Numerical investigation of the effect of external helical fins reinforced with rectangular fins on improving convective heat transfer in helical coils
Haydar A.S. Aljaafari, Abbas J. Sultan, Laith S. Sabri, Narinderjit Singh Sawaran Singh, Seyed Hossein Hashemi Karouei, Dheyaa J. Jasim, Mehdi Alinia-kolaei, Farid Sadegh Sheshpoli
Abstract
This research investigated the performance of a shell and coil heat exchanger, employing four distinct designs with both water-based fluid and a nanohybrid Water/MgO_TiO_2 fluid. The initial phase compared three helical coil configurations—featuring four, three, and two external helical fins reinforced with rectangular fins—against a basic helical coil lacking such strips, across various Reynolds numbers. Results indicated that the helical coil with four external helical fins significantly boosted fluid mixing and heat transfer rates. Importantly, this four-finned coil exhibited superior heat transfer and overall performance. At Re = 1500, these four-fin, three-fin, and two-fin designs improved efficiency by 67 %, 63 %, and 60 %, respectively, compared to the simple helical coil. In the study's second stage, at Re = 1000, the thermal efficiency (η) values for the Counter Flow Water/MgO_TiO_2 (CFWM), Parallel Flow Water/MgO_TiO_2 (PFWM), Counter Flow Pure Water (CFPW), and Parallel Flow Pure Water (PFPW) cases were found to be 85 %, 78 %, 67 %, and 37 % higher than the simple helical coil, respectively.