Experimental Investigation on Contact Angle of Sintered Copper Powder Wick

Abstract:

Heat pipes are widely used in electronic cooling and other applications that require efficient transport or spreading of heat from local sources of high heat flux. One factor that most affect the performance of this device is the wetting properties of the wick material, whereby a hydrophilic wick material is required to transport the liquid from the evaporator to the condenser. The performance of heat pipe will decrease when the wick surface becomes hydrophobic as indicated by changes in its contact angle (CA). This study aims to determine the effect of ambient air exposure on the wettability of wick material. Wettability for a surface by a certain liquid can be shown by measuring the contact angle of liquid droplets on the surface. In this experiment, the contact angle was captured using a high speed video camera followed by image processing and then measured using Image J software. The surface of the sample/wick is a sintered copper powder which in this study through a process of forming or compaction by various parameters such as powder particle size, compacting pressure and sintering temperature. From the results of this study was found that the longer wicks were exposed in the ambient air, the contact angle of the liquid on the wick surface will be getting increased. After 7 days were contaminated on the ambient air, then all samples have been turned into hydrophobic, CA>90°.

References

[1] N. Putra, W. N. Septiadi, H. Rahman, and R. Irwansyah, Thermal performance of screen mesh wick heat pipes with nanofluids, Experimental Thermal and Fluid Science, vol. 40, pp.10-17, 7/ (2012).

DOI: 10.1016/j.expthermflusci.2012.01.007

[2] R. -T. Wang, Y. -W. Lee, S. -L. Chen, and J. -C. Wang, Performance effects of heat transfer and geometry on heat pipe thermal modules under forced convection, International Communications in Heat and Mass Transfer, vol. 57, pp.140-149, 10/ (2014).

DOI: 10.1016/j.icheatmasstransfer.2014.07.023

[3] N. Putra, R. Saleh, W. N. Septiadi, A. Okta, and Z. Hamid, Thermal performance of biomaterial wick loop heat pipes with water-base Al2O3 nanofluids, International Journal of Thermal Sciences, vol. 76, pp.128-136, 2/ (2014).

DOI: 10.1016/j.ijthermalsci.2013.08.020

[4] N. Putra, W. N. Septiadi, and R. Irwansyah, Effect of Concentration and Loading Fluid of Nanofluids on the Thermal Resistance of Sintered Powder Wick Heat Pipe, Advanced Materials Research, vol. 651, pp.728-735, (2013).

DOI: 10.4028/www.scientific.net/amr.651.728

[5] S. -C. Wong and Y. -C. Lin, Effect of copper surface wettability on the evaporation performance: Tests in a flat-plate heat pipe with visualization, International journal of heat and mass transfer, vol. 54, pp.3921-3926, (2011).

DOI: 10.1016/j.ijheatmasstransfer.2011.04.033

[6] F. Dominguez Espinosa, T. Peters, and J. Brisson, Effect of fabrication parameters on the thermophysical properties of sintered wicks for heat pipe applications, International Journal of Heat and Mass Transfer, vol. 55, pp.7471-7486, (2012).

DOI: 10.1016/j.ijheatmasstransfer.2012.07.037

[7] M. R. Shirazy, S. Blais, and L. G. Fréchette, Mechanism of wettability transition in copper metal foams: From superhydrophilic to hydrophobic, Applied Surface Science, vol. 258, pp.6416-6424, (2012).

DOI: 10.1016/j.apsusc.2012.03.052

[8] C. Zhang, W. Zhou, Q. Wang, H. Wang, Y. Tang, and K. Hui, Comparison of static contact angle of various metal foams and porous copper fiber sintered sheet, Applied Surface Science, vol. 276, pp.377-382, (2013).

DOI: 10.1016/j.apsusc.2013.03.101

[9] K. Tang, X. Wang, W. Yan, J. Yu, and R. Xu, Fabrication of superhydrophilic Cu< sub> 2</sub> O and CuO membranes, Journal of membrane science, vol. 286, pp.279-284, (2006).

DOI: 10.1016/j.memsci.2006.10.005

[10] S. S. Anand, B. K. Philip, and H. M. Mehendale, Volatile Organic Compounds, in Encyclopedia of Toxicology (Third Edition), P. Wexler, Ed., ed Oxford: Academic Press, 2014, pp.967-970.

DOI: 10.1016/b978-0-12-386454-3.00358-4