A mass transfer model of ethanol emission from thin layers of corn silage

Abstract

A mass transfer model of ethanol emission from thin layers of corn silage was developed and validated. The model was developed based on data from wind tunnel experiments, conducted at different temperatures and air velocities. Multiple regression analysis was used to derive an equation that related the effective mass transfer coefficient (KL) to temperature and air velocity. Validation of the model was done using data collected from experiments conducted in a controlled environmental chamber. Ethanol emissions were determined by measuring ethanol concentration in the environmental chamber exhaust over a 24 hour period using a photoacoustic gas analyzer. Silage ethanol concentration was also monitored throughout the duration of the experiment. Predicted ethanol emission rates were strongly correlated (R2 = 0.94) with measured values in the environmental chamber. A high correlation (R2 = 0.96) was also found between predicted and measured ethanol concentrations in the silage. The model was used to estimate ethanol emission rates from thin layers of loose silage under selected weather conditions of a California dairy farm. Model predictions indicate that over 95% of the ethanol present in silage could be emitted in the first 8 hours after exposing the silage to ambient air temperature (18 to 35oC) and air velocity (0.1 to 2.0 m/s).