Development of a mathematical model and simulation of mass transfer of solar ethanol distillation in modified brewery tank

The objective of this study was to develop a mathematical model of the mass transfer in a modified brewery tank for producing fuel ethanol. To reduce fossil fuel consumption, 50 flat-plate solar collectors were used as the heat source for the two stages of a distillation process for increasing the ethanol concentration. A 350-L distillation tank with 10%v/v (Stage 1) and a 70-L distillation tank with 40%v/v (Stage 2) were employed in the experiment used to develop the mathematical model of the mass transfer. A difference of approximately 10% was observed between the model predictions and the experimental results of the distillation product of Stage 1, whereas the predicted concentration was approximately 30% higher than that of the experiment, although this was reduced to approximately 5% by homogeneous mixing of the solution. Regarding the distillation process of Stage 2, there was approximately 10% difference between the predicted and experimental products, and approximately 3% difference between the predicted and experimental concentrations. The differences are attributed to errors in the heat transfer rate prediction of the model, which varies directly with the solar radiation values.