Friction losses and heat transfer of single-phase flow in a mini-channel

Experimental frictional pressure drop and heat transfer during single phase flow in a vertical mini-channel have been studied with the aim of determining the validity of classical correlations available for conventional size channels. A 1 mm square channel etched in a 420 mm long test section of aluminum has been investigated. The Reynolds number has been varied from 310 to 7780 in order to cover the laminar regime as well as the beginning of the turbulent regime. The heat flux supplied to the fluid varies from 1 kW/m2 to 8 kW/m2. Experimental frictional pressure drop measurements show that classical correlations accurately apply. Temperature measurements along the channel show that the temperature profile is drastically different from the expected linear behaviour owing to an important longitudinal heat flux in the channel wall. This heat flux mal-distribution which has been recently discussed in the literature is clearly shown and studied in more details by a numerical simulation of the experiment. This numerical work has allowed to make a correction on temperature measurements. Once corrected, the heat transfer measurements are in fair agreement with the classical literature results.