A
heat exchanger for transfer of heat from a first fluid to a second fluid, including: a housing defining an
interior space, a plurality of tubes spaced apart from each other, fixed in the housing, and extending in a first direction within the
interior space, a first inlet for receiving the first fluid into and through the tubes, and first outlet for discharging the first fluid out of the tubes, a second inlet for receiving the second fluid into the
interior space in an
inlet flow direction generally transverse of the first direction, and a second outlet for discharging the second fluid out of the interior space, and an impingement plate
assembly situated in the interior space of the housing between the second inlet means and the plurality of tubes, with a
fouling area defined as the area in the interior space that includes portions of the tubes directly beneath said impingement plate
assembly, the impingement plate
assembly including: (a) a top plate facing the second inlet, where the top plate lies in a plane generally transverse to the
inlet flow direction and onto which the second fluid flow impinges, and (b) a bottom plate fixedly spaced from and generally parallel to and overlying the top plate, the bottom plate defining therethrough an aperture extending from top to bottom thereof.