Perforated-cut twisted tapes for enhanced laminar flow heat transfer in bio-mechanics applications

This study experimentally analyzes the effect of the cut width ( b ) of perforated-cut twisted tape (PCTT) inserts on the performance of a heat exchanger tube under laminar flow conditions. Heat transfer, friction factor, thermo-hydraulic performance and flow characteristics were investigated for water flow with varying perforated cut widths ( b = 6, 8, 10, & 12 mm) and twist ratios ( y / w = 3, 4, 5 & 6) over Reynolds number ( Re ) ranging from 100 to 1500. The tube’s lateral surface is exposed to a uniform heat flux boundary condition. The results showed that specific PCTT configurations significantly improved the heat transfer, friction factor ( f ), and thermal performance ( η ). The PCTT geometry disrupts flow with perforations and central cuts, enhancing mixing, turbulence, and surface interaction to intensify heat transfer. The PCTT with b = 6 mm and y / w = 3 exhibits the highest Nusselt number and friction factor among all configurations and is increased by up to 53.30% and 85.77%, respectively, compared to plain twisted tape ( y / w = 7). At Re 1500 with a cut width of 6 mm and y / w = 3, the utmost thermal performance of 2.74 is attained. Across all Reynolds numbers, the system demonstrated improved performance relative to previous studies. Empirical correlations were derived for predicting Nusselt number and friction factor with deviations from experimental results within ±5% and ±5%, respectively. Heat exchangers enhanced with perforated-cut twisted tape inserts have gained attention in biomedical engineering due to their ability to improve thermal performance, compactness, and precise temperature control. This study offers important insights into the thermal behavior of enhanced heat transfer systems.