David L. McKain

Chassis Test Cycles for Assessing Emissions from Heavy Duty Trucks

Emissions from internal combustion engines can be evaluated by testing the engine itself or testing a whole vehicle using a chassis dynamometer. Recent concerns over atmospheric pollution and the drive to examine alternative fuel technology have led to an interest in chassis testing of trucks and buses. In particular these chassis tests permit the examination of changing emissions over the life of the vehicle. Identification of the chassis test protocols for heavy duty vehicles remains inchoate, but this paper seeks to assuage part of the problem by offering a practical test schedule for Class 8 trucks and truck-tractors in the 15000 to 36,360 kg GVW range. 8 refs., 15 figs., 1 tab.

Evaluation of Emissions from New and In-Use Transit Buses in Mexico City, Mexico

The West Virginia University Transportable Heavy-Duty Emissions Testing Laboratory was used to evaluate exhaust emissions from nine transit buses from six separate manufacturers, as commissioned by the Mexico City, Mexico, Secretariat of the Environment. The vehicles included a hybrid-drive diesel bus, two buses with lean-burn spark-ignited compressed natural gas (CNG) engines, and six buses powered by conventional diesel engines. Vehicle testing weights (curb weight plus passenger weight) ranged from 26,996 Ib (12,256 kg) to 57,025 Ib (25,889 kg), and passenger capacities ranged from 85 to 161. Two driving cycles, the European Transient Cycle (ETC, also known as the FIGE transient cycle) and a new, three-mode Mexico City Schedule, were used to simulate in-use driving conditions during emissions measurements. Diesel fuels with three different sulfur concentrations (15, 150, and 350 ppm) were also examined, and the lowest-sulfur fuel (15 ppm) was not found to have an appreciable direct effect on emissions....

Correlating local tube surface heat transfer with bubble presence in a fluidized bed

Abstract A fifty-one millimeter outside diameter heat transfer tube of thirteen millimeter wall thickness was fitted horizontally into a cold bubbling bed of sand and fed with a supply of hot water. The surface of the tube was instrumented with five miniature thermocouples and, in addition, two pressure taps were drilled into the tube to infer bubble presence from vertical pressure gradients. The relationships between bubbling frequency and bed height as well as bubbling frequency and fluidizing velocity are reported. The correlation between transient temperature and differential pressure data shows the influence of bubble events on the local tube heat transfer. Velocity of a bubble at the tube surface could also be inferred from multiple thermocouple data.

Testing of a Heavy Heavy-Duty Diesel Engine Schedule for Representative Measurement of Emissions

Abstract The Advanced Collaborative Emissions Study (ACES) program required the use of representative heavy-duty diesel engine activity. This need resulted in an engine test schedule creation program, and a schedule of engine modes representative of modern truck usage was developed based on data collected from engines in trucks operated through the heavy heavy-duty diesel truck (HHDDT) chassis schedule. The ACES test schedule included four active modes of truck operation including creep, transient, cruise, and high-speed cruise (HHDDT_S). This paper focuses on Phase 2 of the program, which was to validate and demonstrate the use of the ACES modes in a test cell. Preliminary testing was performed using a 1992 Detroit Diesel Corporation heavy heavy-duty diesel engine (HHDDE) on only the transient mode. On the basis of these results, each mode was modified slightly to suit implementation in a test cell. The locations of “closed throttle” points in the modes were determined through careful examination of the data. These closed throttle points were simulated during testing by adding negative set point torque values to the input file. After modification, all modes were tested during a final ACES modes demonstration period using a 2004 Cummins ISM HHDDE, obtaining three runs for each mode. During testing, carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), particulate matter (PM), and hydrocarbon (HC) emissions were measured, and engine control unit (ECU) data were recorded. The new ACES modes did not adopt the Federal Test Procedure (FTP) regression criteria. New regression criteria for acceptability of a run were determined for each mode using the data obtained during testing.

Pump-to-Wheels Methane Emissions from the Heavy-Duty Transportation Sector

Pump-to-wheels (PTW) methane emissions from the heavy-duty (HD) transportation sector, which have climate change implications, are poorly documented. In this study, methane emissions from HD natural gas fueled vehicles and the compressed natural gas (CNG) and liquefied natural gas (LNG) fueling stations that serve them were characterized. A novel measurement system was developed to quantify methane leaks and losses. Engine related emissions were characterized from twenty-two natural gas fueled transit buses, refuse trucks, and over-the-road (OTR) tractors. Losses from six LNG and eight CNG stations were characterized during compression, fuel delivery, storage, and from leaks. Cryogenic boil-off pressure rise and pressure control venting from LNG storage tanks were characterized using theoretical and empirical modeling. Field and laboratory observations of LNG storage tanks were used for model development and evaluation. PTW emissions were combined with a specific scenario to view emissions as a percent of throughput. Vehicle tailpipe and crankcase emissions were the highest sources of methane. Data from this research are being applied by the authors to develop models to forecast methane emissions from the future HD transportation sector.

