EV’s

[landroversforever]

3 hours ago, sean f said:

I have heard that if you are fully inside the vapour cloud then you can flick a lighter and there wouldn't be enough oxygen for it to ignite (not sure how that would work with breathing?) and frankly you would have to be bonkers to try it.

You wouldn’t be able to breath at that point and it would be an asphyxiating atmosphere. 

It’s how you get lower and upper explosive limits. Lower being the minimum amount of something flammable to make an explosive atmosphere, and an upper limit where above it there’s too much of the flammable gas and not enough oxygen to burn.  

[fmmv]

My Dad told me he had seen it done during WW2 with (aviation) petrol while in the RAF, and suggested it was like Russian roulette. But it did work. Petrol does have a relatively narrow range of mixtures with air where it is flammable. Hydrogen on the other hand has very wide limits, even 4% burns, so for those advocating as an alternative to electricity, eg for trucks, that too may be problematic.

Edited November 1, 2023 by fmmv

[jeremy996]

This has made me feel old; I remember seeing the remains of Reliant Scimitars along the trunk roads and motorways in the late '70s. ICEs burn quite well, especially if they are GRP bodied. One of the job I remember doing as an apprentice in the motor trade was drilling and pinning the brass petrol pipes into the cards on Ford V6 engines, as the pipes were supposed to be an interference fit and fell out if they got hot.

Hybrids tend to have crowded and complex engine bays, so issues with heat soak, poor installation and indifferent maintenance seem quite plausible. Following the last Emergency Services Show, as a 4x4 responder, I was given the electric vehicle safety protocol training which was quite sobering.  

[Snagger]

I think there are plenty more EV fires than we are told.  But it is not the frequency of the fires that is really the threat but their intensity, as has been said repeatedly.  As for hydrogen, that seems incredibly risky to me, especially the refilling, because preventing leaks is so damned hard.  The Artemis gantry fuelling system cost billions and leaks like a sieve, so what chance for forecourt hoses and privately owned cars with owners who have no comprehension of the risks?

[Stellaghost]

9 hours ago, fmmv said:

Hydrogen on the other hand has very wide limits, even 4% burns, so for those advocating as an alternative to electricity, eg for trucks, that too may be problematic.

JCB have signed a contract to produce super clean hydrogen engines, they have also developed a fueling system for said engines, yes it's construction equipment at the moment, however it will be under the spotlight and if successful and no "accidents" I reckon it will eventually get into the public domain

Toyota are looking at/have developed an ammonia engine and possibly abandoning the EV route altogether

Regards Stephen

[Bowie69]

The JCB hydrogen thing was very interesting.... Good for large sites at the moment, I'd suggest, as need fueling on site, but otherwise great. 

 

[western]

JCB have also converted a Merc truck & a van to run on hydrogen, a twist & lock refuelling coupling like lpg or large pressure refuelled aircraft would make it leak free

[landroversforever]

17 minutes ago, western said:

JCB have also converted a Merc truck & a van to run on hydrogen, a twist & lock refuelling coupling like lpg or large pressure refuelled aircraft would make it leak free

I work with Hydrogen and Deuterium (Tritium occasionally too) and I really can't see a twist and lock type fuel coupling sealing well enough for a hydrogen coupling. Even factory fresh it's going to struggle, let alone after clumsy motorists have bashed it around. H2 will also permeate the rubber seal on top as well, it's a horrible gas to try and contain! All of the connections on my systems are metal-metal, either gasket types, compression or bullnose like your normal cylinder connection. All of them are very susceptible to damage. Even this morning we've got a Nitrogen cylinder that won't seal thanks to the tiniest of scratches on the cylinder side sealing face. 

I really do like the idea of H2 for some things as part of a multi-pronged approach, just not sure of the practicality of the general public using it. 

[FridgeFreezer]

2 minutes ago, landroversforever said:

I really do like the idea of H2 for some things as part of a multi-pronged approach, just not sure of the practicality of the general public using it. 

^ this, I think H2 works for fleets or on sites like JCB are doing where you can plonk a big tank of it on site and refill all your vehicles at the end of the day, but the practicalities in passenger cars (& the infrastructure) are worse than LPG - and EV's are steaming ahead in leaps & bounds because all you need is electricity.

[sean f]

12 hours ago, landroversforever said:

You wouldn’t be able to breath at that point and it would be an asphyxiating atmosphere. 

It’s how you get lower and upper explosive limits. Lower being the minimum amount of something flammable to make an explosive atmosphere, and an upper limit where above it there’s too much of the flammable gas and not enough oxygen to burn.  

Yep above the upper explosive limit. Wasn't quite sure if that also made it an asphyxiating atmosphere as well, can't remember the numbers.

