Back
 JECTC  Vol.6 No.2 , June 2016
Microscale Infrared Observation of Liquid-Vapor Phase Change Process on the Surface of Porous Media for Loop Heat Pipe
Abstract: Loop Heat Pipe (LHP) performance strongly depends on the performance of a wick that is porous media inserted in an evaporator. In this paper, the visualization results of thermo-fluid behavior on the surface of the wick with microscopic infrared thermography were reported. In this study, 2 different samples that simulated a part of wick in the evaporator were used. The wicks were made by different two materials: polytetrafluoroethylene (PTFE) and stainless steel (SUS). The pore radii of PTFE wick and SUS wick are 1.2 μm and 22.5 μm. The difference of thermo-fluid behavior that was caused by the difference of material was investigated. These two materials include 4 different properties: pore radius, thermal conductivity, permeability and porosity. In order to investigate the effect of the thermal conductivity on wick’s operating mode, the phase diagram on the q-keff plane was made. Based on the temperature line profiles, two operating modes: mode of heat conduction and mode of convection were observed. The effective thermal conductivity of the porous media has strong effect on the operating modes. In addition, the difference of heat leak through the wick that was caused by the difference of the material was discussed.
Cite this paper: Odagiri, K. , Nishikawara, M. and Nagano, H. (2016) Microscale Infrared Observation of Liquid-Vapor Phase Change Process on the Surface of Porous Media for Loop Heat Pipe. Journal of Electronics Cooling and Thermal Control, 6, 33-41. doi: 10.4236/jectc.2016.62003.
References

[1]   Nagano, H., Fukuyoshi, F., Ogawa, H. and Nagai, H. (2011) Development of an Experimental Small Loop Heat Pipe with Polytetrafluoroethylene Wicks. Journal of Thermophysics and Heat Transfer, 25, 547-552.
http://arc.aiaa.org/doi/abs/10.2514/1.T3614
http://dx.doi.org/10.2514/1.T3614


[2]   Nishikawara, M., Nagano, H. and Kaya, T. (2013) Transient Thermo-Fluid Modeling of Loop Heat Pipes and Experimental Validation. Journal of Thermophysics and Heat Transfer, 27, 641-647. http://dx.doi.org/10.2514/1.T3888
http://arc.aiaa.org/doi/abs/10.2514/1.T3888


[3]   Mitomi, M. and Nagano, H. (2014) Long-Distance Loop Heat Pipe for Effective Utilization of Energy. International Journal of Heat and Mass Transfer, 77, 777-784.
http://dx.doi.org/10.1016/j.ijheatmasstransfer.2014.06.001
http://www.sciencedirect.com/science/article/pii/S0017931014004669


[4]   Wu, S., Gu, T., Wang, D. and Chen, Y. (2015) Study of PTFE Wick Structure Applied to Loop Heat Pipe. Applied Thermal Engineering, 81, 51-57.
http://www.sciencedirect.com/science/article/pii/S1359431115000629
http://dx.doi.org/10.1016/j.applthermaleng.2015.01.048


[5]   Demidov, A.S. and Yatsenko, E.S. (1994) Investigation of Heat and Mass Transfer in the Evaporation Zone of a Heat Pipe Operating by the “Inverted Meniscus” Principle. International Journal of Heat and Mass Transfer, 37, 2155-2163.
http://www.sciencedirect.com/science/article/pii/0017931094903174
http://dx.doi.org/10.1016/0017-9310(94)90317-4


[6]   Kaya, T. and Goldak, J. (2006) Numerical Analysis of Heat and Mass Transfer in the Capillary Structure of a Loop Heat Pipe. International Journal of Heat and Mass Transfer, 49, 3211-3220.
http://www.sciencedirect.com/science/article/pii/S001793100600113X
http://dx.doi.org/10.1016/j.ijheatmasstransfer.2006.01.028


[7]   Ren, C. (2011) Parametric Effects on Heat Transfer in Loop Heat Pipe’s Wick. International Journal of Heat and Mass Transfer, 54, 3987-3999. http://www.sciencedirect.com/science/article/pii/S0017931011002444
http://dx.doi.org/10.1016/j.ijheatmasstransfer.2011.04.026


[8]   Zhang, X., Li, X. and Wang, S. (2012) Three-Dimensional Simulation on Heat Transfer in the Flat Evaporator of Miniature Loop Heat Pipe. International Journal of Thermal Sciences, 54, 188-198.
http://www.sciencedirect.com/science/article/pii/S1290072911003553
http://dx.doi.org/10.1016/j.ijthermalsci.2011.12.002


[9]   Liao, Q. and Zhao, T.S. (2000) A Visual Study of Phase-Change Heat Transfer in a Two-Dimensional Porous Structure with a Partial Heating Boundary. International Journal of Heat and Mass Transfer, 43, 1089-1102.
http://www.sciencedirect.com/science/article/pii/S0017931099002124
http://dx.doi.org/10.1016/S0017-9310(99)00212-4


[10]   Zhao, T.S. and Liao, Q. (2000) On Capillary-Driven Flow and Phase Change Heat Transfer in a Porous Structure Heated by a Finned Surface: Measurements and Modeling. International Journal of Heat and Mass Transfer, 43, 1141-1155. http://www.sciencedirect.com/science/article/pii/S0017931099002069
http://dx.doi.org/10.1016/S0017-9310(99)00206-9


[11]   Launay, S. and Mekni, N. (2010) Specifically Designed Loop Heat Pipe for Quantitative Characterization. Proceedings of the 15th International Heat Pipe Conference, Clemson, 25-30 April 2010.

[12]   Hemandez, A., Calvo, J.I., Pradanos, P. and Tejerina, F. (1996) Pore Size Distributions in Microporous Membranes. A Critical Analysis of the Bubble Point Extended Method. Journal of Membrane Science, 112, 1-12.
http://www.sciencedirect.com/science/article/pii/0376738895000259
http://dx.doi.org/10.1016/0376-7388(95)00025-9


[13]   Singh, R., Akbarzadeh, A. and Mochizuki, M. (2009) Effect of Wick Characteristics on the Thermal Performance of the Miniature Loop Heat Pipe. Journal of Heat Transfer, 131, 1-10.
http://dx.doi.org/10.1115/1.3109994
http://heattransfer.asmedigitalcollection.asme.org/article.aspx?articleid=1449646


[14]   Society of Japan Thermophysical Properties (2008) Thermophysical Properties Handbook. Yokendo Co., Ltd., Tokyo, 342.

 
 
Top