A general method to analyze the thermal performance of multi-cavity concentrating solar power receivers

Abstract

Concentrating solar power (CSP) with thermal energy storage has potential to provide grid-scale, on-10 demand, dispatachable renewable energy. As higher solar receiver output temperatures are necessary for 11 higher thermal cycle efficiency, current CSP research is focused on high outlet temperature and high 12 efficiency receivers. The objective of this study is to provide a simplified model to analyze the thermal 13 efficiency of multi-cavity concentrating solar power receivers. The model calculates an optimal aperture 14 flux that maximizes the local efficiency, constrained by a maximum receiver working temperature. Using 15 this flux, the thermal efficiency, receiver temperature, and heat transfer fluid (HTF) temperature are 16 calculated based upon an optimized flux distribution. The model also provides receiver design and HTF 17 heat transfer requirements to achieve the necessary overall thermal efficiency. From the results, possible 18 HTFs can be investigated to determine which ones are feasible. A case study was performed on a multi-19 cavity tube receiver design to demonstrate the use of the model. The case study receiver design had an 20 effective absorptivity of 99.8%, and was modeled with conservative values for thermal constraints. It was 21 found that a HTF with a minimum convection coefficient between 250-500 W•m-2 •K-1 , depending on the 22 convective heat transfer to the environment, is necessary to achieve a thermal efficiency greater than 90% 23 for the receiver. The general model can provide a design guideline for attainable thermal efficiencies of 24 multi-cavity concentrating solar power receivers given thermal constraints and heat transfer conditions. 25

The effect of receiver geometry on the optical performance of a small-scale solar cavity receiver for parabolic dish applications

“…Recently, many studies have been conducted on solar tower systems [5][6][7], Stirling engines [8,9], Fresnel lenses [10][11][12] and solar Brayton cycle enhancement [13][14][15]. Furthermore, several studies on the heat losses and the receivers' geometries, dimensions and positions are found in [16][17][18][19][20][21][22][23]. For instance, the combined convection and radiation of a modified hemispherical cavity receiver with fins used with solar parabolic dish was numerically analysed by Ngo et al [16].…”

“…Moreover, for the same given total heat input, the region closer to the cavity aperture experienced larger view factors and as a result, larger radiation loss. The thermal performance of multi-cavity concentration was analysed by Austin et al [19]. Intensive studies on the thermal analysis of cavity receivers for parabolic dish application were achieved by Reddy and Kumar [20][21][22][23].…”

The optical efficiency of three different geometries of a small scale cavity receiver for concentrated solar applications

“…Also, deviation between theoretical and the experimental results ranged between 2.5 % to 8%. A model of multi-cavity receiver for high concentrated flux was analysed by Fleming et al [29]. The study was carried out on a simple model designed with all the necessary parameters for analysing its thermal efficiency by applying an optimal value and distribution of flux.…”

Near-Blackbody Enclosed Particle-Receiver Development

“…As reported in the RPPR2, in the SunShot Particle Receiver Project, NREL and its partners published or submitted 13 papers, including papers listed in references [12][13][14][16][17][18]. NREL filed three U.S. patents that cover the particle-TES design and construction, heat exchanger configuration for steam, s-CO2, and air-Brayton power DE-EE0001586 Near-Blackbody Enclosed Particle Receiver NREL, Zhiwen Ma, PI provides utility-scale electricity storage capacity and could greatly improve the reliability and grid stability of renewable power generation.…”