Performance of nano encapsulated phase change material slurry heat transfer in a microchannel heat sink with dual-circular synthetic jets

Author(s):  
Javad Mohammadpour ◽  
Fatemeh Salehi ◽  
Ann Lee
2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Sarada Kuravi ◽  
Krishna M. Kota ◽  
Jianhua Du ◽  
Louis C. Chow

Microchannels are used in applications where large amount of heat is produced. Phase change material (PCM) slurries can be used as a heat transfer fluid in microchannels as they provide increased heat capacity during the melting of phase change material. For the present numerical investigation, performance of a nano-encapsulated phase change material slurry in a manifold microchannel heat sink was analyzed. The slurry was modeled as a bulk fluid with varying specific heat. The temperature field inside the channel wall is solved three dimensionally and is coupled with the three dimensional velocity and temperature fields of the fluid. The model includes the microchannel fin or wall effect, axial conduction along the length of the channel, developing flow of the fluid and not all these features were included in previous numerical investigations. Influence of parameters such as particle concentration, inlet temperature, melting range of the PCM, and heat flux is investigated, and the results are compared with the pure single phase fluid.


Author(s):  
Rami Sabbah ◽  
Jamal Yagoobi ◽  
Said Al Hallaj

This experimental and numerical study investigates Micro-Encapsulated Phase Change Material (MEPCM) heat transfer characteristics and corresponding pressure drop. To conduct this study, an experimental setup consisting of a steel tube with an inner diameter of 4.3mm, outer diameter of 6.5mm and a length of 1,016mm is selected. A MEPCM mass concentration of 20% slurry with particle diameter ranging between 5–15μm is included in this study. Tube wall temperature profile, fluid inlet, outlet temperatures, the pressure drop across the tube are measured and corresponding Nusselt number are determined for various operating conditions. The experimental results are used to validate the numerical model predictions. The numerical model results show good agreement with the experimental data under various operating conditions. The controlling parameters are identified and their effects on the heat transfer characteristics of micro-channels with MEPCM slurries are evaluated.


Author(s):  
Rami Sabbah ◽  
Jamal Yagoobi ◽  
Said Al Hallaj

This numerical investigation explores the hydrodynamic and thermal boundary layers characteristics of a liquid flow with Micro-Encapsulated Phase Change Material (MEPCM). Unlike pure liquids, the heat transfer characteristics of MEPCM slurry can not be simply presented in terms of corresponding dimensionless controlling parameters such as Peclet number. In the presence of phase change particles, the controlling parameters’ values change significantly along the tube length due to the phase change. As a result, the hydrodynamic and thermal boundary layers are significantly affected by the changing parameters. The numerical results reveal that the growth of the thermal boundary layer for MEPCM slurries is different than for pure liquids. The presence of MEPCM in the working fluid slows the growth of the thermal boundary layer and extends the thermal entry length. The local heat transfer coefficient strongly depends on the location of the melting zone interface.


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