improving intercooler efficiency

[spereira]

Hi everybody,
Rally cars spray water into the IC surface to increase heat transfer thus further reducing IC outlet temperature. This is true due to the huge latent heat of vaporization envolved. The problem is that once the water bottle is finished, no more spay! an HVAC system uses the same principle but operating in a closed circuit by means of the compressor. What would be the problems of using the AC circuit, if possible of course, to improve intercooler efficiency? Is this a stupid idea ?

 

[TZSiR]

Not a stupid idea. I use my A/C routed through an air-liquid intercooler to cool off the charge. I average about 40*F inlet temps. The highest I've ever seen was 78*F. This is with a PWR canister style air-liquid 6"X10". Be sure to take into account the pressure ratios needed to acheive said temperature. Also you might want to add alcohol injection to counter the dry air situation you'll run into. You'll also need to drain the inside of the air passage on the I/C after about a week or so of daily grinding. I think that's all.

This was first used in Boneville cars. That's where I got the idea from.

 

[spereira]

Hi TZSir. Thks for the info but now I'm a little confused !you're using an air-to-water I/C? your idea is to increase it's efficiency by "blowing" its surface with air from the A/C or use this air for further cooling the water inlet of the IC? I mean, you've just "re-routed" the A/C outlet? You manage 40ºF at charge air IC outlet!? I though A/C were limited to ~65ºF Have you changed the pressure ratios somehow? with these temperatures what level of gains have you experienced?
the dry air situation is something I didn't think of! is this due to ambient air moisture condensation at the temperature levels you're runing?
mine's an air-to-air IC (diesel 1.8 TDCi Ford engine)the original idea was to route the AC trought the original IC to have a better refrigeration rate but there are other alternatives. Now I need to calculate the heat loads/flowrates envolved. just wanted to know if someone already did this before...
thks again

 

[Chumley]

Spereira: What kind of additional power drain is the HVAC
compressor going to put on the engine? Will the gain in
air density and the additional power created be greater
than the compressor load? If not, your stealing from
yourself using a fairly inefficient cooler. Water is used
as an inter cooler supplemental coolant because of its high
H(vap) to weight in the first place.

Many vehicles with AC have a compressor cut out switch
which operates at WOT and at coolant overtemp to eliminate
the compressor load. You would be doing the reverse. In
addition to the power drain, AC compressors also
substantially increase the rotating inertia of the engine
which slows throttle response at a time when you would want
it most.(rally racing environment)

Seems like a bigger water tank or filling it more often, if possible, might be a better idea!

Chumley

 

[schmidtj86]

03 or 04 Ford Lightnings are going to use just that - AC cooling the intercooler giving a 40 second blast of 50 extra Hp.

 

[patprimmer]

I havn't done the numbers, but I think I agree with Chumley.

Leave 50 or 60 Kg of A/C system at home, then you won't need quite so much power for the same performance, and your suspension / chassi will be less stressed also, thereby possibly allowing further weight savings Regards
pat

 

[spereira]

hi everyone,
Chumley, I've thought about that and I did a little bit of calculations earlier: I've read somewhere that a supercharger drains about 3cv from the engine (on an 115cv engine this is about 2.5%). I think HVAC systems drains less, not sure though. Now, suppose I have about 70ºC (~160ºF) after my IC (haven't measure it yet, but just suppose so) If by using the AC this can be be reduced to 25ºC (78ºF) the density increase will be ~13%. Further reduction to 15ºC gives 16% density increase. Of course there's still the increased pressure drop to be accounted for but I think there's still some space for improvement, no? am I doing something wrong?
I know water is a great thing but unfortunately it also boils at an elevated temperature :-(
Sure the big bottle would be easier ;-)!

schmitdj86 where can I find information on those 03/04 Ford?

regards,
Susana

 

[GregLocock]

A belt driven Eaton supercharger for a 200 hp engine will typically take 40 hp to drive it at the red line. Cheers

Greg Locock

 

[schmidtj86]

The Ford Lighting info is in the Feb 03 Automotive Engineering International (SAE). Here's a quote from page 50.
"Unlike traditional intercoolers that dissipate heat from the supercharged air by circulating coolant through a front mounted, air cooled radiator, the SuperCooler uses the vehicle's air conditioning system to chill tank stored coolant to approximately 30*F (-1*C). The chilled coolant enters the engine's intercooler during a wide-open throttle condition. "It's sort of like a hot water heater in reverse," said Ford Motor Co. Director of SVT Programs John Coletti. The technology provides the vehicle with 30 to 45 s of up to 50 hp (37 kW) additional power, which can be regenerated within two minutes under normal driving conditions."

