INFLUENCE OF SUPERCOOLING OF HEAT SUPPORT HYDROGEL ON THE EFFICIENCY OF ICE STORAGE BY EVACUATION AND A METHOD FOR BRAKING THE SUPERCOOLING

The proposed ice storage system uses several kinds of hydrogel as heat supports. The vaporization heat of water from highly water-containing gel is stored as the heat of freezing of the remaining water. The fir st key to the realization of this system is development of a vacuum co mpressor with large evacuation rate for water vapor at low pressure an d with high efficiency. It is also important to evaporate water at hig h temperature, as near the freezing point as possible, to produce ice with high efficiency. A 1-liter cylindrical Dewar vessel made of stain less steel was used as a heat container and diaphragm pumps were used for evacuation. Four types of polymer gel materials and two kinds of i ce nucleation active substances (INS), AgI and ice nucleation active p rotein (INAP) produced by an ice nucleation active bacterium (INB: Xan tmonas campestris), were used in the experiments. For practical use, t he evaporation rate of water is described as proportional to the vapor pressure of water at the temperature of the gel. Both kinds of INS we re effective in raising,the break-point of supercooling from -5 approx imately -8-degrees-C (without INS) to -1 approximately -3-degrees-C (w ith INS). INAP is recommended for use in this system as a harmless, re producible organic INS.