Panagiotis Pistikopoulos, Argyris Tzilvelis, Dimitris Katsaounis and Dionysios Mavrodis who helped tremendously in converting Honda Accord into "mobile laboratory" for the needs of the measurements on the road. Theodora Zacharopoulou for her valuable contribution to the development of the model in VeLoDyn and during the duration of the measurements on the road.

General

Particulate matter parameters

In Europe specifically for passenger cars, EURO 5 legislation is currently in force, which implements PM emissions of less than 0.005 g/km during a NEDC (New European Driving Cycle) (Table 1.1).

Diesel engine Particulate Matter composition and formation

Carbonaceous material
Hydrocarbons
Sulfates
Inorganic material

Here we are only interested in the absorbed HC as part of the particulate matter. Also, the fuel pressure is lower at the end of the injection compared to the original.

Diesel engine Particulate Matter health effects

These elements come from engine oil additives (for better lubricating properties), wear of engine parts such as oil pump, piston rings, camshaft, etc.

Diesel engine Particulate Matter emissions reduction

Engine design

Fuel injection
Air induction, combustion, other internal components

Modern diesel engines are practically all supercharged to improve specific engine power. Cylindrical rings affect the residual lubricant after the downward movement of the cylinder, which can increase particulate emissions.

Fuel and lubricants technology

But in the event that a DPF is installed, these additives can affect the regeneration process unpredictably. The amount of sulfated ash, phosphorus, and sulfur (SAPS) can affect the rate of ash accumulation in the aftertreatment devices.

After treatment devices - Diesel Particulate Filter (DPF)

Introduction
Principle of operation
Oxidation by oxygen
Oxidation by nitrogen dioxide

For high levels of oxidation with oxygen, a gas temperature of up to 600 oC is required (Figure 1.14). At a lower temperature, the reaction is limited by kinetics, and at a higher temperature by thermodynamics (Figure 1.15).

On Board Diagnostic (OBD)

Malfunction indicator lamp (MIL) and diagnostic devices

When activated, the light flashes (major malfunction, serious damage may occur to the catalytic converter or other aftertreatment device, stop the engine immediately) or continuously (minor problem with a sensor or an aftertreatment device, visit an authorized service center). It usually has a yellow-orange color and its shape is the outline of an engine (Figure 1.16).

Driving cycles

General issues

New European Driving Cycle

Worldwide harmonized Light vehicles Test Cycle (WLTC)

Common Artemis Driving Cycles (CADC)

ARTEMIS Rural Road was created to illustrate the driving conditions of a typical European country road and as a result is characterized by medium vehicle speed with an average and maximum speed of 57.5 km/h and 112 km/h respectively. Finally, Artemis Motorway includes two different versions depending on the maximum vehicle speed (130 or 150 km/h) and describes the driving profile of European motorways.

FTP75 driving cycle

US06 driving cycle

Laboratory’s main equipment

Chassis and engine dynamometers

According to the type of absorption unit, dynamometers can be classified into electric motor/generator, water brake, electromagnetic (or eddy current) brake, mechanical friction brake, and other variations of the above categories. In the case of the reverse process, the wheels of the vehicle can be driven by the rollers, and thus electric power is consumed by the motor (15).

Micro Soot Sensor (MSS)

Objective of this study

Experimental engine, vehicle and equipment

Vehicle Honda Accord 2.2i CTDi
Honda Accord Diesel Particulate Filters (DPF)

Measurement equipment- ETAS ECU, INCA software

Resistive Soot Sensor
Pegasor Particle Sensor (PPS)

Measuring unit
Heated inlet pipe, heater controller, air supply, air regulator, power supply
PPS compared to MSS results

Vehicle’s ECU

The output signal together with the temperature sensor's signal is read by ETAS ES650.1 thermo and A/D module (Figure 2.11). The configuration in Honda Accord of ES650 thermo and A/D module with the ES600 network module is illustrated in Figure 2.13. The experiment environment within the INCA's main window for Honda road measurements is in Figure 2.14.

This sensor is mounted vertically on the outlet line and consists of two electrodes at a specific distance between them (Figure 2.15). The regeneration process and the transformation of the output signal is controlled by an electronic control unit (ECU) near the sensor's probe (Figure 2.16). The output signal from the sensor's ECU is transferred to Vector VN1630 CAN device (Figure 2.17).

The detection and measurement of the leakage current of the flow results in the number and concentration of the flow in the mass (Figure 2.19). There is also a control unit for the heater, which can be adjusted to the specific temperature desired (Figure 2.23).

Routes specifications for Honda Accord on-road measurements

Only the most representative measured values are available: Resistive soot sensor signal, soot emission measurement from the Pegasor particle sensor [mg/s] and vehicle speed data from the ECU.

VeLoDyn model construction

General

The necessary signals are extracted from the incoming buses with the help of so-called bus connections and fed to the actual model. At the output, signals additionally generated by the Simulink block are fed into the incoming bus and read out. There are two buses, one bus (signal bus) acts as the carrier for a wide range of different physical and model-relevant signals, while the second bus (control bus) is provided for the exchange of control signals.

The diagram below symbolizes the way a Simulink block is embedded in a carrier block (Figure 3.4). VeLoDyn can use this information to generate HTML help texts or provide online help texts via bus signals (Figure 3.6). d) Support files: Support files can be used to store all the data needed to realize the model. When loading the model, these files are automatically extracted and written to the current path (Figure 3.7).

VeLoDyn model for simulation of Honda Accord’s soot concentration

VeLoDyn ConvDrive_MT.mdl carrier block pack (A)
Particulate Matter Simulink block pack (B)
Engine characteristics Simulink block pack (power, torque, engine speed) (C)

The start of the simulation somewhere in the cycle can be moved using a freely definable time delay value. NEDC for the manual transmission was one of the default cycles, but only for the 4-speed transmission. If the gear is set (on), the input torque is reduced by the acceleration torque of the input side and gains with the current ratio and transmission efficiency, which is defined by the input speed and input torque.

