Plate and fin heat exchanger

Claim 1

A PLATE TYPE HEAT EXCHANGER ASSEMBLY, INCLUDING SUPERPOSED STACKED PLATE AND FIN ELEMENTS, SAID PLATE ELEMENTS DEFINING FLOW PATHS OCCUPIED BY SAID FIN ELEMENTS, SAID FIN ELEMENTS BEING ARRANGED IN SETS OF THREE WITH A MIDDLE FIN OF EACH SET BEING SHORT IN RELATION TO THE OTHER FINS OF THE SET TO DEFINE AT LEAST ONE END OF SAID ASSEMBLY AT EACH SET OF SAID ELEMENTS A CHAMBER WHEREIN INTRODUCED FLUID HAS ACCESS TO BOTH SIDES OF SAID MIDDLE FIN AND ACCESS TO ONE SIDE ONLY OF THE SAID OTHER FIN ELEMENTS, A PLATE ELEMENT BEING DISPOSED BETWEEN SAID MIDDLE FIN AND EACH OF SAID OTHER FINS IN HEAT CONDUCTING RELATION THEREBETWEEN, ADJACENT SETS OF FINS HAVING SAID OTHER FINS IN COMMON, AND MANIFOLDING MEANS FOR INTRODUCING FLUIDS OF DIFFERENT TEMPERATURE TO OPPOSITE ENDS OF SAID ASSEMBLY TO FLOW COUNTER TO ONE ANOTHER THROUGH ADJACENT SETS OF FIN ELEMENTS, SAID OTHER FIN ELEMENTS BEING IN PROJECTING RELATION TO SAID MIDDLE FIN ELEMENT AT EACH END THEREOF TO DEFINE CHAMBERS FOR THE ENTRANCE AND EXIT OF A FLUID, SAID PLATE ELEMENTS BEING FORMED TO ALLOW COMMUNICATION THEREBY BETWEEN SAID CHAMBERS AND SAID OTHER FINS ON THE SAID ONE SIDES THEREOF.