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Thesis Information
Title: Carbon/carbon Composites for Next Generation Microvascular Solar Thermal Receivers
Program: Master of Science in Mechanical Engineering
Advisor: Dr. Todd Otanicar, Mechanical and Biomedical Engineering
Committee Members: Dr. Mahmood Mamivand, Mechanical and Biomedical Engineering, Dr. Krishna Pakala, Mechanical and Biomedical Engineering, and Dr. Marta Laporte-Azcue, Mechanical and Biomedical Engineering
Abstract
Concentrating solar power 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 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.
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. Then, these plates are numbered up to create a full-scale receiver based on a design point from Gemasolar’s flux profile.
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. 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.