 

[spereira]

Greg Locock, do you think an HVAC compressor is going to drain that level of power? 40hp out of a 200 hp engine is about 20%!

 

[GregLocock]

No, I've measured about 7 hp to drive an AC compressor in a large sedan, at 5000 rpm engine speed.

Typically the ac will not run at that power level for very long as it will start to exceed operational parameters, in which case our compressor destroke, thereby reducing the power consumption, or in the worst case it declutches, and waits for the heat exchanger to defrost.

Cheers

Greg Locock

 

[Jreyenga]

Am I wrong in thinking that you are running the refrigerant through the liquid passage of the air-to-water intercooler instead of blowing over it with a heat exchanger and fan?

If so, you shouldn't be able to frost the intercooler because of the temperature of air going through it. This is something I've always wondered about doing, because it would be easy to reroute the refrigerant to the intercooler instead of the heat exchanger in the car. If an average AC only takes about 7hp to drive, and you can get very significant cooling, then it would very much be worth it, both for the increased air-density and the increased amount of boost that can be safely made.

 

[spereira]

Hi
you're not about anything because I'm still thinking on ways to do it. I don't have an-air-to water IC so I would need to install a different HE to be able to use the coolant through the liquid passage as you said. I've thought about that but the question is if the actual AC has the thermal capacity needed to significantly cool the intake at WOT. If so, maybe you could even do it with a three way valve operated by an internal switch so you can choose between AC or IC but you would need to keep the original air-to-air IC in series in case you choose AC...this would create an increased pressure drop in the intake, though. I have never studied AC systems untill now so I'm not so familiar with the heat load calculations needed for this. the other idea would be, as you said to blow the air-to-air IC with the cold air coming from the AC increasing the heat transfer capacity.

 

[Jiggery]

Okay, here's an idea! Why not use an aftermarket alternator that produces more voltage at the same engine load as normal and use an electric circulator for the coolant. Run a separate system from your normal A/C system so you don't screw your car up, and see what kind of gains you can get. Picture this: A wider than usual, but shorter than usual custom I/C, with 3 heat exchangers hooked back-to-back on the inside, circulating R-134A, plus the normal air-to-air gain if you set it on the front of the car. This could also be run with a turbo setup as well as the supercharger because of the type of setup. As well as being able to sit on top of the engine directly between the supercharger and intake manifold as in the Ford setup. Hook up a switch that activates the coolant circulation at the full-throttle position, and you could be looking at some significant power gains for a bit depending on the size of your alternate coolant resivoir. So far, I've never heard of anyone trying this, or even thinking of doing it this way. Mostly I think because R-134A hasn't been standard on cars that long yet, and the old freon, when leaked into an internal combustion engine makes something close to nerve gas, which would have made this a real crowd pleaser if something went wrong. Well, what does everyone think?

-Jared

 

[spereira]

Hi Jiggery
the idea was to use the exhisting equipment in the car, specially due to space restrictions. If I understand correctly what you've suggested, you'd have to use a new pulley to "charge" charge the new alternator and then connect it to the new electric compressor. Wouldn't it be more energy efficient to connect directly the new compressor to a new engine pulley like with superchargers? Using a turbo setup would definetly be more energy efficient than a compressor connected to the engine cranckshaft pulley but unless you use a variable geometry turbocharger which can compensate for changes in exhaust gas flow I think it would be difficult to get a stable operation for this extra system. unless it only works at WOT.
You've placed a good point regarding any leak that can contaminate the intake stream with the coolant. Is the emission of something close to nerve gas the only problem or can it also damage any engine components?

 

[Jiggery]

I'm not sure if it would cause any engine damage, to tell you the truth I've never gotten that far with my research. As far as I've found if a leak happened with Freon and you were exposed, you would possibly die or very possibly wish you did. As for R-134A, which is what almost all cars (at least in the US) use at the point, I've not heard of any toxic effects or engine damage from leaks ending up in the combustion chamber.

