Study the effect of axially perforated twisted tapes on the thermal performance enhancement factor of a double tube heat exchanger

The main objective of this numerical study is to investigate the ways to reduce the pressure drop and consequently increase thermal performance enhancement factor (TEF) of a heat exchanger equipped with twisted tapes. For this purpose, axial perforated twisted tapes (PTTs) with various hole diameters are used instead of simple twisted tapes (STTs). Moreover, the variations of the effectiveness with number of transfer units (NTU) for different heat capacity ratios (Cr) were presented. The numerical model was well validated with the available experimental results. The results indicated that the use of perforated twisted tape leads to a reduction in pressure drop and heat transfer rate, subsequently; a significant increase in TEF was seen compared to simple twisted tapes. In addition, some correlations were formulated to present the numerical results.