Figure 1

Drawing of the aerosol gas exchange system. The purge gas flow (N2) is controlled with a Vögtlin red-y mass flow controller. The pressure difference between the sample gas channel and the purge gas channel was measured with a Honeywell TSCSNBN005PDUCV. The controllable valve of another Vögtlin red-y MFC is programmed to keep the pressure difference as low as possible (typically <0.5 mbar). The part highlighted with a green frame represents the counter flow denuder. up and us are the flow velocity in the purge gas channel and the sample channel respectively. C0 and C1 are the concentrations of the substance to be removed at the inlet and the outlet of the system.