Design of a novel carbon/carbon composite microvascular solar receiver

Solar thermal power tower systems are the primary technology being proposed for solar electricity from thermal energy. Operational limits on these towers are often driven by mechanical properties under significant thermal loads, particularly at the receiver where incoming flux is converted to thermal energy. While the solar receiver's efficiency is largely driven by its optical properties, thermomechanical stresses on the receiver limits the operational envelope. One pathway to higher efficiency is greater allowable solar fluxes on the receiver but novel materials are required. The present study uses computational fluid dynamics to describe a parametric design space for a microvascular carbon/carbon composite solar receiver as a new material option for high flux solar receivers. Simulations are conducted for different microvascular geometries considering the role of material properties and heat transfer fluids, for the impact on thermal efficiency, and allowable strain. Results show that microscale receiver modules made of the proposed carbon/carbon composite could achieve thermal efficiencies over 90% and full-scale receivers can achieve up to 85% thermal efficiency for the design explored considering realistic strain limits, flux levels, and material properties. These values are highly dependent on the heat transfer fluid pairing, the through plane thermal conductivity of the carbon/carbon composite, the path architecture of the microscale receiver, and the incident solar flux profiles.

Automated summary

Solar thermal power tower systems are the leading technology for generating solar electricity. The performance of these systems is limited by mechanical properties under high thermal loads, especially at the receiver where incoming flux is converted to thermal energy. This study explores the use of a microvascular carbon/carbon composite solar receiver as a new material option for high flux solar receivers. The results show that the proposed carbon/carbon composite material can achieve thermal efficiencies over 90% for microscale receiver modules and up to 85% for full-scale receivers considering realistic strain limits, flux levels, and material properties. The efficiency is influenced by factors such as the heat transfer fluid pairing, thermal conductivity of the composite, receiver architecture, and solar flux profiles.