An experimental investigation of heat transfer and friction losses of interrupted and wavy fins for fin-and-tube heat exchangers

The present paper discusses the results of an extensive investigation about the performance of various fin configurations, carried out in the Luve Con tardo experimental facilities and aimed to enhance the heat transfer capabi lities of air-cooled condensers and liquid coolers. Test results here discu ssed are relative to 15 coil prototypes, having the same tube and fin geome try (25 x 21.65 mm staggered 5/8 " tube banks, 2 mm fin spacing) but differ ent fin surface geometry, from flat to wavy to louvered to "winglet". Diffe rent rates of heat transfer and pressure loss enhancement were obtained, al so depending on the quality of the pressing process. General approaches to evaluate the "goodness" of one fin design with respect to another one provi ded questionable results: pressure loss influence on the air flow cannot be properly evaluated unless the actual fan head curve and the coil dimension s (front area and rows number) are stipulated. The. performance of air-cool ed condensers was therefore predicted and compared, for various fin design and for coil arrangements of practical interest. The type of fin adopted st rongly influences the heat exchanger performance and louvered fins generall y provide the best results. (C) 2001 Elsevier Science Ltd and IIR. All righ ts reserved.