EXPERIMENTAL AND NUMERICAL STUDY OF CRITICAL FLOW MODEL DEVELOPMENT FOR SUPERCRITICAL CO2 POWER CYCLE APPLICATION

Abstract

Supercritical CO2 (S-CO2) has the potential to be used asthe working fluid in a power cycle since S-CO2 shows a densityvalue high as its liquid phase while the viscosity value remainscloser to its gaseous phase. Thus, it requires much less work tocompress due to its low compressibility as well as relativelysmall flow resistance. However, the S-CO2 leakage flow fromturbo-machinery via seal becomes one of the important issuessince not only it influences the cycle efficiency due to parasiticloss but also it is important for evaluating the system safetyunder various operating conditions.In the previous turbo expo paper, the effect of the toothlength on the critical flow and comparing the results to theexisting two phase system analysis code calculation werepresented. In this paper, the gap effect, which is simulated bychanging the diameter of a orifice and the number of tootheffect in a labyrinth seal geometry nozzle are presented by usingthe same experimental facility described in the previous paper.In addition, this paper includes the experimental results undervarious conditions including not only single phase flow such assupercritical, and gaseous state only but also two phase flowcondition.