Evaluation of Nusselt number and effectiveness for a vertical shell-coiled tube heat exchanger with air bubble injection into shell side

Abstract

Air bubble injection was employed to increase the heat transfer rate (Nusselt number) of a vertical shell and coiled tube heat exchanger in this article. Hot and cold water flowed into the coil side and shell side of heat exchanger, respectively, and air bubbles were injected inside the shell side of heat exchanger via a memorable method. Bubbles' vertical movement due to buoyancy forcing through the heat exchanger can enhance the heat transfer rate by mixing the thermal boundary layer, increasing the turbulence level of the fluid flow and increasing the shell-side fluid Reynolds number.

Keywords::

• air bubble injection
• shell and coiled tube heat exchanger
• Nusselt number
• effectiveness

Acknowledgments

The authors appreciate Mr. Hamed Sadighi Dizaji (from Urmia University) for the use of his personal experimental setup and his valuable remarks, time, and many discussions during the experimental program regarding this research.