Thermal and structural investigation of tubular supercritical carbon dioxide power tower receivers

Advanced power cycle systems with supercritical carbon dioxide (sCO2) as the working fluid provide high power conversion efficiency because of high temperatures attained and are being explored for integration with concentrating solar power (CSP) plants. In a CSP plant, the working fluid flows in a series of tube bundles located on top of a tall receiver. As the working fluid flows in the receiver tubes, the working fluid absorbs the solar energy reflected by a large array of the mirrors onto the receiver surface. With sCO2 as the working fluid, the tubes should withstand high pressures (∼25 MPa) and high temperatures (>650 °C) without any structural damage for at least 30 years of operation. At these high pressure and high temperature conditions, failure by creep damage due to thermal stress is a critical issue in tubular power receivers and behooves careful evaluation of contemporary designs. The present study analyzes the performance of cylindrical tubular receivers for various operating and design conditions through systematic numerical studies. The results from the coupled flow-structural simulations are used to find design and operational envelopes for tubular power receivers that satisfy the U.S. Department of Energy SunShot requirements of lifetime >10,000 cycles and 100,000 h and exit HTF temperature >650 °C.