Solar Parabolic Dish Concentrator Research Articles

Design and Analysis of a Novel Hybrid Solar/Gas Dish Stirling System (HS/GDSS)

In this paper, a 20kW design capacity solar parabolic dish concentrator hybrid solar/gas dish Stirling system (HS/GDSS) is proposed. To ensure a steady operation of an electricity power plant, HS/GDSS uses gas as complement when solar radiation is weak. Thermodynamic models were made to conduct design of system parameters. After detail characteristics were chosen, analysis was carried out to evaluate this system. The results show that within design condition, overall efficiency of the system is 27.58% at daytime and 33.94% at night, which has advantages over single-energy solar dish Stirling electricity power plant.

Optical analysis and optimization of parabolic dish solar concentrator with a cavity receiver

This paper presents an analytical function to predict the performance of a paraboloidal dish solar concentrator with a cavity or flat receiver. The optical efficiency of this system is obtained through the integration of the local optical efficiency of each reflecting point in the whole reflecting area. The effect of directional characteristics of concentrated energy on the focal plane is also considered by the angular dependent model. With Gaussian and polynomial model of effective brightness distribution, the system efficiency can be calculated quickly and precisely. The size of receiver and rim angle of dish are optimized to maximize the annual net thermal energy which is collected at different optical errors, and heat loss coefficients. The results show that it will give better prediction to the performance of the paraboloidal dish with a windowed-cavity receiver or flat receiver, and the optimal rim angle will decrease when the effects of the incidence angle are considered in the model. If the optical error is less than 4mrad, a non-window cavity receiver is preferred and the optimal geometric concentration ratio will be over 3000; if the optical error is large than 4mrad, a windowed-cavity receiver is preferred, with an optimal geometric concentration of less than 1200.

Mathematical model for the study and design of a solar dish collector with cavity receiver for its application in Stirling engines

This paper presents a mathematical model that allows representing the optical behavior of a solar parabolic dish concentrator and the thermal performance of a cavity receiver. A procedure and a graphical method for the design of dish/cavity systems are proposed. A parametric study of the main geometric variables is performed and the influence of climate variables on the thermal behavior of the system coupled to a Stirling engine is analyzed. The model considers errors of solar collector, intercept factor, reflected and emitted radiation, conduction, and convection heat losses. For the validation of the model, the results obtained were compared with theoretical and experimental results reported in the literature. The calculation of the radiation losses, emitted and reflected from the receiver presented errors of up to 14%, and the average error for the rest of the thermal losses, interception factor and the absorber’s temperature, was less than 3%. These results show that the proposed model can be used with sufficient certainty to design and optimize solar dish collectors with cavity receivers.

Year round performance and economic evaluation of solar power plant for Indian tropical condition

In this paper, a 50 MWe design capacity solar parabolic dish concentrator Stirling engine power plant (SPDCSPP) has been modeled for analysis, where 2000 units of 25 kWe parabolic dish concentrator each considered for getting desired capacity. An attempt has been made to carryout the economic evaluation of SPDCSPP for selected Indian tropical condition. Variations of the efficiency of Stirling engine power plant at the variation of the load conditions are considered for year round performance evaluation. The developed model is examined for Indian location, i.e., Delhi. It is found that year round collector-receiver efficiency varies from 69.43% to 77.88%, and overall power plant efficiency varies from 16.86% and 25.79%. The installation cost per MWe electrical capacity is 15.32 crore rupees, and 28.10 lakhs rupees as operation and maintenance cost per MWe electrical capacity. The unit cost of electric energy generation (kWhe) is about 11.06 Indian rupees, with 30 years lifespan of the plant and 10% interest rate on investment.

