Compressed volumetric density

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.

Density or the pressure-volume-temperature (P-V-T) relationship is considered along with enthalpy and vapour-liquid equilibria as the three most essential thermophysical properties in the petroleum refining industry. The compressibility or density is commonly used in the petroleum industry to determine the volumetric properties of gases and liquids, information that is vital for transportation, safety and sale of petroleum fluids. 

One of the biggest problems with hydrogen stored as a compressed gas is its very low volumetric density and the resulting need for large storage facilities. Liquefied hydrogen provides one solution to this problem. 

Fig. 6.2 The six basic hydrogen storage methods and phenomena. The gravimetric density prr, the volumetric density pv, the working temperature T and pressure p are listed. RT stands for room temperature (25°C). From top to bottom compressed gas (molecular H2) in a lightweight composite cylinder (tensile strength of the material is 2000 MPa) liquid hydrogen (molecular H2), continuous loss of a few percent per day of hydrogen at RT physisorption...

Permeability is normally determined using linear flow in the incompressible or compressible form, depending on whether a liquid or gas is used as the flowing fluid. The volumetric flowrate Q (or Q ,) is determined at several pressure drops. Q (or Q ,) is plotted versus the average pressure p . The slope of this line will yield the fluid conductivity K or, if the fluid density and viscosity are known, it provides the intrinsic permeability k. For gases, the fluid conductivity depends on pressure, so that... 

The alloys of from 30% to 40% nickel in iron are noted for their unusual volumetric behavior. For example, it is well known that the thermal expansion of these alloys is anomalously low, with the Invar composition (36-wt% Ni) having a thermal expansion close to zero at room temperature. Furthermore, the atmospheric pressure compressibilities are anomalously large, whereas the atomic lattice spacing and density data show strong departures from Vegard s law in this same composition range. 

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