§ 89.418-96 - Raw emission sampling calculations.

(a) The final test results shall be derived through the steps described in this section.

(b) The exhaust gas flow rate GEXHW and VEXHW shall be determined (see § 89.416-96) for each mode.

(c) When applying GEXHW the measured concentration shall be converted to a wet basis according to the following formula, if not already measured on a wet basis.

$ER17JN94.011$ FFH=1.783 if air/fuel ratio is 1.00 1.865 if air/fuel ratio is 1.35 1.920 if air/fuel ratio is 3.50

(d) As the NOX emission depends on ambient air conditions, the NOX concentration shall be corrected for ambient air temperature and humidity with the factor KH given in the following formulas. Equation (1) of this paragraph is to be used when testing in uncontrolled dynamometer rooms or at other sites with uncontrolled temperatures and humidities. Equation (2) of this paragraph is to be used for all testing when performed in controlled condition rooms. For engines operating on alternative combustion cycles, other correction formulas may be used if they can be justified or validated.

(1) For compression-ignition engines operating in uncontrolled conditions:

$ER17JN94.012$ Where: A=0.309 (f/a)−0.0266 B=-0.209 (f/a)+0.00954 T=temperature of the air in K H=humidity of the inlet air in grams of water per kilogram of dry air in which: $ER17JN94.013$

(2) For compression-ignition engines operating in controlled conditions:

$ER17JN94.014$ If required the dry fuel/air ratio may be calculated from the following equation: Where: $ER17JN94.016$

(e) The pollutant mass flow for each mode shall be calculated as follows:

Gas mass = u×Gas conc.×GEXHW Gas mass = v×Gas conc.×VEXHD Gas mass = w×Gas conc.×VEXHW

The coefficients u (wet), v (dry), and w (wet) are to be used according to the following table:

GasuvwConc.NOX0.0015870.002050.00205ppm.CO0.0009660.001250.00125ppm.HC0.0004780.000618ppm.CO215.1919.6419.64percent.O211.0514.2914.29percent. Note:

The given coefficients u, v, and w are calculated for 273.15 °K (0 °C) and 101.3 kPa. In cases where the reference conditions vary from those stated, an error may occur in the calculations.

(f) The following equations may be used to calculate the coefficients u, v, and w in paragraph (e) of this section for other conditions of temperature and pressure.

(1) For ideal gases at 273.15 °K (0 °C) and 101.3 kPa:

For the calculation of u, v, and w for NOX (as NO2), CO, HC (in paragraph (e) of this section as H1.85; CO2; O2

w=4.4615.10−5 * M if conc. in ppm w=4.4615.10−1 * M if conc. in percent v=w u=w/PAir M=Molecular weight pAir=Density of dry air at 273.15 °K (0 °C), 101.3 kPa=1.293 kg/m3

(2) For real gases at 273.15 °K (0 °C) and 101.3 kPa: For the calculation of u, v, and w

w=gas×10−6 if conc. in ppm v=w u = w/pAir pGas = Density of measured gas at 0 °C, 101.3 kPas in g/m3

(3) General formulas for the calculation of concentrations at temperature (designated as T) and pressure (designated as p):

—for ideal gases $ER17JN94.017$ —for real gases $ER17JN94.018$ with: 1% = 104 ppm M = Molecular weight in g/Mo1 Mv = Molecular Volume = 22.414 × 10−3 m3/Mol for ideal gases T = reference temperature 273.15 K p = reference pressure 101.3 kPa T = Temperature in °C p = pressure in kPa pGas = Density of the measured gas at 0 °C, 101.3 kPa Conc. = Gas concentration

(g) The emission shall be calculated for all individual components in the following way:

$ER17JN94.019$ The weighting factors and the number of modes (n) used in the above calculation are according to § 89.410-96.