Tab::Losses

Wall loss for Aerosols

This option turns the wall loss parametrization on. The options for the chamber are given below in the Chamber properties. This parametrization is based on Teflon surface chamber, but you might have to adjust the values of Friction velocity (related to the turbulence in the chamber), as well as the wall accomodation coefficient (this is related to how effective the deposition is).

Wall loss for Gases

This turns on the wall loss for condensing vapours.  The options for the chamber are given below in the Chamber properties. This parametrization is based on Teflon surface chamber, but you might have to adjust the values of Eddy diffusion coefficient (related to the turbulence in the chamber), as well as the wall accomodation coefficient (this is related to how effective the deposition is). 

First order loss rate file

If provided, the particle loss will be calculated from the provided first order loss coefficients (1/s). The chamber parametrization will not be used simultaneously. The loss file should have similar structure to the ”BG particles” file. An example is shown below:

This file defines a time-dependent (at times 1,2,3,4 and 5, the unit is selected in the GUI) loss rate for diameters in the first row. If the rates are constant in time, only two lines need to be included: diameter and rates (+ the first column, which should be 0,0). The diameters or number of bins do not have to match that used in the model setup.

Constant first order loss rate

If constant loss rate is sufficient, it can be inserted in the file name text area as a number, preceeded with a  "hash":

#0.00003

The example above would set the loss rate to 3×10⁻⁵ /s, constant in time and all particle sizes.

Unit of time

Similar as in the ENV and MCM files, this setting sets the unit of time used in the first order loss file. This setting has no effect if constant rate is used.

Chamber properties

Area, height

Physical dimensions of the chamber

Friction velocity, Eddy diffusion coefficient and wall accommodation coefficient

The parameters that take account for the turbulence and efficiency of the deposition. These are characteristic for the chamber and the experiment setup, and could sometimes be measured, but the values would very likely not be comparable. The best option to get these right is to tune them with calibration runs. The wall accommodation coefficients can be set compound-specifically in the Vapour-file.