The effect of Center-Perforated tapered twisted tape insert in tube on the performance of heat exchanger: A numerical approach

Abstract Inserts of twisted tapes in tubes with a large number of variations have long been used to enhance heat transfer rate and improve heat exchanger performance. Although, this improved the heat transfer rate but tends to increase the friction factor simultaneously. This paper primarily focuses on the investigation of inserts of twisted tapes with varying widths instead of constant ones to improve thermos-hydraulic performance with an adequate reduction in friction factor. Further perforated twisted tape insert is expected to provide a reduction in the wetted area of the tube and reduce pressure drop. A numerical investigation using the ANSYS FLUENT is carried out to analyze the performance of the center-perforated tapered twisted tape with water as working fluid under laminar flow conditions i.e. 500 ≤ Re ≤ 1750. In addition to this, twin tapered TT configuration is also analyzed; a total of 36 cases are evaluated. The computational results revealed that the flow resistance is reduced with the proposed twisted tape configuration as compared to the plain twisted tape; however, thermal performance is affected only marginally. In the optimization study, it is advised to use the tapered twisted tape arrangement because it results in a significant reduction of pressure drop, about 65 percent, as well as the power input for the marginal reduction in thermal performance.