Patent ID: 6928730

Claim:
A method for making a multi-pass heat exchanger core comprising the steps of: providing at least one coolant plenum for containing flowing coolant; installing adjacent to the at least one coolant plenum as least on first-pass plenum for containing a flowing heated gas and defining a first area-in-flow of the heated gas; and disposing adjacent to the at least one coolant plenum at least one subsequent-pass plenum for containing the heated gas and defining a second area-in-flow of the heated gas; and arranging the plenums so that the contained heated gas flow past a coolant plenum at least twice; wherein the step of defining a first area-in-flow comprises defining a ratio of the first area-in-flow to the second area-in-flow to be between about 1.3 to 1 and about 1.7 to 1.