Experimental study of thermal characteristics of alternatively twisted swirl generator tape in a heat exchanger tube

The heat transfer capacity of a convectional heat exchanger needs to be increased to minimize size and cost. Inserts are a promising way to enhance heat transfer at a bearable penalty in pressure drop. The objective of this study is to evaluate experimentally the thermal-hydraulic characteristics of a heat exchanger tube inserted with a novel alternatively twisted swirl generator (ATSG) tape. The experimental data has been collected for nine distinct combinations of ATSG tapes, includes the tapes with three twist angles (45 degrees, 60 degrees, and 90 degrees) and three twist ratios (3, 4 and 5) for Reynolds numbers of 4,000 to 20,000. The use of ATSG tapes resulted in a considerable improvement in heat transfer rate compared to simple twisted tapes (TT). Over the range evaluated, heat transfer coefficient, pressure drop and thermal performance factor (TPF) with ATSG tapes in a tube are, respectively, 1.57-1.82, 1.58-2.54, and 1.22-1.46 times to that of simple TT in a tube. The maximum TPF achieved is 1.52 for ATSG tape with twist ratio of 3 and twist angle of 90 degrees. The TPF for any combination of ATSG tapes is greater than one, which signifies that it is an efficient approach.

Automated summary

This study aims to evaluate the thermal-hydraulic characteristics of a novel heat exchanger tube inserted with an alternatively twisted swirl generator (ATSG) tape. The experimental results show that the use of ATSG tapes can significantly enhance heat transfer efficiency with lower pressure drop compared to simple inserts.