This page contains news about my research such as new publications, new project grants, happenings, collaborations, or other topics of significance which I think could be of interest to others.
Ailo Aasen receives poster award
In the poster, he presented some of our ongoing work to unravel the curvature dependence of the surface tension for multicomponent mixtures. He presented, for the first time in history, values for the Tolman length (first order curvature correction) and rigidity constants (second order curvature corrections) of a two-component mixture. It turns out that these quantities have a highly non-trivial and exciting dependence on the composition. The developed method and results may shed new light on nucleation in mixtures. A paper is under preparation on the topic.
Received two international awards for PhD thesis
My thesis entitled Equilibrium and Nonequilibrium thermodynamics of planar and curved interfaces, has just been awarded with two prestigious international awards! The European Federation of Chemical Engineers (EFCE) awarded the thesis with the EFCE excellence prize in thermodynamics for 2017. The thesis was evaluated in terms of dissemination of knowledge, quality of publications and presentations, duration of the work, originality of the topic studied, the methodology followed, its innovation and industrial relevance, as well as scientific impact. The jury had members from academia and industry. The prize was awarded at the 29th European Symposium on Applied Thermodynamics – ESAT, 2017 in Bucharest, May 21.
The second prize awarded was the Ilya Prigogine Prize 2017 for best PhD over the last two years in basic and applied thermodynamics in competition with more than 25 other candidates from all over the word. The jury consisted of six well-known professors in thermodynamics. The prize was awarded at The 14th Joint European Thermodynamics Conference, in Budapest, May 24.
Markus Solberg Wahl has joined the team
In his PhD, Markus Solberg Wahl works on sensor-technology with the goal of developing techniques to accurately measure temperature and precisely determine the state where solid forms by use of optical sensors. His work is important to a wide range of processes such as hydrogen liquefaction, low-temperature CO2 separation, air separation, natural gas processing, flow assurance in pipelines and much more. Small, yet robust and accurate optical sensor technology can provide a much needed tool to detect and hinder undesired formation of solids in these systems.
Markus has a Msc. Techn. degree in Nanotechnology and several years of experience from work in the industry. His main supervisor is Prof. Dag Roar Hjelme, and I will serve as the co-supervisor. We are excited for the results to come and the progress Markus will make on this topic, which is of outmost importance to experimental thermodynamics.
Elisa Magnanelli successfully defended her PhD
Elisa Magnanelli, whom I have served as a co-supervised for together with Prof. Signe Kjelstrup (main supervisor) and Eivind Johannessen (co-supervisor), successfully defended her PhD entitled “Understanding and Reducing the Entropy Production in Membrane Systems”. The purpose of her thesis work was to understand how energy is dissipated in various systems, in order to find general guidelines that can help increasing the energy efficiency of such systems. The thesis mainly focused on membranes for separation of CO2 from natural gas.
A first important step was to gain a better understanding of how the CO2 permeates through the membrane. In particular, part of the thesis explored the possibility to use a heat source to improve the membrane separation performances through nonequilibrium coupling effects. This possibility is quite attractive, since large amounts of “free” waste heat are available at the sites of extraction of natural gas. A second important step was to identify the operation of membrane systems that dissipates the least energy (i.e. operation that gives the minimum entropy production). By studying the characteristics of the optimal systems, the thesis identifies operating and design guidelines that can lead to more energy efficient membrane separation processes.
A second and wider objective of the project aimed at increasing the energy efficiency of engineering designs by gathering knowledge from natural systems that are very energy efficient. Reindeer are known to be able to survive under very difficult conditions. In the winter, temperatures at Svalbard can be as low as -40 degree Celsius, food is scarce, and water is available only in the form of snow. Therefore, reindeer living at Svalbard need to lose as little energy as possible, and their special breathing system helps them in that. Further knowledge on this system might guide the development of new and more efficient Nature-inspired processes. As an example, recovery ventilators in buildings have very similar tasks and operate under similar conditions. Thus, knowledge from the first system can be used to improve the second.
Professor Karl-Heinz Hoffmann from the Department of Physics at Chemnitz University of Technology in Germany served as the main opponent and Professor Natalya Kizilova from the Department of Theoretical and Applied Mechanics, University of Kharkiv in Ukraine served as the second opponent of the PhD. The Administrator of the committee was Professor Truls Gundersen from the Department of Energy and Process Engineering at NTNU. The picture below was taken at the defense and shows from left to right: Signe, Natalya, Elisa, Karl, Truls, me and Eivind.
Center of Excellence granted on flow through porous media
Our application for center of excellence, Porous Media Laboratory, was granted by the Norwegian Research Council!! The topic is fundamental knowledge on flow through porous media. Progress in the center will contribute to safer and more efficient extraction of oil and injection of carbon dioxide in subsea reservoirs, improved understanding of fuel-cells and catalyst materials and more efficient extraction of water in areas with drought. The total funding of the center is approximately 400 MNOK for the duration of 10 years.
The center leader and primus motor behind the application is Prof. Alex Hansen. My involvement in the center is together with Prof. S. Kjelstrup and Prof. D. Bedeaux, who were key contributors to the application. I am involved in two work-packages dealing with thermodynamic driving forces and application of the theory. Researchers from NTNU, UiO and SINTEF (me) are involved in the center, which combines experimental and theoretical work and methods from physics, chemistry, geology and geophysics.
The center is of outmost importance as it provides steady funding for the next ten years to make progress on fundamental research. The picture below shows some of the center members celebrating the granted application.
