Can a Steel Vessel Contain Liquid Hydrogen at 15,000 PSI and 25C?

In summary, the conversation discusses the concept of liquid hydrogen boil off and the potential outcome of placing 1L of liquid H2 in a sealed steel vessel in a room at 25C. Calculations are done to determine the pressure that would result from this scenario, with the potential for the vessel to withstand up to 15,000 PSI. It is also mentioned that the ideal gas law may not hold true at such high pressure and a phase diagram would be a better reference.
  • #1
zlj06
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I've read a fews post about liquid hydrogen boil off, but could use a bit more clarification; insight on the following thought experiment would be really helpful: What happens if I take a 1 L steel vessel, put 1 L of liquid H2 into it, seal it off, and let it sit in a room at 25C?

The density of LH2 is ~71 g / L, which at a molecular density of 2.016 g / mol works out to ~35.2 mols. At STP, this has a volume of ~ 790L, so solving for P = (nRT/V) gets me to a pressure of ~ 12,600 PSI at 25 C.

So my question is, if my vessel can withstand, say, 15,000 PSI, the H2 just sits there as a gas under pressure, right? And maybe there is some negligible rate at which the H2 gas diffuses through the steel over long periods of time? Of course, if the vessel can't withstand at least 12,600 PSI, it blows up and kills me, which is very likely unless it's encased in carbon fiber.
 
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  • #2
I would think at that pressure the ideal gas law might break down. It would probably be better to look at a phase diagram.
 

FAQ: Can a Steel Vessel Contain Liquid Hydrogen at 15,000 PSI and 25C?

1. What is liquid hydrogen boil-off?

Liquid hydrogen boil-off refers to the process of hydrogen changing from a liquid state to a gaseous state due to an increase in temperature. As the temperature rises, the molecules in the liquid hydrogen gain energy and become more active, eventually escaping from the liquid form and becoming a gas.

2. What causes liquid hydrogen to boil-off?

The main cause of liquid hydrogen boil-off is an increase in temperature. This can be due to external factors such as exposure to heat or internal factors such as the hydrogen's own heat generation. Other factors that can contribute to boil-off include changes in pressure and agitation of the liquid.

3. Is liquid hydrogen boil-off dangerous?

Liquid hydrogen boil-off can be dangerous if not properly managed. The gaseous hydrogen that is released during boil-off is highly flammable and can ignite with even a small spark. Additionally, the rapid phase change from liquid to gas can cause pressure buildup, leading to potential explosions. However, with proper safety measures in place, the risk of danger can be minimized.

4. How is liquid hydrogen boil-off controlled?

Liquid hydrogen boil-off is controlled through a combination of insulation and active cooling. Insulation helps to minimize external heat sources from affecting the liquid hydrogen, while active cooling systems, such as cryocoolers, are used to maintain the temperature of the liquid. Additionally, the boil-off gas can be collected and either stored for later use or safely vented into the atmosphere.

5. Can liquid hydrogen boil-off be prevented?

While it is not possible to completely prevent liquid hydrogen boil-off, it can be minimized through careful design and management. This includes using high-quality insulation, implementing effective cooling systems, and minimizing agitation of the liquid. Additionally, regular maintenance and monitoring can help to identify and address any potential issues before they lead to significant boil-off.

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