Experimental Investigation of Heat Transfer Enhancement in Circular Tube Using Twisted Tape Inserts

Abstract

Experimental investigation of heat transfer and friction factor characteristics in a double pipe heat exchanger fitted with typical twisted tape elements, were studied. The inner and outer diameters of the inner tube are 19.9 and 22.2 mm, respectively. Cold and hot water were used as working fluids in inner and outer side of heat exchanger. The twisted tapes were made of aluminum strip with thickness of (0.8) mm and the length of (1) m. They were inserted in the test tube section in full-length twisted tape at different twisted ratios (5, 4.5, 4 and 3.5). The results, obtained from the tube with twisted tape insert, were compared with those without twisted tape. The experiment result showed that the improvement for heat transfer rate ranging from (50.54% to 52.22%) at twisted tape 5, (52.42% to 55.15 %) at twisted tape 4.5 and (52.41% to 56.98%) at twisted tape 3.5, for plain tube with twisted tape tubes with respect to plain tube without twisted tape.