Because of this, the resulting gearbox output torque is multiplied by the reciprocal of the efficiency if the input torque is negative. If neutral gear is required, the input side of the transmission acts as an open shaft (inertia). The inertia of the input side depends on the current gear, defined by the gear-dependent map.

During neutral condition, an output speed dependent loss torque is applied to the output torque of the transmission. The comparative limit value to decide on the DPF's condition 3.1.2.2.1 The post-DPF soot calculation block pack.

Engine-out simulation

Engine-out VeLoDyn’s soot emission simulation

NEDC engine-out VeLoDyn’s soot emission simulation
Artemis engine-out VeLoDyn’s soot emission simulation
Artemis Road engine-out VeLoDyn’s soot emission simulation
WLTC engine-out VeLoDyn’s soot emission simulation
US06 and FTP75 engine-out VeLoDyn’s soot emission simulation
Comparison NEDC, Artemis Urban & Road and WLTC on simulated and measured

In Figure 4.10 there are 2 points (A & B) that create a large rise in route map to these areas. The results for soot emissions using the coefficient of determination (R2) value and the cumulative deviation [%], were not acceptable (Figure 4.26).

Post-DPF (1.5 x T.A.) simulation – Filtration efficiency

NEDC post-DPF (1.5 x T.A.) VeLoDyn’s soot emission simulation

The simulation of soot emissions after a DPF is complicated by the inconsistency of DPF filtration efficiency in a second-by-second simulation. The first approach was to insert the constant filter efficiency calculated above after the engine soot emissions in the NEDC simulation into VeLoDyn. There is no difference between simulation and measurement and therefore the filtration efficiency for 1.5 x T.A.

For future use, the effect of car acceleration, intake manifold airflow, and DPF inlet temperature on filtration efficiency was studied. It has been demonstrated that good convergence between MSS and VeLoDyn can be achieved with appropriate transfer functions obtained from engine shutdown and post-DPF measurements.

Artemis Urban post-DPF (1.5 x T.A.) VeLoDyn’s soot emission simulation

Artemis Road post-DPF (1.5 x T.A.) VeLoDyn’s soot emission simulation

WLTC post-DPF (1.5 x T.A.) VeLoDyn’s soot emission simulation

Comparison NEDC, Artemis Urban & Road and WLTC on measured post-DPF emissions

On-road 1.5 x T.A. Extra Urban driving cycle
Gear shifting identification

The on-road measurements have no specific and official driving cycles that could be repeated over and over and entered into VeLoDyn's model. The driving cycles for on-road measurements were created and are described in section 3.2.7.1 based on the above routes. It is obvious that there is no convergence between Urban on-road and NEDC and therefore NEDC characteristics were rejected.

The highlighted areas in both diagrams above were chosen to create an urban road driving cycle. Upon closer examination of this area, the differences could be assessed as negligible (table 4.19) and thus the first road driving cycle was created. In this case there are points where the values on the road and ARTEMIS Road are very close at only 1.5 x T.A.

The highlighted areas in Figure 4.67 and Figure 4.68 were chosen for the creation of additional urban driving on the road. If you look more closely at this area, the differences could be assessed as insignificant (table 4.21), and thus the driving cycle Extra Urban on the road was created.

Filtration efficiency for VeLoDyn’s model (Honda Accord on-road measurements)

Final PM map and results for VeLoDyn’s model (Honda Accord on-road measurements)

For the second driving cycle on the road, the Extra Urban, the results with test #7 as NEDC, Artemis Urban and WLTC are very satisfactory (Figure 4.76). Furthermore, the measurements on the road led to the formation of a large database for soot emissions on real-world driving conditions that could be the source for many other theses in this field. The first part of this thesis was the road measurements with Honda Accord 2.2i-CTDi vehicle.

In order to have a broader view of emissions regardless of filtration efficiency, on-road measurements with the engine off could be helpful. The analysis of on-road measurements should be extended to all measurement dates (only applications for the urban driving cycle were here). In this case, safer and more reliable results for on-road measurements could be produced.

Retrieved from http://www.acea.be/images/uploads/files/POCKET_GUIDE_13.pdf Ahmed Hassaneen et al. Retrieved from http://www.wgsoft.de/shop/obd-2-komplettsysteme/obdlink-wlan-usb-bluetooth/obdlink-wlan-wifi-usb-scanmaster-elmscan.html.

ACRONYMS

86 Figure 4.31: Cumulative deviation of MSS and VeLoDyn for 1Hz recording frequency and moving average of 5 values. 87 Figure 4.32: VeLoDyn's results compared to MSS measurements (final soot map) and with 1Hz recording frequency and moving average of 5 values. 87 Figure 4.33: VeLoDyn's results compared to MSS measurements (final soot map) and with 1Hz recording frequency and moving average of 17 values.

88 Figure 4.34: Two peaks in NEDC and soot model response compared to MSS for 10Hz and 1Hz recording frequency with moving average of 5 values. 90 Figure 4.37: Micro soot sensor data (#1 from above diagram) compared to VeLoDyn results with final soot map for ARTEMIS urban driving cycle. 91 Figure 4.39: Micro soot sensor data compared to VeLoDyn results with final soot map for Artemis Road driving cycle.

93 Figure 4.41: Micro soot sensor data compared to VeLoDyn results with final soot map for WLTC. 117 Figure 4.76: Pegasor Particle Soot Sensor data compared to VeLoDyn results with PM card from the test.

Table of Figures

Table of Tables