Proceedings of the ASME Internal Combustion Engine Division 9 Fall Technical Conference ICEF9 September -, 9, Lucerne, Switzerland ICEF9- CRANKCASE EMISSION CONTRIBUTIONS TO PM FOR TWO TIER NE-HAUL LOCOMOTIVES Dustin T. Osborne Southwest Research Institute Joseph McDonald United States EPA Imad Khalek Southwest Research Institute ABSTRACT This paper documents the quantification and characterization of particulate matter (PM) emitted from two Tier diesel locomotives, and the impact of crankcase ventilation (CCV) on PM. Emission testing was performed on one General Electric (GE) model ESDC locomotive, and one Electro-Motive Diesel (EMD) model SDACe. A semicontinuous organic carbon/elemental carbon (OC/EC) analytical procedure was used to collect and determine the OC and EC of PM. PM was also measured gravimetrically using membrane filters. Testing was performed for the locomotives in an unmodified configuration with CCV, and then again without the CCV included in the measurements. Without CCV, the two-stroke SDACe brake specific filterbased PM and OC/EC PM, over the Line-haul Locomotive Duty Cycle (LHLDC), were reduced by approximately % to %, respectively, compared to testing with CCV. The - stroke ESDC showed a reduction of % for the OC/EC PM which was mainly due to a reduction in OC PM. When crankcase were not included, OC PM was reduced for nearly all throttle notches, and especially under high load conditions, although the differences were not always significant at a 9% confidence interval. With CCV, the relative OC portion of the Line-haul composite PM value for both locomotives was approximately -%. Without CCV, the absolute brake-specific OC PM over the LHLDC was reduced by %, thereby reducing the relative OC portion to approximately -%. This work showed that the OC PM fraction is significant for the locomotives tested, and controlling OC can lead to more than percent reduction in PM. Furthermore, almost onethird of the OC PM was contributed by CCV, therefore better control of blow-by PM from both locomotive types can lead to a significant reduction in OC PM. INTRODUCTION On April, the U.S. Environmental Protection Agency (U.S. EPA) proposed Tier and Tier exhaust emission standards for new locomotives. These proposed standards were finalized on May,. The transition from Tier to Tier standards for line-haul locomotives consists of a % reduction in line-haul composite PM. Also, by, Tier line-haul locomotives will have to meet Tier switch cycle standards, which include a % PM reduction from the current Tier switch cycle PM limit. Tier Locomotive Standards apply to newly manufactured locomotives starting January,. The same standards will apply to newly remanufactured Tier line-haul locomotives starting January,. Tier exhaust emission standards for locomotives will take effect in and will require an additional % reduction in PM from Tier standards, as well as approximately a % reduction in oxides of nitrogen (NO x ). The most likely technological pathway towards meeting Tier Locomotive Standards is the transfer of exhaust catalyst technology developed to control NOx and PM from onhighway and nonroad heavy-duty engines in the U.S., Europe, and Japan into heavy-haul and switch locomotives. Diesel exhaust PM is comprised of the following materials: elemental carbon (EC) or soot, organic carbon (OC), metallic ash, and sulfates. The sulfate portion of PM is derived from sulfur contained in fuel and lubricant. This portion of PM is minimized with the use of ultra low sulfur diesel (ULSD) fuel, which is currently available for use as an EPA certification fuel for locomotives. Metallic ash is a small portion of PM and is derived from lubricant additives and engine wear metals. The OC portion of PM is made of condensed hydrocarbons originating from fuel or lubricant. This portion of PM is of particular interest because diesel oxidation catalyst (DOC) technology can be effective in removing OC PM precursors from engine exhaust. However, one source of OC PM that is difficult to apply DOC technology toward is crankcase ventilation. This is mainly due to the low blow-by temperature that is insufficient to promote OC oxidation over the DOC. For most locomotive engines, blow-by is filtered using a coalescent filter to minimize the entrained lubricant before venting to exhaust. In order to reduce this source of PM, it will likely be necessary to optimize the effectiveness of blow-by filtering for the transition to Tier and Tier locomotive PM standards.
