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Investigation of thermophysical properties of gases for energy transition

The key challenge of the energy transition is the fluctuating power generation with renewable energies like photovoltaic or wind energy. Efficient storage of the power could be obtained by the production of hydrogen with electrolysis (Power to Gas). The hydrogen can either be converted back to power carbon neutrally in a fuel cell or it may be fed in the already existing natural gas grid. The changing thermophysical properties of the natural gas need to be known on a high level to ensure correct billing. Developing the underlying equation of state necessitates measurements of mixtures of hydrogen and the different natural gas components. For this application, a new measurement apparatus for the determination of dielectric and density virial coefficients of gases and binary hydrogen mixtures is being built. Four identical measurement chambers are equipped with cylindrical, highly stable measurement capacitors. They are connected by an ultra pure, symmetric gas handling system, which enables the application of dielectric-constant gas thermometry. This method has already been successfully used to determine the density virial coefficients of various noble gases (C. Gaiser, B. Fellmuth, T. Zandt, Dielectric-Constant Gas Thermometry and the Relation to the Virial Coefficients, Int. J. Thermophys. 35 (2014) 395-404). The measurements of pressure, capacitance and temperature are realized by commercially available equipment, which will be calibrated traceably against the standards available at Physikalisch-Technische Bundesanstalt to surpass the specifications of the manufacturers.

Design of the new apparatus based on the dielectric-constant gas thermometer principle with four identical cylindrical capacitors. The measurement cells are mounted on a massive copper plate to ensure thermal equilibrium. All surfaces, which are exposed to the measuring gas, are gold plated to prevent hydrogen absorption.


1. C. Guenz, C. Gaiser, M. Richter, Concept of a new technique for the combined determination of dielectric and density virial coefficients, Meas. Sci. Technol. 28 (2017) 027002

2. C. Gaiser and B. Fellmuth, Polarizability of Helium, Neon, and Argon: New Perspectives for Gas Metrology, PRL 120 (2018) 123203

3. C. Gaiser and B. Fellmuth, Highly-accurate density-virial-coefficient values for helium, neon, and argon at 0°C determined by dielectric-constant gas thermometry, J. Chem. Phys. 150 (2019) 134303

4. E. S. Burnett, Compressibility determinations without volume measurements, J. Appl- Mech. 3 (1936) A136