Measurements and Modelling for Heat Transfer Corrected Exhaust Gas Temperatures in a Gasoline Engine

Sammanfattning: This thesis is treating the modelling of a thermocouple (tc) to compensate forheat transfers due to convection, radiation and conduction when performingtemperature measurements in an SI-engine. An experiment plan was developedwhich covered experiments in an stc-rig and on a 4-cylinder SI-engine. The measurementsin the stc-rig was mainly to develop the model, while the measurementsin the engine lab was mainly to examine the characteristics of the engineand evaluate the modelled tc.Measurements with an exposed thin tip tc in the stc-rig showed a symmetricaltemperature profile in the pipe. By examining how the 1.5 mm tc behaved inthis environment with known gas temperature profile, the obtained knowledgecould be applied to cross-sectional measurements in the SI-engine. It was foundthat the temperature profile in the engine deviated from the temperature profilemeasured in the stc-rig. The temperature was higher near the top of the pipethan in the center and lower part. In the horizontal direction, the temperaturewas found to be constant.Conclusions drawn from measurements in the engine lab points to that the crosssectionaltemperature and mass flow profiles have a strong connection with theengine’s operation point. The cross-sectional profiles, along with respective profileover time, is crucial when estimating the energy content of an exhaust gaspulse.The inverted sensor model with optimized parameters could estimate the meanvalue of the measured gas temperature during stationary runs within 6 degC.