A significant number of city buses, city tractors and utility trucks are already operating on alternative fuels such as methanol, ethanol and natural gas. In response to the need for reliable emissions data from these vehicles, a transportable laboratory has been constructed and has operated on six different dates over the past nine months. This laboratory consists of a semi–trailer incorporating a chassis rolls dynamometer and a second trailer containing the necessary emissions and controls equipment. The semi–trailer can be lowered to the ground using specially designed hydraulic jacks and the vehicle to be tested is driven up ramps onto the rolls. Power is taken from the vehicle to flywheels and air–cooled eddy–current absorbers which simulate inertia and road load. The vehicle is driven through a speed–time cycle by a driver receiving a prompt on a screen, and vehicle speed is monitored by shaft encoders at three locations. The load applied to the vehicle is found using a road load equation: part of this energy is dissipated in rotating component parasitic losses determined during a calibration procedure and the remainder is dissipated by the computer–controlled power absorbers. Tailpipe emissions are ducted to a dilution tunnel, powered by a blower with critical flow venturies, while probes in the tunnel draw continuous samples to an analyser bench. Total hydrocarbons, oxides of nitrogen, carbon monoxide and carbon dioxide are all monitored, while a composite particulate matter sample is obtained on a filter. A bank of such data for methanol, diesel, jet fuel and natural gas powered buses operating primarily on the Central Business District Cycle is presently being gathered and analysed.

An appropriate chassis dynamometer simulation of an actual vehicle road load is essential if a realistic emissions assessment is to be obtained. This requires a full understanding of the effects of actual road load parameters and the factors associated with their determination, as well as an accurate model to predict the dynamometer dissipated power at each vehicle speed of the testing cycle. In this study, details of the model which predicts the performance of an emissions testing facility are described. The model, based on a combination of fundamental energy balance relations and calibration data, includes predictions of the dissipated energy of the system's main components. This energy is mainly attributed to friction rubbing between mating parts and pumping losses. A quadratic least square fit for dissipated torque measured at different steady–speed calibration tests is provided, and the physical meaning of each term is discussed. Employing the lumped thermal capacitance method, the subsystems' temperature profiles are predicted. The developed model is made to simulate the dynamometer's performance during selected driving test cycles. Cycles are categorised as either being actual or synthesised after an evaluation of their events. A scale of fourteen parameters has been used to characterise each of the selected test cycles. Results of the simulation are pesented, which include the total energy consumed, flywheel wall shear losses, power absorber blower pumping work, the rubbing losses of the dynamometer main components, and predictions of the temperature history for each subsystem. The effect of the tested vehicle weight on the dynamometer's performance is also investigated.

Distance-specific fuel economy (FE) and emissions of carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NOx), and particulate matter (PM) from transit buses representing diesel, retrofitted diesel, hybrid-electric diesel, and lean-burn natural gas technologies are presented in this paper. Emissions were collected from these buses at the Washington Metropolitan Area Transport Authority (WMATA) test site in Landover, Maryland. In this program, one bus each from diesel, retrofitted diesel, hybrid-electric diesel, and natural gas technologies was tested on 17 chassis cycles and the other buses were tested on a subset of these cycles. Data show that the test cycle has a profound effect on distance-specific emissions and FE, and relative emissions performance of technology is also cycle dependant. Lean-burn natural gas buses demonstrated their low PM output, diesel engines showed low HC output, benefit of exhaust filtration was evident, and the positive effect of hybrid-electric drive technology was most pronounced for low-speed transient cycles.

The key aspects and features of curved composites using acoustic emission and Fibre Bragg Gratings (FBG) are discussed. The improved knowledge of the low ratio of delamination strength to ultimate tensile strength for the laminates tested is of benefit for designers.

