Division 1.1 General symbols

United Kingdom

Section 2	Section 3	Unit	Quantity
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.
	A	m²	Area
	A_t	m²	Venturi throat cross-sectional area
b, D ₀	a ₀	t.b.d.^f1	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	^f2	ppm, % vol	Concentration on dry basis
c _w		ppm, % vol	Concentration on wet basis
c_b		ppm, % vol	Background concentration
D	x _dil	—	Dilution factor^f3
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		$[(\sqrt{K} \times m^{4} \times s) ∕ kg]$	CFV calibration function
k _f		m³/kg fuel	Fuel specific factor
k _h		—	Humidity correction factor for NO_x, 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
q_m _ad	ṁ	kg/s	Intake air mass flow rate on dry basis
q_m _aw		kg/s	Intake air mass flow rate on wet basis
q_m _Ce		kg/s	Carbon mass flow rate in the raw exhaust gas
q_m _Cf		kg/s	Carbon mass flow rate into the engine
q_m _Cp		kg/s	Carbon mass flow rate in the partial flow dilution system
q_m _dew		kg/s	Diluted exhaust gas mass flow rate on wet basis
q_m _dw		kg/s	Dilution air mass flow rate on wet basis
q_m _edf		kg/s	Equivalent diluted exhaust gas mass flow rate on wet basis
q_m _ew		kg/s	Exhaust gas mass flow rate on wet basis
q_m _ex		kg/s	Sample mass flow rate extracted from dilution tunnel
q_m _f		kg/s	Fuel mass flow rate
q_m _p		kg/s	Sample flow of exhaust gas into partial flow dilution system
q_V	V̇	m³/s	Volume flow rate
q_V _CVS		m³/s	CVS volume rate
q_V _s		dm³/min	System flow rate of exhaust gas analyzer system
q_V _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
q_V	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
	$\bar{x}$	mol/mol	Flow-weighted mean concentration
X ₀	K _s	s/rev	PDP calibration function
	y	—	Generic variable
$\bar{y}$	$\bar{y}$		Arithmetic mean
	Z	—	Compressibility factor

Annotations

Footnotes

f1: t.b.d.= to be defined.
f2: See subscripts; e.g.: ṁ _air for mass rate of dry air, ṁ _fuel for fuel mass rate, etc.
f3: 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.