NOx emission on-line measurement for the diesel engine based on tunable diode laser absorption spectroscopy

An on-line measurement for the diesel engine NOx emission based on tunable diode laser absorption spectroscopy (TDLAS) technique is realized. Two absorption lines 1900.07059 cm−1 and 1626.91952 cm−1 are chosen for NO and NO2 measurement. Two ICL inter-band cascade (ICL) lasers are used to measure NO and NO2 separated. In this work, we use the TDLAS system to research the NOx emissions on a four-stroke four-cylinder diesel engine. Optical windows are installed on the exhaust pipe of the diesel engine symmetrical to realize the on-line measurement. The direct detection method is adopted in this work, which can avoid the effect from unknown concentration of particulate matter (PM) in the exhaust. The NOx emission characteristic under different load power and different rotating speed is researched. This work can support the research on the combustion process of diesel engines.