The Modelling of the Urea Fertilizer Dissolution Process in Finite/Infinite Volumes of Water

This research aims to provide a model to investigate the impact of some parameters such as impeller speed, temperature, and solid concentration on mass transfer coefficient and the dissolution rate of urea fertilizer in the water. To study the effect of solid concentration two models are presented for finite and infinite-volume fluids using mass balance. Then the urea-water mass transfer coefficient was calculated at various impeller speeds and temperatures by measuring the time to complete dissolution. To investigate the effect of impeller speed and turbulence on the mass transfer coefficient, the impeller speed and Reynolds number were set in a range of 10-50 rpm and 300-3000, respectively. The Schmidt number also was used to study the effect of temperature on the mass transfer coefficient in the range of 5-25 °C. The results show that in both finite and infinite fluid volumes, at a constant impeller speed with decreasing Schmidt number, and at a constant temperature with increasing Reynolds number, the mass transfer coefficient, and mass transfer rate increase. Furthermore, four models are presented for mass transfer coefficient in finite and infinite volume, which that shows the mass transfer coefficient and release rate in finite volume were lower than that of infinite volume at a constant impeller speed and temperature.