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Research Papers

# Development and Evaluation of a Prototype Solid Particle Receiver: On-Sun Testing and Model Validation

[+] Author and Article Information
Nathan P. Siegel

Department of Solar Technologies, Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185-1127npsiege@sandia.gov

Clifford K. Ho, Siri S. Khalsa, Gregory J. Kolb

Department of Solar Technologies, Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185-1127

The receiver dimensions are not optimal from an optics point of view. They were selected to test particle drop heights more representative of a commercially sized cavity. An optimal cavity would have an aperture that is smaller and likely circular.

Ten TCs were installed in the back wall at 300 cm increments. Five were installed in the east and west walls at 1.2 m increments. Five TCs for air temperature measurement were installed above the aperture at 60 cm increments. Several more were installed near the top of the cavity extending from the east and west walls.

Mass flow rates are normalized to the length of the discharge slot in the hopper and reported in units of $kg/s m$. Since the slot is rectangular, this number gives an indication of the width of the opening at the discharge position.

The mass flow rates in this document are given per unit width of the curtain, which was 0.98 m in all cases.

J. Sol. Energy Eng 132(2), 021008 (May 06, 2010) (8 pages) doi:10.1115/1.4001146 History: Received November 23, 2009; Revised December 02, 2009; Published May 06, 2010; Online May 06, 2010

## Abstract

A prototype direct absorption central receiver, called the solid particle receiver (SPR), was built and evaluated on-sun at power levels up to $2.5 MWth$ at Sandia National Laboratories in Albuquerque, NM. The SPR consists of a 6 m tall cavity through which spherical sintered bauxite particles are dropped and directly heated with concentrated solar energy. In principle, the particles can be efficiently heated to a temperature in excess of $900°C$, well beyond the stability limit of existing nitrate salt formulations. The heated particles may then be stored in a way analogous to nitrate salt systems, enabling a dispatchable thermal input to power or fuel production cycles. The focus of this current effort was to provide an experimental basis for the validation of computational models that have been created to support improved designs and further development of the solid particle receiver. In this paper, we present information on the design and construction of the solid particle receiver and discuss the development of a computational fluid dynamics model of the prototype. We also present experimental data and model comparisons for on-sun testing of the receiver over a range of input power levels from $1.58–2.51 MWth$. Model validation is performed using a number of metrics including particle velocity, exit temperature, and receiver efficiency. In most cases, the difference between the model predictions and data is less than 10%.

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Copyright © 2010 by American Society of Mechanical EngineersThe United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States Government purposes.

## Figures

Figure 7

Single-pass particle-temperature increase

Figure 8

A comparison of simulated and experimentally measured particle-temperature increase

Figure 1

The SPR prototype cavity and particle-curtain path

Figure 2

Photo and drawing of the solid particle receiver tested at Sandia National Laboratories

Figure 6

Simulated wall incident radiation (left), particle tracks colored by temperature (middle), and gas flow colored by velocity (right)

Figure 9

Measured and simulated receiver efficiency. In general, increasing the particle flow rate improves the efficiency as the curtain is more opaque and intercepts a greater fraction of the incoming solar energy.

Figure 10

Simulated relative heat loss from convection and radiation for all nine tests

Figure 11

Simulated and measured vertical temperature distributions along the center of the back wall of the receiver for the test conducted on 2/22/08 (5.32 kg/s m, 2.39 MW)

Figure 12

The particle curtain as it passes through the cavity. In all cases, the velocity is between 8.5–10 m/s. Wind entering the cavity is disrupting the curtain in the case where the mass flow rate is 3.84 kg/s m.

Figure 3

Drawing of the model used in FLUENT

Figure 4

Simulated versus measured particle velocities for unheated test (24). The flow rate is 4.5 kg/s m.

Figure 5

Simulated versus measured particle volume fraction for an unheated test. The flow rate is 4.5 kg/s m.

## Errata

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