s_nz, you sound like you have more than a basic knowledge on the subject and what you say is logical. You are now BANNED from this discussion as you will upset all the "experts".
gsimpson,
Jul 13, 4:41pm
Then it is now being stored as ammonia and not hydrogen.
gsimpson,
Jul 13, 5:06pm
In order to be liquid at usable temperatures (including the rocket industry) Hydrogen has to be compressed to 700bar (compared to 7 bar for LPG or ammonia) I call that a massive pressure! Energy density compared to other fuels (MJ per litre) Diesel 35.8 Petrol 34.2 LPG 26.0 Methanol 15.6 Hydrogen 9.17 So using these figures the the fuel consumption will be 4 times higher on H2 compared to petrol or diesel and the joy of a 700 bar bomb in your car.
apollo11,
Jul 13, 6:21pm
Although it is going through a fuel cell, which is probably going to be a few times more efficient than an ICE. Agree about the pressure, 10 000 psi is nearly 4 times what a scuba tank is filled to, and they make a mess of a car if the pressure relief valve goes. Imagine what would happen to your composite hydrogen tank in a car fire.
milkath,
Jul 14, 5:42am
If hydrogen was to be used a better system would be like the old forklift battery’s that used hydrogen and oxygen in a fuel cell. There was a lot of R&D being done on this a while back. excess water was the by product and it could be removed to later reversed into hydrogen and oxygen.
mojo49,
Jul 14, 5:47am
Haha, NH3 used to be used as a refrigerant and leaks caused large numbers of deaths. It is till used in the cheap 3 way fridges sold by Warehouse etc (We have one)
mojo49,
Jul 14, 5:50am
And when you break the H from the N you get NO2. Oh dear, that is one of the undesirable outputs from diesel! It the reacts in the air to form HNO3 and acid rain. No problems with that idea.
s_nz,
Jul 14, 7:20am
Automotive industry (other than some proof of concept cars like the BMW 7 series) uses 350 or 700 bar (700bar in toyota Mirai) at ambient Temperature. Hydrogen's critical temperature is 33 Deg Kelvin (-240 Deg C). It is not possible to liquefy hydrogen above this temperature.
When you liquefy something at cryogenic temperatures, generally the whole point is so you don't have to deal with massive pressures. As an example in the rocket industry, the space shuttle hydrogen tank has an operating pressure range of 32 - 34 psi absolute (cira 2.3 bar absolute).
Essentially the hydrogen will be constantly boiling, and the process of evaporation cools the remaining hydrogen. Boil off is vented so the tank isn't over pressurized. Tanks need to be well thermally insulated or the hydrogen will boil off too quickly.
The Massive LNG tanker ships work on the same principal. (they often burn the boil off LNG in the ships engines rather than venting it).
elect70,
Jul 14, 9:43am
Tel me l how a modern EFI diesel truck will be made to run on hydrogen ? that is what the COl want it for not cars or are they talking about fuel cells? . Boi deisel would be better bet to extend deisel . Plus have to use electricity to run the compressoprs to liquify it waste of energy in losses stick to EV battery tech getting better all the time .
gsimpson,
Jul 14, 10:35am
Still is used extensively as a refrigerant. We have about 25 tonnes of it at work. Had a small leak this morning but gas mask and gloves plus spanner to nip up the gland and all good. Dihydrogen monoxide kills more people. Our plant is over 100years old and only 1 person died due to ammonia (in 1931). People tend to run a mile before it gets to dangerous levels.
s_nz,
Jul 14, 1:23pm
Remove diesel engine, replace with electric motor, battery, and hydrogen fuel cell. Or replace the entire truck.
Basically you have to do fuel cells as are so much more efficient than running hydrogen in combustion engines.
Efficiency is important as it is hard to store much hydrogen onboard, so you need massive tanks or your range is going to suck.
The blue box behind the cab here is the amount of space that you need to set aside for hydrogen tanks:
Sounds like an old freezing works. I worked at AFFCO Head Office during the change over period at Southdown from NH3. Those old NH3 compressors were works of art.
gsimpson,
Jul 15, 7:05am
104 years old be precise. Apart from the pump out compressors our compressors are screw compressors with several on VSDs with SCADA control. It is still pre war layout though with lots of manual valves. If there is a problem the computer shuts things down, throws it's hands in the air and says "help me". Basically a computer controlled 1940's machine.
elect70,
Jul 15, 8:45am
Funny that a client of mine (hotel ) were looking at 40 new room fridges as "green" but I told them they were ammonia absorption fridges & they changed their mind scared of it . . I worked at the old Gear Meat & & the alarm would go off daily in peak season & we all ignored it & cheif engineer would cancel it unles it was a big leak . Old plant was 60 years old in 70 s even had 2 old in line CO2 compressors .
gsimpson,
Nov 23, 12:58pm
Some people panic at the slightest whiff of ammonia and ask me if it is safe. I just say " If I start running, try and keep up"
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