Abstract
In this work, an experimental study of a novel microfabricated heat sink
configuration that tends to uniform the wall temperature, even with increasing flow
temperature, is presented. The design consists of a series of microchannel sections with
stepwise varying width. This scheme counteracts the flow temperature increase by reducing the
local thermal resistance along the flow path. A test apparatus with uniform heat flux and
distributed wall temperature measurements was developed for microchannel heat exchanger
characterisation. The energy balance is checked and the temperature distribution is analysed for
each test. The results show that the wall temperature decreases slightly along the flow path
while the fluid temperature increases, highlighting the strong impact of this approach. For a
flow rate of 16 ml/s, the mean thermal resistance of the heat sink is 2,35·10-5 m2·K/W which
enhances the results compared to the millimeter scale channels nearly three-fold. For the same
flow rate and a heat flux of 50 W/cm2, the temperature uniformity, expressed as the standard
deviation of the wall temperature, is around 6 ºC.