Surface Tension and Surface Excess Analysis of Binary Mixtures of Pentane and 2-Methylpentane for Use in Wickless Heat Pipes*

Binary mixtures have been shown to improve the function of wickless heat pipes, which offer greater longevity over conventional heat pipes [1]. Fabrication of such wickless heat pipes rely on surface tension effects, such as Marangoni forces, making it essential to understand the interface properties of the liquid and its vapor. Recent improvements in Surface Light Scattering Spectroscopy instrumentation and its software, have not only improved its ease of use but have made possible a substantial improvement in the accuracy of surface tension measurements. With these improvements, we present surface tension and viscosity measurements of a binary mixture system of pentane and 2-methylpentane. The data are fit to an extended Langmuir isotherm model, giving insight into the relative concentration of the various components near the interface, quantified by the surface excess.

[1] T. T. T. Nguyen, A. Kundan, P. C. Wayner, J. L. Plawsky, D. F. Chao, and R. J. Sicker, Int. J. Heat Mass Transf. 95, 765 (2016).