EMISSION MEASUREMENT
The emission regulations specify the type, principle of operation used and generic construction of the exhaust gas analyzers which can be employed for emission certification of vehicles and engines. Table 4.9 gives the type of analyzers used for measurement of different exhaust gas constituents.
Table 4.9 |
Measurement Principles of Exhaust Gas Analyzers |
| Gas component |
Measurement Principle |
CO |
NDIR (Non-dispersive infrared) |
HC |
FID (Flame Ionization detector) |
| NO x |
CLD (Chemiluminescence detector) |
CO and CO2 NDIR Analyzers
Beer-Lambert's Law is used for operation of NDIR analyzers by measuring the degree of absorption of infrared (IR) radiations when they pass through a column of gas. The fraction of incident radiations absorbed is given by,
 |
(4.1) |
where
I = Radiation energy absorbed
I0 = Incident radiation energy
k = characteristic absorption constant for the gas, m2 /gmol
c = concentration of the gas, gmol/m 3
d = length of the gas column, m
|
