Freeze concentration is a thermal separation process that is used to purify aqueous solutions. One application of recent interest is seawater desalination. For freeze concentration to be an effective desalination method, a high ice growth rate and product purity must be achieved with energy usage comparable to that of competing technologies. The purpose of this thesis is to develop a coupled heat and mass transfer model to predict the growth rate and purity of the solid phase for ice grown about a horizontal, immersed tube. By simultaneously solving the heat and mass transfer problems, this model improves upon previous attempts found in the literature. In addition, an experimental apparatus was constructed and a series of ten experiments was run, considering a range of cooling rates, process times, and saltwater concentrations. Average ice growth velocities ranged from 3.1-13.1 mm/h and the observed partition coefficient ranged from 0.42-0.71. The model was calibrated using experimental data, and the coefficients of variation for the fitted model's prediction of ice mass and capture concentration were 15.4% and 7.6% respectively. Based on insights from modeling and experimentation, a series of suggestions are made regarding future modeling and process design. / Master of Science / Freeze concentration is a thermal process that is used to purify a liquid containing dissolved solids. One application of recent interest is seawater desalination. For freeze concentration to effectively purify seawater, a high ice growth rate and product purity must be achieved with energy usage comparable to that of competing technologies. The purpose of this thesis is to develop a coupled heat and mass transfer model to predict the growth rate and purity of the solid phase for ice grown about a horizontal, immersed tube. By simultaneously solving the heat and mass transfer problems, this model improves upon previous attempts found in the literature. In addition, an experimental apparatus was constructed and a series of ten experiments was run, considering a range of cooling rates, process times, and saltwater concentrations. Average ice growth velocities ranged from 3.1-13.1 mm/h and the salinity of the ice ranged from 0.42-0.71% of the original concentration. Based on insights from modeling and experimentation, a series of suggestions are made regarding future modeling and process design.