Countercurrent heat exchanger/reactor

A device including channels arranged for countercurrent flow comprising:

• a bundle of channels comprising a first plurality of channels and a second plurality of channels configured to flow fluids counter-currently in opposite directions whereby opposing streams of fluid are arranged in a checkerboard pattern, such that for any given channel there exist alongside, in four directions, laterally on both sides, above and below, channels containing the opposite fluid;
• wherein the second plurality of channels confines one of the opposing streams through a plenum area at either end of the bundle, and extends into a cavity through which fluid enters or exits the device by second flowstream ports in a wall of the cavity;
• and
• wherein the second plurality of channels that penetrates the plenum area may be altered in size or shape, or both size and shape, so as to ensure free space completely around the second plurality of channels, such that fluid is free to flow between the second plurality of channels to or from first flowstream ports.

A method of heat transfer between a first fluid stream and a second fluid stream in a countercurrent single pass heat exchanger, the method comprising:

• flowing the first fluid stream and the second fluid stream in a bundle of channels such that the first and second fluid streams flow countercurrently to each other to exchange heat within an interior region of the bundle along a longitudinal axis of the bundle in four directions with respect to an individual channel without mixing the first and second fluid streams, the four directions comprising above the individual channel, below the individual channel, and along at least a portion of each lateral side of the individual channel;
• collecting the first fluid stream in a first fluid receiving member the second fluid stream being confined within a plurality of channels extending through a plenum area of the first fluid receiving member to separate the first and second fluid streams, wherein the plurality of channels may be altered in size or shape, or both size and shape, so as to ensure free space completely around the plurality of channels such that fluid is free to flow between the plurality of channels to or from a flow stream port;
• and
• collecting the second fluid stream in a second fluid receiving member.