Manufacture of multiple flow path body

The method of fabricating a multiple flow path body having a plurality of contiguous flow paths extending therethrough for separate fluid flow, the method comprising the steps of

• a. providing a honeycombed body having a matrix of thin walls defining a multiplicity of open-ended cells extending from one face thereof to another face end thereof and being bounded on sides generally parallel to cell axes by generally opposed upper and lower boundary surfaces connected by first and second side boundary surfaces, the cells being grouped into a plurality of columns of cells, each column being separated from adjacent columns of cells by a fluid barrier wall surface extending continously from the upper boundary surface to the lower boundary surface and from the one face end of the honeycombed body to the other face end thereof,
• b. providing an entrance for a first fluid into selected columns of cells near one face end of the honeycombed body and an exit for the first fluid out of the selected columns of cells near the other face end thereof by forming openings in at least one of the upper boundary surface and the lower boundary surface,
• c. forming entrance and exit fluid flow grooves from the entrance and exit openings, respectively, to cells in the selected columns of cells by removing portions of the cell walls joining opposed fluid barrier wall surfaces near face ends in the selected columns of cells, and
• d. sealably enclosing entrance and exit fluid flow grooves near face ends of the honeycombed body to form, respectively, entrance and exit fluid flow conduits, such that first fluid flow paths are formed from the first fluid entrance openings through the entrance fluid flow conduit, the cells in the selected columns of cells, the exit fluid flow conduit, and to the first fluid exit openings;
• and second fluid flow paths are formed through open-ended cells in unselected columns of cells.