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Technical Paper

The Calculation of Mass Fraction Burn of Ethanol-Gasoline Blended Fuels Using Single and Two-Zone Models

2008-04-14
2008-01-0320
One-dimensional single-zone and two-zone analyses have been exercised to calculate the mass fraction burned in an engine operating on ethanol/gasoline-blended fuels using the cylinder pressure and volume data. The analyses include heat transfer and crevice volume effects on the calculated mass fraction burned. A comparison between the two methods is performed starting from the derivation of conservation of energy and the method to solve the mass fraction burned rates through the results including detailed explanation of the observed differences and trends. The apparent heat release method is used as a point of reference in the comparison process. Both models are solved using the LU matrix factorization and first-order Euler integration.
Technical Paper

Methods of Pegging Cylinder Pressure to Maximize Data Quality

2019-04-02
2019-01-0721
Engine cylinder pressure measured with piezo-electric pressure transducers must be referenced or pegged to a known pressure at some point in the engine cycle. Traditionally, the pressure has been pegged to the pressure in the intake manifold plenum at Bottom Dead Center (BDC) at the end of the intake stroke. However, an error in pegging induces an error in the cylinder pressure trace, which has an adverse effect on the entire combustion analysis. This research is focused on assessing the pegging error for several pegging methods across a wide range of engine operating conditions, and ultimately determining best practices to minimize error in pegging and its propagation to calculated combustion metrics. The study was conducted through 1D simulations run in the commercially available GT-Power. The points studied included variations of speed, load, intake runner length and intake valve timing (including Late Intake Valve Closing (LIVC) and Early Intake Valve Closing (EIVC)).
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