Deduction of fluidized bed heat transfer coefficients using one- and two-dimensional analyses

Abstract Prior calculations of heat transfer coefficients for an experimental horizontal tube in a bubbling fluidized bed have assumed that heat conduction through the tube wall is a one-dimensional problem. However, a comparison between one-dimensional (1D) and two-dimensional (2D) analyses using experimental data shows that there exists a significant difference between 1D and 2D calculations, especially at the side of the tube. In addition, because of the periodic character of the bubbling fluidized beds, a theoretical analysis of a horizontal tube subjected to a periodic temperature boundary condition which varies in the circumferential direction is presented. The 2D analysis was accomplished by solving the unsteady two-dimensional heat conduction equation numerically, where the boundary conditions were taken from temperature data measured at five different locations of the tube simultaneously.

A chassis test procedure to mimic the heavy-duty engine transient emissions certification test.

ABSTRACT In-use emissions from vehicles using heavy-duty diesel engines can be significantly higher than the levels obtained during engine certification. These higher levels may be caused by a combination of degradation of engine components, poor engine maintenance, degradation or failure of emissions after-treatment devices, and engine and emissions system tampering. A direct comparison of in-use vehicle emissions with engine certification levels, however, is not possible without removing an engine from the vehicle in order to perform engine dynamometer emissions testing. The goal of this research was to develop a chassis test procedure that mimics the engine performance, and as such the expected emissions levels, from the engine certification emissions test prescribed in the U.S. Code of Federal Regulations. Emissions measurements were taken from two engines during testing on an engine dynamometer using the transient heavy-duty Federal Test Procedure (FTP). Additionally, each engine was installed in an appropriate vehicle, and emissions measurements were taken using a chassis dynamometer while employing a vehicle driving schedule

Future methane emissions from the heavy-duty natural gas transportation sector for stasis, high, medium, and low scenarios in 2035

ABSTRACT Today’s heavy-duty natural gas–fueled fleet is estimated to represent less than 2% of the total fleet. However, over the next couple of decades, predictions are that the percentage could grow to represent as much as 50%. Although fueling switching to natural gas could provide a climate benefit relative to diesel fuel, the potential for emissions of methane (a potent greenhouse gas) from natural gas–fueled vehicles has been identified as a concern. Since today’s heavy-duty natural gas–fueled fleet penetration is low, today’s total fleet-wide emissions will be also be low regardless of per vehicle emissions. However, predicted growth could result in a significant quantity of methane emissions. To evaluate this potential and identify effective options for minimizing emissions, future growth scenarios of heavy-duty natural gas–fueled vehicles, and compressed natural gas and liquefied natural gas fueling stations that serve them, have been developed for 2035, when the populations could be significant. The scenarios rely on the most recent measurement campaign of the latest manufactured technology, equipment, and vehicles reported in a companion paper as well as projections of technology and practice advances. These “pump-to-wheels”(PTW) projections do not include methane emissions outside of the bounds of the vehicles and fuel stations themselves and should not be confused with a complete wells-to-wheels analysis. Stasis, high, medium, and low scenario PTW emissions projections for 2035 were 1.32%, 0.67%, 0.33%, and 0.15% of the fuel used. The scenarios highlight that a large emissions reductions could be realized with closed crankcase operation, improved best practices, and implementation of vent mitigation technologies. Recognition of the potential pathways for emissions reductions could further enhance the heavy-duty transportation sectors ability to reduce carbon emissions. Implications: Newly collected pump-to-wheels methane emissions data for current natural gas technologies were combined with future market growth scenarios, estimated technology advancements, and best practices to examine the climate benefit of future fuel switching. The analysis indicates the necessary targets of efficiency, methane emissions, market penetration, and best practices necessary to enable a pathway for natural gas to reduce the carbon intensity of the heavy-duty transportation sector.

Novel NOx Emission Reduction Technology for Diesel Marine Engines

Emissions from diesel marine engines are significant contributors to the emissions inventories of commercial ports. Prior to 1998, these emissions were unregulated and current EPA regulations apply predominantly to new engines. Considering that the useful life of marine engines in work vessels, such as tugboats, may be 20 years or longer, retrofit emission reduction technologies are needed for these legacy engines. Oxides of nitrogen (NOx ) have negative health and environmental impacts and are difficult to reduce substantially without aftertreatment. A scrubber system for NOx reduction was proposed; the presented research focuses on the verification of operating principles and the quantification of possible NOx reduction from this system. Major elements of the proposed scrubber system are exhaust heat exchangers, a catalyzed particulate filter (CPF), a diesel oxidation catalyst (DOC), and a packed bed wet scrubber. The system works on the principle of absorption of NOx species into water. The majority of engine-out NOx is in the form of nitric oxide (NO) which is relatively insoluble in water. A CPF and a DOC are utilized to convert up to 80% of the NO into nitrogen dioxide, NO2 . NO2 and NO exist in equilibrium with N2 O3 and N2 O4 , species of NOx that are highly soluble in water. The use of a CPF and DOC also reduces carbon monoxide, hydrocarbons, and particulate matter, reducing possible scrubber contamination. The scrubber liquor operates on a closed loop with zero discharge, its final composition is weak nitric acid; a byproduct of capturing the NOx . Research to support this design was conducted on a Mack E7 298 kW, 12 liter engine operating over 8 steady state points. Modal NOx absorption ranged from 4–66%. Cycle average NOx absorption ranged from 15–58%. It was concluded that NOx absorption varies with gas residence time, absorption surface area, temperature, and NOx concentration. Separately, a system was constructed and operated to convert the stored concentrated NOx into diatomic nitrogen, carbon dioxide, and water.Copyright