Abstract:
This paper investigates the thermal behaviour
of two micro-channel elements cooled by Newtonian and
non-Newtonian fluids, with the objective to maximise
thermal conductance subject to constraints. This is done
firstly for a two-dimensional duct micro-channel and secondly
for a three-dimensional complex micro-channel. A
numerical model is used to solve the governing equations
relating to flow and temperature fields for both cases. The
geometric configuration of each cooling channel is optimised
for Newtonian and non-Newtonian fluid at a fixed
inlet velocity and heat flux. In addition, the effect of
porosity on thermal conductance is investigated. It was
found, in both cases, that the non-Newtonian fluid characteristics
result in a significant variation in thermal conductance
as inlet velocity is increased. The characteristics
of a dilatant fluid greatly reduce thermal conductance on
account of shear thickening on the boundary surface. In
contrast, a pseudoplastic fluid shows increased thermal
conductance. A comparison of the complex micro-channel
and the duct micro-channel shows the improved thermal
conductance resulting from greater flow access to the
conductive area, achieved by the complex micro-channel.
