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Emission Test Cycles

European Stationary Cycle (ESC)

The ESC test cycle was introduced together with the ETC (European Transient Cycle) and the ELR (European Load Response) tests by the Euro III emission regulation—Directive 1999/96/EC, effective year 2000—for emission measurement from heavy-duty diesel engines [2870]. The ESC is a 13-mode, steady-state procedure that replaced the R-49 test. Initially, the test was also referred to as OICA cycle or ACEA cycle.

The engine is tested on an engine dynamometer over a sequence of steady-state modes (Table 1, Figure 1). The engine must be operated for the prescribed time in each mode, completing engine speed and load changes in the first 20 seconds. The specified speed shall be held to within ±50 rpm and the specified torque shall be held to within ±2% of the maximum torque at the test speed. Emissions are measured during each mode and averaged over the cycle using a set of weighting factors. Particulate matter emissions are sampled on one filter over the 13 modes. The final emission results are expressed in g/kWh.

Table 1
ESC test modes
ModeEngine SpeedLoad, %Weight, %Duration
1Low idle0154 minutes
2A10082 minutes
3B50102 minutes
4B75102 minutes
5A5052 minutes
6A7552 minutes
7A2552 minutes
8B10092 minutes
9B25102 minutes
10C10082 minutes
11C2552 minutes
12C7552 minutes
13C5052 minutes
[SVG image]
Figure 1. European Stationary Cycle (ESC)

The engine speeds are defined as follows:

  • The high speed nhi is determined by calculating 70% of the declared maximum net power. The highest engine speed where this power value occurs (i.e., above the rated speed) on the power curve is defined as nhi.
  • The low speed nlo is determined by calculating 50% of the declared maximum net power. The lowest engine speed where this power value occurs (i.e., below the rated speed) on the power curve is defined as nlo.
  • The engine speeds A, B, and C to be used during the test are then calculated from the following formulas:

    A = nlo + 0.25(nhi - nlo)(1)

    B = nlo + 0.50(nhi - nlo)(2)

    C = nlo + 0.75(nhi - nlo)(3)

During emission certification testing, the certification personnel may request additional random testing modes within the cycle control area (Figure 1). Maximum emission at these extra modes are determined by interpolation between results from the neighboring regular test modes.

The ESC test is characterized by high average load factors and very high exhaust gas temperatures.