Award Date

1-1-2008

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Committee Member

Yitung Chen

Number of Pages

84

Abstract

This thesis develops and analyzes a three-dimensional computational model of a solid particle solar receiver (SPSR) for providing the heat source in a hydrogen production process using the sulfur iodine thermochemical water splitting reaction. In this reaction, a heat input of at least 850°C is necessary to keep high hydrogen production efficiency. Previous studies to achieve higher efficiency on a SPSR include changing particle materials, sizes, flow rates, and the geometry designs. The present study is concerned with the use of an air-jet in front of the open aperture and different operation conditions for the SPSR design optimization; The conceptual design of the SPSR is provided by Sandia National Laboratories (SNL). There is an open aperture in front of the receiver cavity, and heat will leak to outside without any protection. Different research topics have suggested that an air-jet consisting of a transparent gas stream injected across the receiver aperture is a good method for isolating the interior from the surroundings. The main purpose of this research is to use numerical analysis to study the SPSR with the influence of an air-jet. A two-way coupled Euler-Lagrange method is applied which includes the continuity, heat, momentum exchanges between the solid and gas two-phase flows. A two-band discrete ordinate solar ray tracing model is used for the radiation interactions and heat transfer within the particle clouds, and between the cloud and the internal surface of the receiver. Different air-jet velocities are compared to evaluate the thermal performance of the receiver. Parametric studies also include varying particle size, mass flow rate, solar flux, and air-jet temperature to determine the optimal operating conditions. The temperature and velocity profiles inside the cavity are also analyzed. In all the parametric studies and thermal analysis, the SPSR with a downward air-jet velocity of 8 m/s, air-jet temperature of 300 K, and particle diameter in the range of 70-80 micron provides the best performance in the presence of a radiant flux of 920 suns. This cavity efficiency is 85%, and average exit particle temperature is 1199 K.

Keywords

Air; Analysis; Influence; Jet; Numerical; Particle; Receiver; Solar; Solid

Controlled Subject

Mechanical engineering

File Format

pdf

File Size

2140.16 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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