# Thermo-Hydraulic Performance Analysis on the Effects of Truncated Twisted Tape Inserts in a Tube Heat Exchanger

^{1}

Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam

^{2}

Faculty of Electrical–Electronic Engineering, Duy Tan University, Da Nang 550000, Vietnam

^{3}

Research & Development Team, Couette Limited, Altrincham WA14 2PX, UK

^{4}

Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 8415683111, Iran

^{5}

Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia

^{6}

Metamaterials for Mechanical, Biomechanical and Multiphysical Applications Research Group, Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam

^{7}

Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam

^{8}

CanmetENERGY Research Centre, Natural Resources Canada, 1 Haanel Drive, Ottawa, ON K1A 1M1, Canada

^{*}

Authors to whom correspondence should be addressed.

Received: 10 September 2020 / Revised: 28 September 2020 / Accepted: 29 September 2020 / Published: 9 October 2020

(This article belongs to the Special Issue Heat Transfer in Engineering)

This paper investigates the convective heat transfer in a heat exchanger equipped with twisted tape elements to examine effects of the twisted tape truncation percentage, pitch value, position and Reynolds number using 3D numerical simulation. A symmetric heat flux is applied around the tube as the studied heat exchanger. Based on the influences in both heat transfer enhancement and pressure drop, the performance evaluation criterion (PEC) is utilized. Inserting twisted tape elements and reducing the pitch value significantly augment the Nusselt number, friction coefficient and PEC number compared to the plain tube. For the best case with a Reynolds number of 1000, the average Nusselt number increases by almost 151%, which is the case of fully fitted twisted tape at a pitch value of L/4. Moreover, increasing the twisted tape truncation percentage reduces both heat transfer and pressure drop. Furthermore, the highest heat transfer rate is achieved when the truncated twisted tape is located at the entrance of the tube. Finally, it is concluded that for P = L, L/2, L/3 and L/4, the optimum cases from the viewpoint of energy conservation are twisted tapes with truncation percentages of 75, 50, 50 and 0%, in which the related PEC numbers at a Reynolds number of 1000 are almost equal to 1.08, 1.24, 1.4 and 1.76, respectively.