A solar dish concentrator based on ellipsoidal polyester membrane facets

The design of a solar parabolic dish concentrator is proposed based on an array of polyester mirror membrane facets that are clamped along their edges by elliptical rims and focused by applying a slight vacuum underneath the membranes, creating an ellipsoidal shape. The axes ratio of the elliptical rims varies with the position on the dish to approach the paraboloidal shape. The elastic mirror membrane deformation under uniform pressure load is simulated by finite element structural analysis and the resulting radiative flux distribution at the focal plane of the dish is determined by the Monte Carlo ray-tracing technique. Optimization of the membrane deflection is accomplished for maximum solar flux concentration at the focal plane. Two dish geometries are examined: (i) a 1.5-m radius 3-m focal length small dish, comprising 19 facets of 0.275-m radius with four different curvatures, yielding a peak solar concentration ratio of 5515 suns and a mean solar concentration ratio of 1435 suns with an intercept factor of 90% over a 3-cm radius disk target and (ii) a 10.9-m radius 11-m focal length large dish, comprising 121 facets of 0.9-m radius with 15 different curvatures, yielding a peak solar concentration ratio of 23,546 suns and mean solar concentration ratio of 8199 suns with an intercept factor of 90% over a 10.4-cm radius disk target. The performance of the second geometry is compared to that of the more conventional design of a multi-facet dish concentrator consisting of identical circular facets and shown to reach - on the same target area - a 12% higher mean solar concentration ratio as well as a 6.6% higher intercept factor. The simulated membrane shape is experimentally verified with photogrammetrical measurements carried out on a prototype facet of the small dish.

Thermodynamic analysis of solar parabolic dish thermoelectric generator

This paper presents thermodynamic analysis of solar parabolic dish thermoelectric generator (TEG) using energy and exergy efficiencies to a given set of operating parameters. The system contains solar parabolic dish concentrator (PDC) and TEG on its focal point, the analytical expression for energy and exergy efficiency equation is used for each component to evaluate its thermodynamic performance. It is found in TEG that the maximum energy loss is 95.80% and exergy loss is 89.28% when compared to PDC wherein the energy loss is 27.09% and exergy loss is 69.87%. The overall solar TEG energy efficiency and exergy efficiency obtained are 2.81% and 2.97% respectively.

Analysis and Design of Two Stretched-Membrane Parabolic Dish Concentrators

The state-of-the-art of parabolic dish solar concentrators is the faceted, glass-metal dish. The mass production costs of glass-metal dishes may be high because they do not incorporate the innovations of design and materials developed over the last eight years. Therefore, Sandia National Laboratories has undertaken to develop two stretched-membrane parabolic dish concentrators for the Department of Energy’s Solar Thermal Program. These solar concentrators are being designed for integration with an advanced solar receiver and a Stirling engine/generator in a 25-kWe power production unit. The first dish, which builds on the successful design of the stretched-membrane heliostats, is to be a low risk, near-term commercial solar concentrator. This solar concentrator comprises 12 large, 3.6-m diameter, stretched-membrane facets that are formed into parabolic shapes either with a large vacuum or by performing the thin membranes plastically. The focal length-to-diameter ratios (f/Ds) for the facets are about 3.0, relatively large for a dish but much lower than heliostats where they typically range from 50 to 100. Two contractors are currently fabricating facets for this dish, and a third contractor is designing the facet support structure and pedestal for the dish. The second stretched-membrane concentrator is a single-element monolithic dish with an f/D of 0.6. The dish is shaped into a parabola by plastically yielding the membrane using a combination of uniform and nonuniform loading. Initial measurements of the dish indicate that it has a slope error of 2.6 milliradians (one standard deviation) relative to a perfect parabola. In this paper, the designs of the two stretched-membrane dishes are analyzed using the computer code CIRCE to model the optical performance of the concentrators and a thermal model, which includes conduction, convection, and radiation heat transfer, to calculate the thermal losses from the cavity solar receivers. The solar collector efficiency, defined as the product of the optical efficiency of the collector and the thermal efficiency of the receiver, is optimized for comparing the performance of several solar concentrator configurations. Ten facet arrangements for the faceted stretched-membrane dish and the single-element stretched-membrane dish are modeled and their performances compared with that of a state-of-the-art glass-metal dish. Last, the initial designs of these two stretched-membrane dishes are described along with the results of preliminary performance measurements on their respective optical elements.