Investigation of H₂O Adsorption on Solid Fuel Particles

As part of the SFB project Oxyflame, the adsorption behavior of H₂O on solid biofuels was investigated. Alongside CO₂ and O₂, H₂O is a potentially reactive component of the oxyfuel atmosphere. The intraparticle pore surface is an important reaction site. The influence of surface functionalization and pore structure on H₂O adsorption was systematically analyzed, while experimental gravimetric adsorption data were correlated with molecular dynamics simulations of simplified slit pores. The results were recently published in Fluid Phase Equilibria.

Symposium on Thermophysical Properties 2024

Every three years, the International Symposium on Thermophysical Properties is organized in Boulder, Colorado. For our team, this is the central thermophysical properties conference. In 2024, 10 scientists of our team attended the conference.

Honored with the Ared Cezairliyan Best Paper Award 2024

Each year, the Ared Cezairiliyan Best Paper Award is awarded to the best paper in the International Journal of Thermophysics. This year, a paper authored by a team of scientists from the chair of thermodynamics of RUB and from the National Institute of Standards and Technology of the USA was selected for the award. The award ceremony took place at the International Symposium on Thermophysical Properties in Boulder, Colorado.

Low Temperature Vibrating Tube Densimeter

Within the scope of a colaboration with the Professorship Applied Thermodynamics at Chemnitz University of Technology, a feasibility study was performed for density measurement at low temperatures using an vibrating tube densimeter (VTD). The utilized VTD is specified by the manufacturer for temperatures of (263 to 473) K at pressures of up to 140 MPa. The conducted study demonstrates the operational functionality even at temperatures of 100 K. The results of the study, including calibration and validation measurements, have recently been published in the International Journal of Thermophysics.

Viscosity measurements of hydrogen and a (hydrogen + methane) mixture

The viscosity of pure hydrogen and a binary (hydrogen + methane) mixture was measured using a two-capillary viscometer, which was recently completed and commissioned at SINTEF Energy Research in Trondheim. The measurements were made possible as part of the HYDROGENi and HYSTORM projects and complement ongoing research work in the field of viscosity measurements on hydrogen-containing mixtures in the thermodynamic laboratory at RUB. The results are available open-access in the International Journal of Thermophysics.

Hydrate modeling of hydrogen-water mixtures

In the transition to a carbon-neutral society, hydrogen is considered as one of the most promising energy carriers. However, hydrogen transportation and storage remain challenges. Hydrate formation with hydrogen is either a risk to be avoided during transportation, or an opportunity for cheap, reversible, and environmentally friendly energy storage. In cooperation with the czech CAS and TU Dresden, the theoretic framework for modeling thermodynamic properties of hydrogen hydrates formation has now been published.

Investigation of Mass Transport of Oxygen in Solid Fuels from Biomass

As part of the SFB project Oxyflame, the mass transport of oxygen as the main component of an oxyfuel atmosphere in porous solid fuels from biomass was examined. The majority of the gas and fuel reaction during combustion takes place at the inner surface of the particles, and the diffusion of gases through the porous structure can be a limiting factor for the reaction rate. The occupation of the fuels inner surface wit reactive gases can be experimentally determined using adsorption kinetics and further described with a pore structure-dependent adsorption kinetics model. The results were published in Chemical Engineering Science.

Density measurements on mixtures of Helium and Neon

If extremely low temperatures are required in technical processes, besides hydrogen, only noble gases can be employed as fluid refrigerants. Here, concepts for hydrogen liquefaction are based on mixtures of helium and neon for efficient pre-cooling of the hydrogen. Due to the limited experimental data available, current equations of state work purely predictively over a wide temperature range. In order to significantly improve the data situation, new high-precision densities of three binary helium and neon mixtures as well as the pure substances were measured using a low-temperature single-sinker densimeter and published open-access in the Cryogenics Journal.

COREu project

The Chair of Thermodynamics is involved in a new EU project that aims to show how infrastructures for carbon capture and storage (CCS) can be developed and expanded. The 43 project partners from industry and research, led by the Norwegian research institute SINTEF Energy, are considering and demonstrating the entire process chain from CO2 capture to storage.

doctor honoris causa

On November 17, the renowned Norges Teknisk-Naturvitenskapelige Universitet (NTNU) in Trondheim awarded an honorary doctorate to the Head of the Chair of Thermodynamics at Ruhr-Universität. This is the highest academic honor a university can bestow and is based on his significant contributions in the field of thermodynamic material data research. The Rectorate of NTNU particularly emphasizes Prof. Span's contributions to the development and introduction of sustainable energy technologies in the fields of carbon capture, transport and storage as well as the production and transport of hydrogen.

