Small Business Innovation Research/Small Business Tech Transfer
An Instrument to Measure Aircraft Sulfate Particle Emissions, Phase I
Project Description
Aircraft particle emissions contribute a modest, but growing, portion of the overall particle emissions budget. Characterizing aircraft particle emissions is required to improve aircraft combustor design and aircraft operating practices. Aircraft particle emissions are a complex mixture of soot and semi-volatile material, primarily inhabiting sizes smaller than 100 nm. New instruments are required to characterize aircraft particle emissions. We propose to build a new instrument for sensitive (>200 ng m-3 on a 1 Hz cycle) measurements of particle sulfate. The key instrument component will be a tunable infrared diode absorption spectrometer (TILDAS). Compared to existing sulfate measurement instruments, the TILDAS-sulfate instrument will be able to reject NO interferences, a key capability required for aircraft exhaust applications. Prior to reaching the TILDAS, gas phase SO2 will be removed using an acid gas denuder and particle sulfate will be converted to SO2 in a quartz oven. By running the TILDAS-sulfate in tandem with a commercial differential mobility analyzer, we anticipate obtaining size resolved sulfate mass loadings (10 size bins, from 10 nm to several hundred nm). Phase I tasks include evaluating acid gas denuder and SO2-to-sulfate technologies, determining the instrument detection limits, demonstrating instrument discrimination against NO and other interferences, and demonstrating the use of the instrument to characterize simulated aircraft exhaust gas.
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Anticipated Benefits
NASA is one of several U.S. stakeholders in the aircraft particle emissions community. FAA, EPA, SERDP, U.S. Air Force, airport operators, and engine manufacturers all have a stake in understanding aircraft particle emissions and all of these are potential consumers of the TILDAS-sulfate instrument and its data. In addition to aircraft exhaust characterization, sulfate aerosol makes an important contribution to global climate forcing. Moreover, sulfuric acid has been shown to be a key component in atmospheric nucleation events. Improved instruments are required for rapid, size- and composition resolved measurements of sulfate particles. Current instruments are inadequate for characterizing particles smaller than 50 nm, suffer severe interferences from other atmospheric gases, lack composition resolution, lack size resolution, or lack the required sensitivity. The primary application of the proposed TILDAS-sulfate instrument will be characterization of aircraft particle emissions. NASA has sponsored a number of major aircraft particle characterization tests, including the three APEX experiments and the AAFEX experiment. These measurement activities have contributed to a growing understanding of aircraft exhaust particles. However, despite substantial effort, many questions remain. The most important outstanding question is the relative contribution of soot and semi-volatile particles to the overall particle mass emissions loading. Depending on the engine, fuel, and operating conditions, semi-volatile mass loadings vary from almost zero to more than 100 mg kg-1. A second outstanding question is the conversion efficiency of SO2 to SO3. By directly measuring particle bound sulfate and with limited restrictions on the particle size that can be detected the TILDAS-sulfate instrument will help answer these two important outstanding questions faced by NASA.
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Primary U.S. Work Locations and Key Partners
| Organizations Performing Work | Role | Type | Location |
|---|---|---|---|
| Aerodyne Research, Inc. | Lead Organization | Industry | Billerica, Massachusetts |
Glenn Research Center
(GRC)
|
Supporting Organization | NASA Center | Cleveland, Ohio |
Primary U.S. Work Locations
-
Massachusetts
-
Ohio
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