Optical Modeling of Reflectivity Loss Caused by Dust Deposition on CSP Mirrors and Restoration of Energy Yield by Electrodynamic Dust Removal

2014 ◽  
Author(s):  
Jeremy Stark ◽  
Julius Yellowhair ◽  
John N. Hudelson ◽  
Mark Horenstein ◽  
Malay Mazumder
Keyword(s):  
Power Plants ◽  
Specular Reflection ◽  
Mie Scattering ◽  
Dust Removal ◽  
Dust Particles ◽  
Energy Yield ◽  
Dust Deposition ◽  
Optical Modeling ◽  
Specular Reflectivity ◽  
Semi Arid

For large scale CSP power plants, vast areas of land are needed in deserts and semi-arid climates where uninterrupted solar irradiance is most abundant. These power facilities use large arrays of mirrors to reflect and concentrate sunlight onto collectors, however, dust deposition on the optical surfaces causes obscuration of sunlight, resulting in large energy-yield losses in solar plants. This problem is compounded by the lack of natural clean water resources for conventional cleaning of solar mirrors, often with reflective surface areas of large installations exceeding a million square meters. To investigate the application of transparent electrodynamic screens (EDS) for efficient and cost effective dust removal from solar mirrors, both optical modeling and experimental verifications were performed. Prototype EDS-integrated mirrors were constructed by depositing a set of parallel transparent electrodes into the sun-facing surface of solar mirrors and coating electrodes with thin transparent dielectric film. Activation of the electrodes with a three-phase voltage creates an electrodynamic field that charges and repels dust electrostatically by Coulomb force and sweeps away particles by a traveling electrodynamic wave. We report here brief discussions on (1) rate of deposition and the properties of dust with respect to their size distribution and chemical composition in semi-arid areas of the southwest US and Mojave Desert and their adhesion to solar mirrors, (2) optical models of: (a) specular reflection losses caused by scattering and absorption by dust particles deposited on the surface based on Mie scattering theory, and (b) reflection loss by the integration of EDS on the mirror surface, computed by FRED ray-tracing model. The objective is to maintain specular reflectivity of 90% or higher by frequent removal of dust by EDS. Our studies show that the incorporation of transparent EDS would cause an initial loss of 3% but would be able to maintain specular reflectivity more than 90% to meet the industrial requirement for CSP plants. Specular reflection measurements taken inside a climate controlled environmental chamber show that EDS integration can restore specular reflectivity and would be able to prevent major degradation of the optical surface caused by the deposition of dust.

scholarly journals Study on Dust Deposition Mechanics on Solar Mirrors in a Solar Power Plant

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4550 ◽  
Author(s):  
Xueqing Liu ◽  
Song Yue ◽  
Luyi Lu ◽  
Jianlan Li
Keyword(s):  
Power Plants ◽  
Solar Power ◽  
Renewable Energy Sources ◽  
Dust Particles ◽  
Particle Collision ◽  
Energy Sources ◽  
Solar Power Plant ◽  
Dust Deposition ◽  
Research Results ◽  
Solar Power Plants

Solar energy is considered to be one of most promising renewable energy sources because of its availability and cleanliness. The phenomenon of dust deposition on solar mirrors greatly reduces the power generation of solar power plants. In this work, the motion behaviors and deposition mechanics of dust particles are analyzed by the discrete element method (DEM). The effects of environmental and solar mirror conditions and particle self-factors on dust deposition weight are systematically studied here. The research results show that dust particles, after particle collision, immediately adhere to the mirror or rebound and finally flow away from the mirror, or they otherwise may remain stationary after making some relative motion. Alternatively, they may glide for some distance and finally come to rest on the mirror or leave from the system. Different motion behaviors after particle collision depend on different leading forces. Here, the leading forces are the liquid bridge force (Fc) and the contact force (Fb). When the leading forces are Fc, or Fc, and Fb, the dust particles will be deposited on the solar mirror. Besides, the force Fc cannot be negligible when studying the motion processes of dust particles. The dust deposition weight on solar mirrors can be controlled by altering the environmental and solar mirror conditions, and particle self-factors. In essence, dust deposition weight on solar mirrors decreases when decreasing the leading force Fc or increasing the leading force Fb. The research results give theoretical guidance for the prevention and removal of dust deposition on solar mirrors.

