کالیبراسیون و صحه‌گذاری دستگاه دیافراگم سل برای اندازه‌گیری ضریب نفوذ مایعات

In simulation and modeling of mass transfer phenomena and design of separation equipment; and prediction of mass transfer in miscible fuels, it is necessary to have the mass transfer coefficients. In this work, a diaphragm- cell was manufactured to measure the liquid-liquid diffusion coefficient. Then the cell constant was obtained to be 0.188 cm-2 with 0.5 molar solution of potassium chloride solution. Based on this obtained value, the binary diffusion coefficients of 0.5 molar sodium chloride and heptane-benzene were obtained to be 1.6*10-5 and 2.38*10-5 cm-2/s at 25 °C, respectively. These coefficients have been reported 1.5*10-5 and 2.29*10-5 cm-2/s at 25 °C in the references, respectively. Afterward, the infinite dilution diffusion coefficients of heptane in benzene and benzene in heptane at 25 °C were obtained to be 3.14*10-5 and 1.88*10-5 cm-2/s, respectively.  These coefficients have been reported3.4*10-5 and 2.10*10-5 cm-2/s in the references, respectively. The measured diffusion coefficients showed a good agreement with literature value. Ultimately, investigating the effect of liquid density of upper and lower part of the diaphragm cell on the measured value of diffusion coefficient showed that the solution with higher density shall be charged in the lower part of the cell.