Phase Composition Curves in Frozen Porous Materials


PI:  Zhen Liu

The relationship between unfrozen water content and temperature, which is referred to as the Phase Composition Curve (PCC) in frozen soils, has long been observed. However, this relationship has not been extensively studied and widely used, possibly due to the lack of a physical understanding. Recent studies of the Pl succeeded in obtaining a physical description, a physically-based equation, and a physic-empirical prediction method for this relationship. Based on the common nature of porous materials, it is hypothesized that there is a relationship between unfrozen water content and temperature in all frozen porous materials. This study will experimentally investigate the existence of the PCC in typical porous materials. Optimization analyses will be conducted for the design of a Time Domain Reflectometry sensor. The TOR sensor together with thermal couples, which is suitable for the measurement of the PCC in the selected porous materials, will be fabricated and calibrated. The sensor will be utilized to measure the PCC by strictly following a specially designed procedure. The measured PCCs will be analyzed using the physically-based equation proposed by the PL The parameters in the equation will be obtained by means of curve fitting to the measured results. The values of the parameters for different porous materials will be categorized and compared.

The research will not only offer a definite answer to the wide existence of the PCC, but also obtain the characteristics of that of different porous materials. The research will provide a clear understanding of phase transition of water in porous materials which is currently absent. The resultant conclusions may advance many engineering applications involving the freezing process of porous materials. The research thus will lay down a necessary basis for the exploration in extraterrestrial environments, where both porous materials and the phase change of water or other liquid are very likely to exist. Also, this study will open a new research area for the PI and will answer a key question for preparing a solid proposal which will be submitted to the NSF.

Zhen Liu
Zhen Liu