scholarly journals Synergistic removal of dust using the wet flue gas desulfurization systems

2019 ◽  
Vol 6 (7) ◽  
pp. 181696 ◽  
Author(s):  
Qirong Wu ◽  
Min Gu ◽  
Yungui Du ◽  
Hanxiao Zeng
Keyword(s):  
Removal Efficiency ◽  
Flue Gas ◽  
Power Plants ◽  
Flue Gas Desulfurization ◽  
Dust Removal ◽  
Dust Particles ◽  
Experimental Conditions ◽  
Collision Model ◽  
Sieve Tray ◽  
Spray Scrubber

Coal is still a major energy source, mostly used in power plants. However, the coal combustion emits harmful SO 2 and fly ash. Wet flue gas desulfurization (WFGD) technology is extensively used to control SO 2 emissions in power plants. However, only limited studies have investigated the synergistic dust removal by the WFGD system. Spray scrubbers and sieve-tray spray scrubbers are often used in WFGD systems to improve the SO 2 removal efficiency. In this study, the synergistic dust removal of WFGD systems for a spray scrubber and a sieve-tray spray scrubber was investigated using the experimental and modelling approaches, respectively. For the spray scrubber, the influence of parameters, including dust particle diameters and inlet concentrations of dust particles, and the flow rates of flue gas and slurry of limestone/gypsum on the dust removal efficiency, was investigated. For the sieve-tray spray scrubber, the influence of parameters such as the pore diameter and porosity of sieve trays on the dust removal efficiency was examined. The study found that the dust removal efficiency in the sieve-tray spray scrubber was approximately 1.1–10.6% higher than that of the spray scrubber for the same experimental conditions. Based on the parameters investigated and geometric parameters of a scrubber, a novel droplets swarm model for dust removal efficiency was developed from the single droplet model. The enhanced dust removal efficiency of sieve tray was expressed by introducing a strength coefficient to an inertial collision model. The dust removal efficiency model for the sieve-tray spray scrubber was developed by combining the droplets swarm model for the spray scrubber with the modified inertial collision model for the sieve tray. The results simulated using both models are consistent with the experimental data obtained.

Development and Evaluation of Prototype Transparent Electrodynamic Screen (EDS) Integrated Solar Collectors for Automated Dust Removal

2014 ◽  
Author(s):  
John N. Hudelson ◽  
Jeremy Stark ◽  
Hannah Gibson ◽  
Fang Hao ◽  
Zhongkai Xu ◽  
...  
Keyword(s):  
Specular Reflection ◽  
Short Circuit ◽  
Test Chamber ◽  
Short Circuit Current ◽  
Dust Particles ◽  
Laboratory Evaluation ◽  
Solar Collectors ◽  
Solar Panels ◽  
Dust Deposition ◽  
Self Cleaning

