Abstract: A heat exchanger includes first and second plates joined together with portions of the inner surfaces spaced apart to define a plurality of fluid flow passages for flow of a heat transfer fluid. A dividing rib separates the heat exchanger into an inlet section and an outlet section, each of which includes a plurality of fluid flow passages. Inlet and outlet ports are located near a first end of the heat exchanger, on opposite sides of the dividing rib. The heat transfer surface area of the inlet section is less than that of the outlet section due to the presence of one or more flow obstructions between the inlet port and first ends of the fluid flow passages in the inlet section. Each flow obstruction may be a dead channel including a continuous outer rib completely surrounding a depressed middle region.