Sub-zero temperature profile and chilling energy storage behaviour of aqua-glycol eutectics for milk cold chain

Sub-zero temperature behaviour, super-cooling degree and cooling energy storage capabilities of aqua-glycol eutectics for milk cold chain were studied experimentally for propylene glycol and ethylene glycol at various concentrations (5-30%) into distilled water as well as for potable water. The degree of super cooling was more pronounced in case of ethylene glycol solution followed by propylene glycol solutions. At higher concentrations of glycols, the degree of super-cooling was more while cooling energy storage capabilities were less. The highest temperature drop (ΔT) for distilled water as well as all aqua-glycol solutions was observed in the first hour of freezing. The highest temperature drop (ΔT) for DW as well as all solutions in DW was observed in the first hour of freezing. The total ΔT of DW, 5, 10, 15, 20, 25 and 30% PG upon freezing for 12 h were 26.3, 29.5, 32.5, 34.9, 37, 39.3 and 40.7°C, respectively. The total ΔT of DW, 5, 10, 15, 20, 25 and 30% EG upon freezing for 12 h were 26.3, 29.4, 33.1, 36.3, 38, 41 and 44.4°C, respectively.