Modeling of Compressed Air Hybrid Operation for a Heavy Duty Diesel Engine

This paper presents the analysis and modeling of a 10.8 l heavy-duty diesel engine modified for operating compressed air hybrid engine cycles. A lumped parameter model is developed to first investigate the engine cylinder-air tank mass and energy interaction. The efficiency of compressed air energy transfer is defined based on the second law of thermodynamics. A high fidelity model is developed using commercially available software (GT-POWER) to capture the effects of engine friction, heat transfer, gas dynamics, etc. Engine valve timing for optimal efficiency in air regeneration and the corresponding engine speed-torque maps are established using the detailed engine model. The compressed air hybrid engine maps are then incorporated into vehicle simulation (ADVISOR) to evaluate the potential fuel economy improvement for a refuse truck under a variety of driving cycles. Depending on the particular driving cycle, the simulation has shown a potential 4–18% fuel economy improvement over the truck equipped with the conventional baseline diesel engine.

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Modeling of Compressed Air Hybrid Operation for a Heavy Duty Diesel Engine

ASME 2008 Internal Combustion Engine Division Spring Technical Conference ◽

10.1115/ices2008-1679 ◽

2008 ◽

Cited By ~ 1

Author(s):

Xiaoyong Wang ◽

Tsu-Chin Tsao ◽

Chun Tai ◽

Hyungsuk Kang ◽

Paul N. Blumberg

Keyword(s):

Diesel Engine ◽

Fuel Economy ◽

Internal Combustion Engines ◽

Compressed Air ◽

Valve Timing ◽

Heavy Duty ◽

Vehicle Simulation ◽

Heavy Duty Diesel Engine ◽

Fuel Economy Improvement ◽

Heavy Duty Diesel

Internal combustion engines can be modified to operate regenerative braking cycles by using compressed air power. This paper presents a particular air hybridization design from among many possible configurations. The engine cycles are enabled by a highly flexible engine valvetrain, which actuates engine valves to generate desired torque with optimal efficiency. A lumped parameter model is developed first to investigate the cylinder-tank mass and energy interaction based on thermodynamic relationships and engine piston kinematics. Special consideration is given to the engine valve timing and air flow. A high fidelity, detailed model using the commercially available GT-Power software is developed for a commercial 10.8 liter heavy-duty diesel engine with a 280 liter air tank in order to capture the effects of engine friction, heat transfer, gas dynamics, etc. The model is used to develop optimal valve timing for engine control. The established engine maps are incorporated into the ADVISOR vehicle simulation package to evaluate the potential fuel economy improvement for a refuse truck under a variety of driving cycles. Depending on the particular driving cycle, the simulation has shown a potential 4% – 18% fuel economy improvement over the truck equipped with the conventional baseline diesel engine.

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Impact of military JP-8 fuel on heavy-duty diesel engine performance and emissions

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1243/09544070jauto211 ◽

2007 ◽

Vol 221 (8) ◽

pp. 957-970 ◽

Cited By ~ 48

Author(s):

G Fernandes ◽

J Fuschetto ◽

Z Filipi ◽

D Assanis ◽

H McKee

Keyword(s):

Particulate Matter ◽

Diesel Engine ◽

Fuel Economy ◽

Engine Performance ◽

Heavy Duty ◽

Heavy Duty Diesel Engine ◽

Performance And Emissions ◽

Heavy Duty Diesel ◽

Engine Performance And Emissions ◽

The Impact

Investigating the impact of jet fuel on diesel engine performance and emissions is very important for military vehicles, due to the US Army Single Fuel Forward Policy mandating that deployed vehicles must refuel with aviation fuel JP-8. There is a known torque and fuel economy penalty associated with the operation of a diesel engine with JP-8 fuel, due to its lower density and viscosity. On the other hand, a few experimental studies have suggested that kerosene-based fuels have the potential for lowering exhaust emissions, especially particulate matter, compared to diesel fuel #2 (DF-2). However, studies so far have typically focused on quantifying the effects of simply replacing the regular DF-2 with JP-8, rather than fully investigating the reasons behind the observed differences. This research evaluates the effect of using JP-8 fuel in a heavy-duty diesel engine on fuel injection, combustion, performance, and emissions, and subsequently utilizes the obtained insight to propose changes to the engine calibration to mitigate the impact of the trade-offs. Experiments were carried out on a Detroit Diesel Corporation (DDC) S60 engine outfitted with exhaust gas recirculation (EGR). The results indicate that torque and fuel economy of diesel fuel can be matched, without smoke or NO x penalty, by increasing the duration of injection to compensate for the lower fuel density. The lower cetane number of JP-8 caused an increased ignition delay and increased premixed combustion, and their cumulative effect led to relatively unchanged combustion phasing. Under almost all conditions, JP-8 led to lower NO x and particulate matter (PM) emissions and shifted the NO x-PM trade-off favourably.

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