Alternative Fuel Technologies for Heavy Duty Vehicles: Performance, Emissions, Economics, Safety, and Development Status

1993 ◽  
Author(s):  
David L. Hofeldt
Author(s):  
Paul Schimek

The 1990 Clean Air Act Amendments mandated stricter emissions standards for heavy-duty vehicles. One category of heavy-duty vehicles, urban transit buses, constitutes a highly visible source of pollutant emissions and must meet even more stringent standards. In response, engine manufacturers have produced diesel engines that produce virtually no black smoke and emit several times less particulate matter (PM) than older engines. The tighter PM emissions standards that apply to urban transit buses only were found to be cost-effective ($4,600 to $6,300 per Mg of PM reduced) compared with other control strategies. The Urban Bus Retrofit/Rebuild Program was found to be somewhat less cost-effective ($6,900 to $42,000 per Mg). Both of these programs could be extended to other heavy-duty vehicles. However, the use of compressed natural gas (CNG) in transit buses was found to have a costeffectiveness of $0.9 million to $1.8 million per Mg of PM. Replacing older diesel engines with low-emission diesels is the most cost-effective way to reduce transit bus emissions. By purchasing more clean diesels instead of fewer cleaner CNG buses, transit agencies can produce greater reductions in fleetwide emissions. In fact, the transit agency in this study with the most alternative-fuel buses has the highest fleetwide PM emissions rate. It is premature to expand the alternative-fuel transit bus fleet beyond the experimental level. Regulatory policy should be reassessed as the understanding of the link between diesel emissions and health effects improves.


Author(s):  
Mehmet Emin Mumcuoglu ◽  
Gokhan Alcan ◽  
Mustafa Unel ◽  
Onur Cicek ◽  
Mehmet Mutluergil ◽  
...  

2020 ◽  
Vol 53 (2) ◽  
pp. 13850-13854
Author(s):  
P. Polverino ◽  
I. Arsie ◽  
C. Pianese

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1036
Author(s):  
Yunxia Li ◽  
Lei Li

A countershaft brake is used as a transmission brake (TB) to realize synchronous shifting by reducing the automated mechanical transmission (AMT) input shaft’s speed rapidly. This process is performed to reduce shifting time and improve shifting quality for heavy-duty vehicles equipped with AMT without synchronizer. To improve controlled synchronous shifting, the AMT input shaft’s equivalent resistance torque and the TB’s characteristic parameters are studied. An AMT dynamic model under neutral gear position is analyzed during the synchronous control interval. A dynamic model of the countershaft brake is discussed, and its control flow is given. The parameter identification method of the AMT input shaft’s equivalent resistance torque is given on the basis of the least squares algorithm. The parameter identification of the TB’s characteristic parameters is proposed on the basis of the recursive least squares method (RLSM). Experimental results show that the recursive estimations of the TB’s characteristic parameters under different duty cycles of the TB solenoid valve, including brake torque estimation, estimation accuracy, and braking intensity estimation, can be effectively estimated. The research provides some reliable evidence to further study the synchronous shifting control schedule for heavy-duty vehicles with AMT.


2021 ◽  
Vol 191 ◽  
pp. 116891
Author(s):  
Stijn Broekaert ◽  
Theodoros Grigoratos ◽  
Dimitrios Savvidis ◽  
Georgios Fontaras

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