Electrically powered catalyst heater for fluid treatment systems

1 . A heater assembly comprising:

a heater body comprising a monolithic honeycomb structure comprising a plurality of intersecting walls, wherein the plurality of intersecting walls have a thickness and extend in an axial direction to form a plurality of cells of the honeycomb structure that extend axially from a first end face to a second end face;

a first electrode coupled to the heater body;

a second electrode coupled to the heater body, wherein a current-carrying path is defined over the plurality of intersecting walls between the first electrode and the second electrode; and

a plurality of openings that extend through the thickness of at least some of the plurality of intersecting walls, each of the openings defined by a shape having a downstream side and an upstream side, the upstream side positioned to encounter the flow of gas before the downstream side;

wherein, for each of the plurality of openings:

(i) a first lateral dimension measured at a downstream axial extreme of the downstream side is wider than a second lateral dimension measured at an upstream axial extreme of the upstream side, or

(ii) a flow area of an entirety of a downstream axial half of the shape is larger than an entirety of an upstream axial half of the shape, or

(iii) a maximum lateral dimension of the shape is located in the downstream axial half of the shape, and all lateral dimensions in the upstream axial half are less than the maximum lateral dimension, or

(iv) a combination thereof, and

wherein, each of the plurality of openings taper to a tip that points into an upstream direction, points away from the downstream side, and is positioned to point into the flow of gas and

wherein the plurality of openings are arranged in a plurality of rows, each row comprising at least two of the plurality of openings arranged laterally, and the plurality of rows being axially spaced along the heater body.

2 . The heater assembly of claim 1 , further comprising a plurality of insulating slots that each extend laterally across at least a portion the heater body and disrupt the current-carrying path.

3 . The heater assembly of claim 1 , wherein a cross-sectional shape of each of the plurality of cells is square.

4 . The heater assembly of claim 1 , wherein each cell of the plurality of cells is enclosed by a plurality of segments of the plurality of intersecting walls, and wherein the heater body comprises a plurality of the openings in at least some of the plurality of segments of the plurality of walls that enclose each of the plurality of cells.

5 . The heater assembly of claim 4 , wherein at least some of the plurality of segments comprise a column of the plurality of openings axially-spaced along the at least some of the segments.

6 . The heater assembly of claim 4 , wherein

at least two of the plurality of segments each comprise an array of the plurality of openings, wherein the array comprises the plurality of rows and a plurality of columns, and

the at least two of the plurality of segments are generally parallel to each other and facing each other.

7 . The heater assembly of claim 1 , wherein at least a subset of the plurality of cells are enclosed by a plurality of segments of the plurality of intersecting walls, wherein the plurality of segments for each of the plurality of cells comprises at least a first wall segment and a second wall segment, wherein both of the first wall segment and the second wall segment each comprise at least one opening of the plurality of openings, and wherein the at least one opening in the first wall segment is not axially aligned with any of the at least one opening in the second wall segment.

8 . The heater assembly of claim 1 , wherein at least a subset of the plurality of cells are enclosed by a plurality of segments of the plurality of intersecting walls, wherein the plurality of segments for each of the plurality of cells comprises at least a first wall segment and a second wall segment, wherein both of the first wall segment and the second wall segment each comprise at least one opening of the plurality of openings, wherein the at least one opening in the first wall segment comprises a first set of openings that are axially-spaced from each other along the first wall segment, wherein the at least one opening in the second wall segment comprises a second set of openings that are axially-spaced from each other along the second wall segment, and wherein the first set of openings are axially aligned with respect to the second set of openings.

9 . The heater assembly of claim 7 , wherein the at least one opening in the first wall segment comprises a first set of openings that are axially-spaced from each other along the first wall segment, wherein the at least one opening in the second wall segment comprises a second set of openings that are axially-spaced from each other along the second wall segment, and wherein the first set of openings are axially offset with respect to the second set of openings.

10 . The heater assembly of claim 7 , wherein a cross-sectional shape of the plurality of cells in the subset of cells is rectangular, and the first wall segment and the second wall segment are oppositely disposed sides.

11 . The heater assembly of claim 1 , wherein a first axial distance between at least a first adjacent pair of axially-spaced openings is not equal to a second axial distance between at least a second adjacent pair of axially-spaced openings.

12 . A fluid treatment system comprising the heater assembly of claim 1 and a ceramic honeycomb body in fluid communication with each other.

13 . The fluid treatment system of claim 12 , wherein the ceramic honeycomb body is arranged as a catalyst substrate or a particulate filter in an exhaust aftertreatment system.

14 . A method of treating a fluid with the fluid treatment system of claim 12 , comprising:

applying a voltage potential across the first and second electrodes of the heater assembly to generate heat in the heater body as a result of current flowing through the current-carrying path between the first and second electrodes;

heating a gas flow with the heat generated by the heater body to increase a temperature of the gas flow; and then

heating the ceramic honeycomb body with the gas flow.

15 . A method of manufacturing a monolithic heater body for a heater assembly, the method comprising:

forming a plurality of intersecting walls, wherein the plurality of walls have a thickness and extend in an axial direction to form a plurality of cells of the honeycomb structure that extend axially from a first end face to a second end face; and

forming a plurality of openings that extend through the thickness of at least some of the plurality of walls, each of the openings defined by a shape having a downstream side and an upstream side;

wherein, for each of the plurality of openings:

(i) a first lateral dimension measured at a downstream axial extreme of the downstream side is wider than a second lateral dimension measured at an upstream axial extreme of the upstream side, or

(ii) a flow area of an entirety of a downstream axial half of the shape is larger than an entirety of an upstream axial half of the shape, or

(iii) a maximum lateral dimension of the shape is located in the downstream axial half of the shape, and all lateral dimensions in the upstream axial half are less than the maximum lateral dimension, or

(iv) a combination thereof, and

wherein each of the plurality of openings taper to a tip that points into an upstream direction and away from the downstream side and

wherein the plurality of openings are arranged in a plurality of rows, each row comprising at least two of the plurality of openings arranged laterally, and the plurality of rows being axially spaced along the heater body.

16 . A heater assembly comprising:

a heater body comprising a monolithic honeycomb structure comprising a plurality of intersecting walls, wherein the plurality of intersecting walls have a thickness and extend in an axial direction to form a plurality of cells of the honeycomb structure that extend axially from a first end face to a second end face;

a first electrode coupled to the heater body;

a second electrode coupled to the heater body, wherein a current-carrying path is defined over the plurality of intersecting walls between the first electrode and the second electrode; and

a plurality of openings that extend through the thickness of at least some of the plurality of intersecting walls, each of the openings defined by a shape having a downstream side and an upstream side, the upstream side positioned to encounter the flow of gas before the downstream side;

wherein, for each of the plurality of openings:

(i) a first lateral dimension measured at a downstream axial extreme of the downstream side is wider than a second lateral dimension measured at an upstream axial extreme of the upstream side, or

(ii) a flow area of an entirety of a downstream axial half of the shape is larger than an entirety of an upstream axial half of the shape, or

(iii) a maximum lateral dimension of the shape is located in the downstream axial half of the shape, and all lateral dimensions in the upstream axial half are less than the maximum lateral dimension, or

(iv) a combination thereof, and

wherein, each of the plurality of openings tapers to a tip that points into an upstream direction, points away from the downstream side, and is positioned to point into the flow of gas, and

wherein a first axial distance between at least a first adjacent pair of axially-spaced openings is not equal to a second axial distance between at least a second adjacent pair of axially-spaced openings.