Engineering
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Measuring Sub-23 Nanometer Real Driving Particle Number Emissions Using the Portable DownToTen Sampling System
Chapters
Summary May 22nd, 2020
Presented here is the DownToTen (DTT) portable emission measurement system to assess real driving automotive emissions of sub-23 nm particles.
Transcript
This Protocol can be used to acquire a mobile measurement of currently unregulated sub-23 nanometer particle emissions using a system that was designed and constructed in the Horizon 2020 Project DownToTen. Low Particle losses in the Sub-23 Nanometer Regime of Interest and the high degree of versatility within the system enabled assessment of the different properties of the emitted particles. This exception to the exhaust emissions, This method would be ideal for investigation of the volatility and formation mechanisms of nano-sized particles Begin by selecting an Exhaust Flow Meter with a measurement range matching the expected exhaust flow range of the vehicle to be measured.
Place the Exhaust Flow Meter control-box in the trunk of the vehicle and install the exhaust flow meter on the outside of the car. According to the manufacturer's specifications taking care that the distance upstream and downstream of the meter comply with the Federal Regulations. Check that the connectors from the exhaust flow meter pipe to the exhaust pipe of the vehicle can withstand the exhaust gas temperatures.
When the exhaust flow meter has been installed use connecting pipes and pipe clamps to connect the exhaust to the first pipe, tightening the pipe clamps at the end only to facilitate alignment of the pipes during the fitting. When there is a connection from the exhaust to the exhaust flow meter place the exhaust flow meter control box and the exhaust flow meter mounting bracket into the trunk to ensure that nothing slips during the measurement trip and check that all of the piping is tight and that nothing will come loose during the measurement trip. After a warmup time of up to 15 minutes, depending on ambient temperature, the exhaust mass flow meter is ready to take measurements.
To install The DownToTen measurement system, Place the synthetic air-bottle into the trunk and fix the bottle in place with straps. Place the battery into the trunk of the vehicle and plug in the AC input cable, fix the battery in place and connect the AC cable to a local power source. Fix the vacuum pumps for the sampling system and the condensation particle counters in the trunk of the vehicle and connect the pumps to the battery.
Next place, the DownToTen system in the trunk of the vehicle and fix it to position with straps connect the system to the mobile battery pack and connect the two inlet mass flow controllers of the DownToTen system, to a stationary pressurized air supply. connect the two outlet mass flow controllers of The DownToTen System, to the vacuum pump and use the appropriate tubing to drive the exhaust of the pump, outside of the vehicle. Use a USB cable to connect The DownToTen System to the measurement laptop and connect the inlet of the system to the sampling point, downstream of the Exhaust Flow Meter.
Connect the system power inlet to the battery and connect the condensation particle counter power inlets to the battery pack. Connect the condensation particle counters to the respective external vacuum pump and use appropriate tubing to drive the exhaust of the condensation particle counter and all the external pump outside of the vehicle. Then use a USB cable to connect the condensation particle counters to the measurement laptop To heat and start up the measurement system, Switch on the condensation particle counters and their external vacuum supply.
And open the Condensation Particle Counter Software. Establish communication with the condensation particle counters and close the needle valves of the mass flow controllers. Next, push the red switch of The DownToTen Sampling System pump to turn on the system and open the lab view DownToTen Application.
The communication with the system will start automatically and the Graphical User Interface will display the flow in and out at dilution stages one and two. Enter the mass flow drawn by the connected measurement instruments in standard liters per minute and slowly open the needle valves until both flows out reach 10 plus or minus 0.5 standard liters per minute Adjust the AdFlow of both dilution stages so that the flow rate in the Catalytic Stripper is equal to one plus or minus 0.1 liters per minute through the Catalytic Stripper and a sample inlet flow of Catalytic Stripper sample flow rate equals one plus or minus 0.1 liters per minute. Under the heater tab, set the heater temperatures of the dilution air supply.
The First Pours stoop Diluter and the catalytic stripper to 350 degrees Celsius. The system will begin to heat up. Then wait until the gas temperature downstream dilution stage one, reaches 290 degrees Celsius before starting the measurement drive.
To log the data, on the measurement device connected to The DownToTen Sampling System, quick start Data Logging'to start to log the data of the sampling system. And select a path and a file name in the pop-up window. The log file path will be displayed and the greenlight will indicate that the data are saved.
Then use the appropriate software to log the particle concentration data, of the condensation particle counter and start logging the exhaust flow with the Exhaust Flow Meter. To log the data while driving, before driving the selected route, disconnect the battery charging cable and switch from stationary pressurized air supply to the gas bottle. Then drive the selected route.
After driving, Press Log IN"to stop recording the data and shut down the instruments. Then, recharge the battery to prepare for the next drive Here, an exemplary plot of the Relative Particle Penetration of The DownToTen System as a function of The Particle Mobility Diameter is shown. The Thermophoredic, diffusional and total loss data were plotted to determine the respective particle size dependencies.
In this analysis, the diffusivity rising with the lower particle size made this the dominant loss mechanism for particles less than or equal to 10 nanometers. The total penetration efficiency is also represented, allowing determination of the particle size at which the penetration efficiency amounts to 50%Here, the particle number emission rate over time for the first 10 minutes of a real drive emissions measurement drive is shown. Sharp downward pointing spikes in all three of the signals occurred because the particle measurement devices can report zero particle concentrations temporarily and zeros can not be displayed in logarithmic plots.
The particle emissions measured with the 10 nanometer condensation particle counter were very close to the emissions measured with the 23 nanometer condensation particle counter for the majority of the measurement period. However, between 10 and 25 seconds, there was an occurrence of significant less than 23 nanometer particle emission. As in this analysis, greater than 50%of the total number of particles emitted, were between 10 and 23 nanometers.
When attempting this procedure, it is important to remember to properly insert the exhaust meter and to provide sufficient warmup time for the sampling system. The versatility and low losses of the DownToTen system makes it an ideal tool for the investigation of non-regulated particle emissions such as and total exhaust particles. This system and method were used in the Horizon 2020 Project DownToTen to assess Sub-23 nanometer particle emissions of a variety of vehicles to provide a scientific basis for future emission regulations.
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