As for the other questions in your post, I was speaking of upgrading the *current* alternator, not adding another, so no extra belt-drain on the HP. There should be enough amperage in a good aftermarket high-output alternator to push a small CFM pump for an extra R-134A resivoir. And thank God R-134A is cheap! Plus, the extra amperage is also nice to have if you're pumping a large sound system. All you really need to install is an extra A/C resivoir, sufficient piping, and whatever custom intercooler you can come up with.

I'd suggest buying a stock air/air intercooler off of something like a late 90's Toyota Supra from a local parts yard. Cut it in half, drill the necessary holes and install the necessary plumbing so that the air flowing through the intercooler has to pass over/through 2 or 3 heat exchangers that the coolant is being passed through. The longer that you can keep the air close to the cooling source the better, right? And yes, I would set it up so that the pump circulates the coolant only at WOT. I'd try to place the "supercooler" as close to the intake manifold as possible, as the air would tend to reheat quickly due to the engine temps.

I'm sorry this post is so long, I've been thinking about this kind of a setup for a while now and I think it's definitely possible. Another thought was to hook the piping for the cooler into the stock A/C system. The increased amount of piping may up your capacity for coolant, thereby allowing you to keep the "supercooler" on for longer.

Does anyone have any ideas on using a very small amount of coolant on a closed circuit and circulating it slowly through a "supercooler." Do you think the coolant moving more slowly would still be able to offer significantly lower air temps, or do you need the coolant pushed through quickly to maintain optimum cooling?

 

[GregLocock]

"As far as I've found if a leak happened with Freon and you were exposed, you would possibly die or very possibly wish you did. ". Scaremongering. Didn't do much research did you? Here's an extract from the MSDS:


===========================================================================
Health Hazard Data
===========================================================================
LD50-LC50 Mixture: FREON "115" 800,000 PPM/"22" 220,000 PPM
Route Of Entry - Inhalation: YES
Route Of Entry - Skin: YES
Route Of Entry - Ingestion: NO
Health Haz Acute And Chronic: OVEREXPOS BY INHAL MAY INCLUDE DISCOMFORT-
NAUSEA/HEADACHE/WEAKNESS/TEMP NERV SYS DEPRESS W/ANESTHETIC EFFECTS LIKE
DIZZINESS/CONFUSION/INCOORDINATION/LOSS OF CONSCIOUSNESS OR W/GROSS
OVEREXPOS (>20%), POSS TEMP ALTERATION OF THE HEART'S ELECTRICAL ACTIVITY
W/IRREG PULSE/PALPITATIONS/INADEQ CIRCULATION. MISUSE: DEATH.#
Carcinogenicity - NTP: NO
Carcinogenicity - IARC: NO
Carcinogenicity - OSHA: NO
Explanation Carcinogenicity: N/K #INDIVIDUALS W/PREEXISTING DISEASES OF
THE CENTRAL NERV/CARDIO SYS MAY HAVE INCREASED SUSCEPTIBILITY TO ##
Signs/Symptoms Of Overexp: ##TOXICITY EXCESSIVE EXPOSURES. CARDIAC
SENSITIZATION WAS OBSERVED IN BEAGLE DOGS EXPOSED TO CONCENTRATIONS OF 15%
TO 25% "FREON" 115. VAPOR REDUCES OXYGEN AVAILABLE FOR BREATHING & IS
HEAVIER THAN AIR. SKIN CONTACT WITH THE LIQUID CAN CAUSE FROSTBITE.
"FREON"
22-TOXICITY IN ANIMALS BY INHAL TO CONC RANGING FROM###
Med Cond Aggravated By Exp: N/K ###5 TO 70% INCLUDE EFFECTS ON THE CENTRAL
NERV SYS/LIVER/LUNGS/KIDNEYS/SPLEEN/CARDIAC SENSITIZATION/DECREASED BODY
WEIGHT GAIN/PARTIAL ANESTHESIA. INCREASE OF TUMORS IN MALE RATS AT CONC
OF####
Emergency/First Aid Proc: INHAL: IMMED GET FRESH AIR. KEEP CALM.

etc

So if you breath 15% Freon you may run into problems. Short of sticking a pipe up your nose I really don't see how to achieve that sort of concentration. Cheers

Greg Locock

 

[patprimmer]

Freon is very similar chemically to Teflon. Teflon is used to coat cookware.

