Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.
Three-dimensional numerical studies were carried
out to investigate forced convection heat transfer
and fluid flow in a solid substrate cooled using
different types of micro heat sinks. The objective of
this study is to investigate which heat sink type
gives the lowest temperature variation on the
heated base of the solid substrate which is being
cooled. A low temperature variation indicates a low
temperature gradient which, in practical
application, improves the reliability of the
electronic device. The different heat sinks
considered are single microchannels, two-layer
microchannels with parallel and counter-flow of
fluid, single microchannels inserted with circularshaped
micro pin fins and two-layer microchannels
inserted with circular-shaped pin fins. All the heat
sinks are geometrically optimised using a
computational fluid dynamics code with a goaldriven
optimisation algorithm subject to global
constraints. The thermal performance of the heat
sinks considered in this study is based on two
objectives namely, the minimisation of the peak
temperature which results in maximisation of the
thermal conductance and the lowest temperature
variation on the heated base. The heat sink with the
largest value of thermal conductance and lowest
temperature variation on the heated base for the
range of pressure drop considered is chosen as the
best heat sink design. Numerical results of thermal
performance for fixed axial length of the solid
showed that cooling the solid substrate with the
two-layer microchannel with counter-flow of fluid
gave the lowest temperature difference at base of
the solid substrate and also performed best in
maximising thermal conductance at pressure drops
of 20 and 30kPa.
