WLTP-08-07e
WLTP
Open Issue Phase 1B
Issue: Fuel Consumption calculations for ICE vehicles
ACEA Informal Document 17.10.2014
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1
Proposal:
A generic formula for the fuel consumption (FC) should be added.
The ratios of H/C and O/C for reference fuels shall be taken from
Annex 3. These numbers have to be added to the actual draft.
Some values of the FC calculation in Annex 7, 6.1. to 6.11. should be
adjusted. The numbers change when the correct molar weights of C,
H, and O are used.
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Rationale:
An additional generic formula in combination with the nomination of the
H/C and O/C ratios in Annex 3 results in clarification and standardization of
the FC calculations. This would be consistent with the implementation of
generic formulas for HC densities, dilution factors, etc. and supports the
simple adaption to future reference fuels or changes to the existing ones.
In WLTP-IWG meeting #7 it was agreed to use the correct molar weights
of C, H, and O for the NMHC density calculation (3 significant decimal
places). The correct molar weights should also be used for the FC
calculation. This results in slightly varying numbers in the existing FC
calculation formulas.
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Text of WLTP GTR
6.
Calculation of fuel consumption
6.1.
The fuel characteristics required for the calculation of fuel consumption
values shall be taken from Annex 3 in this gtr.
6.2.
The fuel consumption values shall be calculated from the emissions of
hydrocarbons, carbon monoxide, and carbon dioxide determined from the
measurement results using the provisions defined in this gtr.
6.3.
For a vehicle with a positive ignition engine fuelled with petrol (E0)
FC =
6.4.
0.1154
ρ
× 0.866 × HC + 0.429 × CO + 0.273 × CO2
6.5.
0.118
ρ
× 0.848 × HC + 0.429 × CO + 0.273 × CO2
FC =
0.120
ρ
× 0.830 × HC + 0.429 × CO + 0.273 × CO2
(62)
For a vehicle with a positive ignition engine fuelled with LPG
FCnorm =
0.1212
0.538
× 0.825 × HC + 0.429 × CO + 0.273 × CO2
(63)
6.6.1.
If the composition of the fuel used for the test differs from the
composition that is assumed for the calculation of the normalised
consumption, on the manufacturer's request a correction factor cf may be
applied, as follows:
FCnorm =
0.1212
0.538
0.1336
0.654
× 0.749 × HC + 0.429 × CO + 0.273 × CO2
(66)
6.8.
For a vehicle with a compression engine fuelled with diesel (B0)
FC =
6.9.
6.10.
ρ
× 0.866 × HC + 0.429 × CO + 0.273 × CO2
0.116
ρ
× 0.861 × HC + 0.429 × CO + 0.273 × CO2
0.116
ρ
× 0.859 × HC + 0.429 × CO + 0.273 × CO2
(68)
(69)
For a vehicle with a positive ignition engine fuelled with ethanol (E85)
FC =
0.1742
ρ
× 0.574 × HC + 0.429 × CO + 0.273 × CO2
(70)
where for all equations in paragraph 6:
FC
is fuel consumption in l/100 km (or m³ per 100 km in the case of
natural gas);
HC
are the measured emissions of hydrocarbons, g/km;
CO
are the measured emissions of carbon monoxide, g/km;
CO2
are the measured emissions of carbon dioxide, g/km;
ρ
is the density of the test fuel.
× cf × 0.825 × HC + 0.429 × CO + 0.273 × CO2
(64)
The correction factor cf, which may be applied, is determined as follows
Cf = 0.825 + 0.0693 × nactual
(65)
where:
nactual is the actual H/C ratio of the fuel used.
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(67)
For a vehicle with a compression engine fuelled with diesel (B7)
FC =
6.11.
0.1155
For a vehicle with a compression engine fuelled with diesel (B5)
FC =
(61)
For a vehicle with a positive ignition engine fuelled with petrol (E10)
For a vehicle with a positive ignition engine fuelled with NG/biomethane
FCnorm =
(60)
For a vehicle with a positive ignition engine fuelled with petrol (E5)
FC =
6.6.
6.7.
