MEASUREMENT OF HYDROGEN THERMOPHYSICAL PROPERTIES AT ULTRA HIGH PRESSURES

摘要

Hydrogen is considered to be a promising secondary energy as a fuel for fuel cell systems. Especially, a fuel cell vehicle (FCV) is loaded with a high pressure hydrogen storage tank in 70MPa. However, reliable thermophysical properties of hydrogen in such a high pressure are not available and therefore, the measurements of thermophysical properties up to 100MPa are needed to supply a reliable wide range database. The measurements of hydrogen thermophysical properties at high pressures have been performed in the present study. The properties being measured are the PVT relation, viscosity, thermal conductivity, solubility in water and others. The present paper introduces the measurement systems especially equipped for high pressures and some results are shown. The Burnett method was used to measure the PVT relation in the range up to 100MPa and up to 473K. By making use of measured data and those available in the literature, a new virial equation of state (EOS) has been proposed. The developed EOS represents the PVT data in the deviation within 0.1% of the measurements. The capillary method was used to measure viscosity in the range of temperature and pressure up to 400K and 99MPa, respectively. A new correlation equation predicting hydrogen viscosity has been proposed. The transient short-hot-wire (TSHW) method was adopted for measuring thermal conductivity and thermal diffusivity. By coupling with a numerical analysis, it was found that the TSHW method can effectively be applied to the measurement of hydrogen thermal conductivity. The measured thermal conductivity showed fairly good agreement with the literature within ±1%. A measurement system for the solubility of hydrogen in water and KOH solution was developed and the solubility up to 29MPa was obtained.