Numerical Simulation of Excess Ethanol Evaporation from Biodiesel in a Micro Heat-Exchanger

Abstract

The transesterification is the most common method to produce biodiesel, usually, occurring with alcohol excess in order to displace the chemical reaction equilibrium to the products direction. After the reaction, this alcohol excess can be removed and recovered. In micro and macroscales, this procedure commonly takes place in evaporators or even in distillation columns. Hence, the present paper applied numerical simulation techniques to evaluate the excess alcohol separation from biodiesel in a microchannel heat-exchanger. Three process variables were investigated: temperature (80-120 °C), flow rate (0.1-1.2 mL/min) and ethanol/biodiesel molar ratio, E:B (2-11). The results showed that an increase in the flow rate and molar ratio variables decreases the evaporation performance, in contrast with the positive effect of temperature (i.e., the increment of temperature provided an increase in the process). The use of micro heat-exchangers to perform the excess alcohol separation from biodiesel was numerically demonstrated.