Photo: © Thor Nielsen / NTNU

Impact of additives to anaerobic digestion

The usage of additives is a promising method to increase biogas production from anerobic digestion. In this context, we analyzed the effects of lignite and biochar addition to the anaerobic digestion of dairy manure. Thereby, the influence on biogas and fertilizer production as well as on process stability and microbial community were investigated simultaneously. The experimental data were published in the journal „Bioresource Technology“.

Thermodynamic properties for 1-hexene

Highly accurate measurements of the speed of sound and density were carried out at the Chair of Thermodynamics and Energy Technology at the University of Paderborn. The speed of sound measurements were carried out with two different apparatuses, applying the doublepath-length pulse-echo technique and the density measurements were conducted with a vibrating tube densimeter. The experimental data were used for the development of a new equation of state in the form of Helmholtz energy at the Chair of Thermodynamics at the Ruhr University Bochum. The work has been published in The Journal of Chemical Thermodynamics.

Residual entropy scaling for alkanes

Residual entropy scaling is a promising way to link state variables such as temperature, pressure or residual entropy with transport properties such as viscosity or thermal conductivity. In a cooperation with the TU Dresden, this method was investigated for pure hydrocarbons. It was found that the fluid-specific scaling factor required for this can be described by a linear function of the longest carbon chain, which considerably improves the predictive power of the method.

Connecting with Australia

Stable relationships between exporters and importers will play a crucial role in the development of a global hydrogen market. This also applies to the establishment of research structures. In February, a delegation from the Closed Carbon Cycle Economy Research Department visited the Australia Hydrogen Research Conference 2023, the University of Melbourne, the University of Western Australia and Curtin University to establish and deepen research contacts with Australia. The Faculty of Mechanical Engineering was represented by: Dr. Julia Riese, Dr. Julian Roeder and Prof. Roland Span.

Katz Award 2022

For more than 40 years, the Chair of Thermodynamics works on measurement and modelling of the properties of gaseous energy carriers. The pioneering work of its former chair, Prof. Dr.-Ing. Wolfgang Wagner, has now been recognized by the American Gas Processors Association (GPA). Prof. Wagner was awarded the internationally renowned Donald L. Katz Award. We congratulate cordially!

Ared Cezairliyan Best Paper Award 2022

Since 2020, the International Journal of Thermophysics has annually awarded the Ared Cezairliyan Best Paper Award in recognition of an outstanding contribution to the field of thermophysical research. Among the works published last year, the paper by Cavuoto et al. was awarded this prize.

This work is one of the publications that resulted from an international cooperation between RUB, TU Chemnitz (Germany), INRIM (Italy) and VSL (Netherlands) within the EMPIR LNG III project.

10th GERG Young Researchers’ Awards

Every one or two years, the European Gas Research Group (GERG) organises a competition to highlight the current work by postgraduate students in the field of renewable or other low carbon gases.

One of the three winners of the 10th GERG Young Researcher's Award is Robin Beckmüller from the Chair of Thermodynamics. He was honored for the progress he made in his doctoral thesis entitled "New Fundamental Equations of State for an Improved Description of Hydrogen-Rich Mixtures with the Reference Model GERG-2008".

Eickhoff-Prize

Since 1989, the Eickhoff company has donated one prize each to the Faculty of Electrical Engineering and Information Technology and the Faculty of Mechanical Engineering for outstanding scientific achievements in the doctoral process.

This year, Johnny Chhor (left) and Tobias Neumann (right) have been awarded. Tobias Neumann completed his doctocal thesis entitled “Accurate Description of Mixtures with Minor Components Relevant for CSS Including a New Approach for Reactive Mixtures” at the chair of thermodynamics of RUB.

Model for Gas Solubilities in Seawater

A model was developed to calculate gas solubilities in seawater-like solutions:
The model presented is a combination of a mixture model in the form of the Helmholtz energy and an equation in the terms of the Gibbs energy. The combination allows the quantification of the effect of salt on the solubilities of combustion gases in water. This approach can be used to model the storage of CO2 in saline aquifers, which is captured from combustion gases in the course of CCS (Carbon Capture & Storage). This allows a consistent simulation of the CCS transport and storage processes with Helmholtz equations.

