Accurate Specific Fuel Consumption Measurement and its Application on Piston Friction Reduction for a Heavy-Duty Diesel Engine

Author(s):  
Yu Chen ◽  
Carol Lynn Deck

In recent years the attention of the internal combustion engine industry has been on improving fuel economy. These changes not only decrease the amount of fuel used and improve the efficiency of the engine, but also save the end-user on fuel costs, reduce engine emissions, and aid in the achievement of future government fuel economy regulations. An approach to decreasing fuel consumption is through improvements to engine mechanical and thermal efficiency. MAHLE has developed a testing method to accurately measure engine specific fuel consumption (SFC). SFC is an indicator of engine efficiency, hence it is directly effected by a reduction in friction. Since changes in SFC are small, considerable precision was required to measure it. To achieve this high level of accuracy key engine parameters were controlled along with boundary parameters. This study utilized a firing heavy-duty diesel engine running on a dynamometer. Results are presented to depict the repeatability of the technique over speed and load.

Author(s):  
G Fernandes ◽  
J Fuschetto ◽  
Z Filipi ◽  
D Assanis ◽  
H McKee

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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