1066.605 Mass-based and molar-based exhaust emission calculations.
§ 1066.605 Mass-based and molar-based exhaust emission
calculations.
(a) Calculate your total mass of emissions over a test cycle as
specified in paragraph (c) of this section or in 40 CFR part 1065,
subpart G, as applicable.
(b) See the standard-setting part for composite emission
calculations over multiple test intervals and the corresponding
weighting factors.
(c) Perform the following sequence of preliminary calculations
to correct recorded concentration measurements before calculating
mass emissions in paragraphs (e) and (f) of this section:
(1) For vehicles above 14,000 pounds GVWR, correct all THC and
CH4 concentrations for initial contamination as described in 40 CFR
1065.660(a), including continuous readings, sample bag readings,
and dilution air background readings. This correction is optional
for vehicles at or below 14,000 pounds GVWR.
(2) Correct all concentrations measured on a “dry” basis to a
“wet” basis, including dilution air background concentrations.
(3) Calculate all NMHC and CH4 concentrations, including
dilution air background concentrations, as described in 40 CFR
1065.660.
(4) For vehicles at or below 14,000 pounds GVWR, calculate HC
concentrations, including dilution air background concentrations,
as described in this section, and as described in § 1066.635 for
NMOG. For emission testing of vehicles above 14,000 pounds GVWR,
with fuels that contain 25% or more oxygenated compounds by volume,
calculate THCE and NMHC concentrations, including dilution air
background concentrations, as described in 40 CFR part 1065,
subpart I.
(5) Correct all gaseous concentrations for dilution air
background as described in § 1066.610.
(6) Correct NOX emission values for intake-air humidity as
described in § 1066.615.
(7) Correct all PM filter masses for sample media buoyancy as
described in 40 CFR 1065.690.
(d) Calculate g/mile emission rates using the following equation
unless the standard-setting part specifies otherwise:
Where:
e[emission] = emission rate over the test interval.
m[emission] = emission mass over the test interval. D
= the measured driving distance over the test interval. Example:
mNOx = 0.3177 g DHFET = 10.19 miles
(e) Calculate the emission mass of each gaseous pollutant using
the following equation:
Where:
m[emission] = emission mass over the test interval.
Vmix = total dilute exhaust volume over the test interval,
corrected to standard reference conditions, and corrected for any
volume removed for emission sampling and for any volume change from
adding secondary dilution air. p[emission] = density of the
appropriate chemical species as given in § 1066.1005(f).
x[emission] = measured emission concentration in the sample,
after dry-to-wet and background corrections. c = 10−2 for
emission concentrations in %, and 10−6 for emission concentrations
in ppm. Example: Vmix = 170.878 m 3 (from paragraph (f) of
this section) rNOx = 1913 g/m 3 xNOx = 0.9721 ppm c =
10−6 mNOx = 170.878·1913·0.9721·10−6 = 0.3177 g
(f) Calculation of the emission mass of PM, mPM, is
dependent on how many PM filters you use, as follows:
(1) Except as otherwise specified in this paragraph (f),
calculate mPM using the following equation:
Where:
mPM = mass of particulate matter emissions over the test
interval, as described in § 1066.815(b)(1), (2), and (3).
Vmix = total dilute exhaust volume over the test interval,
corrected to standard reference conditions, and corrected for any
volume removed for emission sampling and for any volume change from
adding secondary dilution air. For partial-flow dilution systems,
set Vmix equal to the total exhaust volume over the test
interval, corrected to standard reference conditions. VPMstd
= total volume of dilute exhaust sampled through the filter over
the test interval, corrected to standard reference conditions.
