Filtration media pack, filter elements, and air filtration media

1. A filtration media pack comprising:

(a) a plurality of layers of single face media comprising a fluted sheet, a facing sheet, and a plurality of flutes extending between the fluted sheet and the facing sheet, the flutes comprising peaks;

(b) a first portion of the plurality of flutes being closed to unfiltered air flowing into the first portion of the plurality of flutes, and a second portion of the plurality of flutes being closed to unfiltered air flowing out of the second portion of the plurality of flutes, such that air passing into one of the first face or the second face of the media pack and out the other of the first face or the second face of the media pack passes through media to provide filtration of the air;

wherein the fluted sheet comprises a plurality of protrusions offset from the peaks of the flutes; and

wherein the filtration media pack exhibits a media volume asymmetry of at least 10 percent.

2. The filtration media pack of claim 1 , wherein the protrusions have a height of from 0.4 to 24 times the thickness of the media forming the fluted sheet.

3. The filtration media pack of claim 1 , wherein the protrusions have a height of at least 2 times the thickness of the media forming the fluted sheet.

4. The filtration media pack of claim 1 , wherein the protrusions are from 10 to 90 percent of the height of the flutes in the fluted sheet.

5. The filtration media pack of claim 1 , wherein the protrusions between the first face of the filtration media pack and the second face of the filtration media pack are of equal height.

6. The filtration media pack of claim 1 , the flutes containing peaks, wherein the peaks do not substantially contact the facing sheet.

7. The filtration media pack of claim 1 , wherein upstream and downstream portions demonstrate an asymmetric volume.

8. A filtration media pack comprising:

(a) a plurality of layers of single face media comprising a fluted sheet, a facing sheet, and a plurality of flutes extending between the fluted sheet and the facing sheet, the fluted sheet comprising a first surface and a second surface opposite the first surface;

(b) a first portion of the plurality of flutes being closed to unfiltered air flowing into the first portion of the plurality of flutes, and a second portion of the plurality of flutes being closed to unfiltered air flowing out of the second portion of the plurality of flutes, such that air passing into one of the first face or the second face of the media pack and out the other of the first face or the second face of the media pack passes through media to provide filtration of the air;

wherein the filtration media pack exhibits a media volume asymmetry of at least 10 percent;

wherein the fluted sheet comprises a plurality of protrusions, the protrusions making contact with the facing sheet; the protrusions positioned on the first surface and second surface of the fluted sheet, with approximately twice as many protrusions on the first surface than the second surface; and

wherein the protrusions are substantially absent from the portions of the fluted sheet not in contact with the facing sheet.

9. The filtration media pack of claim 8 , wherein the protrusion comprises an island.

10. The filtration media pack of claim 8 , wherein the protrusions have a height of from 0.2 to 3 millimeters.

11. The filtration media pack of claim 8 , wherein the protrusions have a height of from 0.4 to 24 times the thickness of the media forming the fluted sheet.

12. The filtration media pack of claim 8 , wherein the protrusions are from 10 to 90 percent of the height of the flutes in the fluted sheet.

13. The filtration media pack of claim 8 , wherein the protrusions are less than 30 percent of the height of the flutes in the fluted sheet.

14. The filtration media pack of claim 8 , wherein the protrusions are at least 15 percent of the height of the flutes in the fluted sheet.

15. The filtration media pack of claim 8 , wherein the repeating pattern of flutes comprises at least one ridge extending along at least a portion of the flute length between adjacent peaks.

16. The filtration media pack of claim 8 , wherein the protrusions between the first face of the filtration media pack and the second face of the filtration media pack are of equal height.

17. The filtration media pack of claim 8 , wherein the protrusions between the first face of the filtration media pack and the second face of the filtration media pack are tapered in height with respect to each other.

18. The filtration media pack of claim 8 , the flutes containing peaks, wherein the peaks do not substantially contact the facing sheet.

19. The filtration media pack of claim 8 , wherein upstream and downstream portions demonstrate an asymmetric volume.

20. A filtration media pack comprising:

(a) a plurality of layers of single face media comprising a fluted sheet, a facing sheet, and a plurality of flutes extending between the fluted sheet and the facing sheet, the flutes comprising flute peaks;

(b) a first portion of the plurality of flutes being closed to unfiltered air flowing into the first portion of the plurality of flutes, and a second portion of the plurality of flutes being closed to unfiltered air flowing out of the second portion of the plurality of flutes, such that air passing into one of the first face or the second face of the media pack and out the other of the first face or the second face of the media pack passes through media to provide filtration of the air;

wherein the fluted sheet comprises a plurality of protrusions extending from a remainder of the fluted sheet, the protrusions are aligned in pairs on either side of the flute peaks, and the protrusions having a non-constant cross-section on the fluted sheet in all axes, and

wherein the filtration media pack exhibits a media volume asymmetry of at least 10 percent.