Idle emissions data from 19 medium heavy-duty diesel and gasoline trucks are presented in this paper. Emissions from these trucks were characterized using full-flow exhaust dilution as part of the Coordinating Research Council (CRC) Project E-55/59. Idle emissions data were not available from dedicated measurements, but were extracted from the continuous emissions data on the low-speed transient mode of the medium heavy-duty truck (MHDTLO) cycle. The four gasoline trucks produced very low oxides of nitrogen (NOx) and negligible particulate matter (PM) during idle. However, carbon monoxide (CO) and hydrocarbons (HCs) from these four trucks were approximately 285 and 153 g/hr on average, respectively. The gasoline trucks consumed substantially more fuel at an hourly rate (0.84 gal/hr) than their diesel counterparts (0.44 gal/hr) during idling. The diesel trucks, on the other hand, emitted higher NOx (79 g/hr) and comparatively higher PM (4.1 g/hr), on average, than the gasoline trucks (3.8 g/hr of NOx and 0.9 g/hr of PM, on average). Idle NOx emissions from diesel trucks were high for post-1992 model year engines, but no trends were observed for fuel consumption. Idle emissions and fuel consumption from the medium heavy-duty diesel trucks (MHDDTs) were marginally lower than those from the heavy heavy-duty diesel trucks (HHDDTs), previously reported in the literature.

National average diesel and compressed natural gas fuel price increased to $4.71 per gallon and $14.41 per thousand cubic feet in July 2008. West Virginia University did a life cycle cost analysis for the Federal Transit Administration on diesel hybrid-electric bus technology, conventional diesel bus technology using ultra low sulfur diesel, conventional diesel bus technology using B20 biodiesel fuel, and compressed natural gas bus technology. The fuel price forecast in the previous analysis ($2.67 per gallon for diesel and $13.34 per thousand cubic feet estimated in 2008) was much lower than the current fuel price. The life cycle cost of the four technologies was recalculated according to the high fuel cost. The report addressed how fuel costs were estimated and presented the life cycle cost summary charts for the four different fuel price scenarios.

The Center for Alternative Fuels, Engines, and Emissions (CAFEE) of West Virginia University (WVU) recently tested a 2000 model year Orion diesel bus on fourteen test cycles to characterize emissions from this bus and to investigate possible correlations between cycle characteristics and emissions. The WVU Heavy-Duty Transportable Emissions Measurement Laboratory was used to collect emissions in accordance with EPA regulations and accepted industry practice. This paper investigates how oxides of nitrogen (NOx), particulate matter (PM), carbon dioxide (CO2), carbon monoxide (CO), and hydrocarbons (HC) emissions from a diesel transit bus correlate with average speed and idle duration of the drive cycles. Analyses showed that distance-specific emissions of these pollutants were significantly affected by both average cycle speed and idle percentage. However, time-specific CO and PM were affected little by average speed. This is reasonable since CO and PM emissions are more strongly affected by the transient nature of drive cycles than their average speed. Idle percentage, however, did not influence time-specific emissions of these pollutants. Available data showed that average vehicle speed could be a reasonable tool in predicting distance-specific emissions of NOx, PM, CO2, CO, and HC from diesel buses.

Heavy-duty diesel vehicle idling consumes fuel and reduces atmospheric quality, but its restriction cannot simply be proscribed, because cab heat or air-conditioning provides essential driver comfort. A comprehensive tailpipe emissions database to describe idling impacts is not yet available. This paper presents a substantial data set that incorporates results from the West Virginia University transient engine test cell, the E-55/59 Study and the Gasoline/Diesel PM Split Study. It covered 75 heavy-duty diesel engines and trucks, which were divided into two groups: vehicles with mechanical fuel injection (MFI) and vehicles with electronic fuel injection (EFI). Idle emissions of CO, hydrocarbon (HC), oxides of nitrogen (NOx), particulate matter (PM), and carbon dioxide (CO2) have been reported. Idle CO2 emissions allowed the projection of fuel consumption during idling. Test-to-test variations were observed for repeat idle tests on the same vehicle because of measurement variation, accessory loads, and ambient conditions. Vehicles fitted with EFI, on average, emitted approximately 20 g/hr of CO, 6 g/hr of HC, 86 g/hr of NOx, 1 g/hr of PM, and 4636 g/hr of CO2 during idle. MFI equipped vehicles emitted approximately 35 g/hr of CO, 23 g/hr of HC, 48 g/hr of NOx, 4 g/hr of PM, and 4484 g/hr of CO2, on average, during idle. Vehicles with EFI emitted less idle CO, HC, and PM, which could be attributed to the efficient combustion and superior fuel atomization in EFI systems. Idle NOx, however, increased with EFI, which corresponds with the advancing of timing to improve idle combustion. Fuel injection management did not have any effect on CO2 and, hence, fuel consumption. Use of air conditioning without increasing engine speed increased idle CO2, NOx, PM, HC, and fuel consumption by 25% on average. When the engine speed was elevated from 600 to 1100 revolutions per minute, CO2 and NOx emissions and fuel consumption increased by >150%, whereas PM and HC emissions increased by approximately 100% and 70%, respectively. Six Detroit Diesel Corp. (DDC) Series 60 engines in engine test cell were found to emit less CO, NOx, and PM emissions and consumed fuel at only 75% of the level found in the chassis dynamometer data. This is because fan and compressor loads were absent in the engine test cell.

