Measurement of freezing point depression of water in glass capillaries and the associated ice front shape

Abstract

Variations of the Kelvin equation [W. Thomson, Philos. Mag. 42, 448 (1871)] to describe the freezing point depression of water in capillaries exist in the literature. The differing equations, coupled with the uncertainty in input parameters, lead to various predictions. The difference between the predictions may become substantial when the capillary size decreases much below micron dimensions. An experiment was designed to investigate the predicted values using a customized directional solidification stage. The capillary freezing point depression for glass tubes with radii of 87 microm-3 microm was successfully measured. The image of the ice-water interface at equilibrium was also digitally captured and analyzed to examine the contact angle and the interface shape as well. Both are important for examining the hemispherical interface assumption that was exclusively used in the theoretical derivations. Finally, an equilibrium analysis of the thermodynamic system leads to a theoretical discussion of the problem. The effect of the temperature gradient on the interface shape is addressed, and an engineering criterion for the critical temperature gradient above which the effect must be considered for the interface shape calculation is derived.

Sensing and Sensibility: Single‐Islet‐based Quality Control Assay of Cryopreserved Pancreatic Islets with Functionalized Hydrogel Microcapsules

“…As shown in SEM images (Figure 2 c) and Figure 5 , the sodium alginate-calcium chloride hydrogel encompasses a compact porous 3D network (pore size ranging from tens to hundreds of nm), which may depress the freezing point, retard or change the propagation trajectories of ice growth. [ 63,64 ] Similar phenomenon was observed in the freezing of articular cartilage with dense structures and small pore sizes. [ 65 ] Meanwhile, large amount of bound water in the hydrogel may act as ice formation inhibitor and decrease the freezing point of hydrogel.…”

Solidification of colloidal suspensions

“…In order to obtain an expression for the ice-entry temperature, we can apply thermodynamic conditions for equilibrium at the pore scale, following the approach of Kuhn et al (1955) and Jackson & Chalmers (1958). The Gibbs-Thomson equation describing the freezingpoint depression due to curvature of the ice in the space between the particles in figure 9 is (Liu et al 2003;Rempel et al 2004)…”

Influence of Shrinkage-Reducing Admixtures on Early-Age Properties of Cement Pastes

“…The surface tension of the pore solution may also influence the freezing point depression obtained in the porous concrete (Acker et al 2001, Fagerlund 1973, Brun et al 1977, Liu et al 2003. For example, Acker et al (2001) have derived the following expression for the equilibrium of ice with an aqueous solution in a capil-lary:…”