PRCI

Recent Results

Engine Emissions and Performance Calculator Tool

Advanced Engine Technologies Corp, has documented the methodology for modeling, calculating and validating reciprocating engine and emissions performance data based on the trapped equivalence ratio (Φ). This methodology has been captured in a computer based calculation tool.

Key Results

Specifically the method takes a dimensionless approach to:

  1. Estimate airflow through an engine based on readily measured parameters and known engine geometry,
  2. Estimate the relative Scavenging Efficiency under varying engine operating conditions for a given make and model, and,
  3. Provide a way to compare scavenging efficiencies for various engine types in order to normalize comparative engine-out NOx levels.

This approach accounts well for the effects of varying speed and air manifold temperature, but it cannot account for the effects of varying ignition timing. In general most ignition timing schemes overcompensate for flame propagation as a function of speed, and once a unit starts, fixed timing suffices throughout the engine operating range. As tested on two field test engines in the Emissions Reduction for Legacy Engines program, the tool clearly demonstrates the use of a φ based model to analyze and qualify a complex engine performance data set. The tool provides several ways to model the improvement afforded by enhanced mixing, including: 1) Reduction on NOx for a given φse, 2) Calculation of “after” NOx based on a before-NOx value, and 3) The allowable increase in φse to obtain a target NOx level.  This is of tremendous value in specifying turbocharger upgrades/replacements, and in confirming a target NOx level and margin of compliance for a NOx retrofit project.

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