Derivation of FC calculations
Carbon fraction in fuel = Carbon fraction in emission
Volumefuel × Carbonsfuel × Densityfuel
∑(CarbonsEmission × MassEmission )
=
Distance
Distance
Volumefuel
∑(CarbonsEmission × MassEmission )
=
Distance
Carbonsfuel × Densityfuel × Distance
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FC calculations
𝐅𝐂 [𝐥/𝟏𝟎𝟎𝐤𝐦] =
𝐌𝐖𝐂 +
𝐇
𝐎
× 𝐌𝐖𝐇 + × 𝐌𝐖𝐎
𝐂
𝐂
×
𝐌𝐖𝐂 × 𝛒𝐟𝐮𝐞𝐥
𝐌𝐖𝐂
𝐌𝐖𝐂
𝐌𝐖𝐂
𝟏𝟎𝟎
× 𝐇𝐂 +
× 𝐂𝐎 +
× 𝐂𝐎𝟐 ×
𝐇
𝐎
𝐌𝐖𝐂𝐎
𝐌𝐖𝐂𝐎𝟐
𝟏𝟎𝟎𝟎
𝐌𝐖𝐂 + × 𝐌𝐖𝐇 + × 𝐌𝐖𝐎
𝐂
𝐂
H/C: ratio of H to C for a specific fuel CxHyOz
(Annex 7, 3.1.2)
O/C: ratio of O to C for a specific fuel CxHyOz
(Annex 7, 3.1.2)
MWC = Molar weight of C = 12.011 g/mol
MWH = Molar weight of H = 1.008 g/mol
MWO = Molar weight of O = 15.999 g/mol
ρfuel = density of test fuel [kg/l]
HC = measured emissions of hydrocarbons [g/km]
CO = measured emissions of carbon monoxide [g/km]
CO2 = measured emissions of carbon dioxide [g/km]
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FC calculations
𝐅𝐂 [𝐥/𝟏𝟎𝟎𝐤𝐦] =
𝟏𝟐. 𝟎𝟏𝟏 +
𝐇
𝐎
× 𝟏. 𝟎𝟎𝟖 + × 𝟏𝟓. 𝟗𝟗𝟗
𝐂
𝐂
×
𝟏𝟐. 𝟎𝟏𝟏 × 𝛒𝐟𝐮𝐞𝐥
calc.
0.1155
0.1180
0.1206
0.1212
0.1336
0.1156
0.1163
0.1165
0.1743
𝟏𝟐. 𝟎𝟏𝟏
𝟏𝟎𝟎
× 𝐇𝐂 + 𝟎. 𝟒𝟐𝟗 × 𝐂𝐎 + 𝟎. 𝟐𝟕𝟑 × 𝐂𝐎𝟐 ×
𝐇
𝐎
𝟏𝟎𝟎𝟎
𝟏𝟐. 𝟎𝟏𝟏 + × 𝟏. 𝟎𝟎𝟖 + × 𝟏𝟓. 𝟗𝟗𝟗
𝐂
𝐂
calc.
0.866
0.848
0.829
0.825
0.749
0.865
0.860
0.858
0.574
fuel
E0
E5
E10
LPG
NG
B0
B5
B7
E85
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FC calculations
𝐅𝐂 [𝐥/𝟏𝟎𝟎𝐤𝐦] =
𝟏𝟐. 𝟎𝟏𝟏 +
𝐇
𝐎
× 𝟏. 𝟎𝟎𝟖 + × 𝟏𝟓. 𝟗𝟗𝟗
𝐂
𝐂
×
𝟏𝟐. 𝟎𝟏𝟏 × 𝛒𝐟𝐮𝐞𝐥
calc.
0.1155
0.1180
0.1206
0.1212
0.1336
0.1156
0.1163
0.1165
0.1743
GTR
0.1154
0.118
0.120
0.1212
0.1336
0.1155
0.116
0.116
0.1742
𝟏𝟐. 𝟎𝟏𝟏
𝟏𝟎𝟎
× 𝐇𝐂 + 𝟎. 𝟒𝟐𝟗 × 𝐂𝐎 + 𝟎. 𝟐𝟕𝟑 × 𝐂𝐎𝟐 ×
𝐇
𝐎
𝟏𝟎𝟎𝟎
𝟏𝟐. 𝟎𝟏𝟏 + × 𝟏. 𝟎𝟎𝟖 + × 𝟏𝟓. 𝟗𝟗𝟗
𝐂
𝐂
calc.
0.866
0.848
0.829
0.825
0.749
0.865
0.860
0.858
0.574
GTR
0.866
0.848
0.830
0.825
0.749
0.866
0.861
0.859
0.574
fuel
E0
E5
E10
LPG
NG
B0
B5
B7
E85
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FC calculations
𝐅𝐂 [𝐥/𝟏𝟎𝟎𝐤𝐦] =
𝟏𝟐. 𝟎𝟏𝟏 +
𝐇
𝐎
× 𝟏. 𝟎𝟎𝟖 + × 𝟏𝟓. 𝟗𝟗𝟗
𝐂
𝐂
×
𝟏𝟐. 𝟎𝟏𝟏 × 𝛒𝐟𝐮𝐞𝐥
calc.