New article on challenges and future development of established equations of state
Our paper entitled: Thermodynamic modeling with equations of state: present challenges with established methods has been accepted for publication in Industrial & Engineering Chemistry Research. In the work, we review present challenges associated with established models, and give suggestions on how to overcome them in the future. The most accurate EoS available, multiparameter EoS, have a second artificial Maxwell loop in the two-phase region that gives problems in phase-equilibrium calculations and exclude them from important applications such as treatment of interfacial phenomena with mass based density functional theory. Suggestions are provided on how this can be improved. Cubic EoS are among the most computationally efficient EoS, but they often lack sufficient accuracy. We show that extended corresponding state EoS are capable of providing significantly more accurate single-phase predictions than cubic EoS with only a doubling of the computational time. In comparison, the computational time of multiparameter EoS can be orders of magnitude larger. For mixtures in the two-phase region, however, the accuracy of extended corresponding state EoS has a large potential for improvement. The molecular-based SAFT family of EoS are preferred when predictive ability is important, e.g. for systems with strongly associating fluids or polymers where few experimental data are available. We discuss some of their benefits and present challenges. A discussion is presented on why predictive thermodynamic models for reactive mixtures such as CO2-NH3 and CO2-H2O-H2S must be developed in close combination with phase- and reaction equilibrium theory, regardless of the choice of EoS. After overcoming present challenges, a next-generation thermodynamic modeling framework holds the potential to improve the accuracy and predictive ability in a wide range of applications such as process optimization, computational fluid dynamics, treatment of interfacial phenomena and processes with reactive mixtures. The work was performed in in collaboration with Ailo Aasen, Geir Skaugen, Peder Aursand, Anders Austegard, Eskil Aursand, Magnus Aa. Gjennestad, Halvor Lund, Gaute Linga and Morten Hammer from SINTEF Energy Research and NTNU (Ailo and me work at both places).
New article about thermodynamic models for carbon dioxide/water mixtures
Our paper entitled: Thermodynamic models to accurately describe the PVTxy-behavior of water / carbon dioxide mixtures has been accepted for publication in Fluid Phase Equilibria. In the work, we present a comprehensive comparison of thermodynamic models for describing their PVTxy behavior, i.e. densities and phase compositions of mixtures with water and carbon dioxide. The most accurate experimental data in the temperature range 273–478 K and at pressures below were selected after a critical data evaluation. The most reliable phase equilibrium data are used to fit the binary interaction parameters of a wide range of thermodynamic models: cubic equations of state (EoS) with quadratic/Wong–Sandler/Huron–Vidal mixing rules, CPA, PC-SAFT and PCP-SAFT with different association schemes, and corresponding states models with various reference fluids. We tested the predictive ability of the models by comparing to data outside of the region used in the parameter-fit. All of the thermodynamic models were fitted with the same experimental data and compared on the same basis, facilitating a general discussion about their strengths and weaknesses. As a benchmark for the performance of the models, we compare with the performance of two multiparameter EoS: GERG-2008 and EoS-CG. At least three fitting parameters are needed to represent the PVTxy behavior of CO2/H2O mixtures within an accuracy of 10%. By including a fourth parameter, it is possible to significantly improve the accuracy for phase compositions, where the Peng–Robinson cubic EoS with the Huron–Vidal mixing rule and volume shift gives the best results with an average accuracy of 4.5% and 2.8% for phase compositions and densities respectively. In comparison, the most accurate multiparameter EoS, EoS-CG, exhibits an average accuracy of 8.0% and 0.6% for phase compositions and densities respectively. The work presented in the paper is part of an ongoing effort to improve the precision in describing the thermo-physical properties of mixtures important for CO2 capture, transport and storage. The work was performed in in collaboration with Ailo Aasen, Morten Hammer, Geir Skaugen and Jana P. Jakobsen from SINTEF Energy Research and NTNU (Ailo, Jana and me work at both places).
New article about using thermoelectric generators in transient environments
Our paper entitled: Harnessing thermoelectric power from transient heat sources: Waste heat recovery from silicon production has been accepted for publication in Energy conversion and management. In the work, we investigate the response of a bismuth-telluride based TEG to the transient environment of a silicon production plant, where there is a periodic change in the average temperature of the heat source. We establish in the paper a dynamic mathematical model that reproduces results from industrial, on site experiments, both at steady-state and under transient conditions. By simultaneously changing the design and location of the TEG, a peak power density of 1971 W/m2 can be obtained without exceeding material constraints of the TEG, with an average power density of 146 W/m2. In the transient case, the average power density generated during one silicon casting cycle is in all investigated cases found to be only 7–10% of the peak power density as the peak value of the power is only maintained for a couple of minutes. We further discuss how the design, cooling capacity and position of the TEG influence its performance in a transient environment. This work is the second in an ongoing effort to understand the potential of thermoelectric generators in recovering waste heat, and how to optimize their performance. The work was performed in in collaboration with Isha Savani, Magnus H. Waage, Marit B. Takla, and Signe Kjelstrup from NTNU.
Ailo Aasen has started his PhD in the group
Ailo Aasen has started his PhD in the group. He has a solid background in mathematics (Msc. degree). In addition, he has more than two years of experience with thermodynamic modelling from his work at SINTEF Energy Research. He was awarded with the "Stubban Prize" in 2014 for promising young mathematicians. The aim of his PhD will be to develop equilibrium and nonequilibrium thermodynamic descriptions in order to enhance the understanding of physical phenomena that occur in the hydrogen liquefaction process to be able to increase its energy efficiency. Ailo will be a much appreciated member of the team.