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The most recent 2010 emissions standards for heavy-duty engines have established a tailpipe limit of oxides of nitrogen (NOX) emissions of 0.20 g/bhp-hr. However, it is projected that even when the entire on-road fleet of heavy-duty vehicles operating in California is compliant with 2010 emission standards, the National Ambient Air Quality Standards (NAAQS) requirement for ambient particulate matter and Ozone will not be achieved without further reduction in NOX emissions. The California Air Resources Board (CARB) funded a research program to explore the feasibility of achieving 0.02 g/bhp-hr NOX emissions.

California Air Resources Board (CARB) has instituted requirements for on-board diagnostics (OBD) that makes a spark-plug sized exhaust particulate matter (PM) sensor a critical component of the OBD system to detect diesel particulate filter (DPF) failure. Currently, non-real-time resistive-type sensors are used by engine OEMs onboard vehicles. Future OBD regulations are likely to lower PM OBD thresholds requiring higher sensitivity sensors with better data yield for OBD decision making. The focus of this work was on the experimental evaluation of a real-time PM sensor manufactured by EmiSense Technologies, LLC that may offer such benefits. A 2011 model year on-highway heavy-duty diesel engine fitted with a diesel oxidation catalyst (DOC) and a catalyzed DPF followed by urea-based selective catalytic reducer (SCR) and ammonia oxidation (AMOX) catalysts was used for this program.

This paper summarizes the Heavy-Duty In-Use Testing (HDUIT) measurement allowance program for Particulate Matter Portable Emissions Measurement Systems (PM-PEMS). The measurement allowance program was designed to determine the incremental error between PM measurements using the laboratory constant volume sampler (CVS) filter method and in-use testing with a PEMS. Two independent PM-PEMS that included the Sensors Portable Particulate Measuring Device (PPMD) and the Horiba Transient Particulate Matter (TRPM) were used in this program. An additional instrument that included the AVL Micro Soot Sensor (MSS) was used in conjunction with the Sensors PPMD to be considered a PM-PEMS. A series of steady state and transient tests were performed in a 40 CFR Part 1065 compliant engine dynamometer test cell using a 2007 on-highway heavy-duty diesel engine to quantify the accuracy and precision of the PEMS in comparison with the CVS filter-based method.

Criteria pollutants were measured from ten Class 7 and 8 (i.e., gross vehicle weights > 33,000 lb) heavy-duty diesel trucks with engine model years between 1953 and 1975. The data was used by EPA to estimate that period's particulate matter emission rates for these type engines and will be used to develop dose response relationships with existing epidemiological data. Particulate samples were analyzed for sulfate and volatile organic fraction. Carbon soot was estimated. The trucks had particulate emissions of 2 to 10 g/mi as compared to 1 to 6 g/mi for trucks with model year engines from 1975 through the mid-1980s, and less than 1 g/mi for post-1988 trucks.

The effects of an oxidation catalytic converter (OCC), an emulsified fuel, and their combined effects on particle number and volume concentrations compared to those obtained when using a basefuel were studied. Particle size and particulate emission measurements were conducted at three operating conditions; idle (850 rpm, 35 Nm), Mode 11 (1900 rpm, 277 Nm) and Mode 9 (1900 rpm, 831 Nm) of the EPA 13 mode cycle. The individual effects of the emulsified fuel and the OCC as well as their combined effects on particle number and volume concentrations were studied at two different particle size ranges; the nuclei (less than or equal to 50 nm) and accumulation (greater than 50 nm) modes. An OCC loaded with 10 g/ft3 platinum metal (OCC1) and a 20% emulsified fuel were used for this study and a notable influence on the particle size with respect to number and volume distributions was observed.

A study was conducted to assess the effects of a water-diesel fuel emulsion with and without an oxidation catalytic converter (OCC) on steady-state heavy-duty diesel engine emissions. Two OCCs with different metal loading levels were used in this study. A 1988 Cummins L10-300 heavy-duty diesel engine was operated at the rated speed of 1900 rpm and at 75% and 25% load conditions (EPA modes 9 and 11 respectively) of the 13 mode steady-state test as well as at idle. Raw exhaust emissions' measurements included total hydrocarbons (HC), oxides of nitrogen (NOx) and nitric oxide (NO). Diluted exhaust measurements included total particulate matter (TPM) and its primary constituents, the soluble organic (SOF), sulfate (SO42-) and the carbonaceous solids (SOL) fractions. Vapor phase organic compounds (XOC) were also analyzed. The SOF and XOC samples were analyzed for selected polynuclear aromatic hydrocarbons (PAHs).

