Dynamic Heat Transfer Modeling, and Simulation of Biomass Fermentation during Beer Processing

Abstract

The study focuses on the modeling of the temperature profile during the fermentation of beer and the selection of the modelled temperature to simulate the growth of a microorganism, the consumption of proteins and the formation of aromatic compounds (ketone and esters). The objective of the study was to determine how to select the best temperature for beer fermentation and how a portion of the biochemical reaction occurs with the controlled (selected) temperature.   Finite element modelling has been used for heat transfer modelling and COMSOL Multiphysics version 5.3 has been used for implementation. Version 17 of MATLAB was used to simulate biochemical changes with the chosen temperature.  The simulated results showed that at high coolant flow, a low-temperature profile was recorded over the fermentation time. As such, the observed temperatures were 1.2m3/hr, 1.3m3/hr and 1.6m3/h, 20 oC, 18 oC and 12.5 oC, respectively. The modelled vorticity results also indicated that at a flow rate of 1.2m3/hr, there was a consistent flow of liquid around the agitation center relative to other coolant flows. Isoleucine was exhausted after 13hr at 12.5°C, 80hr at 18°C and 16hr at 20°C from the start of fermentation. The simulated results also indicated that ethyl acetate had reached a hold-back value of 0.114mol/m3 at 70hr at 12.5oC, 30hr at 18oC, and 22hr at 20oC. However, isoamyl acetate retained a retention value of 0.0105 mol/m3 until the initial concentration of sugar and amino acids was exhausted (throughout fermentation) at all selected temperatures. Valine decreased to nearly 195hr at 12.5°C, 120hr at 18°C and 85hr at 20°C. The simulated nutrient results were again shown to be zero in 210hr at 12.5°C, 110hr at 18°C and 90hr at 20°C of luicine consumption.