[In situ temperature measurement by absorption spectroscopy based on time division multiplexing technology]

Area of Science:

• Spectroscopy
• Laser Technology
• Physical Chemistry

Context:

• Non-contact, in situ gas measurement is crucial for industrial processes.
• Open environments pose challenges for accurate temperature and concentration sensing.
• Tunable diode laser absorption spectroscopy (TDLAS) offers high sensitivity and selectivity.

Purpose:

• To develop and validate an in situ gas temperature measurement technique for open environments using TDLAS.
• To investigate and mitigate the boundary effect on temperature measurements in open systems.
• To assess the accuracy and reliability of the TDLAS method against traditional sensors.

Summary:

• In situ gas temperature measurement in an open environment was achieved by scanning multiple H2O characteristic lines combined with a least-squares algorithm.
• The HITRAN spectral database was used to analyze the boundary effect, demonstrating that scanning multiple lines reduces its impact.
• Experiments in a tubular furnace (573-973 K) showed a maximum temperature difference of 52.4 K and a relative error of 6.8% compared to thermocouple measurements.

Impact:

• Provides a robust, non-contact method for accurate in situ gas temperature monitoring in open environments.
• Reduces measurement errors caused by boundary effects, enhancing data reliability.
• Offers a valuable alternative to contact-based temperature measurements, improving safety and efficiency.