The efficiency of a heat exchanger is significantly improved by forming walls in an air flow structure, which has first grooves formed in the top surface of the structure and second grooves formed in the bottom surface of the structure, that block off alternating ends of the first and second grooves...http://www.google.se/patents/US7108052?utm_source=gb-gplus-sharePatent US7108052 - Low-cost method of forming a heat exchanger with an increased heat transfer efficiency
