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Update on light-duty regulations. Presenter Michael J. McCarthy, California Air Resources Board

In recognizing the potential for large, damaging impacts from climate change, California enacted Executive Order S-03-05, requiring a reduction in statewide greenhouse gas (GHG) emissions to 80% below 1990 levels by 2050. Given that the transportation light-duty vehicle (LDV) segment accounts for 28% of the state's GHG emissions today, it will be difficult to meet the 2050 goal unless a portfolio of near-zero carbon transportation solutions is pursued. Because it takes decades for a new propulsion system to capture a large fraction of the passenger vehicle market due to vehicle fleet turn-over rates, it is important to accelerate the introduction of these alternatives to ensure markets enter into early commercial volumes (10,000s) between 2015 and 2020. This report summarizes the results and conclusions of a modeling exercise that simulated GHG emissions from the LDV sector to 2050 in California.

This study was aimed at experimentally investigating the impact of diesel/natural gas (NG) dual-fuel retrofitting onto gaseous emissions emitted by i) legacy, model year (MY) 2005 heavy-duty engines with cooled EGR and no after-treatment system, and ii) a latest technology engine equipped with DPF and urea-SCR after-treatment systems that is compliant with 2010 US-EPA emissions standards. In particular, two different dual-fuel conversion kits were evaluated in this study with pure methane (CH4) being used as surrogate for natural gas. Experiments were conducted on an engine dynamometer over a 13-mode steady-state test cycle as well as the transient FTP required for engine certification while gaseous emissions were sampled through a CVS system. Tailpipe NOx emissions were observed at a comparable level for diesel and diesel/CH4 dual-fuel operation for the 2010 compliant engine downstream the SCR.

Present motor vehicle particulate matter (PM) emission measurement regulations (Code of Federal Regulations (CFR) 40 Part 1065, 1066) require gravimetric determination of PM mass collected onto filter media from dilute exhaust. To improve the current sampling and measurement procedures for TIER 3 PM emissions standard of 3 mg/mile, CFR part 1066 adopted five alternative PM sampling options. One option of great interest is sampling the entire test using a single flow-weighed filter rather than the conventional three-filter (one filter per test phase) approach. The single filter method could lessen the time needed for gravimetric determination by reducing the quantity of filters used for a test and possibly reduce the uncertainty in gravimetric measurements, particularly at sub 1 mg/mile PM levels. This study evaluates the single filter and, to a limited extent, the 2-filter alternatives adopted in 40 CFR Part 1066.

Recent free piston engine research reported in the literature has included development efforts for single and dual cylinder devices through both simulation and prototype operation. A single cylinder, spring opposed, oscillating linear engine and alternator (OLEA) is a suitable architecture for application as a steady state generator. Such a device could be tuned and optimized for peak efficiency and nominal power at unthrottled operation. One of the significant challenges facing researchers is startup of the engine. It could be achieved by operating the alternator in a motoring mode according to the natural system resonant frequency, effectively bouncing the translator between the spring and cylinder, increasing stroke until sufficient compression is reached to allow introduction of fuel and initiation of combustion. To study the natural resonance of the OLEA, a numeric model has been built to simulate multiple cycles of operation.

Three-way catalyst equipped stoichiometric natural gas vehicles have proven to be an effective alternative fuel strategy that has shown superior low NOx benefits in comparison to diesels equipped with SCR. However, recent studies have shown the TWC activity to contribute to high levels of tailpipe ammonia emissions. Although a non-regulated pollutant, ammonia is a potent pre-cursor to ambient secondary PM formation. Ammonia (NH3) is an inevitable catalytic byproduct of TWCduring that results also corresponds to lowest NOx emissions. The main objective of the study is to develop a passive SCR based NH3 reduction strategy that results in an overall reduction of NH3 as well as NOx emissions from a stoichiometric spark ignited natural gas engine. The study investigated the characteristics of Fe-based and Cu-based zeolite SCR catalysts in storage, and desorption of ammonia at high exhaust temperature conditions, that are typical of stoichiometric natural gas engines.

In-service 1994-2003 heavy-duty trucks were acquired by West Virginia University (WVU), equipped with the WVU Mobile Emissions Measurement System (MEMS) to measure on-road NOx, and driven on road routes near Sabraton, West Virginia, and extending up to Washington, PA to obtain real-world oxides of nitrogen (NOx) emissions data on highways and local roads. The MEMS measured 5Hz NOx, and load was obtained from the electronic control unit. Trucks were loaded to about 95% of their gross vehicle weights. Emissions in g/mi and g/bhp-hr were computed over the various road routes. In addition, some of the trucks were tested 1 to 2 years later to determine emission changes that may have occurred for these trucks. Emission results varied significantly over the different road routes due to different speeds, driving patterns, and road grades.

