Session: 30-05 Heat Exchangers

Paper Number: 152472

Techno-Economic Analysis of Gen3 Concentrated Solar Power With a Topology-Optimized Silicon Carbide Heat Exchanger 

Solid particles have been recognized as a promising thermal carrier and energy storage medium in the third generation of Concentrated Solar Power (CSP) for meeting cost targets established by the Department of Energy (DOE). However, heat transfer between particles and a working fluid is challenging due to the low thermal conductivity and heat transfer coefficient of moving particles. Therefore, the performance and cost of the primary heat exchanger is important to the overall economic viability of a CSP plant. The relationship between the cost and optimal sizing of the primary heat exchanger and its effect on the optimal design of other system components is not well understood. This research is concerned with understanding the relationship between the cost realized by an advanced, topology-optimized (TO) primary heat exchanger (PHX) on the optimal design and cost of the overall CSP system, including thermal energy storage and power block components. To meet aggressive DOE cost targets for CSP, the system must be optimized to minimize the energy-specific cost based on the expected performance of the TO-based PHX.

This research also explores the tradeoff between system performance and the levelized cost of energy. Previous research has suggested that CSP has the potential to reach levelized costs of energy as low as 0.056 $/kWh. These studies have typically approached optimization through parametric analyses or by maximizing power block thermal efficiency subject to constraints on the system, rather than a comprehensive optimization of the system.

The present work outlines a system-level optimization model using a modified version of NREL’s System Advisor Model. The system-level model contains computationally efficient sizing algorithms for the solar field, power tower, and falling-particle receiver, and dedicated sub-models to estimate the costs of the most significant system components. Using a nonlinear optimization routine, the model simultaneously optimizes a supercritical CO2 recompression cycle and optical components of the system. The system-level model is used to identify the optimal power block design, receiver temperature, and thermal energy storage capacity, given a cost per unit of conductance that characterizes the TO-based PHX technology subject to a specific power block nameplate capacity.

Preliminary findings suggest that a 17% decrease in the cost per unit of conductance in the primary heat exchanger will result in a 1 $/MWh decrease in the levelized cost of energy, and that the power block has a cost-optimal thermal efficiency of around 48%. The optimization methods presented in this research have also identified gains in the tradeoff between cost and performance, further reducing the levelized cost of energy. Performance of the primary heat exchanger - including cost per conductance, operating temperature, and lifetime - can be a strong indicator of where capital should be allocated in a CSP system. Such an indicator is helpful for the future design and techno-economic analysis of these systems. This is a promising step toward meeting DOE cost targets for CSP.

Presenting Author: Kaleb Troyer University of Wisconsin-Madison

Presenting Author Biography: Kaleb Troyer is a Mechanical Engineering graduate student in the Energy Systems Optimization Lab at the University of Wisconsin-Madison. His work focuses on design optimization and technoeconomic analysis for a concentrating solar power application involving particle-based heat exchange. Prior to joining UW-Madison, Kaleb was a Mechanical Design Engineer at Building Automation Products, Inc. He holds a Bachelors in Mechanical Engineering from Iowa State University.

Authors:

Kaleb Troyer University of Wisconsin-Madison
Michael Wagner University of Wisconsin-Madison