Multi-Gas Detection System Based on Non-Dispersive Infrared (NDIR) Spectral Technology

Area of Science:

• Environmental Science
• Analytical Chemistry
• Sensor Technology

Background:

• Automobile exhaust gases, including carbon dioxide (CO2), carbon monoxide (CO), and propane (C3H8), contribute to significant environmental issues like the greenhouse effect, photochemical smog, and haze.
• These pollutants pose a threat to urban atmospheric quality and human health, necessitating effective monitoring solutions.

Purpose of the Study:

• To develop an economical and energy-efficient non-dispersive infrared (NDIR) multi-gas detection system for analyzing automobile exhaust gases.
• To establish and validate a concentration inversion model for accurately quantifying CO2, CO, and C3H8 levels.
• To assess and model the interference between these gases to ensure reliable detection.

Main Methods:

• Development of a non-dispersive infrared (NDIR) system featuring a broadband light source, gas cell, and a four-channel pyroelectric detector.
• Establishment of a concentration inversion model using the least squares method to correlate voltage ratios with gas concentrations (C3H8: 0-5000 ppm, CO: 0-14%, CO2: 0-20%).
• Testing of interference coefficients and development of interference models between the three gases using the least square method.

Main Results:

• The developed NDIR system demonstrated accurate detection ranges for C3H8, CO, and CO2.
• Experimental verification of the concentration inversion model showed a full-scale error of less than 3.5%.
• The system achieved a detection repeatability error below 4.5% and detection stability under 2.7%.

Conclusions:

• The developed NDIR multi-gas detection system is an economical and energy-efficient solution for analyzing key automobile exhaust gases.
• The established concentration inversion and interference models provide a reliable method for quantifying gas levels.
• This technology shows promise for effective monitoring of urban air quality and mitigating the adverse effects of vehicle emissions.