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Numerical modelling and validation of Hydrothermal liquefaction of Lignin

Madhawa Jayathilake of the Faculty of Engineering and Science at the University of Agder has submitted his thesis entitled «Numerical modelling and validation of Hydrothermal liquefaction of Lignin» and will defend the thesis for the PhD-degree Tuesday 03 May 2022. (Photo: Private)

For hundreds of years, petroleum crude oil has been used for energy generation. Due to environmental impact and the depletion of petroleum crude oil, biocrude came up as a renewable alternative.

Rukshan Madhawa Jayathilake

PhD Candidate

You may follow the disputation on campus or online. Link for registration as an online spectator at the bottom of this page.

 

Rukshan Madhawa Jayathilake of the Faculty of Engineering and Science at the University of Agder has submitted his thesis entitled «Numerical modelling and validation of Hydrothermal liquefaction of Lignin» and will defend the thesis for the PhD-degree Tuesday 03 May 2022. 

He has followed the PhD-programme at the Faculty of Engineering and Science at the University of Agder with specialisation in Engineering Sciences, Scientific field Renewable Energy.

Summary of the thesis by Rukshan Madhawa Jayathilake:

Numerical modelling and validation of Hydrothermal liquefaction of Lignin:

Shrinking core approach on particle decomposition and a comparative analysis of biocrude and HTL char

For hundreds of years, petroleum crude oil has been used for energy generation. Due to environmental impact and the depletion of petroleum crude oil, biocrude came up as a renewable alternative.

Hydrothermal liquefaction (HTL) is a method that mainly produces a liquid biocrude. In the HTL process, initially, the biomass is decomposed into smaller molecules through hydrolysis.

Newer concepts of liquefaction models and appropriate feedstocks

To improve the HTL process and to make better predictions different models are used. Different models provide different advantages and disadvantages.

In this study, an improved biomass decomposition model is proposed using the shrinking core concept.

The shrinking core concept provides a relatively less complex, nonetheless effective way to model liquefaction at the particle level.

Several relevant cases with different operating conditions were tested on the applied models to see how they worked. Some weaknesses were found. These were related to heat transfer, initial kinetic data, and other kinetic parameters such as rate constants.

Lignin as feedstock

A wide range of feedstock is used for the HTL process.

Lignin is found to be a useful feedstock to be used in the HTL process. Nevertheless, still, there are many aspects to be investigated related to lignin liquefaction such as char formation and co-liquefaction behavior.

Therefore, the liquefaction performances of lignin and its behavior are investigated in different aspects.

In this PhD research, the developed model is evaluated in different stages for its limitations as well as for its reliability.

Further, the behavior of lignin liquefaction is investigated to uncover its true liquefaction potential.

The research study is mainly divided into four stages:

  • A more basic version of the model is used to model the liquefaction of a wood particle where the wood liquefaction is considered the cumulative liquefaction effect of the wood model compounds (cellulose, hemicellulose, and lignin). The basic model guided the study toward more appealing modifications and improvements such as the oily film and ash layer formation during the liquefaction process. The main takeaway from the basic version of the model was the null hypothesis of the equality of cumulative liquefaction effect of model compounds to the wood liquefaction in the same operating conditions.
  • The next step of the study was to develop a more robust and comprehensive version of the model. The formation of oily film and an inorganic layer around the lignin particle and their behavior is modeled considering water transport through layers, diffusion of products, and dissolution of products in water. Moreover, the particle's surface and center point temperatures are measured using a layer model through mass transfer. The model proved to be both quick and robust.
  • The evolution of char production and behavior is then studied in this study. The char is produced at different operating temperatures and residence times. Then they are tested chemically, thermally, and morphologically to understand its characteristics. Finally, a possible formation pathway for HTL char is proposed during the investigation.
  • At the next phase, the synergistic effect of co-liquefaction of lignin with laminaria saccharina (sugar kelp) is explored to see the possibility of lignin being used as a co-liquefaction feedstock.

Disputation facts:

The trial lecture and the public defence will take place on campus in Auditorium C2 040, Campus Grimstad, and online (registration link below) via the Zoom conferencing app - registration link below.

Associate Professor Margrethe Wold, Faculty of Engineering and Science, University of Agder, will chair the disputation.

The trial lecture Tuesday 3 May at 10:15 hours

Public defense Tuesday 3 May at 12:15 hours

 

Given topic for trial lecture: «Biofuel Production and Application - Challenges and Potential to meet the sustainable goals»

Thesis Title«Numerical modelling and validation of Hydrothermal liquefaction of Lignin»

Search for the thesis in AURA - Agder University Research Archive, a digital archive of scientific papers, theses and dissertations from the academic staff and students at the University of Agder.

The thesis is available here:

https://uia.brage.unit.no/uia-xmlui/handle/11250/2991698

 

The CandidateRukshan Madhawa Jayathilake: (1988, Godakawela, Sri Lanka) BSc in Mechanical and Manufacturing Engineering from the University of Ruhuna (2013), MSc in renewable energy from the University of Agder (2016). Present position: Research Scientist at Sintef Industry.

Opponents:

First opponent: Professor Dr. Manosh C. Paul, University of Glasgow, UK 

Second opponent: Professor Dr. Jorge M. Marchetti, NMBU

Associate professor Martin Choux, University of Agder, is appointed as the administrator for the assessment committee.

Supervisor in the doctoral work was Associate Professor Souman Rudra, University of Agder   

What to do as an online audience member:

The disputation is open to the public, but to follow the trial lecture and the public defence digitally, transmitted via the Zoom conferencing app, you have to register as an audience member on this link: (If you attend the disputation in the Auditorium, you do not need to register)

https://uiano.zoom.us/meeting/register/u50vd-iopz4oHdLwrOvex1aE_SGRni36e5eb

A Zoom-link will be returned to you. (Here are introductions for how to use Zoom: support.zoom.us if you cannot join by clicking on the link.)

We ask online audience members to join the virtual trial lecture at 10:05 at the earliest and the public defense at 12:05 at the earliest. After these times, you can leave and rejoin the meeting at any time. Further, we ask audience members to turn off their microphone and camera and keep them turned off throughout the event. You do this at the bottom left of the image when in Zoom. We recommend you use ‘Speaker view’. You select that at the top right corner of the video window when in Zoom.

Opponent ex auditorio:

The chair invites members of the public to pose questions ex auditorio in the introduction to the public defense, with deadlines. It is a prerequisite that the opponent has read the thesis. Questions can be submitted to the chair Margrethe Wold on e-mail margrethe.wold@uia.no