Density volumetric

Nonideal volumetric density variation versus pressure. 

Miller, A., Hess, K., and Barnes, D. (2003). Comparison of Practical Hydrogen Storage Volumetric Densities, DE-FC36-99GO10458. 

This explains, for instance, the higher volumetric density of LH2 as compared with Fig. 11.2 (which shows system performance targets), as the tank is not included. 

Apart from the above-mentioned commercial impasse, which delays the development of the hydrogen economy, there are two important technical issues that also need to be solved hydrogen s volumetric density and energy consumption during hydrogen production. 

Reversible metal hydrides On-board refueling High volumetric densities Lowering desorption temperatures Improving kinetic response Heat management during refill... 

The most established storage systems are high-pressure gas cylinders with a maximum pressure of 20 MPa. New lightweight composite cylinders have been developed that are able to withstand pressures up to 80 MPa and so the hydrogen can reach a volumetric density of 36 kg m, approximately half that in its liquid form at the normal boiling point. 

The volumetric density of hydrogen in a pressure vessel increases with pressure and reaches a maximum above 1000 bar, depending on the tensile strength of the material. However, the gravimetric hydrogen density of the pressure cylinder... 

Figure 5.5 Volumetric density of compressed hydrogen gas as a function of gas pressure including the ideal gas and liquid hydrogen. The ratio of the wall thickness to the outer diameter of the pressure cylinder is shown on the right-hand side for steel with a tensile strength of 460 MPa. A schematic drawing of the pressure cylinder is shown as an inset.

The divergence is less severe either when the charge is described by a volumetric density (as the electronic density) or when point charges (pointwise nuclei) are embedded in a cavity and thus are prevented from approaching the surface too closely. 

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