Graduation Year

2025

Document Type

Thesis

Degree

M.S.C.H.

Degree Name

MS in Chemical Engineering (M.S.C.H.)

Degree Granting Department

Chemical, Biological and Materials Engineering

Major Professor

D. Yogi Goswami, Ph.D.

Committee Member

Venkat Bhethanabotla, Ph.D.

Committee Member

Marimuthu Andiappan, Ph.D.

Keywords

CoPylot, Incidence Angle,, Absorptance, Tilt, Selective Solar Coating

Abstract

Central receiver concentrating solar power (CSP) towers offer significant potential for cost-effective renewable electricity but face increasing optical losses with larger heliostat fields. This thesis introduces enhancements to NREL’s SolarPILOT software through a Python-based API named CoPylot, which enables comprehensive optimization of heliostat field layouts for multi-receiver systems. The enhanced methodology incorporates per-heliostat ray tracing, receiver orientation optimization (tilt angle β), and an incidence-angle-dependent absorptance (α(θ)) model to evaluate optical performance, thermal losses, and techno-economic metrics within an integrated simulation framework.

A case study for Daggett, California demonstrates that transitioning from a baseline single-receiver system (180 m tower, 5×5 m heliostats) with 112 MW absorbed power at 75.2% combined efficiency to a dual-height receiver configuration increases absorbed power to 256 MW, despite absorptance degradation (α < 0.6) at high incidence angles on the upper receiver.

Additionally, this research critically reviews state-of-the-art solar selective absorber coatings suitable for high-temperature CSP applications. Advanced sputtered cermet and nitride multilayer coatings already achieve excellent optical performance (α ≥ 0.94, ε ≤ 0.10) and robust durability at temperatures above 600 °C. Emerging high-entropy ceramic materials offer further improvements, promising prolonged service lifetimes and economic viability. Integrating these advanced coatings with angle-optimized layouts and adaptive receiver tilting presents a clear pathway toward achieving utility-scale CSP installations with significantly reduced levelized electricity costs.

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