Thermogravimetric analysis of high- and low-density sawdust under nitrogen gas atmosphere

ABSTRACT

The paper presents the thermal degradation of low-density wood sawdust (LDS) and high-density wood sawdust (HDS) under a nitrogen gas atmosphere using thermogravimetric analysis together with the assessment of their combustion parameters. A thermal conversion experiment was carried out at three different heating rates (5°C, 10°C, and 15°C/min) for three different particle sizes (<0.6, $0.6\le x\le 0.8$, $0.8>x\le 1$ mm). The DTG_max showed that the HDS ($\le 17.9$) experienced more weight loss than the LDS ($\le 15.8)$, for the three particle sizes at different heating rates. There were no relevant differences in ignition temperature and burnout temperature for the two sawdust at different particle sizes. The HDS had more ignition index (between 2.02 and 58.83 wt.%/min³ *10⁻³) at all particle sizes, indicating better performance than the LDS (between 1.27 and 49.99 wt.%/min³ *10⁻³). The kinetics analysis shows that the activation energy varies with heating rate and particle size. The average activation energy for the HDS ranged between 51.43 and 154.69 kJ/mol, while for the LDS it ranged between 45.90 and 172.78 kJ/mol. This indicates that the HDS burns quicker and is a better fuel. Also, these combustion parameters will aid in optimizing combustion processes and designing efficient combustion systems.

KEYWORDS:

• Sawdust
• Particle sizes
• Heating rates
• Kinetics parameters
• Activation energy

Highlights

• The pyrolytic kinetics of HDS and LDS were studied using Coats-Redfern method.

• The decomposition activities are more for the HDS than the LDS.

• The HDS shows lesser activation energy compared to the LDS.

• There is variation in the activation energy as the heating rate and particles size changes.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Oluwasanmi Iyiola Alonge

Oluwasanmi Iyiola Alonge is a lecturer in the Department of Mechanical Engineering, Elizade University, Ilara-mokin, Ondo State, Nigeria. He holds a doctoral degree in Mechanical Engineering and his areas of specialization are in solid fuel combustion, pyrolysis and gasification, renewable and clean conventional energy systems. He has over the years researched and presented courses in Fluid Mechanics, thermodynamics, and heat transfer. He is a member of Council for the Regulations of Engineering in Nigeria (COREN) and Nigerian Society of Engineers (NSE).

Surajudeen Olanrewaju Obayopo

Surajudeen Olanrewaju Obayopo is presently an Associate Professor in the Department of Mechanical Engineering, Obafemi Awolowo University Ile-Ife Osun State, Nigeria. He completed his PhD research work at the University of Pretoria, on performance enhancement in proton exchange membrane (PEM) fuel cell using numerical modelling approach coupled with an optimization tool. His research interest is in the field of renewable and clean conventional energy systems. He has over the years researched and presented courses in Fluid Mechanics, Fluid Power Engineering and Energy Technology. He is a member of American Society of Mechanical Engineers (ASME), Council for the Regulations of Engineering in Nigeria (COREN) and Nigerian Society of Engineers (NSE). He is also presently serving as a reviewer for Hydrogen Energy (Elsevier), Heat and Mass Transfer (Elsevier), Agricultural International (CIGR Journal) and other reputable International Journals.