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Using HFC-134A to directly cool intercooler core. Dangers? 1

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Baldturbofreak

Baldturbofreak

Mechanical
Nov 25, 2005
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Who can tell me definitivly about potential dangers involved with HFC-134A seeping into the engine and being combusted?

The Intercooler I have constructed is made from a bar/plate liquid/air cores from garrett. It is inside the manifold plenum and used as a diffuser/flow straightener. It's isolated from engine heat Via a 1.5" phenolic plate between it and the Billet intake manifold below it.
I have tested the core to 200psi under water with no leaks present. But it also hasn't seen the vibration of a 2.0L @7500rpm burnin'50lbs/min.(MR-2 T)
If by some series of events a fissure opes up and allows refigerant to seep into the intake and it goes thru the motor will it make a poisinous gas?
I have heard horror stories about mechanics in the early days of EFI accidenatlly sticking the r-12 canister on the fuel rail and killing half the shop off with fozgene gas. I'm no chemical engineer so please anyone, is this urban legend or what?
Please keep discussion to the dangers of HFC-134A being combusted only.
 
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R12 cannot make phosgene as it contains no chlorine and phosgene does. This is easy to see if you look up the MSDS for phosgene.

Here are 2 of the first 4 hits I got on google. It was not at all hard to find.



R12 and I would strongly suspect HFC-134A will make HF or hydrogen fluoride when burnt. This is also a very nasty gas and in contact with water forms hydrofluoric acid, which is so strong that it is used to etch glass.




Bottom line.

DON'T DO IT. SOME PEOPLE MIGHT VERY LIKELY DIE AS A RESULT OF YOU DOING IT. AS YOU HAVE BEEN WARNED IT WOULD MOST DEFINITELY BE YOUR FAULT IF THEY DID.

Regards

eng-tips, by professional engineers for professional engineers
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R134a will not form phosgene.

It will form Carbonyl fluoride, which is pretty nasty.

At typical intercooler temperature R134a will be at a much greater pressure that 200 psi. So your 200 psi pressure test don't mean squat.

Like Pat says, you are very likely going to kill someone. Probably yourself.

 
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Actually pre-nozzle it's 325psi, post discharge orifice (in the core) it's less than 60psi so my 200 psi test does mean "squat" as it were.

But the dangers of combustability are the concern here.
Thankyou for your replies, it's why I asked before doing.
Hydrogen flouride doesnt sound particularly friendly to the lungs,either I will have to find a different referigerant (suggestions) or keep doing it the other way.
But Im trying to get rid of the weight of the water and the ineffcincies of yet another heat tranfer (2nd evap to watertank).

So anything with the clorine molecule is out. Nitrogen has to be compressed to far to be practical. Hmm what other refrigerants are out there?...
 
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Why don't you just do what Ford does, and use the refrigerant to cool an intermediary medium (liquid or gel) that is much less of a threat, and then circulate that thru the liquid side of the core?

My understanding of systems like this is that if you wanted to use the AC to take the full heat load of WOT bursts that were continuous, you are pretty much screwed. However with the Ford system, they cool a reservoir that provides you with up to 40-45 seconds WOT cooling. Then it takes several minutes to "recharge" the system.

Sounds like that would work quite well, at least for a street driven vehicle, and provide you with lower than ambient cooling capability.

 
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okay, that does reduce the risk, but it doesn't eliminate it. the thermal inertia is probably useful, as you point out. You could still (with two leaks instead of one) burn the refrigerant.
 
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I have been using the "ford method" only ford uses the bypass coming out of the main evap core to chill their liquid. I have been setting them up to run with Dual Evaporators. one for th eoccupants (me) and one to chill the watertank for the intercooler.

So when I got done building this billet runner (half at a time) intake/intercooler it wieghed 35lbs. I figured 35 lbs of aluminum is pretty good at storing thermal inertial for the duty cycle on a street/strip car. (10% duty cycle) with 500hp a Mr2 is gonna be at terminal velocity in less than 15 seconds.
I just wanted to try and eliminate the "middleman" as it were and see what kinda data my dyno spit out.
My only concern was killing myself or others,hence the purpose of my thread.

thank you all again for the speedy response on this matter!
 
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I stand corrected.

R12 is dichloridifluoromethane. It will still make some very toxic gasses when burnt including phosgene and HF.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
 
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Why not use LPG as the refrigerant in the a/c?

Despite what the patent holders on R12 and R134a say it is a perfectly good refrigerant from most perspectives, and if it leaks into your engine no one will ever know.





Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
 
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Greg, you have a wonderful brain. I never considered Lpg. I'll have to dig up a phase chart for it to see what pressures will be involved.

Although I ve never looked at it after a good heat soak, highside/lowside pressure is well below 200 psi in every auto system Ive worked on. They seem to have enough volume to absorb it. Again I've never looked into it after a good heat soak.

Im sooo glad I posted before trying this experiment. I have been contemplating removing the liquid medium from the system for a good while. Only recently have I had the opportunity to try it. Althoguh I always take precautions in the dynoroom the potential for hazard was indeed very real.
MYTH= PLAUSABLE !! lol.
 
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LPG (standard US grade, or near HD-5, of at least 90% propane, with trace levels of N & I butane, a minimal amount of propylene and no ethane) has pressures at around:

75 degrees F = 120 psig
100 degrees F = 203 psig
125 degrees F = 250 psig
150 degrees F = 315 psig
170 degrees F = 350 psig

This from the NFPA 58 LP Gas Code.

Franz

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I'm wondering at the logic of it all.

Aren't you trying to remove a great deal of heat here? How are you going to run the refrigeration cycle? I haven't worked the numbers but it would seem many Tons of refrigeration would be required. Which in return would require many HP to run. And the weight that goes with that. Furthermore even with refrigeration you still have to dump the thermal energy the refrigeration removes. Back to an air exchange.

Or am I missing some detail?

Keith Cress
Flamin Systems, Inc.-
 
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It's the duty cycle, Keith.
In a street/strip environment I drive around removing tons of heat from the aluminum mass. opportunity to floor it presents itself,heats up core a bit. repeat.
All intercooler systems operate with peak efficincy as a heat exchanger. If your intercooler actually gets to steady state no matter what the configureation efficincy has plummeted. Especially air to air.
If we were roadracing,endurance or rally racing I would agree you would require HP to remove heat when we are asking for the power.
Just like the waterpump on your car cost power to remove heat. But I highly doubt it would be more than the gains made from chilling charge temps below ambient. Every one of my systems so far that have used the A/c to chill water for the core have easily surpassed this benchmark.

It has worked great with the liquid as the buffer. I just wanted to reduce parts/bulk. I figured why do I need 28lbs of water to store heat entrapy when I have more than that in aluminum.
Since my applicaltionis 10% duty cycle max, plenty of time is present to remove heat from the alumium mass.
 
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