Emissions from existing diesel-powered urban buses are increasingly scrutinized as local, state, and federal governments require enforcement of more stringent emission regulations and expectations. Currently, visual observation of high smoke levels from diesel-powered equipment is a popular indicator of potential emission problems requiring tune-up or engine maintenance. It is important that bus inspection and maintenance (I/M) operations have a quality control “test” to check engine emissions or diagnose the engine state-of-tune before or after maintenance. Ideally, the “emission test” would be correlated to EPA transient emissions standards, be of short duration, and be compatible with garage procedures and equipment. In support of developing a useful “short-test,” equipment was designed to collect samples of raw exhaust over a short time period for gaseous and particulate emissions.

An investigation was performed to determine the effects of applying on-highway heavy-duty diesel engine emissions reduction technology to an off-highway version of the engine. Special attention was paid to the typical constraints of fuel consumption, heat rejection, packaging and cost-effectiveness. The primary focus of the effort was NOx, reduction while hopefully not worsening other gaseous and particulate emissions. Hardware changes were limited to “bolt-on” items, thus excluding piston and combustion chamber modifications. In the final configuration, NOx was improved by 28 percent, particulates by 58 percent, CO and HC were also better and the fuel economy penalty was limited to under 4 percent. Observations are made about the effectiveness of various individual and combined strategies, and potential problems are identified.

Solid and metallic ash particle number (PN) and particulate matter (PM) mass emission measurements were performed on a heavy-duty (HD) on-highway diesel engine and a compressed natural gas (CNG) engine. Measurements were conducted under transient engine operation that included the FTP, WHTC and RMC. Both engines were calibrated to meet CARB ultra low NOX emission target of 0.02 g/hp-hr, a 90% reduction from current emissions limit. The HD diesel engine final exhaust configuration included a number of aftertreatement sub-systems in addition to a selective catalytic reduction filter (SCRF). The stoichiometric CNG engine final configuration included a closed coupled Three Way Catalyst (ccTWC) and an under floor TWC (ufTWC). The aftertreatment systems for both engines were aged for a full useful life (FUL) of 435,000 miles, prior to emissions testing. PM mass emissions from both engines were comparable and well below the US EPA emissions standard.

The objective of this project was to assess the effects of various blends of biodiesel on locomotive engine exhaust emissions. Systematic, credible, and carefully designed and executed locomotive fuel effect studies produce statistically significant conclusions are very scarce, and only cover a very limited number of locomotive models. Most locomotive biodiesel work has been limited to cursory demonstration programs. Of primary concern to railroads and regulators is understanding any exhaust emission associated with biodiesel use, especially NOX emissions. In this study, emissions tests were conducted on two locomotive models, a Tier 2 EMD SD70ACe and a Tier 1+ GE Dash9-44CW with two baseline fuels, conventional EPA ASTM No. 2-D S15 (commonly referred to as ultra-low sulfur diesel - ULSD) certification diesel fuel, and commercially available California Air Resource Board (CARB) ULSD fuel.

Measurement of emissions from small utility engines has usually been accomplished using steady-state raw emissions procedures such as SAE Recommended Practice J1088. While raw exhaust measurements have the advantage of producing modal exhaust gas concentration data for design feedback; they are laborious, may influence both engine performance and the emissions themselves, and have no provision for concurrent particulate measurements. It is time to consider a full-dilution procedure similar in principle to automotive and heavy-duty on-highway emission measurement practice, leading to improvements in many of the areas noted above, and generally to much higher confidence in data obtained. When certification and audit of small engine emissions become a reality, a brief dilute exhaust procedure generating only the necessary data will be a tremendous advantage to both manufacturers and regulatory agencies.

Heavy duty trucks account for about 50 percent of the NOx burden in urban areas and consume about 20 percent of the national transportation fuel in the United States. There is a continuing need to reduce emissions and fuel consumption. Much of the focus of current work is on engine development as a stand-alone subsystem. While this has yielded impressive gains so far, further improvement in emissions or engine efficiency is unlikely in a cost effective manner. Consequently, an integrated approach looking at the whole powertrain is required. A computer model of the heavy duty truck system was built and evaluated. The model includes both conventional and hybrid powertrains. It uses a series of interacting sub-models for the vehicle, transmission, engine, exhaust aftertreatment and braking energy recovery/storage devices. A specified driving cycle is used to calculate the power requirements at the wheels and energy flow and inefficiencies throughout the drivetrain.

As governmental agencies focus on low levels of the oxides of nitrogen (NOx) emissions compliance, new off-road applications are being reviewed for both regulated and unregulated emissions to understand the technological challenges and requirements for improved emissions performance. The California Air Resources Board (CARB) has declared its intention to pursue more stringent NOX standards for the off-road market. As part of this effort, CARB initiated a program to provide a detailed characterization of emissions meeting the current Tier 4 off-road standards [1]. This work focused on understanding the off-road market, establishing a current technology emissions baseline, and performing initial modeling on potential low NOx solutions. This paper discusses a part of this effort, focuses on the emissions characterization from two non-road engine platforms, and compares the emissions species from different approaches designed to meet Tier 4 emissions regulations.

