The overall goal of this video is to present the newly adopted real-driving emissions test for light-duty vehicles, which measures on road emissions using a portable emissions measurement system. In Europe, the real-driving emissions procedure will complement the type of overall of light-duty vehicles when the test is done among meters. So the regulated pollutants are thoroughly controlled under a wide range of normal driving conditions.
This procedure measures vehicle emissions in the real world, on the road, in cities, and on the highway. The procedure provides us with a comprehensive overview of the emissions performance of each test that we occur. Demonstrating the procedure will be Rinaldo Colombo, Mauro Cadario, and Philippe Le-Lijour.
Ideally, install the PEMS main unit and control unit on the exterior of the vehicle, such as on a tow bar or a hook, using a platform or in the trunk. If the PEMS must be installed in the cabin, secure it with straps to the car. Install a vent to the outside for exhaust gases and condensates vented by the PEMS.
Next, following the manufacturers instructions and local regulations, install a carbon dioxide, carbon monoxide, and nitrogen oxides analyzer, accessory units and their connectors, and their heated sampling lines. If the PEMS does not operate using its own batteries, strap two 12 volt batteries into the vehicle cabin. For instance, behind the front passenger seat.
Next, attach the weather station and GPS directly to the exterior of the vehicle. Then, connect the signal cables to the PEMS main unit signal input port. Now select an exhaust flow meter, or EFM, which is capable of measuring the expected exhaust mass flow rate from the text vehicle.
Depending on the specific vehicle, the EFM can be attached to a tow bar, to a bicycle carrier, or to metal brackets. Attach the EFM to the tailpipe using welding metal tubes. Avoid decreasing the inner diameter of the tailpipe using smaller tubes.
Next, fit all the gas sampling probes within 20 centimeters of the exhaust exit but do not congest the flow of the exhaust by placing too many probes at the same position. If an EFM is used, the probes must be at least 20 centimeters from the exhaust exit. Ideally, each probe should sample from the center line of the exhaust flow.
Large probes that span the diameter of the tailpipe can also be used if they have multiple holes along their lengths. Before the zero and span calibration, conduct a leak check. To begin, switch on the PEMS and let it stabilize following the manufacturer's recommendations.
This can take about 40 minutes. Use the current and not the batteries. Connect the PC to the PEMS.
Before proceeding, ensure that the gas sampling lines have reached at least 60 degrees Celsius. Also, deal with any warning or error signals on the PEMS before proceeding. Once warmed up, calibrate the system with zero and span gases.
First, connect the zero gas line. Use nitrogen or synthetic air as the zero gas and set the pressure to that specified by the manufacturer, usually one to two bar. Then, start the zeroing procedure in the PEMS software.
First, open a new session. Then, select the zero gas port and execute the procedure. Now, disconnect the zero gas and prepare for the span calibration.
Choose the span gases to match the range of pollutant concentrations expected during the trip. For carbon dioxide, use a calibration gas between 10 and 14%carbon dioxide. For nitrogen oxides, use standards between 1, 500 and 2, 000 parts per million.
Connect the span gas bottle to the PEMS and set the gas pressure at one to two bar. Then, signal the software. In the user interface, provide the concentrations of the gases in the bottle.
The software will detect and adjust the analyzer response to the span value. If needed, continue the span checks with the rest gases. Optionally, repeat the zeroing procedure.
Then, change from the current connection back to the batteries. Then, before starting the engine, start the data recording. For the sake of time alignment, use a single data recording device.
Now, drive the mapped trip as provided by the navigation system. The trip should last 90 to 120 minutes and be driven in a non-aggressive, non-timid, normal manner. Air-conditioning can be used as needed.
At the end of the trip, keep recording data after the engine is turned off, until the response time of the sampling systems has elapsed. Then, stop the test recording. Before turning off the analyzers, check their drift by remeasuring the zero and span gases that were used before the test.
If the readings have drifted too far, the test must be voided. Finally, export the data. Go to data files and upload the file created before the test.
For the analysis, select all the options, and then under data analysis, choose process the file. And a spreadsheet of the data will be prepared for analysis. Using a Euro 5b light-duty turbo charged gasoline direct injection vehicle with 1.2 liter engine displacement, a PEMS was installed and an RDE compliant trip was conducted.
The trip was verified by checking the boundary conditions, operation conditions, and the normality of the driving. All the trip requirements and operating parameters were within the defined limits. The relative positive acceleration was within the limits, as was the 95th percentiles of the speed multiplied by the positive acceleration.
For comparison, data with more aggressive driving in the same car, as well as other tests from the literature are provided. The results show that the urban nitrogen oxides emissions were on par with or lower than the laboratory WLTC phase emissions, whereas, measured rural and motorway emissions were, in fact, higher. On average, the emissions were below the NTE limits and thus, this specific vehicle would pass the RDE test.
Once mastered, this technique can be done in less than one day. Half a day, is needed for the installation of equipment and half a day is needed for the execution of the trip and the data analysis. While attempting this procedure, it's important to remember that each vehicle is a unique and each set up might be different.
After its development, this technique will pave the way for an effective in-service conformity checks and for vacant street surveillance in the real world driving conditions. Don't forget that working with exhaust gases and span calibration gases can be hazardous and precautions should be taken while performing the procedure. The installation of the equipment should always be conducted in well-ventilated areas.
