is used for each agent, has been proposed in the literature. However, due to the necessity of considering agent-to-agent measurements, additional effort is required to derive information on each individual filter from the available likelihoods. This is necessary because the distance and bearing measurements naturally depend on the states of two agents, which, in MPF, are estimated by two separate filters. Because the required likelihood cannot be analytically derived in general, an approximation is needed. To this end, this work extends current state-of-the-art likelihood approximation techniques based on Gaussian approximation under the assumption that the number of agents to be tracked is fixed and known. Moreover, a novel likelihood approximation method is proposed that enables efficient and accurate tracking. The simulations show that the proposed method achieves up to 22% higher accuracy with the same computational complexity as that of existing methods. Thus, efficient and accurate tracking of wireless agents is achieved.

scholarly journals Window dressing in the Active Share scores in publicly reported portfolios

2021 ◽  
pp. 234094442110246
Author(s):  
Laura Andreu ◽  
Carlos Forner ◽  
José Luis Sarto
Keyword(s):  
Positive Relationship ◽  
Tracking Error ◽  
Jel Classification ◽  
Tracking Errors ◽  
Window Dressing ◽  
Future Performance ◽  
Money Flows

Using a unique database that includes publicly disclosed fund holdings at the end of the quarter as well as the holdings in all non-publicly disclosed months, we found that some funds could alter their portfolios in publicly disclosed months to artificially increase their Active Share scores and consequently appear more active and take advantage of the positive relationship between Active Share and money flows. We show how, consistent with non-informed trades, these funds erode their future performance. However, these funds reach their objective of increasing future money flows. Moreover, we find that window-dresser funds can be identified by controlling the level of tracking error. The funds with high Active Share scores and low tracking errors have the highest levels of Active Share window dressing and the worst future returns. However, compared with less active funds, they are able to capture higher money flows. JEL CLASSIFICATION G23; G11

Analysis of a Hybrid PV/T Concept Based on Wavelength Selective Films

2013 ◽  
Author(s):  
Tejas U. Ulavi ◽  
Jane H. Davidson ◽  
Tim Hebrink
Keyword(s):  
Thin Film ◽  
Monte Carlo ◽  
Total Energy ◽  
Ray Tracing ◽  
Solar Spectrum ◽  
Photovoltaic Module ◽  
Optical Performance ◽  
Technical Performance ◽  
Compound Parabolic Concentrator ◽  
Pv Modules

The technical performance of a non-tracking hybrid PV/T concept that uses a wavelength selective film is modeled. The wavelength selective film is coupled with a compound parabolic concentrator to reflect and concentrate the infrared portion of the solar spectrum onto a tubular absorber while transmitting the visible portion of the spectrum to an underlying thin-film photovoltaic module. The optical performance of the CPC/selective film is obtained through Monte Carlo Ray-Tracing. The CPC geometry is optimized for maximum total energy generation for a roof-top application. Applied to a rooftop in Phoenix, Arizona USA, the hybrid PV/T provides 20% more energy compared to a system of the same area with independent solar thermal and PV modules, but the increase is achieved at the expense of a decrease in the electrical efficiency from 8.8% to 5.8%.

Comparison of Two Linear Collectors in Solar Thermal Plants: Parabolic Trough vs Fresnel

2011 ◽  
Author(s):  
A. Giostri ◽  
M. Binotti ◽  
P. Silva ◽  
E. Macchi ◽  
G. Manzolini
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Research Activity ◽  
Optical Efficiency ◽  
Synthetic Oil ◽  
Yearly Average

Parabolic trough can be considered the state of the art for solar thermal power plants thanks to the almost 30 years experience gained in SEGS and, recently, Nevada Solar One plants in US and Andasol plants in Spain. One of the major issues that limits the wide diffusion of this technology is the high investment cost of the solar field and, particularly, of the solar collector. For this reason, since several years research activity has been trying to develop new solutions with the aim of cost reduction. This work compares commercial Fresnel technology with conventional parabolic trough plant based on synthetic oil as heat transfer fluid at nominal conditions and evaluates yearly average performances. In both technologies, no thermal storage system is considered. In addition, for Fresnel, a Direct Steam Generation (DSG) case is investigated. Performances are calculated by a commercial code, Thermoflex®, with dedicated component to evaluate solar plant. Results will show that, at nominal conditions, Fresnel technology have an optical efficiency of 67% which is lower than 75% of parabolic trough. Calculated net electric efficiency is about 19.25%, while parabolic trough technology achieves 23.6%. In off-design conditions, the gap between Fresnel and parabolic trough increases because the former is significantly affected by high radiation incident angles. The calculated sun-to-electric annual average efficiency for Fresnel plant is 10.2%, consequence of the average optical efficiency of 38.8%, while parabolic trough achieve an overall efficiency of 16%, with an optical one of 52.7%. An additional case with Fresnel collector and synthetic oil outlines differences among investigated cases. Finally, because part of performance difference between PT and Fresnel is simple due to different definitions, additional indexes are introduced in order to make a consistent comparison.

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