A comprehensive analysis of heat transfer in a heat exchanger with simple and perforated twisted tapes based on numerical simulations

Abstract

One of the most important methods to promote heat transfer (HT) in a heat exchanger (HE) is to use a twisted tape (TT) inside tubes. Therefore, in this paper, the result of the effect of TTs on the Nusselt number (Nu), and the performance coefficient of HEs in a laminar flow are investigated. plain tube (PT), simple TTs and perforated twisted tapes (PTTs) at 3 torsion ratio, blade numbers (N) 2, 4, 6 and 8 in the Reynolds numbers (Re) from 200 to 1000 are investigated. Ansys-Fluent computing software is used for this simulation. The findings indicate a positive correlation between the number of blades and both the Nu and the friction factor. It is important to acknowledge that the objective is to enhance the efficiency of the higher HE. Additionally, since there is an undesirable ratio between the rise of the Nu and the boost of the friction factor, so the HE coefficient decreases as the number of blades in TTs increases, from 6 to 8. The PTT with 6 blades provides the best performance coefficient. Compared to the simple TT, in the PTT, the Nu increases to 15.24%, the friction factor decreases to 22.26%, and the coefficient of thermal performance grows to 18.07%.