Limiting Superheat of Aqueous Solutions at Negative Pressures

Abstract

The temperature of the limiting superheat for water-ethyl alcohol, water-isobutyl alcohol and wateracetone solutions has been measured in the region of negative pressures to -10 MPa at water concentration from 0 to 100%. Dependencies of the limiting-superheat temperature for pure liquids and solutions on the value of the negative pressure T *(P)j have been obtained in the region of temperatures exceeding the boiling temperature of pure components at atmospheric pressure. For organic liquids one can observe a continuous transition of the dependence T *(P)j from the region of positive into the region of negative pressures. Experimental results within the limits of experimental error agree with calculations by the formulae of homogeneous nucleation theory. In the case of water, the slope of the curve T *(P)j increases in passing from positive to negative pressures. The discrepancy between experimental data and theory increases with the liquid stretch. Additions of water into organic liquids increase the slope of curves T *(P)j in the region of negative pressures when a certain concentration of water is achieved. Analysis of the results has shown that it happens when the concentration of water in a solution exceeds that of the azeotropic compound.