Space optimized coalescer

A single-stage crankcase ventilation coalescer for coalescing a medium having two immiscible phases, namely a continuous phase comprising air and a dispersed phase comprising oil as a fine mist having droplets of about one micron and smaller in diameter, said continuous phase flowing along a flow direction from upstream to downstream, said coalescer consisting essentially of a coalescer element extending axially along an axis and having coalescer media capturing droplets of said dispersed phase, coalescingly growing said droplets into larger drops which further coalesce and grow to form pools that drain, said element having a closed-loop cross-sectional geometrical shape in a plane transverse to said axis and having an inner surface defining an inner cavity and having an outer surface spaced outwardly of said inner surface by the thickness of said element between said inner and outer surfaces, said media having a depth dimension along said thickness, one of said inner and outer surfaces being an upstream surface, the other of said inner and outer surfaces being a downstream surface,

• wherein said inner surface is said upstream surface, and said outer surface is said downstream surface, such that said element is an inside-out flow element,
• wherein said media is unpleated fibrous depth media, said element and said media have an upstream face provided by said upstream surface and said downstream surface, and said upstream face has a non-circular geometrical shape in said transverse plane,
• wherein said axis is horizontal relative to gravity and said continuous phase flows through said inner cavity along said axis, traversely through said inner surface, and traversely through said outer surface, said pools draining vertically through said media,
• wherein said coalescer element has a first cross-sectional area along a first horizontal plane perpendicular to said upstream face, and a second cross-sectional area along a second horizontal plane perpendicular to said upstream face, said second horizontal plane being vertically below said first horizontal plane, said second cross-sectional area being less than said first cross-sectional area
• wherein said coalescer element has a perimeter defining a given shape in a vertical plane parallel to said upstream face, said perimeter having a plurality of chords thereacross, including vertical chords and horizontal chords and the longest of said chords extends vertically, and
• wherein:
• said element has a face area ratio F greater than or equal to 1.5, where
• F
• =
• L
• I
• ⁢
• D
• A
• 4
• ⁢
• A
• I
• where LI is the length of the perimeter of said inner cavity, DA is the area equivalent diameter of said inner cavity, namely
• D
• A
• =
• 4
• ⁢
• A
• I
• π
• where AI is the area of said inner cavity;
• wherein optionally one or more of the following three criteria are met:
• A) said media has a gradient profile with at least one parameter which varies as a function of depth into said media along said flow direction;
• B) said inner cavity has a minimum cross-sectional area selected according to pressure drop across said element;
• and
• C) said coalescer has a differential volume ratio selected for space efficiency, wherein said differential volume ratio is the ratio of media volume to element volume.