**3. Experimental Setup**

The main details of the experimental setup and tests shown in this work are next briefly described. Further description can be found in [12]. In this work, the results of all tests to which a wall-flow DPF was subjected aimed to characterize its response against the use of pre-DPF water injection are presented. The main characteristics of the wall-flow DPF are summarized in Table 1, where it is identified as DPF #A.

**Table 1.** Characteristics of wall-flow DPFs.


The test campaign was conducted in a Euro 4 turbocharged diesel engine for passenger car use. The main characteristics of the engine are shown in Table 2. The engine was installed in a completely instrumented test cell equipped with all of the required auxiliary facilities for its operation and control. Engine speed and torque were controlled by connecting the engine to an asynchronous dynamometer both under steady-state and transient operating conditions. The engine was also instrumented with sensors to measure the main magnitudes of operation, such as temperature and mean pressure along the intake and exhaust lines, air mass flow, fuel consumption and turbocharger speed. All of these data were completed with the electronic control unit and test cell parameters.



In the particular case of the DPF, its pressure drop was measured by placing two piezoresistive transducers in the inlet and outlet cones of the DPF canning. The temperature was also measured in these locations with K-type thermocouples. The water was injected at the DPF inlet by means of a simple calibrated nozzle [12]. The assessment of the filtration efficiency was performed based on the particle concentration measurements upstream and downstream of the DPF with a TSI™EEPS (Engine Exhaust Particle Sizer) spectrometer.
