Experiments on the influence of inlet charge and coolant temperature on performance and emissions of a DI Diesel engine

The coolant and inlet charge temperature influence the emissions and performances of a DI Diesel engine. A unique test rig was constructed in which their influence could be studied controlling all the important operational parameters of the engine. The air, fuel and EGR circuit of one cylinder of a four cylinder engine were separated to permit a precise control of flow rates and flow temperatures while the original coolant circuit, controlling the wall temperatures, was preserved. The installation demonstrates how a multi-cylinder production engine can be transformed to perform tests with single cylinder precision. For three operating points, representative for the European homologation cycle, tests were performed to assess the influence of the coolant- and air-temperature on engine operation. Raising the coolant and inlet charge temperature diminishes hydrocarbon emissions and increases NOx emissions. The effect of the inlet charge temperature is much more important than the effect of the coolant temperature. At low load the effects are more pronounced. The influence on the performance and the combustion process is limited. (C) 2006 Elsevier Inc. All rights reserved.