Research Projects

Project at a Glance

Project Status: complete

Title: Development of a test method to measure stationary and portable engine emissions.

Principal Investigator / Author(s): Mridul Gautam, Ph.D.

Contractor: West Virginia University

Contract Number: 00-06 & 00-316


Research Program Area: Emissions Monitoring & Control

Topic Areas: Stationary Sources


Abstract:

This study has developed test methods and protocols for determining compliance with emission standards for stationary and portable engines as promulgated by either the California Air Resources Board (CARB) or the U.S. Environmental Protection Agency (EPA). This study has resulted in a simple, cost-effective, yet accurate test method for stationary and portable engines to measure in-use emissions to ensure attainment of emission reduction goals. Additionally, the method will allow determination of compliance with the emission limits established by the Statewide Portable Equipment Registration Program. The method will allow measurement of fuel-specific emissions from both, diesel- and gasoline-fueled portable and stationary engines under real-world conditions. Given the fact that most stationary and portable engines are mechanically controlled engines, measurement of engine speed and load in the field would be not be a viable option, due to the associated complexity of such measurements. Hence, a "Compliance Factor" approach, based upon CO2-specific or fuel-specific emissions-measurements, has been developed and presented to CARB in this report. This method requires measurement of concentration of gaseous pollutants and the mass of particulate matter (PM) emissions. Errors introduced by the measurement of engine load and exhaust flow rate in determining brake-specific emissions are avoided. The Compliance Factor is a ratio of NOx and CO2 concentrations (In-field ratio, I) to the brake-specific mass emissions of NOx and CO2 (Certification ratio, C). The Certification ratio, C, is obtained either from the manufacturer, or from laboratory evaluation of the test engine on an ISO 8178 cycle. The test method presented to CARB was validated by running an extensive series of steady-state 8-mode tests (ISO 8178 cycle) that were conducted on both, mechanically and electronically controlled engines. It was also determined that the front-half of the Method 5 PM measurement methodology is in good agreement with the CVS system based engine certification PM test method. Further, a modified Method 5 sampling train comprising of a multi-hole sampling probe that spans the diameter of the exhaust stack, and a sample transfer tube maintained at ambient temperature could be a likely configuration for measuring PM from stationary and portable diesel engines in the filed. This approach does away with the cumbersome method of modifying the small diameter (2 inches to 6 inches for most applications) exhaust stacks of diesel engines, and traversing the exhaust stack to acquire samples at 8 locations along the stack diameter. WVU has been involved with in-use, in-field measurements from heavy-duty vehicles for a decade using its transportable chassis dynamometer based emissions measurement laboratories. Today, evaluation of in-use, "real world" emissions from on-highway heavy-duty vehicles is gaining momentum due, in part, to the availability of transportable heavy-duty chassis dynamometer facilities developed by WVU, and the new in-use, on-board Mobile Emissions Measurement System (MEMS). Similar advances are essential for stationary and portable engines. However, it should be noted that measurement of in-use mass emission rates from on-highway vehicles is still an issue, and this is due to a lack of a "suitable" chassis test cycle that could be employed for all heavy duty vehicles (buses, trucks with automatic transmissions, as well as those with unsynchronized transmissions and low power-to-weight ratios). This problem of a lack of a single test cycle for the entire body of vehicles is dwarfed by the absence of any test cycle for "real world" testing of stationary and portable equipment and engines. Development of test methods for in-use compliance of stationary and portable engines is now imperative in light of the urgent need to attain emission reduction goals, and develop inspection and maintenance (I/M) programs. The process of development and implementation of the test method presented to CARB for stationary and portable engines tapped into WVU's experiences and "lessons learned" from the on-highway vehicle in-use emissions measurement exercises. Recommendations have been made on the most suitable measurement tools for in-use emissions measurements, and Standard Operating Procedures (SOP) for conducting a in-field tests are also presented. WVU has recommended use of exhaust emission analyzers that can accurately and precisely measure gaseous concentrations, and a micro-dilution tunnel for filter-based gravimetric PM emissions measurements. This approach will reduce the cost of portable analyzer equipment by tens of thousands of dollars compared to the currently available commercial portable emissions measurement systems.


 

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