Abstract:
These days, the cooling of new generation electronic servers is a challenge due to the
immense heat generated by them. In order to avoid overheating caused by the important
rise in temperature appropriate cooling procedures must be used in order to meet the
thermal requirement. The current study aims at addressing the issue of overheating in
this field, and focuses on the thermal management of electronic devices modelled as a
discrete heat sources (mounted in a rectangular cavity) with uniform heat flux applied
from the bottom. A review of the literature published regarding the convective heat
transfer from heated sources as well as a thorough background on the theory of the
cooling of discrete sources by forced convection in rectangular channel is provided in
this study. It was showed that the heat transfer performance in channel is strongly
influenced by the geometric configurations of heat sources. Therefore, the arrangement
and geometric optimisation are the main considerations in the evaluation of thermal
performance. Unlike experimental methods that were carried out widely in the past,
which provided less cost-effective and more time-consuming means of achieving the same
objective, in this study we first explore the possibilities and the advantages of using the
CD-adapco's CFD package Star-CCM+ to launch a three dimensional investigation of
forced convection heat transfer performance in a channel mounted with equidistant heatgenerating
blocks. Numerical results were validated with available experimental data,
and showed that the thermal performance of the heat transfer increases with the strength of the flow. The second objective was to maximise the heat transfer density rate to the
cooling fluid and to minimise both the average and the maximum temperature in the
channel by using the numerical optimisation tool HEEDS/Optimate+. The optimal results
showed that better thermal performance was not obtained when the heated sources
followed the traditional equidistance arrangement, but was achieved with a specific
optimal arrangement under the total length constraint for the first case. Subsequently, for
the second case study, on the volume constraints of heat sources, the results proved that
optimal configurations that maximise the heat transfer density rate were obtained with a
maximum of either the height-to-length ratio or the height-to-width ratio. It was
concluded that the heat transfer rate to the cooling fluid increases significantly with the
Reynolds number and the optimal results obtained numerically are found to be fairly
reliable.
