Experimental Testing of s-CO2 Regenerator for Use as a Replacement to High Cost Printed Circuit Recuperators for Use in s-CO2 Recompression Brayton Cycle

Supercritical Carbon Dioxide (sCO2) power cycles have the potential to deliver high efficiency at low cost. However, in order for s-CO2 cycle to reach high efficiency, highly effective recuperators are needed. These recuperative heat exchangers must transfer heat at a rate that is substantially larger than the heat transfer to the cycle itself and can therefore represent up to 24% of the total power block cost in a recompression Brayton cycle [1]. Lower cost regenerators are proposed as a cost saving alternative to high cost printed circuit recuperators. A regenerator is a heat exchanger that alternately has hot and cold fluid passing through it. During the first half of its cycle the hot gas is passed over a storage media bed (stainless steel balls, screens, or similar fill material) where thermal energy is stored. During the next half of the cycle, cold fluid is passed through in the opposite direction, extracting the thermal energy from the bed. By operating a cycle with two (or more) regenerators, where one is always in a hot to cold (HTC) blow and the other in a cold to hot blow (CTH), a quasi-steady state can be achieved in the cycle to allow continuous operation. A model of the regenerator was created and used in place of a recuperator in a model of a 10MW power plant. The thermal effectiveness of the regenerator cycle was slightly lower than the recuperator cycle, however the regenerator cycle had a saving of about 9.3 percent in the Levelized Cost of Energy (LCoE). A scale model of the regenerator is under construction which will verify the performance of the regenerator model.