Experimental Investigation of Heat Transport by Oscillatory Flows in Ribbed Mini-Tubes
Jaroslav Hemrle, Sadanari Mochizuki and Akira Murata
Experimental results of axial heat transport by oscillating, low Reynolds number flows in 2.5 mm inner diameter tubes with circumferential ribs are presented. Only moderate enhancement of the effective thermal conductivity is observed below the oscillating Reynolds number, Re, of about 100, beyond which the heat transport increases rapidly as a result of vortex mixing generated by the ribs. At Re = 800, approximately 4-fold enhancement of the effective thermal conductivity is achieved, compared to the smooth tube (20-fold compared to the steady state thermal conductivity), with lower enhancement by ribs at larger pitch. Additionally, flow visualization results are reported.