Freezing behaviour and cooling energy storage capabilities of aqua-salt eutectics for milk cold chain

Abstract

Freezing behaviour, super-cooling degree and cooling energy storage capabilities of aqua-salt eutectics for milk cold chain were studied experimentally for calcium chloride (CaCl2), sodium chloride (NaCl) and sugar at concentrations (5-30%) into distilled water as well as for potable water. The degree of super cooling was more pronounced in case of sugar solution followed by CaCl2 and NaCl solutions. The typical freezing point curve loop of potable water indicated by the presence of dip in the cooling curve between 0 and -5 °C was due to super-cooling that took place till formation of ice crystals. The sloping of freezing curves of distilled water containing different concentrations of salt and sugar could be due to continuous increase in concentration of salt and sugar as pure solvent was frozen out of the solution, resulting continuous freezing point depression. The highest temperature drop (ΔT) for distilled water as well as all solutions in distilled water was observed in the first hour of freezing.