As agencies continue to focus on emissions compliance, low NOX discussions have started to propagate beyond the on-highway market. Nonroad applications, which contribute to 29% of the PM emissions and 11% of the NOX emissions in California, are being reviewed to understand the technological challenges and requirements for improved emissions performance. To help facilitate a nonroad low NOX technology demonstration, information from current engine and aftertreatment technologies required a detailed assessment. The following work will discuss the emissions characterization results from two non-road engine platforms. The intention of this study was to compare the emissions species from different approaches designed to meet Tier 4 emissions regulations. The platforms reflect available technology for DPF and non-DPF aftertreatment architectures.

Regulated gaseous, particulate and several unregulated emissions are reported from four heavy-duty diesel engines operated on the chassis version of the 1983 transient procedure. Emissions were obtained from Caterpillar 3208, Mack ENDT 676, Cummins Formula 290 and Detroit Diesel 8V-71 engines with several diesel fuels. A large dilution tunnel (57′ × 46″ ID) was fabricated to allow total exhaust dilution, rather than the double dilution employed in the stationary engine version of the transient procedure. A modal particulate sampler was developed to obtain particulate data from the individual segments of the 1983 transient procedure. The exhaust gas was analyzed for benzo(a)pyrene, metals, N2O, NO2, individual hydrocarbons and HCN. Sequential extractions were performed and measured versus calculated fuel consumptions were obtained.

A heavy duty (150 kW) diesel engine was tested to determine operational problems while running on minimally processed synthetic fuels. A reference No. 2 diesel fuel was compared with liquid products derived from shale, tar sands, and coal. Information on the engine setup and test procedure is presented. The test results include engine power, thermal efficiency, ignition delay, gaseous and particulate emissions, smoke opacity, cylinder pressure, and heat release data. Cold start data at 0°C and −20° C and idle deposit test results are also presented. These data should help to determine future engine modifications to enhance synfuel engine performance.

Recent 2010 emissions standards for heavy-duty engines have established a limit of oxides of nitrogen (NOX) emissions of 0.20 g/bhp-hr. However, CARB has projected that even when the entire on-road fleet of heavy-duty vehicles operating in California is compliant with 2010 emission standards, the National Ambient Air Quality Standards (NAAQS) requirement for ambient particulate matter and Ozone will not be achieved without further reduction in NOX emissions. The California Air Resources Board (ARB) funded a research program to explore the feasibility of achieving 0.02 g/bhp-hr NOX emissions. This paper details engine and aftertreatment NOX management requirements and model based control considerations for achieving Ultra-Low NOX (ULN) levels with a heavy-duty diesel engine. Data are presented for several Advanced Technology aftertreatment solutions and the integration of these solutions with the engine calibration.

The 2010 emissions standards for heavy-duty engines have established a limit of oxides of nitrogen (NOX) emissions of 0.20 g/bhp-hr. However, the California Air Resource Board (ARB) projects that even when the entire on-road fleet of heavy-duty vehicles operating in California is compliant with 2010 emission standards, the National Ambient Air Quality Standards (NAAQS) requirement for ambient particulate matter (PM) and Ozone will not be achieved without further reduction in NOX emissions. The California Air Resources Board (CARB) funded a research program to explore the feasibility of achieving 0.02 g/bhp-hr NOX emissions.

Particle number concentrations and size distributions were measured for the diluted exhaust of a 1991 diesel engine during the US FTP transient cycle for heavy-duty diesel engines. The engine was operated on US 2-D on-highway diesel fuel. The particle measurement system consisted of a full flow dilution tunnel as the primary dilution stage, an air ejector pump as the secondary dilution stage, and an electrical low pressure impactor (ELPI) for particle size distribution measurements. Particle number emission rate was the highest during the Los Angeles Non Freeway (LANF) and the Los Angeles Freeway (LAF) segments of the transient cycle. However, on brake specific number basis the LAF had the lowest emission level. The particle size distribution was monomodal in shape with a mode between 0.084 μm and 0.14 μm. The shape of the size distribution suggested no presence of nanoparticles below the lower detection limit of the instrument (0.032 μm), except during engine idle.

The diesel engine has long been the most energy efficient powerplant for transportation. Moreover, diesels emit extremely low levels of hydrocarbon and carbon monoxide that do not require post-combustion treatment to comply with current and projected standards. It is admittedly, however, difficult for diesel engines to simultaneously meet projected nitrogen oxides and particulate matter standards. Traditionally, measures aimed at reducing one of these two exhaust species have led to increasing the other. This physical characteristic, which is known as NOx/PM tradeoff, remains the subject of an intense research effort. Despite this challenge, there is significant evidence that heavy-duty highway engine manufacturers can achieve substantial emission reductions. Many development programs carried out over the last five years have yielded remarkable results in laboratory demonstrations.