Keywords

Supercritical CO2, Optical Techniques, Heat Transfer, Micro-channel, PIV

Abstract

Supercritical CO2 (sCO2) has been proposed for many 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. Advanced optical techniques should be considered to measure these properties of sCO2. These techniques include Schlieren Imaging to capture the density gradient, LIF ( Laser Induced Fluorescence) for temperature measurement, and PIV ( Particle Image Velocimetry) for measurement of the velocity flow field. Different experimental setups have been built to apply the advanced optical technique. The Schlieren imaging has been used to capture the density gradient of the methane injection into the chamber filled with CO2 at supercritical thermodynamic conditions. The density gradient in the flow helped to define the jet cone angle. The micro-channel setup was implemented through which a mixture of CO2 and Rh6G dye was flowed. The dye particles will act as a thermal probe and measure the temperature of the CO2 flow at near supercritical conditions by applying the LIF ( Laser Induced Fluorescence). Initially, the feasibility of the backlight micro-PIV technique was demonstrated by performing experiments with the methanol and non-fluorescent tracers. Then the author applied the the same technique for the first time to measure the velocity of the liquid CO2 flow through a T-channel. Furthermore, the bottom of the channel was painted with fluorescence color to excite, which helps to observe the shadows of the non-fluorescent particles used to measure the velocity of the flow.

Completion Date

2024

Semester

Summer

Committee Chair

Vasu, Subith

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

MAE

Degree Program

Mechanical Engineering

Format

application/pdf

Identifier

DP0028604

URL

https://purls.library.ucf.edu/go/DP0028604

Language

English

Rights

In copyright

Release Date

August 2025

Length of Campus-only Access

1 year

Access Status

Doctoral Dissertation (Campus-only Access)

Campus Location

Orlando (Main) Campus

Accessibility Status

Meets minimum standards for ETDs/HUTs

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Restricted to the UCF community until August 2025; it will then be open access.

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