After most CO2 is removed from exhaust gas by aqueous KOH in the CO2 absorber, the exhaust gas is recirculated and mixed with a fresh oxygen charge to constitute a CCDE (closed cycle diesel engine) system. This study then improved the combustion and emissions of the diesel engine in the CCDE system using diesel fuel as main fuel with ethanol or gasoline of various energy share ratios inducted into the inlet port. Isothermal lines and velocity distributions in the engine cylinder from the numerical results are used to explain the measured emission results from the diesel engine in the CCDE system with portinducted fuel. The CCDE system effectively decreases smoke, NOx, and CO2 before the CO2 absorber using port-inducting ethanol or gasoline. In addition, the experimental results are consistent with the numerical results for the operating engine. (C) 2013 Elsevier Ltd. All rights reserved.