This paper provides PM measurement results for two Tier heavy-haul locomotives currently operating in the United States. One locomotive from each of the two major U.S. manufacturers, General Electric (GE) and Electro-Motive Diesel (EMD), was tested. Both locomotive manufacturers currently rout crankcase ventilation to the exhaust stack. The effects of crankcase ventilation on tailpipe PM are quantified in this work. PM measurements were taken at the exhaust stack with the locomotive in its original configuration, and again with the crankcase vented away from the stack, so as not to include any crankcase. PM was determined analytically using two OC/EC instruments to measure OC and EC at each operating condition. PM was also determined gravimetrically using mm membrane filters. The differences in PM and speciation between the two configurations are reported. Results from this testing help provide guidance in the transition to Tier and Tier emission levels. NOMENCLATURE BNSF BNSF Railway Company CO Carbon monoxide CCV Crankcase Ventilation EC Elemental Carbon PM EMD Electro-Motive Diesels, Inc. (formerly General Motors Electro-Motive Division) EPA Environmental Protection Agency FTP Federal Test Procedure GE General Electric Company HC Hydrocarbons kw kilowatt NDIR Nondispersive Infrared NO x Oxides of Nitrogen OC Organic carbon PM PFA Perfluoroalkoxy PFDS Partial flow dilution system PM particulate matter ppm parts per million PTFE Polytetrafluoroethylene SwRI Southwest Research Institute TPM Total Particulate Matter ULSD Ultra-Low Sulfur Diesel UPRR Union Pacific Railroad Company locomotive equipped with a -GC, two stroke, Tier engine. Test Fuels A summary of the available fuel properties from this test program is presented in Table. Test Fuel A was a commercial grade of ultra-low sulfur diesel fuel (ULSD) used for testing the ESDC locomotive in the as-received condition which included crankcase. During the course of testing, test fuel A became contaminated with a small fraction of nonroad diesel fuel that increased its fuel sulfur content from ppm to. ppm. The contaminated fuel was designated test Fuel B. Testing of the ESDC locomotive in a configuration that did not include crankcase was inadvertently conducted using Fuel B. All of the testing of the SDACe was conducted using a commercial grade of ULSD designated test Fuel C. Table. Locomotive Specifications Manufacturer and Model GE ESDC EMD SD ACe Road Number BNSF UP Engine Model GEVOLDB -GC- T Year of Manufacture Rated Traction Power (kw) Operating Cycle -Stroke -Stroke Uniflow Scavenged Cylinder Arrangement V- V- Bore mm mm Stroke mm 9 mm Displacement/. L. L Cylinder Rated Engine Speed Fuel Injection 9 Direct Inject Electronic Unit Pump System Direct Electronic Unit Injection TECHNICAL APPROACH Presented below is an overview of the experimental methods used to conduct the engine exhaust testing. Additional description of the test setup can be found in the EPA Locomotive and Marine Docket. Test Locomotives A summary of the specifications of the two locomotives tested is contained within Table. Both locomotives were certified to Federal Tier locomotive emission standards. Locomotive BNSF, shown in Figure, was obtained from the BNSF Railway Company and was a General Electric (GE) ESDC locomotive equipped with a GE GEVO-V, four stroke, Tier engine. Locomotive UP, shown in Figure, was obtained from Union Pacific Railroad Company (UPRR) and was an Electro-Motive Diesel (EMD) SDACe Figure. BNSF GE ESDC Test Locomotive
