Apparatus suitable for dispensing monodispersed liquid droplets into a gas flow, comprising: - liquid droplet producing means for producing monodispersed liquid droplets, said means comprising an outlet for the monodispersed liquid droplets; and - dispensing means comprising: - an outer tube having a length l1, a first end and a second end, the second end comprising a tube outlet; - an inner tube having a length l2 with l2 < l1, a first end and a second end, the first end comprising a tube inlet, the second end comprising a tube outlet, wherein the inner tube being arranged inside the outer tube with the outer surface of the inner tube being disposed at distance from the inner surface of the outer tube, the first end of the outer tube and the first end of the inner tube being co-located, the outlet of the liquid droplet producing means being connected to the tube inlet of the inner tube such that the liquid droplets being dispensed from the said means into the inner tube substantially along a center axis of the inner tube; characterized in that a tube-wall-opening being arranged on a downstream side of the outer tube, wherein the tube wall-opening is extending along a center axis of the outer tube from a distance d1a to a distance d1b, both distances d1a, d1b measured relative to the co-located first ends (130, 140) of the inner tube and the outer tube and with: d1b < l2 and d1a < d1b, and with the inner tube and outer tube being concentrically arranged along a common vertically arranged central axis. - liquid droplet producing means for producing monodispersed liquid droplets, said means comprising an outlet for the monodispersed liquid droplets; and - dispensing means comprising: - an outer tube having a length l1, a first end and a second end, the second end comprising a tube outlet; - an inner tube having a length l2 with l2 < l1, a first end and a second end, the first end comprising a tube inlet, the second end comprising a tube outlet, wherein the inner tube being arranged inside the outer tube with the outer surface of the inner tube being disposed at distance from the inner surface of the outer tube, the first end of the outer tube and the first end of the inner tube being co-located, the outlet of the liquid droplet producing means being connected to the tube inlet of the inner tube such that the liquid droplets being dispensed from the said means into the inner tube substantially along a center axis of the inner tube; characterized in that a tube-wall-opening being arranged on a downstream side of the outer tube, wherein the tube wall-opening is extending along a center axis of the outer tube from a distance d1a to a distance d1b, both distances d1a, d1b measured relative to the co-located first ends (130, 140) of the inner tube and the outer tube and with: d1b < l2 and d1a < d1b, and with the inner tube and outer tube being concentrically arranged along a common vertically arranged central axis. - an outer tube having a length l1, a first end and a second end, the second end comprising a tube outlet; - an inner tube having a length l2 with l2 < l1, a first end and a second end, the first end comprising a tube inlet, the second end comprising a tube outlet, wherein the inner tube being arranged inside the outer tube with the outer surface of the inner tube being disposed at distance from the inner surface of the outer tube, the first end of the outer tube and the first end of the inner tube being co-located, the outlet of the liquid droplet producing means being connected to the tube inlet of the inner tube such that the liquid droplets being dispensed from the said means into the inner tube substantially along a center axis of the inner tube; characterized in that