Equation of State for ​Vinyl Chloride

A fundamental equation in the form of the Helmholtz energy for vinyl chloride has been published in the literature for the first time. The article appeared in the International Journal of Thermophysics.

Accurate thermophysical property data are important for the optimal design of production processes. This publication includes an equation of state that can reproduce the underlying experimental data within its measurement uncertainty. This work, combined with other equations from the literature, provides industry with a complete set for modeling the vinyl chloride manufacturing process. ​

International Cooperation

To access the key role of sorption effects in pyrolysis and char conversion of solid biomass fuels in an oxyfuel atmosphere, a pore-structure dependent kinetic (PSK) adsorption model for the prediction of adsorption and diffusion of relevant oxyfuel agents was developed within the project oxyflame. On basis of already derived parameter sets for the adsorption of O2 and CO2, the model is validated with the measured adsorption kinetics of water vapor. The experimental investigations are performed by Dr. Horacio A. Duarte from the Texas A&M University in cooperation with Tim Eisenbach (RUB). Dr. Horacio A. Duarte is spending 5 months as a guest-researcher at the chair.​

Thermodynamic Properties of Methyl Dienthanolamine

In cooperation with the Paderborn University and the TU Berlin, density and speed of sound measurements for methyl diethanolamine were conducted in wide temperature and pressure ranges. Based on these data and all other thermodynamic property data available in the literature an equation of state in terms of the Helmholtz energy was developed.
The experimental data and the equation of state are published in the International Journal of Thermophysics and are available open-access thanks to Projekt DEAL: https://doi.org/10.1007/s10765-021-02933-7

Speed of Sound Measurements and a Fundamental Equation of State for Propylene Glycol

Highly accurate speed of sound data for liquid propylene glycol were measured using the pulse-echo technique. These data were subsequently used to develop a fundamental equation of state in terms of the Helmholtz energy. For the first time, it allows accurate and consistent calculation of all thermodynamic state variables of propylene glycol.
This equation was developed in cooperation with the NIST (Boulder, USA) and has been published in the Journal of Physical and Chemical Reference Data: https://doi.org/10.1063/5.0050021

Virtual Symposium 2021

Every three years the National Institute of Standards and Technology (NIST), the ASME and the AIChE organize the Symposium on Thermophysical Properties in Boulder, Colorado – the most important international conference for the property related research at the chair of thermodynamics. In normal times the chair has always been represented by several researchers presenting talks and posters in Boulder. However, times are not normal. This year, the thermodynamics team of RUB could only present its results virtually. But still one statement holds (once more): our team was among the most represented groups worldwide.

International Cooperation

The circular use of nitrogen as an important plant nutrient plays an essential role in the transition to a sustainable economy. The Adsorption of nitrogen at chars can distribute to this goal. A cooperation between the chair of thermodynamics and the Future Energy Center of Mäladalens Högskola (MDH) aimes to characterize pyrochar, hydrochar, and lignite towards their suitability as adsorbents as well as their influences on anaerobic digestion. The experiments are conducted by Sebastian Schwede (MDH) and Anna Leithäuser (RUB), who is spending a four-month research stay at the MDH in Sweden. The project is funded by the DS CCCE and a scholarship from “The foundation of dentist Gustav Dahls memory”.

Methods for micropore analysis by CO2 adsorption

Within the framework of the SFB/TRR 129 Oxyflame, we performed a systematic comparison of models for micropore analysis of biomasses using CO2 adsorption and published it in Energy & Fuels (https://doi.org/10.1021/acs.energyfuels.1c00280). The results of the Dubinin-Astakhov (DA) and Dubinin-Radushkevich (DR) models were compared with the non-local density functional theory (NLDFT). By using the following share link, the publication can be downloaded free of charge (limited to 50 accesses): https://pubs.acs.org/articlesonrequest/AOR-FEAR9YA2HNUZ2JH76VQC

Equations of State for hydrogen-rich Mixtures

As a partner of the Fraunhofer High-Performance Center DYNAFLEX and member of the ACT ELEGANCY project, we have developed new equations of state for hydrogen-rich mixtures in cooperation with the National Institute of Standards and Technology (Boulder, USA), which have been recently published in the Journal of Physical and Chemical Reference Data: https://doi.org/10.1063/5.0040533
The mixture models for the binary systems H2+CH4, H2+N2, H2+CO, and H2+CO2 are formulated in terms of the Helmholtz energy and allow for accurate calculations of the thermodynamic properties of hydrogen-rich natural gas mixtures.