Vsdastd = total volume of secondary dilution air sampled
through the filter over the test interval, corrected to standard
reference conditions. For partial-flow dilution systems, set
Vsdastd equal to total dilution air volume over the test
interval, corrected to standard reference conditions. mPMfil
= mass of particulate matter emissions on the filter over the test
interval. mPMbkgnd = mass of particulate matter on the
background filter. Example: Vmix = 170.878 m 3 (from
paragraph (g) of this section) VPMstd = 0.925 m 3 (from
paragraph (g) of this section) Vsdastd = 0.527 m 3 (from
paragraph (g) of this section) mPMfil = 0.0000045 g
mPMbkgnd = 0.0000014 g
(2) If you sample PM onto a single filter as described in §
1066.815(b)(4)(i) or (b)(4)(ii) (for constant volume samplers),
calculate mPM using the following equation:
Where:
mPM = mass of particulate matter emissions over the entire
FTP. Vmix = total dilute exhaust volume over the test
interval, corrected to standard reference conditions, and corrected
for any volume removed for emission sampling and for any volume
change from adding secondary dilution air. V[interval]-PMstd
= total volume of dilute exhaust sampled through the filter over
the test interval (ct = cold transient, s = stabilized, ht = hot
transient), corrected to standard reference conditions.
V[interval]-sdastd = total volume of secondary dilution air
sampled through the filter over the test interval (ct = cold
transient, s = stabilized, ht = hot transient), corrected to
standard reference conditions. mPMfil = mass of particulate
matter emissions on the filter over the test interval.
mPMbkgnd = mass of particulate matter on the background
filter over the test interval. Example: Vmix = 633.691 m 3
Vct-PMstd = 0.925 m 3 Vct-sdastd = 0.527 m 3
Vs-PMstd = 1.967 m 3 Vs-sdastd = 1.121 m 3
Vht-PMstd = 1.122 m 3 Vht-sdastd = 0.639 m 3
mPMfil = 0.0000106 g mPMbkgnd = 0.0000014 g mPM =
0.00222 g
(3) If you sample PM onto a single filter as described in §
1066.815(b)(4)(ii) (for partial flow dilution systems), calculate
mPM using the following equation:
Where:
mPM = mass of particulate matter emissions over the entire
FTP. V[interval]-exhstd = total engine exhaust volume over
the test interval (ct = cold transient, s = stabilized, ht = hot
transient), corrected to standard reference conditions, and
corrected for any volume removed for emission sampling.
V[interval]-PMstd = total volume of dilute exhaust sampled
through the filter over the test interval (ct = cold transient, s =
stabilized, ht = hot transient), corrected to standard reference
conditions. V[interval]-dilstd = total volume of dilution
air over the test interval (ct = cold transient, s = stabilized, ht
= hot transient), corrected to standard reference conditions and
for any volume removed for emission sampling. mPMfil = mass
of particulate matter emissions on the filter over the test
interval. mPMbkgnd = mass of particulate matter on the
background filter over the test interval. Example:
Vct-exhstd = 5.55 m 3 Vct-PMstd = 0.526 m 3
Vct-dilstd = 0.481 m 3 Vs-exhstd = 9.53 m 3
Vs-PMstd = 0.903 m 3 Vs-dilstd = 0.857 m 3
Vht-exhstd = 5.54 m 3 Vht-PMstd = 0.527 m 3
Vht-dilstd = 0.489 m 3 mPMfil = 0.0000106 g
mPMbkgnd = 0.0000014 g mPM =
0.00269 g
(4) If you sample PM onto a single filter as described in §
1066.815(b)(5)(i) or (b)(5)(ii) (for constant volume samplers),
calculate mPM using the following equation:
Where:
mPM = mass of particulate matter emissions over the entire
FTP. Vmix = total dilute exhaust volume over the test
interval, corrected to standard reference conditions, and corrected
for any volume removed for emission sampling and for any volume
change from secondary dilution air. V[interval]-PMstd =
total volume of dilute exhaust sampled through the filter over the
test interval (ct = cold transient, cs = cold stabilized, ht = hot
transient, hs = hot stabilized), corrected to standard reference
conditions. V[interval]-sdastd = total volume of secondary
dilution air sampled through the filter over the test interval (ct
= cold transient, cs = cold stabilized, ht = hot transient, hs =
hot stabilized), corrected to standard reference conditions.
