Study of Energy Storage with Ice Forming by Direct Water Evaporation from Surface of Polymer Gel by Evacuation

Abstract

Kinetic studies of energy storage by ice production in polymer gel were made to show the practicality of the preriously proposed ice storage system. The rates of water evaporation from several kinds of gel were the same as that from pure water. The rate of water evaporation was linearly proportional to the difference between the water vapor pressure and the evacuation pressure, and inversely proportional to the square root of the evaporation temperature (Eq. (2)).
The experiments were conducted under a rather high evacuation pressure of 98 to 99% of the vapor pressure at the vaporization temperature. The vaporization rate constant k 3 was 1g·pa^-1·K^0.5·min^-1·m^-2, and by use of a gel layer with the thickness of around 6 cm the rate was large enough to produce ice required for energy storage during 10 hr evacuation at night.
The procedure of ice formation within the gel was studied by calculating the energy balance of the experimental system. The simulation was proved to be a useful method of elucidating the amount of ice produced in a gel when no other direct method can show the rate of frozen water to total water in the frozen gel.