Towards Engineered Hydrochars: Application of Artificial Neural Networks in the Hydrothermal Carbonization of Sewage Sludge

Sewage sludge hydrochars (SSHs), which are produced by hydrothermal carbonization (HTC), offer a high calorific value to be applied as a biofuel. However, HTC is a complex processand the properties of the resulting product depend heavily on the process conditions and feedstock composition. In this w...

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Bibliographic Details
Main Authors: Theodoros N. Kapetanakis, Ioannis O. Vardiambasis, Christos D. Nikolopoulos, Antonios I. Konstantaras, Trinh Kieu Trang, Duy Anh Khuong, Toshiki Tsubota, Ramazan Keyikoglu, Alireza Khataee, Dimitrios Kalderis
Format: Article
Language:English
Published: MDPI AG 2021-05-01
Series:Energies
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Online Access:https://www.mdpi.com/1996-1073/14/11/3000
Description
Summary:Sewage sludge hydrochars (SSHs), which are produced by hydrothermal carbonization (HTC), offer a high calorific value to be applied as a biofuel. However, HTC is a complex processand the properties of the resulting product depend heavily on the process conditions and feedstock composition. In this work, we have applied artificial neural networks (ANNs) to contribute to the production of tailored SSHs for a specific application and with optimum properties. We collected data from the published literature covering the years 2014–2021, which was then fed into different ANN models where the input data (HTC temperature, process time, and the elemental content of hydrochars) were used to predict output parameters (higher heating value, (HHV) and solid yield (%)). The proposed ANN models were successful in accurately predicting both HHV and contents of C and H. While the model NN<sub>1</sub> (based on C, H, O content) exhibited HHV predicting performance with R<sup>2</sup> = 0.974, another model, NN<sub>2</sub>, was also able to predict HHV with R<sup>2</sup> = 0.936 using only C and H as input. Moreover, the inverse model of NN<sub>3</sub> (based on H, O content, and HHV) could predict C content with an R<sup>2</sup> of 0.939.
ISSN:1996-1073