mPMfil = mass of particulate matter emissions on the filter
over the test interval. mPMbkgnd = mass of particulate
matter on the background filter over the test interval. Example:
Vmix = 972.121 m 3 Vct-PMstd = 0.925 m 3
Vct-sdastd = 0.529 m 3 Vcs-PMstd = 1.968 m 3
Vcs-sdastd = 1.123 m 3 Vht-PMstd = 1.122 m 3
Vht-sdastd = 0.641 m 3 Vhs-PMstd = 1.967 m 3
Vhs-sdastd = 1.121 m 3 mPMfil = 0.0000229 g
mPMbkgnd = 0.0000014 g mPM =
0.00401 g
(5) If you sample PM onto a single filter as described in §
1066.815(b)(5)(ii) (for partial flow dilution systems), calculate
mPM using the following equation:
Where:
mPM = mass of particulate matter emissions over the entire
FTP. V[interval]-exhstd = total engine exhaust volume over
the test interval (ct = cold transient, cs = cold stabilized, ht =
hot transient, hs = hot stabilized), corrected to standard
reference conditions, and corrected for any volume removed for
emission sampling. V[interval]-PMstd = total volume of
dilute exhaust sampled through the filter over the test interval
(ct = cold transient, cs = cold stabilized, ht = hot transient, hs
= hot stabilized), corrected to standard reference conditions.
V[interval]-dilstd = total volume of dilution air over the
test interval (ct = cold transient, cs = cold stabilized, ht = hot
transient, hs = hot stabilized), corrected to standard reference
conditions and for any volume removed for emission sampling.
mPMfil = mass of particulate matter emissions on the filter
over the test interval. mPMbkgnd = mass of particulate
matter on the background filter over the test interval. Example:
Vct-exhstd = 5.55 m 3 Vct-PMstd = 0.526 m 3
Vct-dilstd = 0.481 m 3 Vcs-exhstd = 9.53 m 3
Vcs-PMstd = 0.903 m 3 Vcs-dilstd = 0.857 m 3
Vht-exhstd = 5.54 m 3 Vht-PMstd = 0.527 m 3
Vht-dilstd = 0.489 m 3 Vhs-exhstd = 9.54 m 3
Vhs-PMstd = 0.902 m 3 Vhs-dilstd = 0.856 m 3
mPMfil = 0.0000229 g mPMbkgnd = 0.0000014 g mPM =
0.00266 g
(g) This paragraph (g) describes how to correct flow and flow
rates to standard reference conditions and provides an example for
determining Vmix based on CVS total flow and the removal of
sample flow from the dilute exhaust gas. You may use predetermined
nominal values for removed sample volumes, except for flows used
for batch sampling.
(1) Correct flow and flow rates to standard reference conditions
as needed using the following equation:
Where:
V[flow]std = total flow volume at the flow meter, corrected
to standard reference conditions. V[flow]act = total flow
volume at the flow meter at test conditions. pin = absolute
static pressure at the flow meter inlet, measured directly or
calculated as the sum of atmospheric pressure plus a differential
pressure referenced to atmospheric pressure. Tstd = standard
temperature. pstd = standard pressure. Tin =
temperature of the dilute exhaust sample at the flow meter inlet.
Example: VPMact = 1.071 m 3 pin = 101.7 kPa
Tstd = 293.15 K pstd = 101.325 kPa Tin = 340.5
K
(2) The following example provides a determination of
Vmix based on CVS total flow and the removal of sample flow
from one dilute exhaust gas analyzer and one PM sampling system
that is utilizing secondary dilution. Note that your Vmix
determination may vary from Eq. 1066.605-7 based on the number of
flows that are removed from your dilute exhaust gas and whether
your PM sampling system is using secondary dilution. For this
example, Vmix is governed by the following equation:
Where:
VCVSstd = total dilute exhaust volume over the test interval
at the flow meter, corrected to standard reference conditions.
