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Liquid hydrogen also has a much higher specific energy than gasoline, natural gas, or diesel. [12] The density of liquid hydrogen is only 70.85 kg/m 3 (at 20 K), a relative density of just 0.07. Although the specific energy is more than twice that of other fuels, this gives it a remarkably low volumetric energy density, many fold lower.
Liquid hydrogen is a common rocket propellant, and it can also be used as the fuel for an internal combustion engine or fuel cell. [citation needed] Solid hydrogen can be made at standard pressure, by decreasing the temperature below hydrogen's melting point of 14.01 K (−259.14 °C; −434.45 °F).
At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point.
Liquid nitrogen. Liquefaction of gases is physical conversion of a gas into a liquid state (condensation). The liquefaction of gases is a complicated process that uses various compressions and expansions to achieve high pressures and very low temperatures, using, for example, turboexpanders.
A gas must be below its inversion temperature to be liquefied by the Linde cycle. For this reason, simple Linde cycle liquefiers, starting from ambient temperature, cannot be used to liquefy helium, hydrogen, or neon. They must first be cooled to their inversion temperatures, which are -233 C (helium), -71 C (hydrogen), and -42 C (neon). [11]
Liquid hydrogen tanks for cars, producing for example the BMW Hydrogen 7. Japan has a liquid hydrogen (LH2) storage site in Kobe port. [4] Hydrogen is liquefied by reducing its temperature to −253 °C, similar to liquefied natural gas (LNG) which is stored at −162 °C. A potential efficiency loss of only 12.79% can be achieved, or 4.26 kW ...
1 H hydrogen (H 2) use (H 2) 0.904 CRC (H 2) 0.90 LNG: 0.904 2 He ... Values refer to the enthalpy change in the conversion of liquid to gas at the boiling point ...
The autoignition temperature or self-ignition temperature, often called spontaneous ignition temperature or minimum ignition temperature (or shortly ignition temperature) and formerly also known as kindling point, of a substance is the lowest temperature at which it spontaneously ignites in a normal atmosphere without an external source of ignition, such as a flame or spark. [1]