The integration of transparent electro-dynamic screen (EDS) on the front surface of solar mirrors and glass cover plates of photovoltaic panels has a strong potential to significantly reduce the frequency of water-based cleaning needed to mitigate losses from dust depositions present in arid regions. The objective of our research was to develop and evaluate prototype transparent EDS-integrated mirrors and solar panels for their self-cleaning functions, with an aim to keep the collectors clean at a low cost without water or manual labor. This paper focuses on the design, fabrication, and laboratory evaluation of a prototype EDS integrated second surface mirrors and solar panels. The EDS consists of a set of parallel transparent electrodes screen-printed on the optical surface and embedded in a thin transparent dielectric film. By applying three-phase, low current, low frequency high voltage-pulses to the electrodes, electro-dynamic repulsion forces and a traveling wave are created for removing dust particles from the surface of the collectors. Design and construction of an environmental test chamber to simulate different atmospheric conditions of semi-arid and arid areas with respect to temperature, RH, and dust deposition conditions are briefly described. A non-contact specular reflectometer was designed, constructed and calibrated for measuring specular reflection efficiency of the mirrors. Laboratory evaluation of the performance of the EDS-integrated collectors was completed using humidity controlled environment test chamber where the prototype mirrors and panels were examined for their self-cleaning action. In each experiment, the solar collectors were loaded with dust until the specular reflectance of the test mirror or the short circuit current of the panel showed a significant decrease. The EDS was then operated for one minute and the relative output was recorded. The results show that the specular reflectivity of EDS mirrors and the short circuit current of the EDS panels can be restored by more than 90% of the values measured under the clean conditions.

Development of Self-Cleaning Solar Collectors for Minimizing Energy Yield Loss Caused by Dust Deposition

2013 ◽  
Author(s):  
Malay Mazumder ◽  
Mark Horenstein ◽  
Jeremy Stark ◽  
Daniel Erickson ◽  
Arash Sayyah ◽  
...  
Keyword(s):  
Large Scale ◽  
Yield Loss ◽  
Research Effort ◽  
Large Fraction ◽  
Dust Removal ◽  
Energy Yield ◽  
Solar Collectors ◽  
Dust Deposition ◽  
Prototype Development ◽  
Self Cleaning

Concentrated Solar Power (CSP) systems used for photothermal conversion of solar energy to electricity are capable of meeting a large fraction of the global energy requirements. CSP plants are inherently robust with respect to the availability of materials, technology, and energy storage. However, dust depositions on solar collectors cause energy yield loss annually, ranging from 10 to 50% depending upon their location in the semi-arid and desert lands. Mitigation of energy loss requires manual cleaning of solar mirrors with water. A brief review of the soiling related losses in energy yield of the CSP plants is presented, which shows that cleaning of the CSP mirrors and receivers using water and detergent is an expensive and time-consuming process at best and is often impractical for large-scale installations where water is scarce. We report here our research effort in developing an electrodynamic dust removal technology that can be used for keeping the solar collectors clean continuously without requiring water and manual labor. Transparent electrodynamic screens (EDS), consisting of rows of transparent parallel electrodes embedded within a transparent dielectric film can be integrated on the front surface of the mirrors and on the receivers for dust removal for their application as self-cleaning solar collectors. When the electrodes are activated, over 90% of the deposited dust is removed. A summary of the current state of prototype development and evaluation of EDS integrated solar mirrors and experimental data on the removal of desert dust samples are presented. A brief analysis of cost-to-benefit ratio of EDS implementation for automated dust removal from large-scale solar collectors is included.

scholarly journals A Combined Approach for Model-Based PV Power Plant Failure Detection and Diagnostic

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1261
Author(s):  
Christopher Gradwohl ◽  
Vesna Dimitrievska ◽  
Federico Pittino ◽  
Wolfgang Muehleisen ◽  
András Montvay ◽  
...  
Keyword(s):  
Power Plants ◽  
Large Scale ◽  
Failure Detection ◽  
Energy Yield ◽  
Combined Approach ◽  
Levelized Cost Of Electricity ◽  
Term Operation ◽  
Model Based

Photovoltaic (PV) technology allows large-scale investments in a renewable power-generating system at a competitive levelized cost of electricity (LCOE) and with a low environmental impact. Large-scale PV installations operate in a highly competitive market environment where even small performance losses have a high impact on profit margins. Therefore, operation at maximum performance is the key for long-term profitability. This can be achieved by advanced performance monitoring and instant or gradual failure detection methodologies. We present in this paper a combined approach on model-based fault detection by means of physical and statistical models and failure diagnosis based on physics of failure. Both approaches contribute to optimized PV plant operation and maintenance based on typically available supervisory control and data acquisition (SCADA) data. The failure detection and diagnosis capabilities were demonstrated in a case study based on six years of SCADA data from a PV plant in Slovenia. In this case study, underperforming values of the inverters of the PV plant were reliably detected and possible root causes were identified. Our work has led us to conclude that the combined approach can contribute to an efficient and long-term operation of photovoltaic power plants with a maximum energy yield and can be applied to the monitoring of photovoltaic plants.