Many A/C and refrigeration technicans regular dumped Freon to atmosphere, while standing nearby. The only ill effect I have heard of is frostbite when standing much to close.

One of the many problems associated with finding replacements for Freon was that the replacements were often dangerously toxic, whereby the Freon was not. Other problems were explosions, lubrication of compressor, cooling capacity, compressor head pressure, smell, and corrosion.

Flurocarbons are dangerous if inhaled through a flame, ie when smokeing. I guess the same applies to HFC's to a lesser degree (less Fl and more firmly attached than the H)

When inhaled through a burning cigarette, the PTFE decomposes, releasing Fl, which is quite nasty, but then so is nicotine.

I used to have a few papers on HFC replacement's and the evolving technology at the time, but that was quite some time ago now, and as I was only indirectly involved, I probably dumped most of them.
Regards
pat

 

[spereira]

Jiggery, to increase alternator voltage wouldn't I also need to change all other electrical connections to comply with more than 12V? I really don't understand that much about electrics. Also, a "bigger" alternator might need a wider pulley/belt to drive it, right?
As for "Do you think the coolant moving more slowly would still be able to offer significantly lower air temps, or do you need the coolant pushed through quickly to maintain optimum cooling?" I think this would depend on the heat exhcange coefficients you'd be able to achieve with that particular coolant velocity. Some calculations would be needed to find out the minimum coolant velocity in order to achieve turbulent flow, I think (unless limiting heat transfer film coefficient should be on the air side).
Anyway, it seems to me that it always comes back to this: in order to use the actual AC system I'd need to place a second HE (coolant-to-air) on the intake side to allow for the extra cooling. This increases pressure drop, thus reducing the gains I'd have by these extra cooling capacity. knowing this, is the capacity of my AC system enough to significantely cool down the air coming from the exhisting air-air IC? Also, by lengthening the coolant piping through a new HE I'd be increasing the coolant side pressure drop (not coolant velocity) which would also reduce the compressor efficiency. Does this make any sense?
As for Freon, it's out of the question anyway since it was banned, right? the R134-A should be a good alternative and GregLocock, it's a good idea to check the MSDS for these compounds, thks.
Patprimmer, if you by any chance find any of those papers would you please forward them to me?
regards,
Susana

 

[Jiggery]

Greglock: I'm sorry I didn't clarify the statement about freon, here it is from my previous post:

"freon, when leaked into an internal combustion engine makes something close to nerve gas, which would have made this a real crowd pleaser if something went wrong."

That's what I was referring to when I said the freon could possibly hurt someone. And no, I haven't done any research on normal freon since I never use the stuff. And also no, I don't have any proof about freon winding up being toxic if leaked into the engine. Try it out and let me know if you die or get sick

Spereira: As for the upgraded alternator, it's no larger than the normal, just bigger/better windings and you get extra power. No extra pulleys/larger pulleys needed, also, no extra drag on the engine. Like I said, it's a trick that a lot of guys use to get those extra amps for the big stereo systems.


I was speaking of adding the HE's into the IC, not after it, but inside it. No extra intake piping, so no extra pressure drop inside the IC right?.

Also, if you enlarged the A/C circulation system and added more coolant, why would it bother the compressor? As long as the compressor has the factory spec coolant pressure, it will continue to push the coolant through at the factory preset velocity. Granted, with a larger system that means the coolant has more time in the tubing, therefore the refrigerant would have more time to heat up. So possibly some problems there. What do you think?


My main idea is to not have a traditional IC. Since all that extra piping from the filter, thru the IC, to the intake plenum adds lots of weight and lots of time for the air to heat back up. I'll use a turbo engine as an example: My main thought was to go directly from the turbo to the intake plenum with a larger diameter than normal round tube. Stack 5 or 6 small HE's in there (they can't have too many fins of they will restrict airflow too much) and push the coolant through there at the best velocity for maximum cooling. Less piping from turbo to engine results in less turbo lag, and this setup may be efficient enough to justify running a compressor for the coolant full-time. Maybe it'd be easier to place in tight places for after-market tuning as well. What do you think?