High-temperature split-flow recompression Brayton cycle initial test results.

Supercritical CO2 (S-CO2) power plants offer the potential for better economics because of their small size, use of standard materials, and improved electrical power conversion efficiency at modest temperature (400–750°C) [1]. Sandia National Laboratories (SNL or Sandia) and the U.S. Department of Energy Office of Nuclear Energy (DOE-NE) are operating a supercritical CO2 Brayton cycle power system—the Generation IV (Gen IV) split-flow S-CO2 compressor test loop—currently located in Arvada Colorado, at Barber Nichols, Inc., [2] under contract to Sandia. A photograph of the upgraded loop is shown in Figure E-1. This system is one of the first S-CO2 power-producing Brayton cycles operating in the world. This report provides a summary of the newly installed hardware and briefly describes some of the test results that were performed in the upgraded split-flow Brayton loop during June and July of 2011. The Gen IV S-CO2 split-flow Brayton loop was reconfigured to operate as a simple heated recuperated Brayton loop for the testing in this report period. The test loop had just concluded a phase of construction that substantially increased the capability of the loop by adding heaters, a high-temperature (HT) recuperator, more waste heat removal capability, high-power load banks, larger diameter piping with more bends to reduce thermal stress, and more capable scavenging pumps to reduce windage and friction within the turbomachinery and provide greater cooling capabilities. With these additions, the loop greatly increased its capacity for electrical power generation (30–80 kWe per generator, depending on the loop configuration) and its ability to reach high temperatures (up to 810 K [1000°F]).