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6 Projected Benefits of Technologies on Fuel Consumption
Pages 173-200

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From page 173...
... As an example, the so-called California Air Resources Board (CARB) cycle is shown in Figure 6-1, which is one of the Greenhouse Gas Emissions Model (GEM)
From page 174...
... . The 2027 standards for the vocational vehicles1 are provided in Table 6-5 for CO2, followed by the NHTSA fuel consumption standards in Table 6-6.
From page 175...
... • 2019 baseline 6.7 liter 385 hp ISB diesel (Reinhart, 2015) • Simulated 6.7 liter stoichiometric spark-ignited natural gas engine with EGR • 48% BTE 6.7 liter 385 hp diesel • 42% BTE 3.5 liter turbocharged EGR spark-ignited gasoline engine
From page 176...
... . TABLE 6-3  Phase II Standards through 2027 Day Cab Sleeper Cab Heavy-Haul Class 7 Class 8 Class 8 Class 8 2021 Model Year CO2 Grams per Ton-Mile Low roof 105.5 80.5 72.3 52.4 Mid roof 113.2 85.4 78 High roof 113.5 85.6 75.7 2021 Model Year Gallons of Fuel per 1,000 Ton-Mile   Day Cab Sleeper Cab Heavy-Haul Class 7 Class 8 Class 8 Class 8 Low roof 10.36346 7.90766 7.10216 5.14735 Mid roof 11.11984 8.389 7.66208 High roof 11.14931 8.40864 7.43615 2024 Model Year CO2 Grams per Ton-Mile     Day Cab Sleeper Cab Heavy-Haul Class 7 Class 8 Class 8 Class 8 Low roof  99.8 76.2 68 50.2 Mid roof 107.1 80.9 73.5 High roof 106.6 80.4 70.7 2024 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile   Day Cab Sleeper Cab Heavy-Haul Class 7 Class 8 Class 8 Class 8 Low roof  9.80354 7.48527 6.67976 4.93124 Mid roof 10.52063 7.94695 7.22004 High roof 10.47151 7.89784 6.94499 2027 Model Year CO2 Grams per Ton-Mile     Day Cab Sleeper Cab Heavy-Haul Class 7 Class 8 Class 8 Class 8 Low roof  96.2 73.4 64.1 48.3 Mid roof 103.4 78 69.6 High roof 100 75.7 64.3 2027 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile   Day Cab Sleeper Cab Heavy-Haul Class 7 Class 8 Class 8 Class 8 Low roof  9.4499 7.21022 6.29666 4.7446 Mid roof 10.15717 7.66208 6.83694 High roof  9.82318 7.43615 6.31631     SOURCE: EPA and NHTSA (2016c)
From page 177...
... . TABLE 6-6  NHTSA Fuel Consumption Standards for MY 2027 Class 2b through 8 Vocational Vehicles NHTSA Standard for Vehicle with CI Engine Effective MY 2027 (fuel consumption gallon per 1,000 ton-mile)
From page 178...
... a Urban 502 354 Multipurpose 441 314 Regional 357 275 Baseline Fuel Efficiency Performance in gallon per 1,000 ton-mile Duty cycle Light Heavy-Duty Class 2b-5 Medium Heavy-Duty Class 6-7 Urban 56.4870 39.8335 Multipurpose 49.6230 35.3325 Regional 40.1710 30.9441 aVocational vehicles with gross vehicle weight rating (GVWR) over 33,000 pounds powered by alternate fueled engines must certify to the vehicle standard corresponding with the applicable engine standard.
From page 179...
... For the Class 8 T700 vehicle, compared to a 2019 baseline diesel engine, the 55 percent peak diesel and natural gas engines all show a reduction in CO2 emissions compared to a diesel baseline (Figure 6-2) , but the relative inefficiency of both natural gas options compared to the simulated advanced 55 percent diesel is evident in Figure 6-3.
From page 180...
... HPDI diesel pilot ignited Experimentally derived fuel map from the 2010 Reflects 2010 level performance. Could be natural gas engine Westport HPDI engine, which is based on the Cummins improved with additional development, but ISX 15 liter diesel.
From page 181...
... PROJECTED BENEFITS OF TECHNOLOGIES ON FUEL CONSUMPTION 181 FIGURE 6-2 CO2 reduction in T700 at 50 percent payload versus 2019 baseline diesel simulated over 5 drive cycles. FIGURE 6-3 Fuel energy change in T700 at 50 percent payload with 5 advanced powertrains versus 2019 diesel baseline simulated over 5 drive cycles.
From page 182...
... . The advanced SI engine with gasoline fuel shows comparable CO2 reduction to the advanced diesel over some drive cycles, and roughly 8 percent reduction compared to a 2019 baseline diesel that complies with prevailing standards with a small margin.
From page 183...
