Jason Lam z3252911 Supervisors: Dr Victoria Timchenko A/Prof. Guan Heng Yeoh.
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Transcript of Jason Lam z3252911 Supervisors: Dr Victoria Timchenko A/Prof. Guan Heng Yeoh.
Numerical Study of Heat Transfer Enhancement in Microchannels
Jason Lam
z3252911
Supervisors:
Dr Victoria Timchenko
A/Prof. Guan Heng Yeoh
Problem Definition• Microchannels
• Operating frequency increases with
technological advancement
• Heat generation rates hamper
advancement
Problem Definition• Microchannels
• Applications
• Micro-channel
Heat Exchanger
• Features/Limitations
Features of microchannelsParameter Shell and tube heat
exchanger
Compact heat
exchanger
Micro-channel heat
exchanger
Surface area per unit
volume (m2· m-3)
50 – 100 850 – 1000 >1500
Heat transfer coefficient
(liquid) (W•m-2•K-1)
~ 5000
(tube side)
3000 – 7000 >7000
Heat transfer coefficient
(gas) (W•m-2•K-1)
20 – 100 50 – 300 400 – 2000
Approach Temperature (°C) ~ 20°C ~ 10°C <10°C
Limitations of microchannelsParameter
Shell and tube
heat exchanger
Compact heat
exchanger
Micro-channel heat
exchanger
Flow Regime
Turbulent Turbulent Laminar
Features of microchannels
Synthetic Jet Displacement
AnalysisNumerical Experimental
Institution University of New South WalesThe Institute of Thermomechanics
ASCR
Person Jason Lam Zdeněk Trávníček
Transport
phenomenaHeat Transfer (Temperature) Mass Transfer (Concentration)
Geometry
Geometry
• 2 Cavities
• 4 Orifices
CFX Mesh
CFX Mesh
Special Thermal/Mass Boundary Condition
Numerical Experimental
Source Ts = 25°C Naphthalene Sample
Location Partially applied at the bottom of the channel
Synthetic Jet Displacement
𝑌=𝑌𝑚𝑎𝑥 sin (2𝜋 𝑓𝑡 )
Results – Steady State Heat Transfer
Results – Steady State Heat Transfer
Results – Steady State Heat Transfer
Results – Transient Heat Transfer
Results – Heat Transfer (Comparison)
Results –Heat Transfer (Comparison)
Results – Fluid Flow (Comparison)
Results – Fluid Flow (Comparison)
Results – Fluid Flow (Comparison)
Conclusions
• Numerical data has been validated with the experiment with
fair agreement
• The synthetic jet is a feasible method for promoting mixing
and enhancing heat transfer
• Most appropriate method for cooling microchips.
Questions?