Symbols for general parameters	Definitions
$V_{\mathrm{obs}}$	Observation volume
$w_{\mathrm{l}}$	Laser beam diameter
$d$	Diameter of the inlet nozzle
$C_{\mathrm{d}}$	Concentration of the diluted emission
$C_{\mathrm{r}}$	Real concentration of the exhaust emission
$df$	Dilution factor
$n$	Number of ejectors in parallel
$G_{\mathrm{mix}}$	Mass flow rate after mixing
$G_{\mathrm{suction}}$	Mass flow rate at exhaust suction
$G_{\mathrm{supply}}$	Mass flow rate of dilution air
$G$	Mass flow rate
$Q$	Volumetric flow rate
Symbols for parameters of the fist layout	Definitions
$Q_{\mathrm{T}}$	Total volumetric flow rate of diluted sampling
$Q_{\mathrm{exhaust}}$	Volumetric flow rate of the raw exhaust
$Q_{\mathrm{air}}$	Volumetric flow rate of the environmental air
${\rho }_{\mathrm{T}}$	Total density of the diluted particulate matter
${\rho }_{\mathrm{ex}}$	Density of the exhaust emission
${\rho }_{\mathrm{air}}$	Density of the air
Symbols for parameters of the second layout	Definitions
$Q_{\mathrm{supply}\_\mathrm{air}}$	Volumetric flow rate of the supply air
$Q_{\mathrm{suction}\_\mathrm{air}}$	Volumetric flow rate of the suction air
$Q_{\mathrm{exhaust} \mathrm{gas}}$	Volumetric flow rate of the emission gas
$Q_{\mathrm{Total}-\mathrm{Air}}$	Total volumetric flow rate of air
$Q_{\mathrm{Supply}-\mathrm{ejector}}$	Volumetric flow rate of the supply (last ejector)
$Q_{\mathrm{Total}-\mathrm{ejector}}$	Volumetric flow rate of the supply + suction
$Q_{\mathrm{air}-\mathrm{compressor}}$	Volumetric flow rate of the compressor
Symbols for calculation of the temperature	Definitions
$T_{\mathrm{mix}}$	Temperature of the gas mixture
$T_{\mathrm{air}-\sup }$	Air temperature in the supply ejector
$T_{\mathrm{air}-\mathrm{suc}}$	Air temperature in the suction ejector
$T_{\mathrm{exhaust}-\mathrm{suc}}$	Exhaust temperature suction emission
$G_{\mathrm{air}-\sup }$	Overall supply air mass flow rate of ejectors
$G_{\mathrm{air}-\mathrm{suc}}$	Air mass flow rate of the suction (n-1) ejectors
$G_{\mathrm{exhaust}-\mathrm{suc}}$	Exhaust mass flow rate of the suction ejector
Symbols for calculation of the humidity	Definitions
$M_{{\mathrm{H}}_2\mathrm{O}-\mathrm{tot}}$	Total mass of the $H_{2}O$ in the system
$M_{{\mathrm{H}}_2\mathrm{O}-\mathrm{air}-\mathrm{supply}}$	Mass flow rate of water vapor in air supply ejectors
$M_{{\mathrm{H}}_2\mathrm{O}-\mathrm{air}-\mathrm{suction}}$	Mass flow rate of the $H_{2}O$ in air suction ejectors
$M_{{\mathrm{H}}_2\mathrm{O}-\mathrm{gas}-\mathrm{suction}}$	Mass flow rate of $H_{2}O$ in the emission suction ejector
$M_{\mathrm{dry}-\mathrm{tot}}$	Total mass flow rate of the dry air
$M_{\mathrm{air}-\mathrm{dry}-\mathrm{supply}}$	Mass flow rate of the dry air in supply ejectors
$M_{\mathrm{air}-\mathrm{dry}-\mathrm{suction}}$	Mass flow rate of the dry air in suction ejectors
$M_{\mathrm{gas}-\mathrm{dry}-\mathrm{suction}}$	Mass flow rate of the dry emission in the suction ejector
$x_{\mathrm{mix}}$	Water mixing ratio of the air–exhaust gas mixture
$P_{\mathrm{H}2\mathrm{O}-\mathrm{mix} }$	Partial pressure of the vapor in the mix condition
$P_{\mathrm{STP}}$	Standard ambient pressure
$RH$	Relative humidity
$P_{\mathrm{SAT}}$	Saturation pressure of the vapor