What’s a solution to hydrogen fueling leaks?

RGClark · 2022-09-04 22:57:37

As this article shows hydrogen leaks during fueling have been a recurrent problem going back 40 years with the Shuttle:

Years after shuttle, NASA rediscovers the perils of liquid hydrogen
"Every time we saw a leak, it pretty quickly exceeded our flammability limits."
ERIC BERGER - 9/3/2022, 6:38 PM
https://arstechnica.com/science/2022/09 … -hydrogen/

The readers on this forum are pretty insightful in proposing technical solutions. Anyone have any ideas on solving the problem of hydrogen leaks during fueling?

The problem seems to be in the quick disconnect valves. See image here:

Valve Disconnect
A closeup of the 7-inch quick disconnect that will be replaced on the hydrogen vent line to the Ground Umbilical Carrier Plate of space shuttle Discovery's external fuel tank. The replacement will be made on Launch Pad 39A at NASA's Kennedy Space Center in Florida. A leak of hydrogen at the site during fueling caused the STS-119 mission to be scrubbed at 2:36 p.m. March 11.
Photo Credit: United Space Alliance
March 11, 2009

Hardly an advanced technology. There has to be a way of accomplishing it without recurrent leaks.

Bob Clark

tahanson43206 · 2022-09-05 06:28:02

For RGClark re new topic: Best wishes for success with this important topic.

Public knowledge of best practices for managing Hydrogen will be to the benefit of the human race.

Hydrogen has the capability of becoming as common a fuel as natural gas is today.

Whether that will be achieved is totally dependent upon finding practical, repeatable solutions to the problem to which your topic is addressed.

This is a technical problem, so mathematics will necessarily become part of the record.

Precision engineering seems (to me at least) most likely to be the major factor in success, but physics will surely be applied to finding the optimum solution set.

Chemistry of materials used for managing hydrogen (whether gas or liquid) is surely part of the record your topic invites.

SearchTerm:hydrogen management of
SearchTerm:LH2 management of

(th)

SpaceNut · 2022-09-05 11:17:41

https://blogs.nasa.gov/artemis/2022/09/ … -detected/

https://blogs.nasa.gov/artemis/2022/09/ … replenish/

so, looking for tolerance shift via expansion

https://www.foxbusiness.com/technology/ … nd-attempt

"Engineers will attempt to reseat the seal in the quick disconnect cavity where the leak has been detected. This time they will stop flowing liquid hydrogen to the tank, close the valve used to fill and drain it, then increase pressure on a ground transfer line using helium to to try to reseal it,"

Without seeing more of the internal of the assembly not much can be thought of at this time.

edit
Nasa has had many chances to switch fuels and engines, but the main issue is what is called Human rating.

An engine that humans has flown on or is it testing and redundancy of design with fault detection and shutdowns.

tahanson43206 · 2022-09-05 11:59:29

With a nod to SpaceNut for Post #3 ...

For anyone who might wish to comment ....

Much has been made of how far behind the curve NASA ** seems ** to be, but I just realized (a bit belatedly) that Elon and company are NOT attempting anything this difficult. Their decision to go with methane, while plenty difficult, is (I'm guessing) less difficult than trying to work with hydrogen at this scale.

NASA was successful in the Shuttle era, but as GW Johnson keeps pointing out, all the folks who actually achieved success in that time period are (probably) long gone. It seems possible (to me at least) that the newbies have been burning the phone lines to the old timers in recent days.

This topic is a ** good ** place to store some that "art" that GW Johnson keeps talking about, if anyone can scoop it up.

Meanwhile, is there anyone else on Earth who is attempting what NASA is attempting.

I'm pretty sure that Jeff Bezos is using Hydrogen for his puddle jumper, but the scale of the problem is so much less, I'm doubtful that effort is in the major leagues where NASA is working.

(th)

GW Johnson · 2022-09-06 08:48:29

Hydrogen was originally notorious because there were 2 forms to be managed, para and ortho, and if you didn't do it right, things blew up.

That was solved, but the extreme propensity to leak, and the extreme flammability remains. Hydrogen is unique, methane and oxygen do not exhibit those tendencies. Hydrogen is still notorious for leaking through joints and seals that hold everything else.

It has a very wide range of inflammability limits in air (4 to 74% by volume, if memory serves), and it has an extremely low threshold ignition energy (I have seen it light just from the friction flowing through a valve to escape). Plus, in bright sunlight, small hydrogen flames are essentially invisible. It is quite the hazardous material to handle, until and unless you deal effectively with those properties.

Not everything the safety nannies say about handling it is true, either. I plumbed together copper tubes that the safety nannies said was a no-no, using commercial stainless "swedgelok" fittings, and I never had a problem, to 500 psi. That was to run a hydrogen-air torch intended for a ramjet igniter. I had occasion to try it out, but never got the chance to use it. At 300 psi, I used it as the fuel in a hot gas generator for an infrared decoy, with that same kind of plumbing.

The torch operated at shop air pressure (about 85 psig). When it was running, no one could see the flame at all, even in partial shade on the test stand where I did this. But the waves of density in the plume cast shadows you could see on the ground (concrete slab, actually), rather similar to Schlieren photography. That and the sound was the only way to know the torch was burning.

The decoy flame on hydrogen was hard to see in daylight looking up the open tailpipe. But with the radiating element in place, that glowed brightly, and would blister my face with infrared from 20 feet away.

I never had a fire I couldn't detect and put out while it was small, and no one ever got hurt while I did those projects (some years apart actually). I did my leak checks with a hand-held spray bottle of soapy water. The only unintended fire was a line connected to nothing, that ignited as it blew hydrogen gas out into the open air. I just closed the regulator valve to put it out. And used a checklist after that.

Now, cryogenics makes those problems worse. I was only handling compressed hydrogen gas in 220 cu.ft welding gas bottles, at 2200 psig. It'll leak right through the side of the steel bottle, very slowly over the course of multiple months.

GW

Last edited by GW Johnson (2022-09-06 08:59:26)

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#1 2022-09-04 22:57:37

What’s a solution to hydrogen fueling leaks?

#2 2022-09-05 06:28:02

Re: What’s a solution to hydrogen fueling leaks?

#3 2022-09-05 11:17:41

Re: What’s a solution to hydrogen fueling leaks?

#4 2022-09-05 11:59:29

Re: What’s a solution to hydrogen fueling leaks?

#5 2022-09-06 08:48:29

Re: What’s a solution to hydrogen fueling leaks?

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