Thermophysical Properties of Long-Chained Hydrocarbons, Alcohols, and their Mixtures with Dissolved Gases

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At present, increasing technical interest in processes with liquids containing dissolved gases can be found in chemical and energy engineering. Some examples are the separation of flue gases by suitable absorbents, the production of high-value fuels or petroleum products from synthesis gas, or the storage and transport of hydrogen via liquid carriers. For the design and optimization of corresponding processes, accurate information about the thermophysical properties of the involved fluid systems is necessary. Until now, however, transport and equilibrium properties for liquids with dissolved gases over a wide range of thermodynamic states are scarce. This is caused by limitations of experimental methods as well as the lack of theoretical models and prediction methods. In the suggested Sino-German research project, a systematic study of different thermophysical properties of hydrocarbons, alcohols, and their mixtures with dissolved gases over a wide range of temperatures up to about 600 K is proposed. For these specific systems, the investigations should contribute to a fundamental understanding how the variation of the molecular structure of the liquids and of the dissolved gases influences the thermophysical properties density, solubility, viscosity, and surface tension. The German research team at the University of Erlangen-Nuremberg focuses on the characterization of the systems by molecular dynamics (MD) simulations and surface light scattering (SLS). Besides density and viscosity, the MD simulations should also access solubility and surface tension. While for the latter properties the MD methodology has to be refined within the project, the SLS-technique was recently developed by the German research team for a reliable determination of viscosity and surface tension at high temperatures. For these properties, the Chinese research team at Xi'an Jiaotong University applies theoretical models based on hard sphere and corresponding states theory as well as experimental methods in form of the pedant drop and vibrating wire techniques. Viscosities and surface tensions determined in parallel by the two teams for the same selected systems will serve as mutual reference data. The individual activities in form of the determination of density via the vibrating U-tube method by the German team and of the solubility via a gravimetric technique by the Chinese team are complementary and of joint interest. Thus, the already existing co-operation between both research teams will be further extended within the project. For the selected liquids with dissolved gases, the expectable reliable and comprehensive database should serve as basis for a fundamental understanding of their structure-property relationships. This supports the development of theoretical and empirical models for the description of thermophysical properties of arbitrary systems consisting of hydrocarbons or alcohols with dissolved gases.