scholarly journals Improvement in the Flux Uniformity of the Solar Dish Concentrator System through a Concave Quartz Window

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Du-zhong Nie ◽  
You-duo Peng ◽  
Jian Yan ◽  
Cheng-ji Mi ◽  
Yong-xiang Liu ◽  
...  
Keyword(s):  
Cylindrical Cavity ◽  
Peak Concentration ◽  
Concentration Ratio ◽  
Optimal Parameter ◽  
High Strength ◽  
Hyperbolic Tangent ◽  
Focal Distance ◽  
Optical Efficiency ◽  
Quartz Window ◽  
Parabolic Dish

A nonuniform and high-strength heat flux load would reduce the working efficiency, safety, and in-service life of a cavity receiver. Four types of concave quartz windows, including conical, spherical, sinusoidal, and hyperbolic tangent, were proposed to be used in the cylindrical cavity receiver of a solar dish concentrator system, which can improve the flux uniformity and reduce the peak concentration ratio of the receiver. For each concave quartz window, 36 structural schemes were offered. Based on the Monte Carlo ray-tracing method, the results showed that the nonuniformity coefficient of the receiver was 0.68 and the peak concentration ratio was 1320.21 by using a plane quartz window. At the same time, when the receiver is in the best optical performance, it is the receiver with sinusoidal, conical, spherical, and hyperbolic tangent quartz windows, respectively. The optical efficiency of the receiver with the above four types of quartz windows was basically the same as that of the receiver with the plane quartz window, but their nonuniformity coefficients were reduced to 0.31, 0.35, 0.36, and 0.39, respectively, and the peak concentration ratio was reduced to 806.82, 841.31, 853.23, and 875.89, respectively. Obviously, the concave quartz window was better than the plane quartz window in improving the flux uniformity. Finally, a further study on the sinusoidal quartz window scheme of all of the above optimal parameter schemes showed that when the installation position of the receiver relative to the dish concentrator was changed, the flux uniformity of the receiver could continue to improve. When the surface absorptivity of the receiver was reduced, the optical efficiency would be reduced. For the parabolic dish concentrator with different focal distance, the concave quartz window can also improve the uniformity of the flux distribution of the cylindrical cavity receiver.

scholarly journals Design, simulation and optimization of a solar dish collector with spiral-coil thermal absorber

2016 ◽  
Vol 20 (4) ◽  
pp. 1387-1397 ◽  
Author(s):  
Sasa Pavlovic ◽  
Evangelos Bellos ◽  
Velimir Stefanovic ◽  
Christos Tzivanidis ◽  
Zoran Stamenkovic
Keyword(s):  
Heat Flux ◽  
Flow Simulation ◽  
Energetic Efficiency ◽  
Uniform Heat Flux ◽  
Inlet Temperature ◽  
Focal Distance ◽  
Optical Efficiency ◽  
Spiral Coil ◽  
Simulation And Optimization ◽  
Parabolic Dish

The efficient conversion of solar radiation into heat at high temperature levels requires the use of concentrating solar collectors. The goal of this paper is to present the optical and the thermal analysis of a parabolic dish concentrator with a spiral coil receiver. The parabolic dish reflector consists of 11 curvilinear trapezoidal reflective petals constructed by PMMA with silvered mirror layer and has a diameter of 3.8 m, while its focal distance is 2.26m. This collector is designed with commercial software SolidWorks and simulated, optically and thermally in its Flow Simulation Studio. The optical analysis proved that the ideal position of the absorber is at 2.1m from the reflector in order to maximize the optical efficiency and to create a relative uniform heat flux over the absorber. In thermal part of the analysis, the energetic efficiency was calculated approximately 65%, while the exergetic efficiency is varied from 4% to 15% according to the water inlet temperature. Moreover, other important parameters as the heat flux and temperature distribution over the absorber are presented. The pressure drop of the absorber coil is calculated at 0.07bar, an acceptable value.

Improved Concentration Capabilities of Flat-Plate Fresnel Lenses

2010 ◽  
Vol 74 ◽  
pp. 188-195 ◽  
Author(s):  
Maxim Z. Shvarts ◽  
Andrey A. Soluyanov
Keyword(s):  
Light Flux ◽  
Optical Power ◽  
Fresnel Lens ◽  
Calculation Model ◽  
Minimum Size ◽  
Size Analysis ◽  
Focal Distance ◽  
Optical Efficiency ◽  
Fresnel Lenses ◽  
Lens Formation

This paper presents an experience in designing, manufacturing and testing the Fresnel lenses (FLs) for sunlight concentration in photovoltaic modules with multi-junction solar cells (SCs). A power ray tracing model is used for calculating and optimizing refractive profile parameters and obtaining optical-power characteristics (OPCs) of Fresnel lenses. In searching the optimum combination of the lens aperture, its focal distance and profile configuration, the optimization criterion was the maximum of the average sunlight concentration at high optical efficiency in the focal spot of minimum size. Analysis of characteristics of circular Fresnel lenses with conical (the facet generating lines are straight ones) and curvilinear (the facet generating lines are curved ones) refracting surfaces has been carried out. The effect material parameters on the lens optical efficiency were studied. Molds for Fresnel lens formation and experimental specimens were fabricated and a control of their profile parameters has been done. A degree of the effect of the light flux characteristics and Fresnel lens geometrical imperfections on validity of the experimental data interpretation has been examined. The correction procedure have been applied in the calculation model to establish the lens optical efficiency values at standard irradiance conditions.