... For this vehicle, an advanced medium-duty diesel without waste-heat recovery is compared to natural gas and an advanced turbocharged gasoline SI engine. The baseline is a simulated 2019 ISB 6.7 liter diesel engine.
From page 184...
... Natural gas–powered engines in these vehicles were found to be of similar effectiveness according to the simulation results. In some duty cycles, advanced gasoline engines are on par with the simulated advanced diesels.
From page 185...
... F-650 Engine 6.7 liter I-6 diesel Transmission TBD Mechanical accessory power 5750 W Cd 0.619 C dA 3.151 m2 Tire rolling coefficient 0.010068 average Mass characteristics See Table 6-18 SOURCE: Reinhart (2015)
From page 186...
... 186 REDUCING FUEL CONSUMPTION AND GREENHOUSE GAS EMISSIONS OF MEDIUM- AND HEAVY-DUTY VEHICLES FIGURE 6-6 Fuel energy change for advanced natural gas, diesel, and gasoline powertrains versus 2019 diesel baseline in F-650 at 0 percent payload simulated over 6 drive cycles. FIGURE 6-7 Reduction in CO2 emissions of an F-650 across advanced natural gas, diesel, and gasoline powertrains at 50 percent payload simulated over 6 drive cycles relative to simulated 2019 baseline diesel engine.
From page 187...
... sector and include those vehicles of gross vehicle weight rating from 8,501 to 14,000 pounds that are not regulated under the light-duty vehicle regulations. The Class 2b pickup truck simulation was based on a Dodge Ram 2500, with the basic characteristics shown in Table 6-19 and mass payload characteristics shown in Table 6-20.
From page 188...
... This again is due to the lighter weight of the SI engine plus transmissions, as well as torque-speed characteristics. In Figure 6-12, at gross combined weight both 4 EPA established CO standards in the form of a set of target standard curves, based on a "work factor" that combines a vehicle's payload, 2 towing capacity, and whether or not it has four-wheel drive (instead of a simple vehicle mass or gross vehicle weight rating [GVWR]
From page 189...
... . FIGURE 6-9 Current status of pickup and van CO2 emissions compared to standards.
From page 190...
... FIGURE 6-11 CO2 reduction in Dodge Ram pickup across natural gas, diesel and gasoline powertrains at 0 percent payload compared to baseline 2019 diesel simulated over 6 drive cycles.
From page 191...
... The sensitivity of fuel consumption to payload in the Dodge Ram is illustrated in Figure 6-13 for different powertrains. Shown in Figure 6-14, the CO2 reduction is greatest for the natural gas vehicle, although both the advanced SI and diesel engines show a 9 to 12 percent improvement relative to the baseline.
From page 192...
... FIGURE 6-14 CO2 reduction across natural gas, diesel, and gasoline powertrains in a Dodge Ram 2500 at full 25,000 GCW simulated over 6 drive cycles.
From page 193...
... The reader may wish to revisit the discussion of mass reduction in Chapter 4. In Figures 6-16 and 6-17, the comparison of diesel and NG engines in the Class 8 truck shows the payload sensitivities are somewhat as expected -- that the SI natural gas engine exhibits less efficiency at lighter loads on both transient and steady-speed drive cycles.
From page 194...
... . Sensitivity to payload is minimal for unthrottled engines relative to baseline diesel engine.
From page 195...
... 6.3 DISCUSSION OF ENGINE EFFICIENCIES OVER DRIVE CYCLES SwRI used their engine maps and vehicle simulations to calculate the cycle average engine efficiency, allowing an approximate comparison to the EPA/NHTSA engine standards for fuel consumption and GHG emissions. For general comparison, we provide here the Phase I and proposed Phase II standards for engine efficiency (Table 6-22)
From page 196...
... is approximately 43.7 percent, somewhat short of the committee's expected performance of a feasible diesel engine. For the medium-duty vocational vehicles, the committee's projected feasible efficiencies for advanced diesel as well as the gasoline-based engines appear more optimistic than that of NHTSA and EPA (Figure 6-20)
From page 197...
... on 6 simulated drive cycles at full gross combined weight.
From page 198...
... If we consider those vehicles' package effects with the advanced engines, we would expect the following: • For the T700, for example, aggressive reductions in aerodynamic drag and rolling resistance would yield an additional 8 to 20 percent reduction in fuel consumption across the drive cycles, beyond the impact of the engine. Cycles with low average speed will show more effect of rolling resistance versus aerodynamic drag.
From page 199...
... cAt 1,562 lbs payload, ALVW, average of 55% city and 45% highway cycles. Finding: Combining projections for advanced engines and vehicle improvements, simulations for the committee show potentially over 30 percent reduction in CO2 and fuel usage for all vehicles studied.
From page 200...
... 2011. Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles; Final Rule.


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