An air handling unit for supplying a recirculated flow of air to a conditioned space within a building, comprising:
- a cabinet structure having open inlet and outlet ends;
- blower means positioned in said cabinet structure and selectively operable to flow air through said cabinet structure in a downstream direction from said inlet end thereof to said outlet end thereof;
- air temperature control means selectively operable to alter the temperature of air flowing through said cabinet structure from said inlet end thereof to said outlet end thereof;
- a liquid air purification system operative to remove pollutants from air to be discharged from said outlet end of said cabinet structure, said liquid spray air purification system including:
- a housing positioned exteriorly of said cabinet structure and having an open inlet end and an open outlet end, said housing being adapted to receive a throughflow of air in a downstream direction from its open inlet end to its open outlet end, said outlet end of said housing being communicated with the interior of said cabinet structure upstream of said blower means,
- liquid dispersion filter means, positioned in said housing in the path of air flowing therethrough, for removing pollutants from such air using a liquid spray emanating from a source thereof and directed against said liquid dispersion filter means,
- liquid spray means, positioned in said housing, for receiving pressurized liquid from a source thereof and spraying the received liquid onto said liquid dispersion filter means,
- mist eliminator means, positioned in said housing downstream from said liquid dispersion filter means, for removing liquid entrained in air exiting said liquid dispersion filter means,
- fan means, positioned within said housing downstream from said mist eliminator means, for forcing said throughflow of air through said housing,
- dehumidifying coil means, positioned in said housing between said fan means and said mist eliminator means, for reducing the humidity of air discharged from said housing into said cabinet structure,
- sump means for holding a quantity of liquid to be supplied in a recirculated manner to said liquid spray means, and for receiving liquid draining from said liquid dispersion filter means, said mist eliminator means, and said dehumidification coil means during operation of said liquid spray air purification system,
- fill means for automatically maintaining a predetermined liquid level in said sump means,
- a filter structure through which liquid may be selectively flowed in a filtering direction or an opposite backwashing direction,
- a pump having an inlet communicatable with liquid in said sump means, and an outlet,
- conduit means, interconnecting said pump, said filter structure and said liquid spray means, for forming with said filter structure alternatively selectable first and second sump liquid flow paths,
- said first sump liquid flow path extending sequentially from said pump outlet through said filter structure in said filtering direction, and from said filter structure to said liquid spray means,
- said second sump liquid flow path sequentially extending from said pump outlet to said filter structure, through said filter structure in said backwashing direction, and from said filter structure to a drainage location external to said sump means,
- valve means connected in said conduit means, said valve means being normally operative to cause sump liquid being discharged from said pump outlet to flow through said first sump liquid flow path, but being switchable to cause sump liquid being discharged from said pump outlet to flow through said second sump liquid flow path, and
- first monitoring means for detecting a change in an apparatus operating parameter, indicative of a predetermined lessening in the filtration efficiency of said filter structure, and responsively creating a temporary switching of said valve means from said first position thereof to said second position thereof;
- and
- humidity control means for controlling the humidity of air being discharged from said air handling unit, said humidity control means being operative to sense excess humidity in air being discharged from said air handling unit and responsively cause a portion of said throughflow of air within said housing to be recycled across said dehumidifying coil means, in a manner bypassing said liquid dispersion filter means, said liquid spray means, and said mist eliminator means, before being discharged from said housing into said cabinet structure.