Figure. UP EMD SDACe Test Locomotive Analytical Properties Distillation (ASTM D) Table. Fuel Properties Test Fuel Test Fuel A B Test Fuel C IBP: C C C %: C C C %: 9 C C C 9%: C 9 C C EP: C C C Sulfur (ASTM D). ppm. ppm. ppm HC Composition (ASTM D9) Olefins:.%.%.% Aromatics:.%.%.% Saturates:.9%.%.% Flashpoint (ASTM D9) C C 9 C Kinematic Viscosity (ASTM D). cst. cst. cst Cetane Number (ASTM D).9.9. Cetane Index (ASTM D9)... Carbon Mass Fraction (ASTM D)... Net Heat of Combustion... (ASTM D) Density @. C MJ/kg. g/cm MJ/kg. g/cm MJ/kg. g/cm Gaseous Emissions Gaseous emission measurements of hydrocarbon (HC), carbon monoxide (CO), and oxides of nitrogen (NO x ) were conducted using raw gaseous sampling procedures specified within the Federal Test Procedures for Locomotives. PM Emissions PM were sampled using a partial flow dilution system (PFDS) and were measured using PM sampling and measurement procedures specified in CFR Part. Two exceptions existed to the procedures in CFR Part : ) the raw exhaust sampling probe was not a single holed probe facing upstream, but instead a probe consistent with the locomotive federal test procedures described in CFR Part 9, and ) the dilution ratios for each discrete mode did not follow the guidelines of CFR.(d)()(iv), but instead the dilution ratio was dependent on sample temperature. The new regulatory guidelines on exhaust dilution ratio were not finalized in time to be included in this project. A slight negative pressure was maintained within the PFDS tunnel, and an adjustable valve regulated the flow of dilution air into the system. Also, a valve could be manually adjusted to regulate raw exhaust flow into the dilution tunnel. For each operation mode, the positions of these valves were optimized to provide a sample zone temperature within the tunnel of ± C. The resulting dilution ratio was determined via NO x concentration, and ranged in value from to 9. Two sampling trains were used in parallel to provide duplicate and simultaneous filter sampling from the PFDS. PM mass were determined gravimetrically using mm diameter Polytetrafluoroethylene (PTFE) membrane filters with integral perfluoroalkoxy (PFA) support rings. Following gravimetric analysis, a portion of the PTFE membranes were extracted with a %/% isopropanol/water mixture and sulfate content was determined via ion chromatography analysis of aliquots of the extracted material. Sulfate mass was determined on the basis of H SO hydrated to the temperature and humidity conditions of the PM gravimetric determination. Two Sunset Laboratories semicontinuous OC/EC instruments with NDIR detection were used simultaneously and in parallel to collect and speciate the OC and EC constituents of PM. The first OC/EC instrument sampled directly from a diluted exhaust stream onto a quartz tissue filter placed inside the instrument. The second OC/EC instrument sampled from the same source of dilute exhaust used by the first instrument, but the sample path included a quartz filter placed upstream of the quartz filter used inside the instrument. The OC measured by the second instrument was subtracted from the OC measured by the first instrument to correct for gas-phase positive OC artifacts collected by the quartz filter used in the first OC/EC instrument. Quartz filters are known to adsorb gas phase hydrocarbon species and can overestimate relative to PTFE membrane filters if used without correcting for the gas-phase hydrocarbon artifact. The effort used in the OC/EC work was intended to minimize gas phase hydrocarbon positive artifacts adsorbed onto the quartz filter. A schematic of the PM sampling system described above is displayed in Figure.
Figure. PM sampling system schematic. A partial flow dilution system supplied dilute exhaust for the OC/EC sampling setup and the dual mm filter sampling setup. Crankcase ventilation configuration Exhaust were measured for both locomotives with the crankcase ventilation systems in their original configurations. The arrangement of crankcase ventilation ducting to the exhaust stack for an EMD series engine is shown in Figure, and in Figure for a GEVOLDB engine. To determine the impact of crankcase ventilation on PM, testing was repeated after the crankcase ventilation was diverted away from the exhaust stack using a variable speed positive displacement blower. The blower speed was adjusted to maintain crankcase pressure to within. kpa relative to the original configuration at each tested condition. Figure. Crankcase ventilation system on an EMD -series engine. Crankcase gases and any remaining entrained lubricating oil not trapped with in the coalescing filter are vented to the exhaust stack immediately downstream of the exhaust turbocharger.
