در حضور گازهاي قابل احتراق و هوا در حدود ناحيه استوكيومتري SHO2 سنسور پايه LOW-HIGH رفتار

Low-High Behavior Of SnO2-Based Sensors In Presence Of Combustible Gases And Air In Stoichiometric Region

In the present investigation, the sensitivity of a SnO2-based sensor in the presence of simulated automotive exhaust gases at different temperatures is investigated. The simulated gas is CO and/or ethane mixed with different amounts of air, to provide the corresponding automotive exhaust gases with different air-to fuel ratios at inlet to the engine. The sensor response is investigated at temperatures ranging from 300-400 °C for CO and 400-460 °C for ethane. As the air-to-fuel (CO and/or C2H6) weight ratio is varied, the resistance of the sensor shows an S-shape response: a low value for the sensor resistance at low air-to-fuel (ATF) ratios, a transition region, and a high value at high ATF ratios. The changes in the transition region, depending on the temperature and reducing gas, is as high as one to three orders of magnitude. For CO, the transition region occurs at ATF ratios lower than the stoichiometric value, while for C2H6 it occurs at values higher than that of Stoichiometric. When the simulated gas passes through a catalytic burning chamber upstream of the sensor, a sharp transition in the sensor resistance occurs right at the stoichiometric ATF ratio. Therefore, the sensor can be improved to be used as lambda oxygen sensor.