Publication Date

8-2023

Date of Final Oral Examination (Defense)

5-5-2023

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Mechanical Engineering

Department

Mechanical and Biomechanical Engineering

Supervisory Committee Chair

Todd Otanicar, Ph.D.

Supervisory Committee Member

Krishna Pakala, Ph.D.

Supervisory Committee Member

Mahmood Mamivand, Ph.D.

Supervisory Committee Member

Marta Laporte-Azcué, Ph.D.

Abstract

Concentrating solar power (CSP) is a method of renewable solar power generation where the sun’s radiant energy is collected by a receiver and converted into thermal energy. This thermal energy is then passed into a heat transfer fluid and either sent to thermal storage, or a steam power plant. One path to better CSP systems is improving the operational envelope of the receiver and heat transfer fluid (HTF) system by utilizing more resilient absorbing materials, different path architectures, and HTFs with higher allowable temperatures.

A new carbon/carbon composite is being developed with the potential to function as the absorbing material for a solar thermal receiver. This composite is capable of functioning at higher temperatures than current metallic receivers and could reduce the cost of the supporting structure due to its low density. This composite is readily coupled with microvascular (D < 1mm) channel structures by constructing channels with PLA and melting the plastic out at a later stage. The smaller channel diameters allow for HTF pairings that previously required excessive wall thickness such as supercritical CO2 (sCO2).

A series of computational fluid dynamics simulations have been conducted to first understand the operational limits of a single (20mm x 20mm) microscale receiver plate capable of thermal efficiency above 90%. Then, these plates are numbered up to create a full-scale receiver based on a design point from Gemasolar’s flux profile with an estimated 85.04% thermal efficiency.

The carbon/carbon composite has been characterized for its thermal, optical, and aging properties. Thermal conductivity has been measured for the composite made with both PAN-based and pitch-based fibers where the pitch-based fibers had through plane thermal conductivity 478% higher than that of the PAN-based fibers. Then, the composite underwent an accelerated aging process via cyclic aging in a high flux solar simulator and isothermal aging in a tube furnace. The optical properties were characterized for the carbon/carbon composite throughout the aging processes.

DOI

https://doi.org/10.18122/td.2142.boisestate

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