Experimental investigation on the dispersion characteristics and concentration distribution of unignited low-temperature hydrogen release

Abstract

The risk assessment of hydrogen-based technologies is necessary in the coming of hydrogen economic society. At present, most studies are focused on the room-temperature hydrogen (about 300 K) and cryogenic hydrogen (30–80 K), Low-temperature (200–300 K) hydrogen storage method is another storage option of hydrogen energy due to its high hydrogen storage density and less energy loss during the cooling process, however, the dispersion characteristics and concentration distribution of unignited low-temperature hydrogen during its sudden release is still unknown. In this work, a series of hydrogen release tests are performed with storage pressure at 0.5 MPa, the dispersion characteristics of unignited low-temperature hydrogen under different temperatures (200 K, 250 K and 300 K) and pinhole nozzles (1.0 mm, 1.5 mm and 2.0 mm) are analyzed. It is found that the concentration on the axis of low-temperature hydrogen jet increases with the decrease of the temperature of the hydrogen and increase of the nozzle diameter. The inverse concentration distribution with various hydrogen temperatures and different nozzle diameters by the scaled distance is obtained. The distances to some key levels of hydrogen concentration such as flammable envelope and safe distances are evaluated and the extrapolation model to other jet conditions is proposed. The results can be available for the improvement of the hydrogen safety codes and standards of low-temperature hydrogen storage.