scholarly journals Quantification of PV Power and Economic Losses Due to Soiling in Qatar

2021 ◽  
Vol 13 (6) ◽  
pp. 3364
Author(s):  
Amr Zeedan ◽  
Abdulaziz Barakeh ◽  
Khaled Al-Fakhroo ◽  
Farid Touati ◽  
Antonio S. P. Gonzales
Keyword(s):  
Output Power ◽  
Power Plants ◽  
Economic Loss ◽  
Economic Losses ◽  
Energy Yield ◽  
Solar Pv ◽  
Financial Loss ◽  
Grid Systems ◽  
Dust Density

Soiling losses of photovoltaic (PV) panels due to dust lead to a significant decrease in solar energy yield and result in economic losses; this hence poses critical challenges to the viability of PV in smart grid systems. In this paper, these losses are quantified under Qatar’s harsh environment. This quantification is based on experimental data from long-term measurements of various climatic parameters and the output power of PV panels located in Qatar University’s Solar facility in Doha, Qatar, using a customized measurement and monitoring setup. A data processing algorithm was deliberately developed and applied, which aimed to correlate output power to ambient dust density in the vicinity of PV panels. It was found that, without cleaning, soiling reduced the output power by 43% after six months of exposure to an average ambient dust density of 0.7 mg/m3. The power and economic loss that would result from this power reduction for Qatar’s ongoing solar PV projects has also been estimated. For example, for the Al-Kharasaah project power plant, similar soiling loss would result in about a 10% power decrease after six months for typical ranges of dust density in Qatar’s environment; this, in turn, would result in an 11,000 QAR/h financial loss. This would pose a pressing need to mitigate soiling effects in PV power plants.

scholarly journals Dust Deposition on the Gulf of California Caused by Santa Ana Winds

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 275 ◽  
Author(s):  
Christian A. Álvarez ◽  
José N. Carbajal ◽  
Luis F. Pineda-Martínez ◽  
José Tuxpan ◽  
David E. Flores
Keyword(s):  
Gulf Of California ◽  
Dust Emission ◽  
Positive Influence ◽  
Dust Particles ◽  
Weather Research And Forecasting ◽  
Western Coast ◽  
Emission Rates ◽  
Dust Deposition ◽  
Santa Ana ◽  
Santa Ana Winds

Numerical simulations revealed a profound interaction between the severe dust storm of 2007 caused by Santa Ana winds and the Gulf of California. The weather research and forecasting model coupled with a chemistry module (WRF-CHEM) and the hybrid single-particle Lagrangian integrated trajectory model (HYSPLIT) allowed for the estimation of the meteorological and dynamic aspects of the event and the dust deposition on the surface waters of the Gulf of California caused by the erosion and entrainment of dust particles from the surrounding desert regions. The dust emission rates from three chosen areas (Altar desert, Sonora coast, and a region between these two zones) and their contribution to dust deposition over the Gulf of California were analyzed. The Altar Desert had the highest dust emission rates and the highest contribution to dust deposition over the Gulf of California, i.e., it has the most critical influence with 96,879 tons of emission and 43,539 tons of dust deposition in the gulf. An increase of chlorophyll-a concentrations is observed coinciding with areas of high dust deposition in the northern and western coast of the gulf. This kind of event could have a significant positive influence over the mineralization and productivity processes in the Gulf of California, despite the soil loss in the eroded regions.

scholarly journals Wet and dry deposition of mineral dust particles in Japan: factors related to temporal variation and spatial distribution

