Heat transfer and power consumption in a scraped-surface heat exchanger while freezing aqueous solutions

The heat transfer coefficient and the power consumption of a laboratory scraped-surface heat exchanger (SSHE) were measured when it was used for freezing a 10 wt.% sugar solution. Experimental results show that the heat transfer coefficient with phase change (ice formation) was about three to five times greater than that without phase change. Once onset of ice-growth occurred, the torque for driving the scraper started to increase gradually until the scraper was ‘frozen’. The power consumption of SSHE with phase change was modelled in this work, which was influenced considerably by the ice content in the ice slurry. The initial power consumption at the onset of ice formation was however independent of the cooling surface temperature.