I can remember a quite entertaining experiment for measuring the upper explosive limit for methane, get a large coffee tin or similar, make a small hole in the lid and seal it with a bit of bluetack, make a hole in the side at the bottom (two if you want to put a gas sample probe in to get a reading), fill the tin with methane at as high a concentration as you can get. Remove the blue tack from the top and light the methane, to start you get a decent flame (best done inside in near dark) the flame will get smaller and smaller as the concentration decreases and air is draw into the bottom, just when you think it is about to go out the inside of the tin reaches the upper explosive limit and blows the lid across the lecture theatre with a nice bang. The same thing should work for other gasses that are lighter than air.

Always made a lecture more interesting when we got to blow things up, we moved up to Nobel powergel, det cord, ANFO and special gelatine late but definitely not inside for them.

[fmmv]

Many years ago my (and another student's)  final year uni project was to build and test a hydrogen fuelled engine. We thought fusion reactors would be running and producing hydrogen by now, as the oil was due to run out around 2000. A small block would have been nice, but with the budget we had we settled for a Suffolk mower engine. We used a dynamo to start and load it remotely, but measured revs and torque mechanically. This was very early days of computers so no electronic injection, and we knew it was reactive stuff and might explode in the manifold, so we took off the carburettor and made an inlet valve seat insert with an annular ring in the outside, and drilled fine holes from the seat to this ring, then drilled through the block to the ring. The air intake was open like a diesel. It was deemed too dangerous to run in a building so we  had to use a test cell made from a wartime bomb store. We peered at it through 3" thick glass. 

We were warned of crankcase explosions so we hooked a nitrogen purge to the crankcase. Initially it wouldn't run. We were feeding it through a tap(needle valve) from a low pressure supply. We realised it wasn't running because we were feeding way too much hydrogen which was burning in a nice shimmery haze around it, so dropped the pressure and suddenly it was alive. It ran fine and produced the necessary tumbler of 'water'. The needle valve controlled it fine from tickover to full chat, so making use of the wide range of combustibility. So it is feasible to run ICE on it, but it needs careful handling, and storage is also a problem, hydrides look most promising, liquid hydrogen is worse than bottles for hazard and bottles are are very heavy and bulky

But hydrogen can literally get where water can't, the molecules are so small it leaks where nothing else would. and it burns (readily) as we found with a colourless flame. And I think oxides of nitrogen  and maybe embrittlement will be a problem still. Myabe fuel cells would be better use of it.

Edited November 2, 2023 by fmmv

[landroversforever]

55 minutes ago, fmmv said:

We thought fusion reactors would be running and producing hydrogen by now,

-

But hydrogen can literally get where water can't, the molecules are so small it leaks where nothing else would. and it burns (readily) as we found with a colourless flame. And I think oxides of nitrogen  and maybe embrittlement will be a problem still. Myabe fuel cells would be better use of it.

A fusion reactor uses Hydrogen and/or isotopes of it rather than producing it .

The only reason we as an industry don't use hydrogen as a vacuum leak checking gas is that it's flammable - hence the use of helium instead. A scratch or similar less than the cross section size of a human hair is a gaping leak for Hydrogen (and it's isotopes). 

[landroversforever]

1 hour ago, sean f said:

Yep above the upper explosive limit. Wasn't quite sure if that also made it an asphyxiating atmosphere as well, can't remember the numbers.

Love the coffee tin thing - would love to try that but not sure our Safety bunch would be too happy  

Oxygen levels - our monitoring is usually reading around 20.X%, I think the first alarm level is 19%, then our second alarm level is at 16 or 17%. 

[Snagger]

Yep, hydrogen being such a small atom and making such small molecules is exceptionally hard to confine, especially in pipework that has only temporary connections like refuelling sockets and nozzles.  A tiny grain of dust is enough to utterly compromise the seal and render an almost undetectable hazard.  Forecourts will need to ensure positive forced ventilation over the connections as well as the general refuelling area to make sure that hydrogen can’t build up enough partial pressure to be an issue, but the rest of the vehicle is still going to be at risk in service - even the UK’s annual MoT just aren’t going to cut it.

[landroversforever]

5 minutes ago, Snagger said:

Yep, hydrogen being such a small atom and making such small molecules is exceptionally hard to confine, especially in pipework that has only temporary connections like refuelling sockets and nozzles.  A tiny grain of dust is enough to utterly compromise the seal and render an almost undetectable hazard.  Forecourts will need to ensure positive forced ventilation over the connections as well as the general refuelling area to make sure that hydrogen can’t build up enough partial pressure to be an issue, but the rest of the vehicle is still going to be at risk in service - even the UK’s annual MoT just aren’t going to cut it.