2013 ◽  
Vol 13 (8) ◽  
pp. 21801-21835
Author(s):  
K. Osada ◽  
S. Ura ◽  
M. Kagawa ◽  
M. Mikami ◽  
T. Y. Tanaka ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Wet Deposition ◽  
Mineral Dust ◽  
Temporal Variations ◽  
Dust Particles ◽  
Insoluble Residue ◽  
Spatial Distributions ◽  
Dust Deposition ◽  
Deposition Fluxes ◽  
Deposition Amount

Abstract. Data of temporal variations and spatial distributions of mineral dust deposition fluxes are very limited in terms of duration, location, and processes of deposition. To ascertain temporal variations and spatial distributions of mineral dust deposition by wet and dry processes, weekly deposition samples were obtained at Sapporo, Toyama, Nagoya, Tottori, Fukuoka, and Cape Hedo (Okinawa) in Japan during October 2008–December 2010 using automatic wet and dry separating samplers. Mineral dust weights in water-insoluble residue were estimated from Fe contents measured using an X-ray fluorescence analyzer. For wet deposition, highest and lowest annual dust fluxes were found at Toyama (9.6 g m−2 yr−1) and at Cape Hedo (1.7 g m−2 yr−1) as average values in 2009 and 2010. Higher wet deposition fluxes were observed at Toyama and Tottori, where frequent precipitation (>60% days per month) was observed during dusty seasons. For dry deposition among Toyama, Tottori, Fukuoka, and Cape Hedo, the highest and lowest annual dust fluxes were found respectively at Fukuoka (5.2 g m−2 yr−1) and at Cape Hedo (2.0 g m−2 yr−1) as average values in 2009 and 2010. Although the seasonal tendency of the monthly dry deposition amount roughly resembled that of monthly days of Kosa dust events, the monthly amount of dry deposition was not proportional to monthly days of the events. Comparison of dry deposition fluxes with vertical distribution of dust particles deduced from Lidar data and coarse particle concentrations suggested that the maximum dust layer height or thickness is an important factor for controlling the dry deposition amount after long-range transport of dust particles. Size distributions of refractory dust particles were obtained using four-stage filtration: >20, >10, >5, and >1 μm diameter. Weight fractions of the sum of >20 μm and 10–20 μm (giant fraction) were higher than 50% for most of the event samples. Irrespective of the deposition type, the giant dust fractions were decreasing generally with increasing distance from the source area, suggesting the selective depletion of larger giant particles during atmospheric transport. Because giant dust particles are an important mass fraction of dust accumulation, especially in the north Pacific where is known as a high-nutrient, low-chlorophyll (HNLC) region, the transport height of giant dust particles is an important factor for studying dust budgets in the atmosphere and their role in biogeochemical cycles.

scholarly journals Analysis of transmission characteristics of non-line-of-sight ultraviolet light under complex channel conditions

2021 ◽  
Vol 336 ◽  
pp. 01012
Author(s):  
Xuan Zheng ◽  
Yanfeng Tang ◽  
Jingyi Du
Keyword(s):  
Ultraviolet Light ◽  
Path Loss ◽  
Mie Scattering ◽  
Spherical Particles ◽  
Dust Particles ◽  
Line Of Sight ◽  
Communication Link ◽  
Communication Quality ◽  
Long Distance ◽  
Non Line Of Sight

Using the multiple scattering model of non-line-of-sight ultraviolet light to simulate and analyze the atmospheric channel characteristics in the complex environment of haze and dust. The Mie scattering theory and T matrix method are used to analyze the path loss of spherical particles and non-spherical particles with particle concentration at different communication distances. The results show that when the communication distance is less than 50 meters, the communication quality under severe haze is the best, and for long-distance communication, the path loss under severe haze increases almost proportionally. In the non-line-of-sight ultraviolet light communication link, the higher the concentration of dust particles, the better the communication quality of the non-line-of-sight ultraviolet light communication transmission. Analysis of the scattering coefficient of spherical particles is significantly greater than that of non-spherical particles.

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