Analysis of the dispersion of large unconfined clouds following a massive spillage of liquid helium on the ground

Abstract : Because of hydrogen's low volumetric energy content under its gaseous form, transport and storage of liquid hydrogen will inevitably play a major role in any future hydrogen economy. One of the obstacles to the expected development of the use of liquid hydrogen is the poor state of knowledge on dispersion and explosion hazard in the event of extensive spillage. In order to better understand spillage scenarios, INERIS has set up a large-scale experiment to study the gas cloud formation and dispersion mechanisms resulting from such a spillage and the corresponding mixing process and associated turbulence effects. Large scale dispersion tests have been performed with cryogenic helium presenting similar dispersion characteristics to liquid hydrogen (temperature, buoyancy). Flow rates up to 3 kg/s have been investigated with instrumentation to observe and measure buoyancy effects including internal turbulence. The results bring an original set of data of temperature and velocity fluctuations which can be used as a basis for the development of atmospheric model dispersion in the near field. The proposed paper will present the experimental set up as well as results and their interpretation