Fast Measurements of Particle Emission Using Combined DMA and LII Technologies

ABSTRACT: This topic calls for a fast and accurate sensor for measurements of particle number density, size distribution, and mass-based emission factors (indices) as an alternate to EPA Method 5 currently used by DoD for reporting turbine particulate matter (PM) emission rates. There is a need for thorough research to experimentally determine the accuracy of DMA and CNC, and also to seek alternative intrusive/non-intrusive measurement techniques for characterizing combustion particles generated from aircraft engines. As the topic states, the ultimate goal of these research efforts is to develop a fast technique with ~1 Hz per 10-1000 nm diameter scan that is capable of measuring accurate number densities, size distributions, and mass based emission factors. The technique should be applicable to various engine types and operating conditions under a variety of test environments to provide a sound, accurate basis for DoD to report PM emission rates to the regulatory authorities. We propose an innovative system combining the established DMA technique and a non-intrusive laser-based technique, LII (Laser Induced Incandescence), to address the above requirements listed in this topic. The combined system is expected to enable quantitative and simultaneous measurements of particle number density, size distribution, shape parameters, and mass-emission indices at temporal resolution better than 5 Hz. The goals of this Phase I project are: 1) to identify off-the-shelf components that can be used to build the combined system, 2) to develop robust and unambiguous procedures to calibrate the combined system, and 3) to deliver data processing models, software, and proof-of-concept data for the combined system. These efforts are expected to prepare the groundwork for the delivery of a prototype measurement system ready for gas turbine applications should this project be encouraged for Phase II. BENEFIT: If the Phase-I research effort on the combined DMS+LII technique is successful, it will have a major impact on the characterization of gas turbine particulates. This combined system will enable the simultaneous measurements of particle size, number, and mass at better than 5 Hz temporal resolution, and the measurements will be backed by tractable calibration procedures. The LII technique (and also scattering and photoacoustic techniques) is also well suited for in situ measurement. Instrumentation for measuring particulates is critical in the deployment of propulsion systems for the warfighter. However, current instruments are not capable of real-time (~5 Hz) measurements of particle number density, size distribution, shape parameters, and mass-emission indices. By combining commercially available instruments and developing proper test protocols, it may be feasible to alleviate this deficiency. Such protocols could potentially address a wide range of engine types with different operating conditions under a variety of test environments. The unique market opportunity, therefore, is to develop a new versatile instrument platform that will provide a fast and accurate basis for the DoD to report PM emission rates to the regulatory authorities. Applications of the proposed particulate sensing system include a wide range of devices for transportation, heating, and power generation. Manufacturers invest a significant amount of test time to ensure compliance with emissions regulations. The proposed instrumentation would not only reduce the test time required, it would allow manufacturers to quickly tune each device and potentially improve the effectiveness of various design strategies and abatement systems.