Progress variables to resolve the steady state period in a batch-type fixed bed combustor

Document Type

Journal Article

Publication Title

Combustion Science and Technology


Taylor & Francis


School of Engineering




Edith Cowan University / Higher Education Commission (HEC), Pakistan


Junejo, A., Al-Abdeli, Y. M., & Ikhlaq, M. (2022). Progress variables to resolve the steady state period in a batch-type fixed bed combustor. Combustion Science and Technology. Advance online publication.


Lab scale combustion of solid fuels, such as biomass, is mostly performed using fixed bed combustors. Steady state data detailing various progress variables (temperature and emissions) are widely available within the literature. However, there is very little information available on how the onset of the steady state operation is identified especially in relation to batch operation, which is subject to depleting fuel bed. This paper uses experiments coupled with a systemic post-processing approach based on MATLAB in order to identify the onset of the steady state operation. The results show that by using both the percentile mean deviation and slope of certain measured progress variables (including the fuel bed temperature, freeboard temperature, fuel mass loss, and emissions) the steady state regime can be accurately predicted. The use of freeboard temperature data alone is not sufficient. Based on the methods developed, radiation error in thermocouple data was found to be significant in both non-staged and staged air combustion modes of fixed bed combustor. Moreover, the radiation error was lower for downstream thermocouples in contrast to upstream thermocouples.



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