Here you find an overview of our equipment.
Aerosolgenerator MiniCast The Sootgenerator MiniCast (Cambustion Aerosol Standard from Jing Ltd.) uses a diffusion flame burner, where a propane flame is quenched with nitrogen. Additionally, the burner gas can be diluted with nitrogen. By adjusting the gas flows, the chemical and physical properties of the produced particles can be adjusted, such as size, form or organic to elementary carbon ratio.
Combustion particles consit of carbon (“EC = elementary carbon“) and unburnt hydrocarbons (“OC = organic carbon”). OC is not stable, as it can evaporate and condense. Therefore, after the formation the OC is beeing evaporated (350°C) and stabilized by cold dilution. Here you can see pictures recorded by a transmission electron microscope of particles produced on our test bench. They were classified at 75nm. Left: with thermal treatment, right: without thermal treatment.
To select the particles according to their size, we are using a differential mobility analyser (DMA). At first a radioactive source is used to give them a defined charge distribution (bipolar diffusion charging). Then the electrically charged particles are guided into a stream of particle free air where they are deflected from an electrical field. Particles of a single “electrical mobility” are leaving the DMA through a gap and can be used for adjustment of the following measurement devices.
The reference is a Faraday-Cup Electrometer. Charged particles are directed to an electrode and the current flowing away is being measured. With that current and the gas flow the number of particles can be determined, when one particle contains one elementary charge. Also, a Condensation Particle Counter can be used as reference, in total there are 3 CPCs available.