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Research Papers

Design of a New $45 kWe$ High-Flux Solar Simulator for High-Temperature Solar Thermal and Thermochemical Research

[+] Author and Article Information
K. R. Krueger, J. H. Davidson

Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455lipinski@umn.edu

W. Lipiński1

Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455lipinski@umn.edu

In the following text, a circular disk target of diameter $dtarget$ in the focal plane and coaxial with the simulator axis will be referred to as the target.

We use the standard deviation $σf$ to quantitatively estimate the degree of flux nonuniformity; however, this quantity should not be interpreted as the standard deviation of a Gaussian distribution due to anticipated differences between the actual flux distribution and a Gaussian distribution.

1

Corresponding author.

J. Sol. Energy Eng 133(1), 011013 (Feb 03, 2011) (8 pages) doi:10.1115/1.4003298 History: Received August 02, 2010; Revised December 13, 2010; Published February 03, 2011; Online February 03, 2011

Abstract

In this paper, we present a systematic procedure to design a solar simulator for high-temperature concentrated solar thermal and thermochemical research. The $45 kWe$ simulator consists of seven identical radiation units of common focus, each comprised of a $6.5 kWe$ xenon arc lamp close-coupled to a precision reflector in the shape of a truncated ellipsoid. The size and shape of each reflector is optimized by a Monte Carlo ray tracing analysis to achieve multiple design objectives, including high transfer efficiency of radiation from the lamps to the common focal plane and desired flux distribution. Based on the numerical results, the final optimized design will deliver 7.5 kW over a 6 cm diameter circular disk located in the focal plane, with a peak flux approaching $3.7 MW/m2$.

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Figures

Figure 1

Schematic of the array of lamp-reflector modules: (a) front view showing the seven lamp/reflector assemblies and (b) center cross section depicting the relationship to a prototype receiver/reactor

Figure 2

Spectral distributions of the xenon arc lamp chosen for this application (solid line) (20) and air mass 1.5 (dashed line) (9)

Figure 3

Schematic of the inner surface of a single reflector (bold outline) with respect to a full ellipse (thin outline)

Figure 4

Analytical relationships among ϕrim, ψ2, l3, and d with l1=1.45 m. The shaded areas indicate values that satisfy the design requirements.

Figure 5

Analytical relationships among ϕrim, ψ2, l3, and l1 with d=0.75 m. The shaded areas indicate values that satisfy the design requirements.

Figure 6

The specular error is defined as the standard deviation σs of a distribution of the cone angle θs measured from the normal of a perfectly smooth reflector surface to the normal of a real reflector surface

Figure 7

Transfer efficiency and flux standard deviation on (a) 6 cm and (b) 10 cm diameter targets. The solid lines correspond to transfer efficiency η and the dashed lines correspond to flux standard deviation σf.

Figure 8

Flux maps for the geometry listed in Tables  12 with eccentricity e=0.890 and varying values of specular error: (a) σs=0 mrad, (b) σs=5 mrad, and (c) σs=10 mrad, and with specular error σs=5 mrad and varying values of eccentricity: (d) e=0.850, (e) e=0.900, and (f) e=0.925. The inner circle is 6 cm in diameter and the outer circle is 10 cm in diameter. Note that the scale differs for each plot.

Figure 9

Variation of transfer efficiency η with reflector specular error σs and target radius rtarget for the geometry listed in Tables  23

Figure 10

Variation of transfer efficiency η (solid line) and flux standard deviation σf (dashed line) with target radius for the final geometry (Tables  23) and σs=5 mrad and 108 rays per lamp

Figure 11

Cumulative average flux (solid line) and power (dashed line) as a function of the target radius for the geometry described in Tables  23 with σs=5 mrad

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