Optical Analysis of a Heliostat Array With Linked Tracking

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
M. T. Dunham ◽  
R. Kasetty ◽  
A. Mathur ◽  
W. Lipiński
Keyword(s):  
Concentration Ratio ◽  
Tracking System ◽  
Average Concentration ◽  
Solar Concentrator ◽  
Optical Performance ◽  
Optical Analysis ◽  
Optical Efficiency ◽  
The North ◽  
The Individual ◽  
East West

The optical performance of a novel solar concentrator consisting of a 400 spherical heliostat array and a linked two-axis tracking system is analyzed using the Monte Carlo ray-tracing technique. The optical efficiency and concentration ratio are compared for four different heliostat linkage configurations, including linkages of 1 × 1, 1 × 2, 2 × 2, 4 × 4, and 5 × 5 heliostats for 7-hour operation and the selected months of June and December. The optical performance of the concentrator decreases with the increasing number of heliostats in the individual groups due to increasing optical inaccuracies. In June, the best-performing linked configuration, in which 1 heliostat in the east-west direction and 2 heliostats in the north-south direction are linked, provides a monthly-averaged 7-hour optical efficiency and average concentration ratio of 79% and 511 suns, respectively. In December, the optical efficiency and the average concentration ratio decreases to 61% and 315 suns, respectively.

scholarly journals Ray Tracing Study of Optical Characteristics of the Solar Image in the Receiver for a Thermal Solar Parabolic Dish Collector

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Saša R. Pavlovic ◽  
Velimir P. Stefanovic
Keyword(s):  
Ray Tracing ◽  
Low Cost ◽  
Optical Design ◽  
Solar Concentrator ◽  
Solar Collectors ◽  
Focal Distance ◽  
Medium Temperature ◽  
Parabolic Dish ◽  
Parabolic Dish Concentrator ◽  
Temperature Levels

This study presents the geometric aspects of the focal image for a solar parabolic concentrator (SPC) using the ray tracing technique to establish parameters that allow the designation of the most suitable geometry for coupling the SPC to absorber-receiver. The efficient conversion of solar radiation into heat at these temperature levels requires a use of concentrating solar collectors. In this paper detailed optical design of the solar parabolic dish concentrator is presented. The system has diameter D=3800 mm and focal distance f=2260 mm. The parabolic dish of the solar system consists of 11 curvilinear trapezoidal reflective petals. For the construction of the solar collectors, mild steel-sheet and square pipe were used as the shell support for the reflecting surfaces. This paper presents optical simulations of the parabolic solar concentrator unit using the ray tracing software TracePro. The total flux on the receiver and the distribution of irradiance for absorbing flux on center and periphery receiver are given. The goal of this paper is to present the optical design of a low-tech solar concentrator that can be used as a potentially low cost tool for laboratory scale research on the medium-temperature thermal processes, cooling, industrial processes, polygeneration systems, and so forth.

Design, Evaluation, and Testing of a Moderately Concentrating, Nontracking Solar Energy Collector

1981 ◽  
Vol 103 (1) ◽  
pp. 34-41 ◽  
Author(s):  
A. Olvera ◽  
R. B. Bannerot
Keyword(s):  
Solar Energy ◽  
Heat Loss ◽  
Thermal Performance ◽  
Heat Recovery ◽  
Concentration Ratio ◽  
Side Wall ◽  
Recovery Factor ◽  
Design Evaluation ◽  
Optical Efficiency ◽  
Overall Heat Loss Coefficient

The thermal performance of a moderately concentrating, nontracking, trough-like solar energy collector is predicted based on a series of experimental evaluations of its components. Four reflector designs were constructed and tested. Two were one-facet side wall (reflector) designs; two were two-facet designs. Six simple tubular, nonevacuated receiver designs were tested. A collector utilizing one of the reflector designs, geometric concentration ratio of 2.6, and one of the receiver designs was constructed and tested. The predicted performance (an effective overall heat loss coefficient of 4.6 W/m2–°C, an optical efficiency of 0.71 and a heat recovery factor of 0.95) closely approximated the actual thermal performance of the collector. The component evaluations are discussed in such detail that the analysis could easily be extended to other designs by the reader.

