| | Category | EN | P18 | Humidity and Impact on EGR Scheduling |
| | Abstract | The purpose of the project was to study the effect of humidity on the |
| | usage of EGR (Exhaust Gas Recirculation) in boosted engine applications. |
| | The study concentrated on non-trivial behavior of humidity and the physics |
| | behind the behavior with respect to temperature, pressure, engine |
| | operating conditions, etc. Based on the empirical relationships of humidity |
| | and its interaction with other changing engine variables, a mathematical |
| | model was developed to calculate the limitation of EGR that can be used |
| | under different operating conditions without condensation. The results |
| | show that the condensation that limits the EGR% is directly related to |
| | humidity, temperature, and pressure. EGR decreases whenever relative |
| | humidity, ambient temperature and pressure increase. To avoid |
| | condensation, the increase in charge temperature (Air + EGR) over |
| | ambient temperature is a strong function of the ambient temperature. The |
| | hypothesis was verified in the dynamometer laboratory using a barometer |
| | under various conditions. The EGR limit calculations were tested by |
| | changing the ambient air temperature, humidity, EGR, and pressure at the |
| | CAC outlet and comparing them to the expected results. A user-friendly |
| | tool was developed with all the mathematical relationships and the models |
| | implemented for ease of use by the engine dyno and vehicle calibration |
| | teams. This study provides critical conclusions on the EGR operating |
| | conditions and limitations to avoid condensation and other failure modes. |
| | Bibliography | Van Basshuysen, Richard, and Schäfer, Fred, "Internal Combustion Engine |
| | Handbook," SAE International, 2004. |