Investigation on flow and heat transfer characteristics of ice slurry without additives in a plate heat exchanger

摘要

Ice slurry without additives plays a positive role in direct contact food and medical protective cooling applications, as we all now there are not adequate research on the flow and heat transfer characteristics of ice slurry without additives. Thus, experiments are conducted to determine the flow and heat transfer characteristics of 0-20 wt% ice slurry without additives through a plate heat exchanger (PHE) in present research. The results indicate that the pressure drop of ice slurry is about 5.5-61.0 kPa as the flow rate increased from 0.414 to 1.1 m(3)/h, it is about 1.2-1.6 times of that of chilled water. The pressure drops of ice slurry could be presented as a function of flow rate, ice fraction and Reynolds number, which are greater than that of the chilled water. The flow rate has a greater impact than ice fraction on pressure drop, which has an increment of 20% as the flow rates varying from 0.414 to 1.270 m(3)/h. The pressure drop of melting ice slurry is much smaller than that without heat exchanging, and it has no significant change as ice fraction decreases from 5% to 20% during heat exchanging. Based on the experimental results, the flow friction factor correlation is developed, and the local heat transfer correlation for ice slurry is also established with consideration of effect of latent heat on the heat transfer. In addition, the heat transfer analysis shows that the overall heat transfer coefficient of heat exchanger increases with the increase of flow rate. The flow rate plays a more important role than ice fraction in determining the overall heat transfer coefficient. The overall heat transfer coefficient and cooling duty increase with the of increase inlet water temperature and flow rate. And cooling duty has about 18.5-32.6% increment as the ice fraction varies from 0 to 5 wt%, but its increment is very small as the ice fraction is between 5 wt% and 20 wt%. (C) 2018 Elsevier Ltd. All rights reserved.