A functional fluid was made by adding a small amount of additive to a water-silicon oil mixture with 90 vol% water content, and the functional fluid could be transformed into an ice slurry by cooling with stirring. The ice slurry had many excellent characteristics compared with the former ones. By a new ice formation system which authors proposed for ice storage based on previous results of authors' studies, the ice slurry could be formed continuously for 5-10 hours. In this paper, experiments were carried out, varying operating condition, and then, optimal operating conditions were discussed to improve performance of present system still more. From experimental results, the conditions that amount of recovery ice increased were clarified. Moreover, time-dependencies of shape and size for formed ice particles were also shown. Moreover, it was clarified the reason why the freezing point of functional fluid was risen by repeated ice formation, its measure was discussed, and then, it was found that it was possible to form and recover more amount of ice than that before rise of the freezing point.
