Acousto-chemical analysis in multi-transducer sonochemical reactors for biodiesel production

Abstract

Biodiesel is a powerful alternative fuel that is less polluting and problematic to produce and implement. The production process of biodiesel also gives us the byproduct glycerol, which is a useful feedstock to produce hydrogen and syngas as fuels. With such high value as a fuel we are in need of better production technologies for biodiesel, which is currently being pursued through sonochemical reactors. The development of continuous sonochemical reactors for biodiesel production is a crucial requirement for the biofuel industry. Sonochemical reactors make use of ultrasound and acoustic cavitation to produce biodiesel from waste cooking oils (WCO). In this work we carried out both numerical simulation and experimental analysis of sonochemical reactors with multiple transducers. Through simulation, the effect of double vs a single transducer has been tested for a continuous flow sonochemical reactor. In experimental work three different cases with different ultrasound systems (bath, probe and bath+probe) have been tested. In both the studies, acoustic pressure and biodiesel conversion are analyzed. Results for the simulation show that in shorter reactors, the high cavitation from two transducers dampens the acoustic pressures leading to low conversion. However, at taller heights the effect of combined cavitation is less severe and the acoustic pressure and biodiesel yield are very similar between the designs having single and double transducers. From experiments it was found that the biodiesel conversion depends on several acoustic conditions mainly cavitation. A meticulous and insightful analysis was made to understand the difference in bath type and probe type ultrasound systems on acoustic pressure and biodiesel conversion.