Crankcase gases vented to exhaust stack via eductor Coalescing filter Figure. Crankcase ventilation system on a GEVOLDB engine. Crankcase gases and any remaining entrained lubricating oil not trapped with in the coalescing filter are vented to the exhaust stack immediately downstream of the exhaust turbocharger. PM measurements were performed three times during each steady state test condition. Each measurement consisted of twin mm filters and simultaneous OC/EC sampling. Table presents the sampling matrix completed for each test. A full test was completed for both locomotives in the as-received configuration, and again with the crankcase vented separately from the exhaust stack, for a total of four tests. Test cycle Most line-haul locomotives are equipped with the dynamic brake feature in which the electric motors normally used for traction are reverse-excited to become generators for slowing the train. The electrical power generated is dissipated in onboard resistance grids. Locomotives with the self-load feature can dissipate the main alternator power into these dynamic brake resistance grids. The ESDC and SDACe are both equipped with dynamic brake grids capable of dissipating full engine power, and they were used to load the engine during testing. Power was determined by measurement of main alternator voltage and current, and measurement of the auxiliary power. GE and EMD supplied alternator efficiencies were used to calculate brake power. Test conditions included operation at low and high idle, operation at the dynamic brake setting and operation at all eight loaded locomotive power settings or throttle notches. Each throttle setting consists of a manufacturer assigned engine speed and load. The ESDC and SDACe are equipped with multiple idle speeds that were activated for separate test modes. For dynamic brake mode operation during testing, the locomotive dynamic brake control was activated resulting in notch engine speed with a reduced engine load. Table presents the duty cycles that were applied to the individual steady-state notch data points to compute the EPA line-haul and switch duty cycle weighted composite results. The duty cycles were originally developed by the EPA with industry input and are a result of event recorder data collected from in-use locomotives. Gaseous and particulate were measured per EPA locomotive test procedures and did not include transient during throttle notch position changes. Table. EPA Locomotive Line-haul Duty Cycle used to compute weighted averages Throttle Notch Setting Low Idle Idle Dynamic Brake Notch Notch Notch Notch Notch Notch Notch Notch TOTAL EPA Line- EPA Switch Haul Cycle Cycle 9. % 9.9% 9. % 9.9%. %.%. %.%. %.%. %.%. %.%. %.%.9 %.%. %.%. %.%. % %
Table. The sampling matrix that was completed for each test configuration (with and without crankcase ) for each of the two locomotives. a Throttle Notch Number of OC/EC Samples Low Idle Idle Dynamic Brake Table. Summary of brake specific weighted over the EPA Switcher Locomotive Duty Cycle with both locomotives in the stock configuration (blowby included) Number of mm filter samplesa BNSF UP GE EMD Pollutant ESDC SDACe Locomotive Locomotive ULSD Fuel ULSD Fuel PM.. NOx.. HC.. CO.. d. U.S. EPA c Tier limits d....... c Tier line-haul locomotives must also meet Tier switch standards. The switch cycle PM standard for new Tier locomotives will change from. to. g/kw-hr on January,. d Twin mm filter samples taken in conjunction with each OC/EC Sample. TEST RESULTS Regulated brake-specific weighted over the EPA Line-haul Locomotive Duty Cycle are shown in Table for both locomotives in their original configurations. Table summarizes the brake-specific weighted over the EPA Switch Locomotive Duty Cycle. All regulated from the two locomotives were within future Tier locomotive standards during the testing for this program. However, due to factors such as process variation, deterioration factor, and compliance at altitude, these results may not meet manufacturer s Tier compliance margins. Table and Table present the line-haul cycle PM summary for the ESDC and the SDACe, respectively. Gravimetric measurements from filter loadings are listed along with the carbonaceous PM analytical results from the OC\EC and the relative portion of OC over the linehaul cycle. The data from Table and Table is shown graphically in Figure for the ESDC, and Figure for the SDACe. Filter measurements and OC\EC analyses correlated well to each other for the SDACe locomotive, where the relative change induced by the exclusion of crankcase was close to % for both the filter derived PM and OC/EC carbonaceous PM over the line-haul cycle. Line-haul composite carbonaceous PM for the ESDC was reduced by % as measured with OC/EC analyses, but the total PM measured gravimetrically from the filters was reduced by only % over the line-haul cycle. For all testing in this work, sulfate PM was less than % of the total brake specific PM over the Line-haul Locomotive Duty Cycle. OC PM accounted for approximately % to % of total carbon PM over the Line-haul cycle for both locomotives in their stock configurations. The relative OC portion of total carbon PM was reduced to approximately % to % of the line-haul composite when the crankcase were not included in the measurements. Table. Summary of brake specific weighted over the EPA Line-haul Locomotive Duty Cycle with locomotives in the stock configuration (blowby included) BNSF UP Current GE EMD U.S. Pollutant ESDC SDACe EPA Locomotive Locomotive Tier ULSD Fuel ULSD Fuel limits PM b... NOx..9. HC... CO.9.. Current U.S. EPA Tier limits U.S. EPA Tier limits.... Table. BNSF ESDC Summary of brake specific PM weighted over the EPA Line-haul Locomotive Duty Cycle b The PM standard for newly remanufactured Tier line-haul locomotives will change to. g/kw-hr on January,. Locomotive Configuration Stock e %change e PM OC/EC PM, %OC,, mm OC/EC OC/EC instruments instruments Filters.. %.. % -% -% -9% Percentages calculated before rounding of numbers for table
