Patent ID: 7147036

Claim:
A heat exchanger comprising a first spiral passage; a second spiral passage formed along said first passage, which is adjacent to said first passage via walls; first and second end plates which cover both end faces of said first and second passages, respectively; a first passage inlet consisting essentially of a group of openings formed in a first region continuous along radial direction in said first end plate, which openings are open only to said first passage; a first passage outlet consisting essentially of a group of openings formed in a second region continuous along radial direction in said first or second end plate, which openings are open only to said first passage; a second passage inlet consisting essentially of a group of openings formed in a third region continuous along radial direction in said first or second end plate, which third region is located at an area other than said first and second regions, which openings are open only to said second passage; and a second passage outlet consisting essentially of a group of openings formed in a fourth region continuous along radial direction in said first or second end plate, which fourth region is located at an area other than said first and second regions, and is formed in the first or second end plate other than the one in which said second passage inlet is formed, which openings are open only to said second passage; said first passage being tightly closed except for said first passage inlet and said first passage outlet; said second passage being tightly closed except for said second passage inlet and said second passage outlet; a first fluid entering said first passage from said first passage inlet being discharged from said first passage outlet after passing through said first passage for less than one turn only; a second fluid entering said second passage from said second inlet being discharged from said second passage outlet after passing through said second passage in axial direction; heat being exchanged between said first and second fluids through said walls during said first and second fluids pass through said first and second passages, respectively.