5 research outputs found
Constructal design of single microchannel heat sink with varying axial length and temperature-dependent fluid properties
The objective of this numerical study is to investigate the best geometric configuration that maximises heat transfer from the heated base by allowing both the length of the solid substrate and the microchannel heat sink freedom to morph. The thermal performance of the microchannel is based on the minimised peak temperature on the heated surface which gives a global minimised thermal resistance. The optimisation of the geometric parameters of the heat sink and solid substrate is carried out using a computational fluid dynamics code with a goal-driven optimisation algorithm. Results of the effect of Bejan number on the minimised peak temperature and minimised thermal resistance for solid substrate with varying axial lengths of 1 to 10 mm but fixed volume of 0.9 mm3 is presented. Results of optimal channel aspect ratio, solid volume fraction and channel hydraulic diameter of the microchannel were also presented.NRF, TESP, University of
Stellenbosch/ University of Pretoria, SANERI/SANEDI,
CSIR, EEDSM Hub and NAC.http://www.iieta.org/Journals/IJHTam2016Mechanical and Aeronautical Engineerin
Constructal design of combined microchannel and micro pin fins for electronic cooling
This paper presents a three-dimensional numerical study of steady, laminar, incompressible flow and
forced convection heat transfer through a microchannel heat sink with micro pin fin inserts for both fixed
and variable axial lengths. The objective of the study was to optimise the geometric configuration of an
integrated microchannel and micro pin fins for different solid volumes so that the peak temperature in
the configuration was minimised. The effect of the micro pin fins on the optimised microchannel was also
investigated. The geometric optimisation of the integrated microchannel and micro pin fin was carried
out using a computational fluid dynamics (CFD) code with a goal-driven optimisation tool subject to global
constraints. The optimisation procedure was carried out in two steps. Firstly, the microchannel configuration
was optimised without the micro pin fins inserted and the results were compared with similar
work found in the open literature. This optimisation was carried out for both fixed and relaxed lengths.
Thereafter, the integrated design of the microchannel and micro pin fins was optimised. The effect of the
Bejan number on the solid volume fraction, channel aspect ratio and hydraulic diameter, pin fin aspect
ratio, minimised peak temperature and maximised thermal conductance were reported.
Results showed that as the Bejan number increased, the minimised peak temperature decreased. Also,
the maximum thermal conductance increased with the optimised microchannel structure with three to
six rows of micro pin fin inserts. Diminishing return set in when the number of rows of micro pin fin
inserts was greater than three for the fixed length but for the relaxed length, as the number of rows
increased, the results improved but when it exceeded six diminishing returns set in for a fixed solid volume
of 0.9 mm3. For each Bejan number used in this study, there was an optimum channel hydraulic
diameter and aspect ratio, solid volume fraction and pin fin aspect ratio that satisfied the global objective.NRF, TESP, University of Stellenbosch, University of Pretoria, SANERI/SANEDI, CSIR, EEDSM Hub and NAChttp://www.elsevier.com/locate/ijhmthb2014ai201
Constructal design of single microchannel heat sink with varying axial length and temperature-dependent fluid properties
The objective of this numerical study is to investigate the best geometric configuration that maximises heat transfer from the heated base by allowing both the length of the solid substrate and the microchannel heat sink freedom to morph. The thermal performance of the microchannel is based on the minimised peak temperature on the heated surface which gives a global minimised thermal resistance. The optimisation of the geometric parameters of the heat sink and solid substrate is carried out using a computational fluid dynamics code with a goal-driven optimisation algorithm. Results of the effect of Bejan number on the minimised peak temperature and minimised thermal resistance for solid substrate with varying axial lengths of 1 to 10 mm but fixed volume of 0.9 mm3 is presented. Results of optimal channel aspect ratio, solid volume fraction and channel hydraulic diameter of the microchannel were also presented.NRF, TESP, University of
Stellenbosch/ University of Pretoria, SANERI/SANEDI,
CSIR, EEDSM Hub and NAC.http://www.iieta.org/Journals/IJHTam2016Mechanical and Aeronautical Engineerin
Temperature variation on the heated base of a solid substrate cooled with different types of heat sink
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.dc201