Locomotive Configuration Stock %change e OC/EC PM %OC,, OC/EC OC/EC instruments instruments.. %.9.9 % -% -% -%.. TPM EC % %... TPM % EC. % OC.. % %. mm Filters OC+EC w/o crankcase mm Filters w/o crankcase Figure. The relative contribution of EC and OC PM measured over the Line-haul Duty Cycle using the OC/EC instrument setup for the UP EMD SDACe locomotive. The percentages indicate the contribution of OC and EC to total carbon (EC+OC) PM. The error bars represent a 9% confidence interval.... OC+EC Percentages calculated before rounding of numbers for table Line-ha ul cycle compos ite PM e PM, mm Filters Line-haul cycl e com posite PM (g /kw-hr) Table. UP SDACe Summary of brake specific PM weighted over the EPA Line-haul Locomotive Duty Cycle OC.. % Emissions of EC and OC for each locomotive throttle notch position are shown in Figure and Figure for the locomotives in their stock configurations. OC PM accounted for approximately % to % of the total carbon PM mass at the high-load notch position and notch position (maximum power) conditions. OC PM on a massrate basis were highest at the notch position condition for both locomotives. The relatively high organic fraction over the Line-haul Duty Cycle and particularly at high-load conditions differs considerably from results of modern highspeed diesel engines tested over steady-state cycles or at high load conditions., EC PM mass were highest at notch positions and for the ESDC and notch position for the SDACe. OC PM both with and without the inclusion of crankcase are shown in Figure and Figure. OC measurements taken from the ESDC locomotive with the normal crankcase ventilation system routing into the exhaust stack were more variable than OC measurements for the other tested conditions. This was particularly the case at the locomotive notch position, where OC variability significantly contributed to variability in total carbon PM (Figure ). %. OC+EC mm Filters OC+EC w/o crankcase mm Filters w/o crankcase Figure. The relative contribution of EC and OC PM measured over the Line-haul Duty Cycle using the OC/EC instrument setup for the BNSF GE ESDC locomotive. The percentages indicate the contribution of OC and EC to total carbon (EC+OC) PM. The error bars represent a 9% confidence interval. The gravimetrically determined PM mass emission rates with and without crankcase are shown for each throttle notch in Figure for the ESDC, and Figure 9 for the SDACe. Although a general trend of reduced PM through the notches existed for both locomotives in the configuration without crankcase, the reduction was not always significant at a 9% confidence interval. The largest PM reduction measured was at notch for the SDACe locomotive, where the exclusion of crankcase caused a % drop in PM mass emission rate.
Stock Configuration Elemental Carbon PM PM Mass Emission Rate ( g/hr) PM Mas s Emission R ate (g/hr) Organic Carbon PM % % % % % Idle DB Idle DB % % % % % % Figure. PM mass emission rates measured with mm membrane filters for each locomotive throttle notch position for the BNS F GE ESDC locomotive. The error bars represent a 9% confidence interval. Figure. The relative contribution of EC and OC to total Carbon PM measured at each locomotive throttle notch position for the BNSF GE ESDC locomotive in the stock configuration. The percentages indicate the contribution of OC to total carbon (EC+OC) PM. The error bars represent a 9% confidence interval for total carbon PM. Stock Configuration Elemental Carbon PM Organic Carbon PM PM Mass Emissio n Rate (g/hr) PM Mass Emission Rate (g/hr) 9% Idle DB % % % 9% Figure 9. PM mass emission rates measured with mm membrane filters for each locomotive throttle notch position for the UP EMD SDACe locomotive. The error bars represent a 9% confidence interval. Idle DB % % % % % % Figure. The relative contribution of EC and OC to total Carbon PM measured at each locomotive throttle notch position for the UP EMD SDACe Locomotive in the stock configuration. The percentages indicate the contribution of OC to total carbon (EC+OC) PM. The error bars represent a 9% confidence interval for total carbon PM. Similar to the filter measured PM, there was a trend of reduced OC PM when tested without crankcase for nearly all of the throttle notch settings, although the differences were not always significant at a 9% confidence interval for all of the locomotive throttle notch positions. Reductions in OC PM of % to % were observed during operation in notch position when testing without crankcase. These results suggest that OC from crankcase is a significant contributor to OC PM at high load conditions. For model year and later heavy-duty diesel on-highway truck engines, crankcases are closed under regulation in the sense that crankcase count toward the emission limits of the engine. However, for many of these applications improvements in filtration of crankcase gases have allowed venting of crankcase gases into the atmosphere while still achieving stringent PM limits. Based on the current test results, a similar approach may provide improvements over the current PM.
