ISSN Online: 2379-1748
ISBN Flash Drive: 978-1-56700-472-4
ISBN Online: 978-1-56700-471-7
3rd Thermal and Fluids Engineering Conference (TFEC)
COIL HEAT EXCHANGER WITH REVERSED LOOPS
Abstract
In this study, flow and heat transfer characteristics of water flowing through different helical coil heat exchanger
(CHX) configurations was investigated. A structural modification of the traditional CHX was proposed aiming
to improve its thermal effectiveness. A 360° reversed loop was added after each 180° of the main CHX loop to
redistribute the velocity field and vorticity to enhance the thermal performance of the CHX. Experimental results
reveal reverse loops do enhance heat transfer rates by more than 20%, while pressure drop penalty also increases
but not at the same rate. The results suggest that adding reversed loops lead to stronger secondary flows and
enhanced turbulence mixing in the CHX test section. Experimental results to date show that the curvature of the
reverse loops with respect to the main coil is a critical factor in terms of thermal performance. Specifically, as
the size of reversed loop decreases, the heat transfer enhancement and pressure drop penalty for the modified
CHX increase. However, the results also suggest that there may exist an optimum radius of curvature for the
reversed loop, which might lead to the best combination of pressure drop penalty increment and heat transfer
enhancement.