Modelling And Simulation Of Flexible Microfluidic-Integrated Micro Thermoeletric Generator
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Date
2014-08
Authors
Heng, Yeh En
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The potential of a micro thermoelectric generator (μTEG) which harvest
energy from small temperature difference is preeminent among public concerns. The
conventional μTEG gave considerable insight into different employment of materials
and structural modification to enhance the thermal efficiency and output performance
of the generator. In effort to increase the output power, the manipulation of heat
source becomes the solitary necessity for a given structural design of μTEG. This
thesis presents the design optimization of an emerging concept with the employment
of a polydimethylsiloxane (PDMS) microfluidic channel as the heat sink with the
silicone oil which has wide working temperature as the working fluid in the
thermoelectric generator. This combination shows its superiority particularly when
the heat source experiences inconsiderable temperature changes. Unlike in
conventional μTEG, integration of microfluidic system into the generator allows the
manipulation of both the heat source and heat sink, thereby the output power can be
increased significantly. The efforts to predict the optimized performance of the
model are based on the length of thermo-elements, channel geometry and fluid flow
rate by using COVENTORWARE, GAMBIT and FLUENT. Analyses were first
carried out by optimizing the thermoelectric elements by varying the length of the
thermopiles until the most appropriate length with appreciable integration density
was obtained. After the optimum length was established, the effects of the channel
geometry were discussed in detail, and emphasis was placed on the hydrodynamic
and thermal development of the flow. The corresponding output power and pumping
power were calculated to predict the best channel dimension. As the geometry
optimization of the thermoelectric elements and channel were introduced, particular
attention was given to the suitable flow rates for the working fluid to make sure
positive net power was accomplished. The ultimate decision derived from the
numerical simulations exhibit that an optimized microfluidic-integrated μTEG
should possess thermocouple length of 36 μm, channel cross-section of 50 μm x 50
μm and the range of applicability of the flow rate must be within the range of 0.05
m/s. The recommended best range for the working fluid is within 0.057 m/s while
voltage efficiency factor (φv) as high as 11.752 V/cm2 K and power efficiency factor
(φp) as high as 0.2377 μW/cm2 K2 could be obtained at the optimum fluid velocity of
0.03 m/s. The simulation results of the optimized μTEG shows the potential
increment of φv and φp compared to the conventional μTEG and its flexibility also
allows wider scope of applications.
Description
Keywords
Modelling and simulation of flexible , microfluidic-integrated