Abstract
In diesel engines, increasing exhaust gas recirculation EGR ration promotes NOx reduction but gives an increase in PM emission. Diluting engine intake air with CO_2 (CO_2 selective EGR) extends the EGR ratio window with no PM increase. Nevertheless, extraction of CO_2 from diesel exhaust is not easy due to the moisture existence, which diminishes the CO_2 adsorption efficiency of conventional absorbents such as zeolites. In this study, CO_2 was chemically adsorbed using potassium carbonate K_2CO_3-on-Carbon by the reaction K_2CO_3+CO_2+H_2O⇔2KHCO_3. Then, entrapped CO_2 was released by decomposition of KHCO_3 by steam flushing which reverses the mentioned reaction. This method offers a high CO_2 extraction efficiency even when gas contains a high amount of moisture.
