Chemical sensor systems for emission control from combustions

Abstract

Environmental and health concern has increased the importance to monitor and control emissions from combustion processes like toxic gases and particulate matter. The SiC-FET technology offers versatile and powerful sensors for gas detection also in combination with combustion of particles. Emission control has been demonstrated e.g. for small and medium sized power plants and diesel exhausts. The potential danger of nanoparticles makes such detectors interesting not only for detection of concentration and size of particles but also detection of the content of particles. The SiC-FET technology lends itself for smart sensing and smart data evaluation, which largely improves the information from such a sensor system. Here we report progress on the sensor technology itself, the application of a sensor system as an alarm for ammonia emission and preliminary results of particle detection.

Capacitive soot sensor for diesel exhausts

“…Regarding the sensor signal of the conductometric device (type 1), one can observe the well-known behavior, as often reported in literature [11][12][13][15][16][17][18][19][25][26][27]. As described above, after a certain blind time, the current increases monotonously with soot loading.…”

Improved chemical sensors track and control emissions

“…Once we cycled the temperature of the particles up to 430 ı C, they released the ammonia to be detected by an ammonia sensor. 5 The released gas acted as a 'fingerprint' for the chemical content of the particulate.…”

Conductometric Sensor for Soot Mass Flow Detection in Exhausts of Internal Combustion Engines

“…Driven by on-board diagnostics (OBD) regulations to monitor DPF filtration efficiencies and tailpipe particulate matter (PM) emissions, recently, PM sensors have been developed to estimate excessive PM emissions downstream of a DPF in case of a filter failure [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. In-use PM sensors are based on the conductometric principle.…”

“…Driven by electrophoresis, soot particles deposit on the sensor surface and a current, I , occurs after a certain percolation time and continuously increases with more and more soot deposited on the sensor. This time span or the electrical current (respectively the resistance) at a certain time can be a measure for the amount of soot in the exhaust [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Some authors call this type of sensors “accumulating (or collecting) soot sensors” [ 7 ], since the occurring sensor current is a measure for the accumulated amount of soot on the sensor.…”