Radial mass flow in electrohydrodynamically-enhanced forced heat transfer in tubes

Abstract Experimental results of an electrohydrodynamically-enhanced oil heater of annular cross-section are presented. When a high d.c. voltage (typically 30 kV) was applied across the annular gap, it induced a very strong radial motion of the fluid resulting in a heat transfer increase of more than 20 fold over the fully-developed laminar flow, yet the pressure drop only increased 3 fold. The electrohydrodynamically-enhanced Nusselt number correlates well with electrical current passed, which is typically a few millionths of an ampere per metre of tube.