Session: 05-03: Concentrating Solar Power I: Receiver Applications

Paper Number: 138191

138191 - Development of a Light-Trapping, Planar-Cavity Receiver for Enclosed Solar Particle Heating 

Abstract: 

Concentrating solar thermal power (CSP) technology development has recently focused on high efficiency power cycles and chemical reactions that require high operating temperatures. An increase in receiver operating temperatures relative to current commercial CSP technology is necessary to support more efficient, high temperature power cycles or thermochemical processes. Solar receivers operating with heat transfer media temperatures >700°C face various challenges including thermal performance, scalability, thermal-mechanical issues, and receiver service life. In addition, heat transfer media selection for high-temperature processes has been moving towards inert solid particles in Gen3 CSP, and reactive solid media and/or gases in solar thermochemical processes. To overcome the shortcomings and limitations of conventional designs for molten salt or particle receivers and receiver reactors, we introduce a unique light-trapping, planar cavity receiver (LTPCR) configuration and will present the current development progresses to demonstrate receiver feasibility through modeling, testing, and prototype demonstration.

The light trapping mechanism of the LTPCR receiver evolved from a near-blackbody tubular light absorber and extends the previous tubular geometry to a vertical planar cavity to allow solar beam spreading across the cavity panel walls. Flux spreading via the cosine projection onto the cavity wall transforms high incident aperture solar flux to comparatively low absorbed heat flux on receiver panel walls to accommodate relatively low heat transfer rates by solid particles or reaction gases, thus enabling enclosed particle receivers or thermochemical solar receiver reactors. Meanwhile, the planar cavity reduces thermal losses to the environment and can achieve high efficiency at high temperatures >700°C. The enclosed cavity receiver applied to heat particles in Gen3 CSP conditions avoids particle loss to the environment compared to open-cavity designs in which wind directly interacts with the falling particle curtain. Planar cavities can be arranged using arrays of modular receiver panels to a large area to scale up to a commercial receiver capacity without cavity size limitation of open cavity or volumetric cavity receiver, and the design is suitable for a modular commercial-scale CSP system to generate electricity or to produce fuels or chemicals.

Comprehensive modeling tools have been developed to assess the receiver design, performance, reliability, and scalability, and laboratory tests have been conducted to mitigate receiver operation risks including leading-edge protection, efficient particle/wall heat transfer, and flux spreading effects. A key principle to realize the LTPCR design approach is the solar flux-receiver interaction from heliostat layout to cavity geometry. A modeling tool based on SolarPILOT and SolTrace has been developed to characterize solar flux conditions and incident flux distribution uniformity. The modeling efforts identified and verified feasible receiver designs with suitable absorbed solar flux conditions, and thermal-mechanical modeling tools based on ANSYS software have been developed and used to simulate the receiver performance and service life of a 50-MW_t design. The modeling results show promising design paths to achieve >750°C media temperatures with thermal efficiency between 85% and 90% and a projected 30-year service life. A 100kWt prototype receiver under development will be tested on-sun to verify the modeling tools, receiver design, and fabrication methods.

Successful development of the LTPCR technology will enable low-cost particle thermal energy storage (TES) for CSP power generation and industry process heat. Additionally, it provides a scalable enclosed receiver reactor configuration for thermochemical processes. This presentation will show the LTPCR principle and thermal-mechanical modeling of performance and service life in a real operating environment. The development progress on the solar particle receiver provides an alternative to open-cavity receivers by resolving the issue of particle losses, and a promising path towards supporting solar thermochemical processes to expand CSP technology beyond power generation to fuel and chemical production.

Presenting Author: Zhiwen Ma National Renewable Energy Laboratory (NREL)

Presenting Author Biography: Zhiwen joined the NREL Thermal Sciences Group in 2009 to work in the field of concentrating solar power. His experience includes combustion, fluidization, hydrogen and fuel cells, electronic thermal management and packaging, and gas turbines. He taught in the Department of Engineering Mechanics at Tsinghua University for three years, conducted multiphase flow research, and developed pyrometer techniques for measuring gas turbine temperatures. Beginning in 2001, he was a test and modeling engineer in fuel cell energy, and worked on molten carbonate fuel cell performance and life improvement for cost reduction. He was also involved in the Solid State Energy Conversion Alliance program, supporting the testing and modeling of solid-oxide fuel cell stacks and system design. Zhiwen has published papers and a book chapter, and was awarded two patents in the areas of fuel cells and thermal fluids. Before joining NREL, he worked for GE Aviation on gas turbine flow and heat-transfer design. He works on system analysis, measuring the properties of heat-transfer fluids, and developing thermal-storage concepts for concentrating solar power technology.

Authors:

Zhiwen Ma National Renewable Energy Laboratory (NREL)
Janna Martinek National Renewable Energy Laboratory (NREL)
Munjal Shah NREL
Jason Hirschey National Renewable Energy Laboratory (NREL)
Shin Young Jeong National Renewable Energy Laboratory (NREL)
Keaton Brewster Colorado School of Mines
Gregory Jackson Colorado School of Mines
Krutika Appaswamy Purdue University
Punchi Wedikkarage C Punchi Wedikkara Purdue University
Aaron Morris Purdue University
Ouidad Abourazzouk University of Central Florida
Like Li University of Central Florida
Eldwin Djajadiwinata King Saud University
Hany Al-Ansary King Saud University