At higher temperatures reverse osmosis membrane coefficients increase and cause permeation rates to increase. Diffusion coefficients also increase and viscosity coefficients decrease causing concentration polarization to decrease and improve permeation. Experiments were performed with 15 (w/w) sucrose solutions in tubular cellulose acetate reverse osmosis membranes at 500 psig for low flow rates (Reynolds numbers between 10 and 1000). Depending upon the flow rate and mode of heating, raising the temperature from 25 to 35°C increased permeation rates up to 20, and from 25 to 45°C up to 55. Two methods of heating were tested: preheating the entire feed to the system, and heating the boundary layer at the membrane surface. Comparisons with theory are discuss
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