Heat exchanger with flow obstructions to reduce fluid dead zones

A heat exchanger comprising at least one plate pair, wherein each plate pair of said at least one plate pair comprises:

• (a) a first plate, a second plate, a first end and a second end;
• (b) a fluid flow passage for flow of a first fluid defined between the first plate and the second plate;
• (c) an inlet opening and an outlet opening, wherein the fluid flow passage extends between the inlet opening and the outlet opening, and wherein the inlet opening and the outlet opening are proximate to the first end;
• (d) an elongate flow barrier separating the fluid flow passage into an inlet portion in which the inlet opening is located, and an outlet portion in which the outlet opening is located, wherein the flow barrier extends from the first end toward the second end, the flow barrier having a terminal end proximate to the second end and spaced from the second end by a gap through which fluid flow communication is provided between the inlet portion and the outlet portion of the fluid flow passage;
• and
• (e) a flow obstruction located in the gap, the flow obstruction having a middle portion, a pair of opposed ends, a first side and an opposed second side, wherein the first and second sides are arcuate, with the first side facing the terminal end of the flow barrier and spaced therefrom, wherein a central longitudinal axis of each of the first and second plates extends through the middle portion of the flow obstruction;
• wherein the flow obstruction is crescent-shaped and the first and second sides of the flow obstruction meet at the opposed ends thereof;
• wherein each of the first and second sides of the flow obstruction is smoothly and continuously rounded and describes a portion of a smoothly rounded shape, wherein the portion of the smoothly rounded shape described by the second side is larger than the portion of the smoothly rounded shape described by the first side;
• wherein a width of the flow obstruction, as measured radially from a point along the central longitudinal axis, increases in a gradual manner from the opposed ends of the flow obstruction to the middle portion of the flow obstruction.