Given the outside nature of UK petrol stations the hydrogen isn't going to hang around anywhere and build up. From our rules on gas storage, it's classed as outside if it's got a roof and still got 50% of the walls open or mesh. So it's going to to be more than open enough not to be an issue. 

[Snagger]

1 minute ago, landroversforever said:

Given the outside nature of UK petrol stations the hydrogen isn't going to hang around anywhere and build up. From our rules on gas storage, it's classed as outside if it's got a roof and still got 50% of the walls open or mesh. So it's going to to be more than open enough not to be an issue. 

Most of the time, I’d agree, but on those calm summer days, any leaking hydrogen could be trapped in any overhangs (car and station), hence the need for forced ventilation.  The cars should be safe enough on the move or with moderate winds as any small leaks would be blown away.

[landroversforever]

26 minutes ago, Snagger said:

Most of the time, I’d agree, but on those calm summer days, any leaking hydrogen could be trapped in any overhangs (car and station), hence the need for forced ventilation.  The cars should be safe enough on the move or with moderate winds as any small leaks would be blown away.

Nahh, there would be more than enough air changes on a still day for that to disperse. Even then nothing is going to be that well sealed for it to stay put anyway. 

 

[Bowie69]

Convection currents would help a lot with that.

[Snagger]

I know hydrogen naturally wants to float up and away very quickly, but I have concerns over it being trapped in voids under vehicles and their body panels when there is no ambient airflow.

[landroversforever]

2 minutes ago, Snagger said:

I know hydrogen naturally wants to float up and away very quickly, but I have concerns over it being trapped in voids under vehicles and their body panels when there is no ambient airflow.

If it doesn't  want to stay in something you're trying to keep it in, the risk of pockets being trapped anywhere really are minimal to none. 

[FridgeFreezer]

Another way to look at EV's is this: If someone offered you a motor for your car that had full torque from 0rpm, was way more efficient than any existing ICE engine, was 1/4 the size of an ICE engine, needed 3 wires to make it go, didn't need a multi-speed gearbox or clutch, didn't need an exhaust, required minimal cooling & lubcrication, and had only one moving part that was perfectly balanced rather than reciprocating, most sane people would jump at it.

Yes batteries are still catching up, and yes there's a load of electronics around the basic system like any modern car - but on paper the electric drivetrain is miles ahead on everything except making fruity noises.

[Chicken Drumstick]

7 minutes ago, FridgeFreezer said:

Another way to look at EV's is this: If someone offered you a motor for your car that had full torque from 0rpm, was way more efficient than any existing ICE engine, was 1/4 the size of an ICE engine, needed 3 wires to make it go, didn't need a multi-speed gearbox or clutch, didn't need an exhaust, required minimal cooling & lubcrication, and had only one moving part that was perfectly balanced rather than reciprocating, most sane people would jump at it.

Yes batteries are still catching up, and yes there's a load of electronics around the basic system like any modern car - but on paper the electric drivetrain is miles ahead on everything except making fruity noises.

They still potentially need gears. The Tacan is a 2 speed and I believe either Renault or Citroen have announced a manual EV on its way. The motors also need a lot more than 3 wires to make them go, they need an entire speed controller setup.

[Gazzar]

Pump up the bass!

[Gazzar]

38 minutes ago, FridgeFreezer said:

Another way to look at EV's is this: If someone offered you a motor for your car that had full torque from 0rpm, was way more efficient than any existing ICE engine, was 1/4 the size of an ICE engine, needed 3 wires to make it go, didn't need a multi-speed gearbox or clutch, didn't need an exhaust, required minimal cooling & lubcrication, and had only one moving part that was perfectly balanced rather than reciprocating, most sane people would jump at it.

Yes batteries are still catching up, and yes there's a load of electronics around the basic system like any modern car - but on paper the electric drivetrain is miles ahead on everything except making fruity noises.

But, but, but, how would we stop the chassis from rusting workout the leaks?

[Snagger]

43 minutes ago, FridgeFreezer said:

Another way to look at EV's is this: If someone offered you a motor for your car that had full torque from 0rpm, was way more efficient than any existing ICE engine, was 1/4 the size of an ICE engine, needed 3 wires to make it go, didn't need a multi-speed gearbox or clutch, didn't need an exhaust, required minimal cooling & lubcrication, and had only one moving part that was perfectly balanced rather than reciprocating, most sane people would jump at it.

Yes batteries are still catching up, and yes there's a load of electronics around the basic system like any modern car - but on paper the electric drivetrain is miles ahead on everything except making fruity noises.

Absolutely.  Get the batteries sorted and it’s a no-brainier.