0.1155
0.1180
0.1206
0.1212
0.1336
0.1156
0.1163
0.1165
0.1743
GTR
0.1154
0.118
0.120
0.1212
0.1336
0.1155
0.116
0.116
0.1742
𝟏𝟐. 𝟎𝟏𝟏
𝟏𝟎𝟎
× 𝐇𝐂 + 𝟎. 𝟒𝟐𝟗 × 𝐂𝐎 + 𝟎. 𝟐𝟕𝟑 × 𝐂𝐎𝟐 ×
𝐇
𝐎
𝟏𝟎𝟎𝟎
𝟏𝟐. 𝟎𝟏𝟏 + × 𝟏. 𝟎𝟎𝟖 + × 𝟏𝟓. 𝟗𝟗𝟗
𝐂
𝐂
calc.
0.866
0.848
0.829
0.825
0.749
0.865
0.860
0.858
0.574
GTR
0.866
0.848
0.830
0.825
0.749
0.866
0.861
0.859
0.574
fuel
E0
E5
E10
LPG
NG
B0
B5
B7
E85
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Proposal (1) – Adjustment of values in GTR
6.
Calculation of fuel consumption
6.1.
The fuel characteristics required for the calculation of fuel consumption
values shall be taken from Annex 3 in this gtr.
6.2.
The fuel consumption values shall be calculated from the emissions of
hydrocarbons, carbon monoxide, and carbon dioxide determined from the
measurement results using the provisions defined in this gtr.
6.3.
For a vehicle with a positive ignition engine fuelled with petrol (E0)
FC =
6.4.
× 0.866 × HC + 0.429 × CO + 0.273 × CO2
(60)
0.118
× 0.848 × HC + 0.429 × CO + 0.273 × CO2
ρ
(61)
For a vehicle with a positive ignition engine fuelled with petrol (E10)
FC =
6.6.
ρ
For a vehicle with a positive ignition engine fuelled with petrol (E5)
FC =
6.5.
𝟎.𝟏𝟏𝟓𝟓
𝟎.𝟏𝟐𝟎𝟔
ρ
× 0.829 × HC + 0.429 × CO + 0.273 × CO2
(62)
For a vehicle with a positive ignition engine fuelled with LPG
FCnorm =
0.1212
0.538
× 0.825 × HC + 0.429 × CO + 0.273 × CO2
(63)
6.6.1.
If the composition of the fuel used for the test differs from the composition
that is assumed for the calculation of the normalised consumption, on the
manufacturer's request a correction factor cf may be applied, as follows:
FCnorm =
0.1212
0.538
× cf × 0.825 × HC + 0.429 × CO + 0.273 × CO2
(64)
The correction factor cf, which may be applied, is determined as follows
Cf = 0.825 + 0.0693 × nactual
(65)
where:
nactual is the actual H/C ratio of the fuel used.
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Proposal (1) – Adjustment of values in GTR
6.7.
For a vehicle with a positive ignition engine fuelled with NG/biomethane
FCnorm =
0.1336
0.654
× 0.749 × HC + 0.429 × CO + 0.273 × CO2
(66)
6.8.
For a vehicle with a compression engine fuelled with diesel (B0)
FC =
6.9.
× 0.865 × HC + 0.429 × CO + 0.273 × CO2
(67)
0.1163
ρ
× 0.860 × HC + 0.429 × CO + 0.273 × CO2
(68)
For a vehicle with a compression engine fuelled with diesel (B7)
FC =
6.11.
ρ
For a vehicle with a compression engine fuelled with diesel (B5)
FC =
6.10.
0.1156
0.1165
ρ
× 0.858 × HC + 0.429 × CO + 0.273 × CO2
(69)
For a vehicle with a positive ignition engine fuelled with ethanol (E85)
FC =
0.1743
ρ
× 0.574 × HC + 0.429 × CO + 0.273 × CO2
(70)
where for all equations in paragraph 6:
FC
is fuel consumption in l/100 km (or m³ per 100 km in the case of
natural gas);
HC
are the measured emissions of hydrocarbons, g/km;
CO
are the measured emissions of carbon monoxide, g/km;
CO2
are the measured emissions of carbon dioxide, g/km;
ρ
is the density of the test fuel.
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