Patent ID: 8128069

Claim:
An apparatus for applying a fog, formed primarily of fine non-vaporized liquid particles, to humidify a stream of gas passing through a duct, comprising: a liquid container remotely mounted from said duct; a plurality of liquid mist producing elements mounted in said container to produce a mist mixture of fog and droplets from liquid within the container at a pressure that is near ambient pressure prevailing outside said liquid container; a fog dispersal structure being arranged in said duct to extend across at least a part of the stream of gas, said structure having an inlet manifold to receive fog and having fog output apertures in flow communication with said inlet manifold, said apertures in the aggregate being cross-sectionally distributed so as to expose a cross-sectional area of said gas stream to said fog; a fog conveying conduit connected between said container and said fog dispersal structure, said fog conveying conduit having an inlet and an outlet, with said fog conveying conduit inlet located at said container to receive fog drawn from a plurality of said elements and with said fog conveying conduit being sized and its outlet being located to discharge fog into the inlet manifold of the fog dispersal structure; said fog dispersal structure apertures being located to receive said fog from the inlet manifold and being further sized and distributed to facilitate said stream of gas within the duct to receive, entrain and absorb a flow of fog from inside the container through said fog conveying conduit to said apertures into and generally uniformly across a cross-sectional part of the gas stream for evaporation of the fog within a short distance from the fog dispersal structure; wherein said mist producing elements comprise piezoelectric elements; and drive circuits to energize said piezoelectric elements and a heat sink in heat removing relationship with said drive circuits, said heat sink being mounted to said duct for cooling by said humidified gas stream.