Summary
We conducted ice making exyriments for two winter seasons using an ice-pond with a capacity as large as 200m3 by controlling an ice making sub-system with an automatic ice making control program described in part1 of this study. We obtained the following results:HomePage
1) Ice was automatically produced according to climate conditions and the final ice height reached over 2 m for both winter seasons in Sapporo.
2) If a precipitation mixing ratio (PMR, a ratio of precipitation to the TWIN-equivalent spray thickness), is given by X, and a TWIN-freezing index for unit thickness of ice, is given by Y, in K¥h¥mm-1 - ice, the relationship between them can be expressed by Y=8.07+1.10 X-19.83X2. This shows that the TWIN-freezing index decreases with an increase of precipitation.
3) Because of snowfall during the ice making yriod, the water content and the porosity of the ice produced was relatively high indicating a lower quality compared with pure ice. Suppose the PMR is oven by X, and a volumetric thermal purity (VTP, a ratio of latent heat of fusion of unit volumes of produced ice to that of pure ice) is given by Y, then the regression formula, given by Y=0.754-0.260X, showed decreasing VTP with an increase of precipitation.
4) Precipitation had little effect on the energy efficiency of latent heat storage by ice making because the quality of ice decreased with an increase in precipitation while the volume of ice produced increased at the same time.
5) When data on the winter-seasonal TWIN and precipitation of a certain place is available it is feasible to calculate the required scale of the ice pond by estimating the ice height and VTP of ice to be produced using the formulas given above.Keywords: ice pond, cold storage, ice making, properties of ice, TWIN freezing index, volumetric thermal purity of ice