Baseline-optimized differential absorption spectroscopy for resolving blended spectral lines in high-pressure...

Area of Science:

• Spectroscopy
• Combustion Science
• Chemical Engineering

Background:

• Accurate combustion diagnostics are crucial for understanding and optimizing combustion processes.
• High-temperature and high-pressure environments present significant challenges for spectral measurements due to signal blending and baseline drift.
• Existing methods struggle with reliable measurements in severe combustion conditions.

Purpose of the Study:

• To develop and validate a novel method for combustion diagnostics in harsh environments.
• To enable simultaneous measurement of temperature and carbon monoxide (CO) concentration.
• To overcome spectral blending and baseline extraction challenges.

Main Methods:

• Developed a baseline extraction algorithm for blended spectral signals.
• Integrated the algorithm with differential absorption spectroscopy (DAS).
• Utilized a CO absorption band near 4.86 μm for sensing.

Main Results:

• Achieved measurement uncertainties of 4% for CO concentration and 2.6% for temperature in a static cell (800-1000 K, 0.5-3 atm).
• Demonstrated practical applicability in C2H4/air sooting flames, with temperature deviations of 45-66 K and CO relative error within 3%.
• Results showed excellent agreement with CFD simulations and thermocouple measurements.

Conclusions:

• The proposed method is robust and reliable for advanced combustion diagnostics.
• Successfully addresses spectral blending and baseline extraction issues in high-temperature, high-pressure combustion.
• Offers a valuable tool for in-situ measurements in challenging combustion environments.