DESIGN OF A SCROLL-CENTRIFUGAL COMPRESSOR FOR SUPERCRITICAL CARBON DIOXIDE POWER CYCLES

Supercritical carbon dioxide (S-CO2) Brayton cycle is a promising power cycle in the field of energy conversion applications. When the cycle is applied for waste heat recovery of gas turbine power system, the operating state will change more drastically compared to other power generation applications, and it is more likely to operate near the critical point, where the thermophysical properties of CO2 vary largely. To meet the requirements of S-CO2 Brayton power cycle for gas turbine power system, a new type of S-CO2 compressor, named scroll-centrifugal compressor, was proposed in this paper. This new compressor consists of two stages. The low pressure stage is scroll compression and the high pressure stage is centrifugal compression. It can operate at two modes, scroll compression mode and scroll-centrifugal compression mode, to adapt the drastic operating state change of the cycle. In this paper, the preliminary design considerations of this new compressor were introduced. The design progress of the scroll stage and centrifugal stage was illustrated, respectively. The computational fluid dynamics (CFD) simulation was carried out to analysis the aerodynamic performance of this new compressor. The simulation results shows that this new type compressor can achieve the pressure ratio 1.97 as the inlet state near the critical point.