Sensitivity Analysis of a Fixed Bed Combustion Model

Journal article, 2007

The ability to model the combustion of biofuels in a fixed bed is evaluated by a sensitivity analysis. The analysis treats the uncertainty of model parameters related to heat transport, reaction rates, and composition of volatiles. The scatter of the parameters is estimated from the differences between several published correlations. The results are compared with measurement data and possible model simplifications are discussed. It is shown that the bed model is able to reproduce the ignition rate and the maximum temperature. Prediction of these properties is relatively insensitive to the uncertainty of most of the parameters. Gas concentrations within the bed are more difficult to predict. They are greatly influenced by the composition of the volatile gas released during devolatilization. Also the composition of the volatile gas has a significant influence on the ignition of the gas in the model, affecting the ignition rate, particularly at low airflows. Moreover, the investigation shows that treatment of radiation can be simplified, and the number of gas species included in the model can be restricted without significant losses of model generality.