Micro-PIV Investigation of Near-Critical and Liquid CO2 Conditions Inside a T-Channel Setup

Abstract

Abstract Supercritical CO2 (sCO2) has been proposed for a plethora of applications, such as power generation, air conditioning, and thermal management of electronic equipment. In proximity to critical conditions, the thermal and transport properties of the CO2 vary abruptly, promoting a significant heat transfer enhancement. Revealing the heat transfer processes associated with CO2 flows requires measuring fluid temperature, pressure, heat transfer coefficients, velocities, etc. However, fundamental knowledge about the heat transfer processes at near-critical conditions is not fully understood. An advanced optical technique with microparticle image velocimetry (PIV) was applied to measure the velocity flow field of liquid CO2 near critical thermodynamic conditions flowing through a T -channel. The captured flow field of the CO2 was processed using a micro-PIV 2D2C (Two Directional Two Component) cross-correlation method for obtaining the velocity vectors. Silver-coated hollow glass microspheres with a range of diameters of 5 microns to 30 microns were used as a tracer and mixed with CO2 to track the flow patterns. The experimental setup consists of the integrated manifold for CO2 flow, RTD probes for temperature measurements, digital pressure transducers for pressure measurements, and PIV arrangement with laser. The present experimental study is an initial step to fully reveal the velocity distribution of liquid CO2 inside a T-channel in near-critical thermodynamic conditions.