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 lb (12,256 kg) to 57,025 lb (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. When the ETC was used, oxides of nitrogen (NOx) emissions varied from 5.5 to 11.6 g/mi, whereas particulate matter emissions varied from 0.02 to 0.86 g/mi. Significant differences in emissions and fuel economy for the two CNG buses raised the issue that fuel delivery systems must be optimized for operation at high altitudes. The differences in fuel economy and NOx emissions from the hybrid bus for congested and noncongested driving conditions were significantly less than those from the conventional diesel and CNG buses.

The California Air Resources Board (ARB) developed a Medium Heavy-Duty Truck (MHDT) schedule by selecting and joining microtrips from real-world MHDT. The MHDT consisted of three modes; namely, a Lower Speed Transient, aHigher Speed Transient, and a Cruise mode. The maximum speeds of these modes were 28.9, 58.2 and 66.0 mph, respectively. Each mode represented statistically selected truck behavior patterns in California. The MHDT is intended to be applied to emissions characterization of trucks (14,001 to 33,0001b gross vehicle weight) exercised on a chassis dynamometer. This paper presents the creation of the MHDT and an examination of repeatability of emissions data from MHDT driven through this schedule. Two trucks were procured to acquire data using the MHDT schedule. The first, a GMC truck with an 8.2-liter Isuzu engine and a standard transmission, was tested at laden weight (90% GVW, 17,5501b) and at unladen weight (50% GVW, 9,7501b). The second, a Freightliner with a 7.2-liter Caterpillar engine and an automatic transmission, was tested only at 13,000lb (50% GVW). The test runs were performed using the West Virginia University (WVU) medium-duty chassis dynamometer, located in Riverside, CA. Vehicle inertia was mimicked using a flywheel set, and tire and wind drag were mimicked using an eddy current power absorber. The truck exhaust was ducted to a full-scale dilution tunnel, with HEPA filtered dilution air, and a flow rate of approximately 1,500scfm. Particulate matter (PM) mass was found gravimetrically, using filtration, while carbon dioxide (CO 2 ), carbon monoxide (CO), oxides of nitrogen (NO x ) and hydrocarbons (HC) were measured using research grade analyzers. Data were computed in units of g/cycle, g/mile, g/ahp-hr, g/gallon and g/minute, and were examined most carefully in units of g/mile. Preliminary runs showed that the GMC truck did deviate from the target trace when tested at laden weight, and the completed distance for the MHDT Lower Speed Transient mode varied from 0.906 to 0.954 miles. Laden data from the GMC truck demonstrated that emissions were repeatable for all three modes of the MHDT schedule. Averaged GMC truck results for all laden runs of the Lower Speed Transient mode were 8.99g/mile NO x and 0.26g/mile PM results for the Higher Speed Transient mode were 6.50g/mile NO x and 0.20g/mile PM and for the Cruise mode were 4.73g/mile NO x and 0.09g/mile PM. Unladen data from the GMC truck also showed acceptable repeatability, with emissions of NO x that were about 87% of the laden values. The Freightliner, with an automatic transmission, produced 16.39g/mile NO x and 0.33g/mile PM on the Lower Speed Transient mode, 12.59g/mile NOX and 0.25g/mile PM on the Higher Speed Transient mode, 7.93g/mile NO x and 0.14g/mile PM on the Cruise mode and 7.57g/mile NO x and 0.19g/mile PM on the UDDS (Test D). when three runs of thee same mode were run back-to-back, the standard deviation of NO x values for six sequences of runs were under 4% of the average for all three modes on both the manual transmission truck at laden test weight and the automatic transmission truck at unladen weight. CO 2 variation was under 4% as well, except in one instance. In two of the six sequences PM variability exceeded 10%. The researchers concluded that the MHDT was suitable for characterizing the emissions from trucks in future inventory research. Data also showed that emissions from a mode were unaffected by whichever mode was run previously.