A work-based window method has been developed to calculate in-use brake-specific oxides of nitrogen (NOx) emissions for all engine speeds and engine loads. During an in-use test, engine speed and engine torque are read from the engine's electronic control unit, and along with time, are used to determine instantaneous engine power. Instantaneous work is calculated using this power and the time differential in the data collection. Work is then summed until the target amount of work is accumulated. The emissions levels are then calculated for that window of work. It was determined that a work window equal to the theoretical Federal Test Procedure (FTP) cycle work best provides a means of comparison to the FTP certification standard. Also, a failure criterion has been established based on the average amount of power generated in the work window and the amount of time required to achieve the target work window to determine if a particular work window is valid.

As part of the 1998 Consent Decrees concerning alternative ignition strategies between the six settling heavy-duty diesel engine manufacturers and the United States government, the engine manufacturers agreed to perform in-use emissions measurements of their engines. As part of the Consent Decrees, pre- (Phase III, pre-2000 engines) and post- (Phase IV, 2001 to 2003 engines) Consent Decree engines used in over-the-road vehicles were tested to examine the emissions of oxides of nitrogen (NOx) and carbon dioxide (CO2). A summary of the emissions of NOx and CO2 and fuel consumption from the Phase III and Phase IV engines are presented for 30 second “Not-to-Exceed” (NTE) window brake-specific values. There were approximately 700 Phase III tests and 850 Phase IV tests evaluated in this study, incorporating over 170 different heavy duty diesel engines spanning 1994 to 2003 model years. Test vehicles were operated over city, suburban, and highway routes.

Pollutants are a major issue of diesel engines, with oxides of nitrogen (NOx) and airborne total particulate matter (TPM) of primary concern. Current emission standards rely on laboratory testing using an engine dynamometer with a standard test procedure. Results are reported as an integrated value for emissions from a transient set of engine speed and load conditions over a length of time or a set of prescribed speed-load points. To be considered a valid test by the US EPA, the measured engine speed and load are compared to the prescribed engine speed and load and must be within prescribed regression limits.

This paper discusses the design and qualification of a High Temperature Sampling System (HTSS), capable of stripping the volatile fraction from a sample flow stream in order to provide for quantification of total, solid and volatile particulate matter (PM) on a near real-time basis. The sampling system, which incorporates a heated diesel oxidation catalyst, is designed for temperatures up to 450°C. The design accounts for molecular diffusion of volatile compounds, solid particles diffusion and reaction kinetics inside one channel of the oxidation catalyst. An overall solid particle loss study in the sampling was performed, and numerical results were compared with experimental data gathered at the West Virginia University Engine and Emissions Research Laboratory (EERL) and West Virginia University's Transportable Heavy-Duty Vehicle Emissions Testing Laboratory (THDVETL).

Oxides of nitrogen (NOx) emissions, produced by engines that burn fuels with atmospheric air, are known to cause negative health and environmental effects. Increasingly stringent emissions regulations for marine engines have caused newer engines to be developed with inherent NOx reduction technologies. Older marine engines typically have a useful life of over 20 years and produce a disproportionate amount of NOx emissions when compared with their newer counterparts. Wet scrubbing as an aftertreatment method for emissions reduction was applied to ocean-going marine vessels for the reduction of sulfur oxides (SOx) and particulate matter (PM) emissions. The gaseous absorption process was explored in the laboratory as an option for reducing NOx emissions from older diesel engines of harbor craft operating in ports of Houston and Galveston. A scrubber system was designed, constructed, and evaluated to provide the basis for a real-world design.

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.

A cooperative vehicle exhaust emissions test program was conducted by the California Air Resources Board and Chevron Research and Technology Company. The focus of the program was to determine the effect of aromatics content on nitrogen oxides (NOx) emissions. The program consisted of testing nine vehicles on three different fuels. The fuels ranged in aromatics content from 10% to 30%.* Other fuel properties were held as constant as possible. The tests were conducted in two different laboratories. In addition to the measurement of criteria emissions (hydrocarbons, carbon monoxide, and NOx), some of the hydrocarbon emissions were speciated and a reactivity of the exhaust was calculated. Only slight changes in the exhaust emissions and reactivity were observed for a change in aromatics content from 30% to 10%.

