Development of All-Solid-State Sensors for Measurement of Nitric Oxide and Carbon Monoxide Concentrations by Optical AbsorptionEPA Grant Number: R828180
Title: Development of All-Solid-State Sensors for Measurement of Nitric Oxide and Carbon Monoxide Concentrations by Optical Absorption
Investigators: Walther, Thomas , Caton, Jerry , Lucht, Robert P.
Institution: Texas A & M University
EPA Project Officer: Shapiro, Paul
Project Period: July 1, 2000 through June 30, 2002
Project Amount: $225,000
RFA: Exploratory Research - Engineering, Chemistry, and Physics) (1999) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Water , Land and Waste Management , Air , Engineering and Environmental Chemistry
The objective of this research is the development of new optical sensors for the detection of nitric oxide (NO) and carbon monoxide (CO) in the exhaust streams of combustion systems. Sensors based on absorption measurements combine high sensitivity and real-time capabilities. Present sensors rely on physical sampling techniques which are inherently slow.
The specific objectives of this research are:
- The development of a fiber-amplified, diode laser based UV optical sensor for NO measurements and mid-infrared sensor for CO measurements.
- Characterization of the performance of the sensors by absorption measurements in a gas cell, simulated combustion exhaust streams, and a well-characterized flame, and by comparison with Fourier Transform Infrared (FTIR) measurements and probe sampling.
- Completion of a feasibility study of the incorporation of the sensor systems in practical systems for pollutant monitoring and control.
The sensors for NO and CO are based on absorption measurements in the UV (NO) and mid-infrared frequency (CO) regions. The optical sensor for NO is based on a sequence of frequency-conversion steps to obtain tunable ultraviolet laser radiation from the output of two infrared external-cavity diode laser (ECDL) systems of approximately 1064 nm and 1535 nm amplified by the use of fiber amplifiers.
The optical sensor for carbon monoxide is based on frequency difference mixing of the fiber-amplified radiation from ECDL systems operating at approximately 1017 nm and 1308 nm in a periodically poled Lithium Niobate crystal.
The proposed research will produce new optical sensors for nitric oxide and carbon monoxide that are at least 2 orders of magnitude more sensitive than previous sensors. In addition these sensors will be capable of real-time measurements and could be used for combustion control applications.
Improvement in Risk and Risk Assessment and Risk Management: Because of its role in the chemistry of photochemical smog, nitric oxide (NO) is one of the most important pollutant species emitted by practical combustion devices. It is subject to increasingly stringent environmental regulations, and because of this billions of dollars are spent every year by manufacturers of automobiles, aircraft engines, power generating gas turbines and other practical combustion devices to control NO emissions. Due to their increased sensitivity and real-time capability our sensors will enable on the one hand capability to enforce these stricter emission standards and on the other hand make combustion control applications with the goal of reduced pollutant emission possible.