Exhaust emission from a vehicle engine operating in dynamic states and conditions corresponding to real driving

The article presents the exhaust emission results from a diesel engine in dynamic states of engine operation in the driving tests: NEDC (New European Driving Cycle) and Malta test, developed at the Poznan University of Technology. The NEDC and Malta tests were carried out as simulations on the engine test bench mimicking the driving tests conditions. The test results of the emission of carbon monoxide, hydrocarbons and nitrogen oxides obtained in each of the tests were presented. The dynamic states have been classified depending on the time derivative value of the torque and engine rotational speed. Both the positive and negative as well as zero time derivative values of torque and rotational speed were considered. Therefore, overall six types of dynamic states were analyzed. A high sensitivity of exhaust emission to various types of dynamic states was found. The exhaust emission sensitivity to dynamic states in the Malta test was found to be higher than for the NEDC test, although these tests have similar properties (average rotational speed and average torque). This is due to the fact that the NEDC test is created on the basis of the similarity of zero-dimensional characteristics of the car's speed characteristic, whereas the Malta test was designed in accordance with the principle of faithful representation in the time domain of the NEDC speed curve.