UWE Bristol Engineering showcase 2015

David Nason
MEng Mechanical Engineering
Project Supervisor
Dr. Rohitha Weerasinghe
Optimisation of a Microfluidic Flat-Plate Thermal Solar Collector Design
Through Computational Fluid Dynamics Analyses
Introduction
This investigation follows on from an
investigation into combining solar energy
enhancing techniques with microfluidics.
After producing several potential designs
incorporating microfluidics with both
thermal solar collectors and photovoltaic
solar panels, it was decided that the best
course of action was to use a design for
thermal solar collector.
The selected design then needed to be
optimised in order to give the collector
maximum efficiency capabilities.
Design
The design that was analyzed was the
simple replacement of 10mm risers in a
thermal solar collector, with layers of
copper containing thousands of
microchannels. The idea behind this is that
the fluid in the centre of the risers would
be cooler than that at the heated pipe wall.
This system provides the heat to be spread
to all parts of the fluid. This idea eventually
led to the deduction that an effective way
to increase collector efficiency was to
minimize the difference in temperature
between the average collector temperature
and the fluid inlet temperature.
Testing
Computational fluid dynamics tests were
completed in order to test various
configurations of collector to establish
which provided the most optimal results.
Results
The simulations proved that the optimal
configuration uses two layers of
microchannels with dimensions 0.29 x
0.145mm. This configuration showed
improved results of reduced heat loss in
comparison to results of the test
performed on a conventional solar
collector design. The implications for this
configuration show a profound potential
for the reduction of heat losses in a
thermal solar system, which would lead to
an increase in conventional solar collector
efficiency. For all collector plate fluid
temperatures that this system could be
exposed to, there is a fixed temperature
difference between that fluid temperature
and the adjacent collector plate
temperature.
Heat maps were found for various
configurations from the CFD tests
Above is a heat map for the optimal design
Project summary
This investigation has been performed with the aim
of c of completing an optimised design of the
absorber within a glazed flat-plate thermal solar
collector incorporating microfluidics that would aid
the efficiency of the collector.
Project Objectives
The objectives of this investigation were to:
•Perform an in-depth analysis of heat losses that occur in
conventional thermal solar collectors
•Analyse in detail all the variable properties of the design
•Perform computational fluid dynamics (CFD) analyses on
various configurations of the design.
•Analyse all results and compare to results from
conventional collector testing.
Project Conclusion
The investigation has been successful, in that the
main aim of the study was to complete an optimized
design of the absorber within a glazed flat-plate
thermal solar collector incorporating microfluidics
that would aid the efficiency of the collector.
Heat map for a conventional configuration of thermal solar
collector