Vgasstd = total volume of sample flow through the gaseous
emission bench over the test interval, corrected to standard
reference conditions. VPMstd = total volume of dilute
exhaust sampled through the filter over the test interval,
corrected to standard reference conditions. Vsdastd = total
volume of secondary dilution air flow sampled through the filter
over the test interval, corrected to standard reference conditions.
Example:
Using Eq. 1066.605-8:
VCVSstd = 170.451 m 3, where VCVSact = 170.721 m 3,
pin = 101.7 kPa, and Tin = 294.7 K Using Eq.
1066.605-8: Vgasstd = 0.028 m 3, where Vgasact =
0.033 m 3, pin = 101.7 kPa, and Tin = 340.5 K Using
Eq. 1066.605-8: VPMstd = 0.925 m 3, where VPMact =
1.071 m 3, pin = 101.7 kPa, and Tin = 340.5 K Using
Eq. 1066.605-8: Vsdastd = 0.527 m 3, where Vsdaact =
0.531 m 3, pin = 101.7 kPa, and Tin = 296.3 K
Vmix = 170.451 + 0.028 + 0.925 − 0.527 = 170.878 m 3
(h) Calculate total flow volume over a test interval,
V[flow], for a CVS or exhaust gas sampler as follows:
(1) Varying versus constant flow rates. The calculation
methods depend on differentiating varying and constant flow, as
follows:
(i) We consider the following to be examples of varying flows
that require a continuous multiplication of concentration times
flow rate: raw exhaust, exhaust diluted with a constant flow rate
of dilution air, and CVS dilution with a CVS flow meter that does
not have an upstream heat exchanger or electronic flow control.
(ii) We consider the following to be examples of constant
exhaust flows: CVS diluted exhaust with a CVS flow meter that has
an upstream heat exchanger, an electronic flow control, or
both.
(2) Continuous sampling. For continuous sampling, you
must frequently record a continuously updated flow signal. This
recording requirement applies for both varying and constant flow
rates.
(i) Varying flow rate. If you continuously sample from a
varying exhaust flow rate, calculate V[flow] using the
following equation:
Where:
Example:
N = 505 Q CVS1 = 0.276 m 3/s Q CVS2 = 0.294 m
3/s frecord = 1 Hz Using Eq. 1066.605-11, Δt = 1/1 =
1 s VCVS = (0.276 + 0.294 + ... + Q CVS505)·1
VCVS = 170.721 m 3
(ii) Constant flow rate. If you continuously sample from
a constant exhaust flow rate, use the same calculation described in
paragraph (h)(2)(i) of this section or calculate the mean flow
recorded over the test interval and treat the mean as a batch
sample, as described in paragraph (h)(3)(ii) of this section.
(3) Batch sampling. For batch sampling, calculate total
flow by integrating a varying flow rate or by determining the mean
of a constant flow rate, as follows:
(i) Varying flow rate. If you proportionally collect a
batch sample from a varying exhaust flow rate, integrate the flow
rate over the test interval to determine the total flow from which
you extracted the proportional sample, as described in paragraph
(h)(2)(i) of this section.
(ii) Constant flow rate. If you batch sample from a
constant exhaust flow rate, extract a sample at a proportional or
constant flow rate and calculate V[flow] from the flow from
which you extract the sample by multiplying the mean flow rate by
the time of the test interval using the following equation:
Example:
Q CVS = 0.338 m 3/s Δt = 505 s VCVS =
0.338·505 VCVS = 170.69 m 3 [79 FR 23823, Apr. 28, 2014, as
amended at 80 FR 9121, Feb. 19, 2015; 81 FR 74203, Oct. 25, 2016]