Abstract
We have proposed a numerical calculation method for predicting the solidification caaracteristics of paraffin oil droplets(tetradecane, CH3(CH2)12, melting point 5.8°C, diameter from 4 mm to 6 mm)ascending in a cold water solution layer(a mixture of ethyleneglycol(CH2OH·CH2OH)and water, temperature from -2°C to -10°C)due to buoyancy. The oil droplets started to ascend with several initial velocities and initial temperatures(10°C-60°C)in the water solution layer. The oil droplets were decelerated by hydraulic resistance of the water solution flow. The water solution flowed vertically downward at a low velocity of 0.1 m / s. The temperature of the oil droplet decreased due to direct-contact heat transfer with the cold water solution, and the oil droplet started to solidify when its surface temperature reached its freezing point. The solidified fraction of the oil droplet was calculated by taking into account a combination of the flow behavior and solidification characteristics of the oil droplet. As a result, the motion of the oil droplet, the completion height and time taken for solidification were determined. The parameters used were the diameter, initial velocity and initial temperature of the oil droplet, and temperature and velocity of the water solution.
