Graduation Year

2022

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Chemical Engineering

Major Professor

D. Yogi Goswami, Ph.D.

Committee Member

Antonio Bula, Ph.D.

Committee Member

Babu Joseph, Ph.D.

Committee Member

John Kuhn, Ph.D.

Committee Member

Elias Stefanakos, Ph.D.

Keywords

Brayton cycles, cascaded system, central receivers, concentrated solar power, supercritical carbon dioxide

Abstract

This dissertation presents an investigation of the specification and operation of multiple central solar receivers (CSR) sharing a heliostat field and an analysis of the receiver's thermal performance. A heliostat field was modeled in which different parts of the field aimed at different external or cavity receivers located on the same tower. Optical and thermal performance are analyzed, including the receivers' heat flux, solar thermal efficiency, and annual energy output. Some of the contributions of this research are:

1. Propose a novel configuration for a CSP power generation system using two receivers in a single central tower suitable for Brayton cycles. Including the analysis of three cases:

1.1. External receivers, working with different heat transfer fluids in a cascaded configuration suitable for hybrid sCO2 Brayton cycles.

1.2. External receivers in a cascaded configuration that can operate independently suitable for recompression Brayton Cycles

1.3. Cavity receivers in a cascaded configuration that can operate independently suitable for recompression Brayton Cycles

2. Propose a method to assist the operation and adaptation of two external or cavity receivers in a central tower power generation system under varying irradiance conditions.

The study compared a cascading external receiver system with a single external receiver providing the same total thermal power (120 MWth) and a cascading cavity receiver system with its equivalent single cavity receiver (75 MWth). We found that the solar field optical efficiency is lower for the cascading configuration as compared to an equivalent single receiver. The factor that contributes the most to the reduction is the interception factor (spillage losses). However, once the operational strategy is used, cascading arrangements have higher solar to thermal efficiency than their equivalent single receiver configurations when the DNI is lower than 800 W/m2.

Finally, the box and wisher plots analysis of the incident heat flux shows a more uniform distribution for the external cascading configuration with lower and maximum heat flux. Therefore, the results presented in this dissertation demonstrate the potential of using more than one receiver on top of the same tower sharing a common solar field.

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