On fluid flow and heat transfer in a pipe with a U-bend

Document Type

Conference Proceeding

Publication Date


Publication Title

ASME 2013 Heat Transfer Summer Conf. Collocated with the ASME 2013 7th Int. Conf. on Energy Sustainability and the ASME 2013 11th Int. Conf. on Fuel Cell Science, Engineering and Technology, HT 2013




Dean number, Fluent, Numerical analysis, Reynolds number, Turbulent flow, U-bend


Vertical ground source heat pumps operate by pumping a heat transfer fluid through a pipe buried in the ground. There is a U-Bend at its deepest point to return the fluid to the surface. Incidentally, the U-Bend does more than packing the extensive length of the heat transferring conduit within a single compact borehole. Large flow structures called Dean's vortices are generated in the bend and these, along with the resulting turbulence produced, are known to significantly enhance the heat transfer processes, and hence, shorten the required length. This study examines the specific roles of Reynolds and Dean numbers on the flow structure and the resulting heat transfer in a pipe with a U-Bend. Water flowing in a pipe without and with heated wall was simulated using FLUENT. The model was verified based on available data in the literature. The efficacy of the local heat transfer rate along the pipe was cast with respect to the subtle changes in the flow characteristics under varying Reynolds number and Dean number. Copyright © 2013 by ASME.