DEVELOPMENT OF ULTRA-LOW EMISSION DIESEL FUEL-FIRED MICROTURBINE ENGINES FOR VEHICULAR HEAVY DUTY APPLICATIONS: COMBUSTION MODIFICATIONS

摘要

Worldwide regulations currently set very stringent emissions standards for new on-road heavy-duty diesel engines (HDDE's). For example, the United States Environmental Protection Agency (US EPA) and the California Air Resources Board (CARB) will require 2010 and subsequent HDDE to emit less than 0.2 g/bhp-hr (0.27 g/kW-hr) NO_x and 5.0 g/bhp-hr (6.7 g/kW-hr) CO in addition to other strictly regulated pollutants such as formaldehyde, volatile organic compounds, and paniculate matter. Diesel or biodiesel fired Microturbine engines are in use in hybrid electric vehicular (HEV) urban bus applications in part because of their low emissions. A vehicular test cycle based on practical driving data of The New York City M60 route duty cycle for an urban bus is presented and discussed. Engine only test cycles that would represent in vehicle engine usage are also discussed. In the process of developing new technologies to meet the upcoming 2010 EPA and CARB HDDE regulations, Capstone Turbine has demonstrated a significant reduction in the emissions of its C30 family engines fired with ultra low sulfur diesel (ULSD) without any post-combustion treatment. The technical approaches which yielded the emissions improvements, included enhancements to the fuel vaporization and mixing processes in an effort to reduce local primary zone temperatures. With only injector modifications the ULSD-fired engine achieved emission levels of 0.046 g/hp-hr NOx, 0.87 g/hp-hr CO, 0.003 g/hp-hr PM, 0.013 g/hp-hr NMHC and 0.006 g/hp-hr HCHO in a recent third party demonstration test. NOx levels of 5-7 ppmV at 15% O2 were achieved for a power range of 50-100% while running on diesel fuel #2. With these new injector modifications the C30 engine has the potential capability to meet the same HDDE standards while burning other opportunity liquid fuels, including biodiesel, and ethanol.