A study was conducted by the California Air Resources Board to investigate the effects that altitude has on in-use heavy-duty diesel truck smoke opacities. The understanding of these effects may allow for the establishment of a high altitude opacity standard for diesel trucks operating at or above altitudes of 5800 feet. During a three-week study, 170 heavy-duty diesel trucks were tested at an altitude of 5,820 feet using a test procedure consisting of rolling acceleration and snap idle tests. Eighty-four (84) of these trucks were recaptured and retested at an altitude of 125 feet. Results from a regression analysis indicates that, on average, truck smoke opacities increased by 23 opacity points when tested at altitudes near 6000 feet. Possible high altitude cutpoints and failure rates are also discussed.

Emissions from heavy-duty vehicles are a major contributor to California's air quality problems. Emissions from these vehicles account for approximately 30% of the nitrogen oxide and 75% of the particulate matter emissions from the entire on-road vehicle fleet. Additionally, excessive exhaust smoke from in-use heavy-duty diesel vehicles is a target of numerous public complaints. In response to these concerns, California has adopted an in-use Heavy-Duty Vehicle Smoke and Tampering Inspection Program (HDVIP) designed to significantly reduce emissions from these vehicles. Pending promulgation of HDVIP regulations, vehicles falling prescribed test procedures and emission standards will be issued citations. These citations mandate expedient repair of the vehicle and carry civil penalties ranging from $300 to $1800. Failure to clear citations can result in the vehicle being removed from service.

The California Air Resources Board requires that new California vehicles be equipped with on-board diagnostic (OBD) systems. Starting with the 1988 models, these systems were required on new passenger cars, light-duty trucks and medium-duty vehicles equipped with three-way catalysts and feed-back fuel controls. The purpose of the OBD system is to expedite the proper repair of emission-related malfunctions and, thus, reduce vehicle emissions. When malfunctons are detected, a malfunction indicator light (MIL) mounted in the dash panel illuminates cautioning the vehicle operator that a repair is needed. Also, a fault code is stored in the OBD computer memory. When the vehicle is brought to a repair facility, the fault code provides the mechanic with the likely areas of malfunction for repairing the vehicle. After the repair is performed, the fault code is cleared, the MIL is extinguished, and the OBD system will subsequently confirm if the proper repair has been performed.

Since the mid-1990s, light-duty vehicles equipped with gasoline direct injection (GDI) engines have been added to the vehicle fleet in increasing numbers. Compared to conventional port fuel injection (PFI) engines, GDI engines provide higher power output for the same size engine, higher fuel efficiency, and lower carbon dioxide (CO₂) emissions. Due to the paucity of particulate matter (PM) emission data for light-duty gasoline vehicles in general and the increasing interest in these emissions relative to climate and air quality concerns, it is important to investigate PM emissions from current-generation GDI technologies. In this study, nine 2007-2010 light-duty GDI vehicles equipped with either wall-guided or spray-guided fuel injection systems were tested using California commercial gasoline fuel containing six percent ethanol by volume. Criteria pollutants including gaseous and PM emissions were measured over the Federal Test Procedure (FTP) transient test cycle.

The impact of biodiesel and new generation biofuels on emissions from heavy-duty diesel engines was investigated using a California Air Resources Board (CARB) certified diesel fuel as a base fuel. This study was performed on two heavy-duty diesel engines, a 2006 engine and a diesel particle filter (DPF) equipped 2007 engine, on an engine dynamometer over four different test cycles. Emissions from soy-based and animal-based biodiesel, renewable diesel fuel, and gas-to-liquid (GTL) diesel fuel were evaluated at blend levels ranging from 5 to 100%. Consistent with previous studies, particulate matter (PM), hydrocarbons (HC), and carbon monoxide (CO) emissions generally showed increasing reductions with increasing biodiesel and renewable/GTL diesel fuel blend levels for the non-DPF equipped engine. The levels of these reductions were generally comparable to those found in previous studies performed using more typical Federal diesel fuels.

The key to overcoming Low Temperature Combustion (LTC) load range limitations is based on suitable control over the thermo-chemical properties of the in-cylinder charge. The proposed alternative to achieve the required control of LTC is the use of two separate fuel streams to regulate timing and heat release at specific operational points, where the secondary fuel, with different autoignition characteristics, is a reformed product of the primary fuel in the tank. It is proposed in this paper that the secondary fuel is produced using Thermo-Chemical Recuperation (TCR) with steam/fuel reforming. The steam/fuel mixture is heated by sensible heat from the engine exhaust gases in the recuperative reformer, where the original hydrocarbon reacts with water to form a hydrogen rich gas mixture. An equilibrium model developed by Gas Technology Institute (GTI) for n-heptane steam reforming was applied to estimate reformed fuel composition at different reforming temperatures.