Expeimental study of mixed convection and pressure drop in helically dimpled tubes for laminar and transition flow

摘要

This paper presents the experimental results carried out in dimpled tubes for laminar and transition flows and completes a previous work of the authors focused on the turbulent region. It was observed that laminar flow heat transfer through horizontal dimpled tubes is produced in mixed convection, where Nusselt number depends on both the natural convection and the entry region. Employing water and ethylene glycol as test fluids, the following flow range was covered: x-10~4-10~-2 and Ra=10~6-10~8.