Energy and Exergy Analysis of Solar Parabolic Dish Thermoelectric Generator

2014 ◽  
Vol 592-594 ◽  
pp. 2437-2441 ◽  
Author(s):  
Gunalan Muthu ◽  
Subramaniam Shanmugam ◽  
Arunachalam R. Veerappan
Keyword(s):  
Energy Efficiency ◽  
Concentration Ratio ◽  
Thermoelectric Generator ◽  
Exergy Analysis ◽  
Exergy Loss ◽  
Thermal System ◽  
Increase With Increase ◽  
Energy And Exergy ◽  
Parabolic Dish ◽  
Energy And Exergy Analysis

The Performance of a thermal system is generally analysed by carrying out energy and exergy analysis of its different subsystems. In the present study the performance of subsystem namely PDC, receiver plate and PDC in a system of solar parabolic dish thermoelectric generator is studied. It is found that the energy and exergy loss are minimum in the receiver plate as compared to PDC and thermoelectric generator (TEG) at a particular direct normal irradiation (DNI). The exergy and energy efficiency in the PDC and TEG increase with increase in concentration ratio.

A Novel Lens-Walled Compound Parabolic Concentrator for Photovoltaic Applications

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Yuehong Su ◽  
Gang Pei ◽  
Saffa B. Riffat ◽  
Hulin Huang
Keyword(s):  
Concentration Ratio ◽  
Incidence Angle ◽  
Small Degree ◽  
Photovoltaic System ◽  
Acceptance Angle ◽  
Optical Efficiency ◽  
Concentrate Solar Radiation ◽  
Compound Parabolic Concentrator ◽  
Photovoltaic Applications ◽  
The Common

A compound parabolic concentrator (CPC) is a nonimaging concentrator that can concentrate solar radiation coming within its acceptance angle. A low concentration CPC photovoltaic system has the advantages of reduced Photovoltaics (PVs) cell size, increased efficiency and stationary operation. The acceptance angle of a CPC is associated with its geometrical concentration ratio, by which the size of PV cell could be reduced. Truncation is a way to increase the actual acceptance angle of a mirror CPC, but it also reduces the geometrical concentration ratio. On the other hand, a solid dielectric CPC can have a much larger acceptance angle, but it has a larger weight. To overcome these drawbacks, this study presents a novel lens-walled CPC that has a thin lens attached to the inside of a common mirror CPC or has the lens to be mirror coated on its outside surface. The shape of the lens is formed by rotating the parabolic curves of a CPC by a small degree internally around the top end points of the curves. The refraction of the lens allows the lens-walled CPC to concentrate light from wider incidence angle. The commercial optical analysis software PHOTOPIA is used to verify the principle of the presented lens-walled CPC and examine its optical performance against the common CPCs. As an example, the simulation is aimed to evaluate whether a lens-walled CPC with a geometrical concentration ratio of 4 has any advantage over a common CPC with a geometrical concentration ratio of 2.5 in terms of actual acceptance angle, optical efficiency and optical concentration ratio.

scholarly journals Optical Design of a Novel Two-Stage Dish Applied to Thermochemical Water/CO2 Splitting with the Concept of Rotary Secondary Mirror

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3553
Author(s):  
Song Yang ◽  
Jun Wang ◽  
Peter D. Lund
Keyword(s):  
Mathematical Model ◽  
Ray Tracing ◽  
Concentration Ratio ◽  
Thermal Water ◽  
Optical Design ◽  
Two Stage ◽  
Optical Efficiency ◽  
Primary Mirror ◽  
Secondary Mirror ◽  
Ray Tracing Simulation

In this paper, a novel two-stage dish concentrator (TSD) with a rotary secondary mirror (SM) is presented for solar thermal water/CO2 splitting. An in-house code for ray-tracing simulation of the concentrator was developed and validated. Among all feasible geometries, a hyperboloid with an upper sheet is the most popular option and is widely used as a secondary reflector, which is mainly discussed here. All para-hyperboloid geometric combinations can be categorized into three typical patterns (φ1 < π/2, φ1 = π/2, φ1 > π/2, φ1 = field angle of PM). The initial designs of the TSD, respective to different off-axis levels for each combination, were first designed. Then a new mathematical model was introduced to reshape the SM to reach optimal truncated designs. Finally, a new concept of an off-axis primary mirror (PM) combined with the truncated SM was evaluated by using the in-house ray-tracing code. The results include the optical efficiency, concentration ratio and intercepted radiant flux. The best solutions with the highest optical efficiency fall in the range π/2 ≤ φ1 ≤ (π − arcsin 0.8) rads and 0.4 ≤ NA2 ≤ 0.6 (NA2 = sin φ2, φ2 = field angle of SM), which vary with the concentration ratio and inclination angle.

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