# Commission Delegated Regulation (EU) 2017/654 of 19 December 2016 supplementing Regulation (EU) 2016/1628 of the European Parliament and of the Council with regard to technical and general requirements relating to emission limits and type-approval for internal combustion engines for non-road mobile machinery, Division 1.1: General symbols

Extent: E+W+S+N.I.

See subscripts; e.g.: ṁ air for mass rate of dry air, ṁ fuel for fuel mass rate, etc.
Dilution ratio r d in section 2 and DR in section 3: different symbols but same meaning and same equations. Dilution factor D in section 2 and x dil in section 3: different symbols but same physical meaning; equation (7-124) shows the relationship between x dil and DR.
t.b.d.= to be defined.
Section 2
Section 3
Unit
Quantity
A
m2
Area
At
m2
Venturi throat cross-sectional area
b, D 0
a 0
t.b.d.
y intercept of the regression line
A/F st
—
Stoichiometric air to fuel ratio
C
—
Coefficient
C d
C d
—
Discharge coefficient
C f
—
Flow coefficient
c
x
ppm, % vol
Concentration/mole fraction (μmol/mol = ppm)
c d
ppm, % vol
Concentration on dry basis
c w
ppm, % vol
Concentration on wet basis
cb
ppm, % vol
Background concentration
D
x dil
—
Dilution factor
D 0
m3/rev
PDP calibration intercept
d
d
m
Diameter
d V
m
Throat diameter of venturi
e
e
g/kWh
Brake specific basis
e gas
e gas
g/kWh
Specific emission of gaseous components
e PM
e PM
g/kWh
Specific emission of particulates
E
1 – PF
%
Conversion efficiency (PF = Penetration fraction)
F s
—
Stoichiometric factor
f
Hz
Frequency
f c
—
Carbon factor
γ
—
Ratio of specific heats
H
g/kg
Absolute humidity
K
—
Correction factor
K V
K × m 4 × s ∕ kg
CFV calibration function
k f
m3/kg fuel
Fuel specific factor
k h
—
Humidity correction factor for NOx, diesel engines
k Dr
k Dr
—
Downward adjustment factor
k r
k r
—
Multiplicative regeneration factor
k Ur
k Ur
—
Upward adjustment factor
k w,a
—
Dry to wet correction factor for the intake air
k w,d
—
Dry to wet correction factor for the dilution air
k w,e
—
Dry to wet correction factor for the diluted exhaust gas
k w,r
—
Dry to wet correction factor for the raw exhaust gas
μ
μ
kg/(m·s)
Dynamic viscosity
M
M
g/mol
Molar mass
M a
g/mol
Molar mass of the intake air
M e
v
g/mol
Molar mass of the exhaust gas
M gas
M gas
g/mol
Molar mass of gaseous components
m
m
kg
Mass
m
a 1
t.b.d.
Slope of the regression line
ν
m2/s
Kinematic viscosity
m d
v
kg
Mass of the dilution air sample passed through the particulate sampling filters
m ed
kg
Total diluted exhaust gas mass over the cycle
m edf
kg
Mass of equivalent diluted exhaust gas over the test cycle
m ew
kg
Total exhaust gas mass over the cycle
m f
mg
Particulate sample mass collected
m f,d
mg
Particulate sample mass of the dilution air collected
m gas
m gas
g
Mass of gaseous emissions over the test cycle
m PM
m PM
g
Mass of particulate emissions over the test cycle
m se
kg
Exhaust gas sample mass over the test cycle
m sed
kg
Mass of diluted exhaust gas passing the dilution tunnel
m sep
kg
Mass of diluted exhaust gas passing the particulate collection filters
m ssd
kg
Mass of secondary dilution air
N
—
Total number of a series
n
mol
Amount of substance
ṅ
mol/s
Amount of substance rate
n
f n
min– 1
Engine rotational speed
n p
r/s
PDP pump speed
P
P
kW
Power
p
p
kPa
Pressure
p a
kPa
Dry atmospheric pressure
p b
kPa
Total atmospheric pressure
p d
kPa
Saturation vapour pressure of the dilution air
p p
p abs
kPa
Absolute pressure
p r
p H2O
kPa
Water vapour pressure
p s
kPa
Dry atmospheric pressure
1 — E
PF
%
Penetration fraction
qm
ṁ
kg/s
Mass rate
qm ad
ṁ
kg/s
Intake air mass flow rate on dry basis
qm aw
kg/s
Intake air mass flow rate on wet basis
qm Ce
kg/s
Carbon mass flow rate in the raw exhaust gas
qm Cf
kg/s
Carbon mass flow rate into the engine
qm Cp
kg/s
Carbon mass flow rate in the partial flow dilution system
qm dew
kg/s
Diluted exhaust gas mass flow rate on wet basis
qm dw
kg/s
Dilution air mass flow rate on wet basis
qm edf
kg/s
Equivalent diluted exhaust gas mass flow rate on wet basis
qm ew
kg/s
Exhaust gas mass flow rate on wet basis
qm ex
kg/s
Sample mass flow rate extracted from dilution tunnel
qm f
kg/s
Fuel mass flow rate
qm p
kg/s
Sample flow of exhaust gas into partial flow dilution system
qV
V̇
m3/s
Volume flow rate
qV CVS
m3/s
CVS volume rate
qV s
dm3/min
System flow rate of exhaust gas analyzer system
qV t
cm3/min
Tracer gas flow rate
ρ
ρ
kg/m3
Mass density
ρ e
kg/m3
Exhaust gas density
r
—
Ratio of pressures
r d
DR
—
Dilution ratio
Ra
μm
Average surface roughness
RH
%
Relative humidity
r D
β
m/m
Ratio of diameters (CVS systems)
r p
—
Pressure ratio of SSV
Re
Re#
—
Reynolds number
S
K
Sutherland constant
σ
σ
—
Standard deviation
T
T
°C
Temperature
T
Nm
Engine torque
T a
K
Absolute temperature
t
t
s
Time
Δt
Δt
s
Time interval
u
—
Ratio between densities of gas component and exhaust gas
V
V
m3
Volume
qV
V̇
m3/s
Volume rate
V 0
m3/r
PDP gas volume pumped per revolution
W
W
kWh
Work
W act
W act
kWh
Actual cycle work of the test cycle
WF
WF
—
Weighting factor
w
w
g/g
Mass fraction
x –
mol/mol
Flow-weighted mean concentration
X 0
K s
s/rev
PDP calibration function
y
—
Generic variable
y –
y –
Arithmetic mean
Z
—
Compressibility factor

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Source: https://www.legislation.gov.uk/eur/2017/654/annex/VII/division/1/division/1.1 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-1/division-1.1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.