On the use of electrical resistance and temperature as measures of the solid fraction in a mushy layer

Abstract

An experiment is described in which an aqueous solution of sodium nitrate is partially solidified by cooling from below. The solid fraction in the mushy layer is measured in two ways: by a two-wire electrical resistance method, and by temperature measurements combined with the assumption of equilibrium between the phases. The methods give different results, and it is concluded that the resistance method is biased towards high values by the growth of ice a short extra distance along the wires. The implications of the measurements, and the relative merits of the two methods, are discussed.