For gravimetrically determined PM, the exclusion of crankcase caused a reduction over the line-haul cycle of % for the GE ESDC locomotive, and % for the EMD SDACe locomotive. OC/EC determined total carbon PM was reduced by % for the ESDC and % for the SDACe over the line-haul cycle when crankcase were not included. The relative OC portion of total carbon PM over the Line-haul Locomotive Duty Cycle was reduced from % for the ESDC in stock configuration, to % when crankcase were not included in the measurement. Similarly, the SDACe total carbon PM over the Line-haul Cycle was % OC in stock configuration, and % OC without the inclusion of crankcase. Stock Configuration OC PM Mass Emission R ate (g/hr) ACKNOWLEDGMENTS The authors wish to thank Michael E. Iden of Union Pacific Railroad for use of the UP locomotive and Mark Stehly of BNSF Railway for use of the BNSF locomotive. The authors also wish to thank Steve G. Fritz, P.E. of Southwest Research Institute for his assistance with locomotive testing and test logistics. Idle DB Figure. A comparison of organic carbon PM from the BNSF GE ESDC locomotive with and without the inclusion of crankcase. The error bars represent a 9% confidence interval. REFERENCES Stock Configuration CFR Parts 9,, et al., Control of Emissions of Air Pollution From Locomotive Engines and Marine Compression-Ignition Engines Less Than Liters per Cylinder; Final Rule, Federal Register, Vol., No., Tuesday, May,, Rules and Regulations, p. O C PM Mass Emission Rate ( g/hr) PM Emissions from Two Tier Locomotives, Locomotive and Marine Docket, EPA-HQ-OAR-9-9.,. Title of the U.S. Code of Federal Regulations, Part 9,. Idle DB Title of the U.S. Code of Federal Regulations, Part,. Y.J. Kim, M.J. Kim, K.H. Lee, S.S. Park. Investigation of carbon pollution episodes using semi-continuous instrument in Incheon, Korea. Atomospheric Environment, Volume, No., pg. -, July. Figure. A comparison of organic carbon PM from the UP EMD SDACe locomotive with and without the inclusion of crankcase. The error bars represent a 9% confidence interval. SUMMARY The -% contribution of organic carbon PM to total PM over the Line-haul Duty Cycle is approximately twice the amount that would be predicted if PM composition was based solely on data acquired from high-speed heavy duty on-highway diesel engines. At high load conditions, this appears to be in part due to the manner in which crankcase gases are scavenged and filtered from the engine. For both the GE and EMD engines, crankcase ventilation contributed to %-% of the tailpipe OC PM at rated power. OC PM was reduced for nearly all throttle notches, although the differences were not always significant at a 9% confidence interval. Emissions of elemental carbon PM are comparable to that of modern high-speed diesel engines on a brake-specific basis. Khalek, I.A. Diesel Particulate Measurement Research. CRC Project E- Phase Final Report, Coordinating Research Council, C.Y. Liang, K.J. Baumgard, R.A. Gorse, Jr., J.E. Orban, J.M.E. Storey, J.C. Tan, J.E. Thoss, W. Clark. Effects of Diesel Fuel Sulfur Level on Performance of a Continuously Regenerating Diesel Particulate Filter and a Catalyzed Particulate Filter. SAE Technical Paper Series, No. --,. E. Jacob, R. Lämmermann, A. Pappenheimer, Diether Rothe. Exhaust Gas Aftertreatment System for Euro Heavy-duty Engines. MTZ Motor Technische Zeitschrift, June. 9
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