(a) If you measured an oxygenated hydrocarbon's mass concentration, first calculate its molar concentration in the exhaust sample stream from which the sample was taken (raw or diluted exhaust), and convert this into a C1-equivalent molar concentration. Add these C1-equivalent molar concentrations to the molar concentration of NOTHC. The result is the molar concentration of THCE. Calculate THCE concentration using the following equations, noting that equation 1065.665-3 is only required if you need to convert your OHC concentration from mass to moles:
xTHCE = The C1-equivalent sum of the concentration of carbon mass contributions of non-oxygenated hydrocarbons, alcohols, and aldehydes.
xNOTHC = The C1-equivalent sum of the concentration of nonoxygenated THC.
xOHCi = The C1-equivalent concentration of oxygenated species i in diluted exhaust, not corrected for initial contamination.
xOHCi-init = The C1-equivalent concentration of the initial system contamination (optional) of oxygenated species i, dry-to-wet corrected.
xTHC[THC-FID]cor = The C1-equivalent response to NOTHC and all OHC in diluted exhaust, HC contamination and dry-to-wet corrected, as measured by the THC-FID.
RFOHCi[THC-FID] = The response factor of the FID to species i relative to propane on a C1-equivalent basis.
C# = The mean number of carbon atoms in the particular compound.
Mdexh = The molar mass of diluted exhaust as determined in § 1065.340.
mdexhOHCi = The mass of oxygenated species i in dilute exhaust.
MOHCi = The C1-equivalent molecular weight of oxygenated species i.
mdexh = The mass of diluted exhaust.
ndexhOHCi = The number of moles of oxygenated species i in total diluted exhaust flow.
ndexh = The total diluted exhaust flow.
(b) If we require you to determine NMHCE, use the following equation:
xNMHCE = The C1-equivalent sum of the concentration of carbon mass contributions of non-oxygenated NMHC, alcohols, and aldehydes.
RFCH4[THC-FID] = response factor of THC-FID to CH4.
xCH4 = concentration of CH4, HC contamination (optional) and dry-to-wet corrected, as measured by the gas chromatograph FID.
(c) The following example shows how to determine NMHCE emissions based on ethanol (C2H5OH), methanol (CH3OH), acetaldehyde (C2H4O), and formaldehyde (HCHO) as C1-equivalent molar concentrations: