§ 86.144-94 Calculations; exhaust emissions.

The final reported test results shall be computed by use of the following formula:

(a) For light-duty vehicles and light duty trucks:

Where:

(1) Y_WM = Weighted mass emissions of each pollutant, i.e., THC, CO, THCE, NMHC, NMHCE, CH₄, NO_X, or CO₂, in grams per vehicle mile.

(2) Y_ct = Mass emissions as calculated from the “transient” phase of the cold start test, in grams per test phase.

(3) Y_ht = Mass emissions as calculated from the “transient” phase of the hot start test, in grams per test phase.

(4) Y_s = Mass emissions as calculated from the “stabilized” phase of the cold start test, in grams per test phase.

(5) D_ct = The measured driving distance from the “transient” phase of the cold start test, in miles.

(6) D_ht = The measured distance from the “transient” phase of the hot start test, in miles.

(7) D_s = The measured driving distance from the “stabilized” phase of the cold start test, in miles.

(b) The mass of each pollutant for each phase of both the cold start test and the hot start test is determined from the following:

(1) Total hydrocarbon mass:

HC_mass = V_mix × Density_HC × (HC_conc/1,000,000)

(2) Oxides of nitrogen mass:

NOx_mass = V_mix × Density_NO2 × K_H × (NOx_conc/1,000,000)

(3) Carbon monoxide mass:

CO_mass = V_mix × Density_CO × (CO_conc/1,000,000)

(4) Carbon dioxide mass:

CO_2mass = V_mix × Density_CO2 × (CO_2conc/100)

(5) Methanol mass:

CH₃OH_mass = V_mix × Density_CH3OH × (CH₃OH_conc/1,000,000)

(6) Formaldehyde mass:

HCHO_mass = V_mix × Density_HCHO × (HCHO_conc/1,000,000)

(7) Total hydrocarbon equivalent mass:

THCE_mass = HC_mass + 13.8756/32.042 × (CH₃OH_mass) + 13.8756/32.0262 × (HCHO_mass)

(8) Non-methane hydrocarbon mass:

NMHC_mass = V_mix × Density_NMHC × (NMHC_conc/1,000,000)

(9) Non-methane hydrocarbon equivalent mass:

NMHCE_mass = NMHC_mass + 13.8756/32.042 × (CH₃OH_mass) + 13.8756/30.0262 × (HCHO_mass)

(10) Methane mass:

CH_4mass = V_mix = Density_CH4 = (CH_4conc/1,000,00)

(11) Nitrous Oxide Mass:

V_mix × Density_N2O × (N₂O_conc/1,000,000)

(c) Meaning of symbols:

(1)

(i) HC_mass = Total hydrocarbon emissions, in grams per test phase.

(ii) Density_HC = Density of total hydrocarbon.

(A) For gasoline-fuel, diesel-fuel and methanol fuel; Density_HC = 16.33 g/ft −carbon atom (0.5768 kg/m −carbon atom), assuming an average carbon to hydrogen ratio of 1:1.85, at 68 °F (20 °C) and 760 mm Hg (101.3 kPa) pressure.

(B) For natural gas and liquefied petroleum gas-fuel; Density_HC = 1.1771 (12.011 + H/C (1.008)) g/ft −carbon atom (0.04157(12.011 + H/C (1.008))kg/m −carbon atom), where H/C is the hydrogen to carbon ratio of the hydrocarbon components of the test fuel, at 68 °F (20 °C) and 760 mm Hg (101.3 kPa) pressure.

(iii)

(A) HC_conc = Total hydrocarbon concentration of the dilute exhaust sample corrected for background, in ppm carbon equivalent, i.e., equivalent propane × 3.

(B) HC_conc = HC_e−HC_d(1−1/DF).

Where:

(iv)

(A) HC_e = Total hydrocarbon concentration of the dilute exhaust sample or, for diesel-cycle (or methanol-fueled vehicles, if selected), average hydrocarbon concentration of the dilute exhaust sample as calculated from the integrated THC traces, in ppm carbon equivalent.

(B) HC_e = FID HC_e−(r)C_CHOHe.

(v) FID HC_e = Concentration of total hydrocarbon plus methanol in dilute exhaust as measured by the FID, ppm carbon equivalent.

(vi) r = FID response to methanol.

(vii) C_CHOHe = Concentration of methanol in dilute exhaust as determined from the dilute exhaust methanol sample in ppm carbon. For vehicles not fueled with methanol, C_CHOHe equals zero.

(viii)

(A) HC_d = Total hydrocarbon concentration of the dilution air as measured, in ppm carbon equivalent.

(B) HC_d = FID HC_d−(r)C_CHOHd.

(ix) FID HC_d = Concentration of total hydrocarbon plus methanol in dilution air as measured by the FID, ppm carbon equivalent.

(x) C_CHOHd = Concentration of methanol in dilution air as determined from dilution air methanol sample in ppm carbon. For vehicles not fueled with methanol, C_CHOHd equals zero.

(2)

(i) NOx_mass = Oxides of nitrogen emissions, in grams per test phase.

(ii) Density_NO2 = Density of oxides of nitrogen is 54.16 g/ft3 (1.913 kg/m ) assuming they are in the form of nitrogen dioxide, at 68 °F (20 °C) and 760 mm Hg (101.3kPa) pressure.