Density Measurements of Amines

We measured densities of monoethanolamine and diethanolamine and published them open-access in the International Journal of Thermophysics, thanks to Projekt DEAL: https://doi.org/10.1007/s10765-021-02808-x 
In the scope of the present study, a vibrating-tube densimeter (VTD) was utilized to measure densities at temperatures up to 423 K and pressures up to 90 MPa. The familiar setup of the VTD was modified to enable measurements of liquid DEA, due to its melting point which is significantly above ambient temperature. The newly gained datasets provides the only densities for pressures above 0.7 MPa and cover wide ranges of temperature.

Speed of Sound Measurements in Methanol

Following the publication of densities of methanol, we additionally provide speeds of sound in methanol, now published in the International Journal of Thermophysics and available open-access thanks to Projekt DEAL: https://doi.org/10.1007/s10765-021-02811-2 
The utilized speed of sound apparatus employs the double-path length puls-echo technique. Here, the time difference between two captured echoes is determined after unequal path-lenghts are covered. The newly gained dataset complement the data situation available from literature and insists to advance the development of a new equation of state.

Density Measurements of Methanol

We provide density measurements of methanol and related correlation equations, developed in cooperation with the Chemnitz University of Technology, recently published in Industrial & Engineering Chemistry Research: https://doi.org/10.1021/acs.iecr.0c06248 
In the scope of the present study, a vibrating-tube densimeter was utilized to measure densities at temperatures up to 423 K and pressures up to 90 MPa. Additionally, equations of two different approaches were correlated to the newly gained dataset and allow the calculation of densities in methanol over wide ranges of temperature and pressure.

Speed of Sound Measurements in Alkanes

In cooperation with the Chemnitz University of Technology speed of sound measurements in n-hexane and n-heptane were published in the International Journal of Thermo-physics and are available open-access thanks to Projekt DEAL: https://doi.org/10.1007/s10765-020-02778-6
The utilized speed of sound apparatus employs the double-path length puls-echo technique. Here, the time difference between two captured echoes is determined after unequal path-lenghts are covered. The newly gained datasets complement the data situation available from literature and advance the development of new equations of state.

Heat transfer coefficients in highly viscous mixtures

In cooperation with the Chemnitz University of Technology and the Dutch Metrology Insitute VSL, a study on the application of different liquefaction techniques for natural gases was conducted as part of the EMPIR LNG III project. Now it was published open-access in the AIChE Journal (https://doi.org/10.1002/aic.17128).​
In this study, we present the design of a reference liquefier that prevents a compositional distortion of the liquefied sample via a supercritical liquefaction technique. Moreover, the applicability of condensation for liquefaction as an alternative method was assessed by experimental investigations and VLE calculations.​

Study on the laboratory-scale liquefaction of natural gases

In cooperation with the Chemnitz University of Technology and the Dutch Metrology Insitute VSL, a study on the application of different liquefaction techniques for natural gases was conducted  as part of the EMPIR LNG III projekt. Now it was published open-access in the AIChE Journal (https://doi.org/10.1002/aic.17128).
In this study, we present the design of a reference liquefier that prevents a compositional distortion of the liquefied sample via a supercritical liquefaction technique. Moreover, the applicability of condensation for liquefaction as an alternative method was assessed by experimental investigations and VLE calculations.

International Cooperation

Thermophysical properties play an important role in all industrial processes and are addressed in research projects both at RUB, SINTEF Energy Research and the Norwegian University of Science and Technology (NTNU). For accurate viscosity measurements of binary (H2 + CO2) and (H2 + CH4) mixtures, an international cooperation has been initiated between a current project carried out in the thermodynamic laboratory of RUB, funded by the Fraunhofer High Performance Center DYNAFLEX, and a project at SINTEF and NTNU, which is part of the framework of the Norwegian CCS Center (NCCS). As part of this cooperation, measurements are carried out by Benjamin Betken (RUB) and Bahareh Khosravi (NTNU), who is currently at RUB for a four months research stay.

New kinetic adsorption model published

Within the SFB/TRR 129 Oxyflame, a new adsorption model was published in the journal "Chemical Engineering Science" (https://doi.org/10.1016/j.ces.2020.116281). The pore-structure dependent kinetic adsorption (PSK) model allows the time-resolved determination of mass transport coefficients, effective diffusion coefficients, and adsorption flow rates.