scholarly journals Pool Boiling Heat Transfer from Aluminum Alloy Circular Surface Using Al2O3 and CuO Water Based Nano-fluids

2019 ◽  
Vol 64 (2) ◽  
pp. 283-292
Author(s):  
Adel A. Fahmy ◽  
Ali A. Abdel Aziz
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Aluminum Alloy ◽  
Boiling Heat Transfer ◽  
Volume Fraction ◽  
Heated Surface ◽  
Pool Boiling ◽  
Nano Particles ◽  
Pool Boiling Heat Transfer ◽  
Demineralized Water

The present work aims to study the effect of nano-particles volume fraction of nano-fluid on the heat transfer during pool boiling with different values of heat flux. The concentration ratios by volume in demineralized water are taken as 0.02 %, 0.20 %, 0.40 %, 0.60, and 0.80 % for Al2O3 nano-particles and 0.02 %, 0.06 %, and 0.20 % for CuO nano-particles. Heat transfer coefficients for pool boiling were established experimentally for different values of volume fraction and heat flux. The heating element is made from an aluminum alloy (AL 6061) with a circular smooth surface of 100 mm diameter and 10 mm thickness. The nano-particles porous layer that builds up during boiling is observed by a scanning electron microscope of the heated surface before and after the boiling. The results demonstrate that the heat transfer rate depends on the concentration ratios and heat flux. Using nano-particles decreases the pool boiling heat transfer in comparison with demineralized water. Due to the deposition of nano-particles on the heated surface, lower heat transfer is obtained for a lower bubble departure compared with demineralized water for the small wall superheat.

Nucleate Pool Boiling Heat Transfer of R134a and R134a-PVE Lubricant Mixtures on Smooth and Five Enhanced Tubes

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Wen-Tao Ji ◽  
Ding-Cai Zhang ◽  
Nan Feng ◽  
Jian-Fei Guo ◽  
Mitsuharu Numata ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Saturation Temperature ◽  
Transfer Coefficients ◽  
Pool Boiling Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Enhanced Tubes ◽  
Mass Fractions

Pool boiling heat transfer coefficients of R134a with different lubricant mass fractions for one smooth tube and five enhanced tubes were tested at a saturation temperature of 6°C. The lubricant used was polyvinyl ether. The lubrication mass fractions were 0.25%, 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 7.0%, and 10.0%, respectively. Within the tested heat flux range, from 9000 W/m2 to 90,000 W/m2, the lubricant generally has a different influence on pool boiling heat transfer of these six tubes.

Effect of Nano-Particles on Pool Boiling Heat Transfer of Refrigerant 141b

2007 ◽  
Author(s):  
Da-Wei Liu ◽  
Chien-Yuh Yang
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Heat Transfer Performance ◽  
Pool Boiling ◽  
Nano Particles ◽  
Test Results ◽  
Tube Surface ◽  
Transfer Coefficients ◽  
Pool Boiling Heat Transfer ◽  
Heat Transfer Coefficients

Fluids with nano-sized particles have been proved that may effectively enhance the single-phase convective heat transfer performance. For pool boiling heat transfer, the published test results seems conflicted to each other. Some measured heat transfer coefficient decreased with increasing particle concentration but some showed no appreciable difference. This study provides an experimental investigation on pool boiling heat transfer performance of refrigerants R-141b with and without nano-sized Au particles on horizontal plain tubes. The test results show that the boiling heat transfer coefficients increase with increasing nano-particles concentration. At particles concentration of 1.0%, the heat transfer coefficient is more than twice higher than those without nano-particles. However, the heat transfer coefficients decreased for each test after every 5 days and finally close to those of R-141b without nano-particles. The SPM investigation shows that the test tube surface roughness decreased from 0.317 μm before boiling test to 0.162 μm after test. Further investigation by TEM and Dynamic Light Scattering particle analyzer shows that the nano-particles aggregated from 3 μm before test to 110 μm after test. This results show that the nano-sized Au particles are able to significantly increase pool boiling heat transfer of refrigerant R-141b on plain tube surface. The tube surface roughness and particle size changed after boiling test. Both of these effects degrade the boiling heat transfer coefficients.

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