Compressor Design with Highly Variable Fluid Properties Near the Critical Point and Liquid Region of

• 作 者: Mark R. Anderson
• 机 构: Concepts NREC, LLC
• 出 处: 风机技术
• 发表日期: 2021年3期
• 关键词: Super Critical Carbon Dioxide SCO2 Radial Compressor Non-linear Thermodynamics T

It is well known that the fluid properties near the critical point are highly variable and complicate the design process for compressors operating in this region. This had been well documented in the literature and improved analysis methods using highly accurate thermodynamic models are now routinely included in SCO2 design. Depending on the cycle conditions and heat sources, moderate to strong variation in inflow conditions to the compressor can be expected in many cycles and their effects on compressor performance must be considered. Perhaps less well understood is the potential for even more non-linear behavior when the inflow conditions to the compressor shift toward the liquid side of the saturation curve. In this work, both 1D and 3D numerical and analytical methods are used to demonstrate highly unexpected behavior of the fluid near the critical point and where the inlet conditions move over to the liquid side of the saturation dome. This paper describes usual fluid dynamic behavior in the saturated liquid region of CO2 which includes choking flows at Mach numbers significantly less than unity as well as shock-like behavior at Mach numbers well below the typical sonic point. These effects are expected to have a strong influence on compressor performance as inlet conditions vary. The applicability of common turbulence and two-phase modeling approaches for SCO2 is also discussed.