A mixer includes a fresh air tube defining a passage having an inlet receiving
conditioned air from an air conditioning pack. The fresh air tube includes an outlet
providing mixed air to a cabin of the aircraft. An outer tube at least partially
surrounds the fresh air tube and receives recirculated air from the cabin. A circumferential
corrugation in the fresh tube forms multiple lobes in the fresh air tube fluidly
connect the outer tube to the fresh air tube. The warm recirculation air surrounds
the portion of the fresh air tube to heat it preventing ice from forming. The warm
recirculation air entering the fresh air tube through the lobes homogeneously mixes
with the conditioned air from the pack to provide a uniform mixture of air within
the fresh air tube, which further ensures the prevention of ice build up.