Influences of pitch-length louvered strip insert on thermal characteristic in concentric pipe heat exchanger

Mechanical Engineering Department, Faculty of Engineering, Sebelas Maret University, 57126 Surakarta, Indonesia

^* Corresponding author: indriyaningsih@staff.uns.ac.id

Abstract

The effects of pitch-length louvered strip inserts with a forward arrangement on heat transfer and friction factor characteristics in a concentric pipe heat exchanger were experimentally investigated. Louvered strip insert was installed inside the tube. For comparison, the experiment without louvered strip (plain tube) was conducted. All cases were tested under steady state condition for Reynolds number ranging from 5300-17,500. The results show that the utilization of louvered strip insert produced a higher heat transfer rate compare to a plain tube. Nusselt number, friction factor, and heat transfer coefficient ratio increased with decreasing pitch length. The Nusset number for louvered strip insert with S of 40, 50, and 60 mm increasing in the value of 67% - 77%; 48% - 53%; and 21% - 24% than plain tube, respectively. While the tube fitted with louvered strip insert by S of 40, 50, and 60 mm, friction factor increased 2.91 - 3.84; 2.41 - 2.92; and 1.88 - 2.08 times greater than a plain tube. The addition of louvered strip insert with S of 40, 50, and 60 mm producing heat transfer coefficient ratio in the range of 1.02 - 1.12; 1.03 - 1.07 and 1.03 - 1.04.