Anyone ever try a phase change IC?

[tkelly27]

Has anyone tried to get a phase change going on in their air/liquid intercooler?

You can basically set the coolant fluid temp to whatever you want with this situation (think constan temp boiling water, only tunable with pressure), and you can pull huge amounts of heat energy out compared to just heating and cooling a fluid.

I've not seen any even attempted, so I figured there has to be a good reason putting "phase change" into the search bar get's nothing.

*addition*

Ok, looking at it, if your water starts at 0*C and goes to 100*C you can pull out about 400kJ/kg. and have 100*C outlet temps. Less energy taken from the charge @ lower outlet temps. Anyone know what temp water their air to water IC's spit out?

http://www.physchem.co.za/Heat/Latent.htm

if we believe the bottom of that page, then using ethanol we can get over 800kJ/kg and have outlet temps @ 170*C. With an expansion valve and/or using engine vacuum to put the whole system under low pressure we could theoretically get the stuff to boil at a negative temperature pretty easily. How much heat it will pull out at those points, I do not know, but if it's anything like water, it will take more energy to boil it at lower pressures, at a lower temp.

I would choose ethanol over water because of it's super low freezing point. Water could be used, but it would take an obscene vacuum to get it to boil at anything close to colder than ambient. Also, if this half assed setup breaks, it will be less likely to harm the engine as the ethanol can evaporate and burn, while water is bad news.

Good idea, bad idea bad math?

 

[eboy0]

I wish I could find the thread, it wasn't on this forum but someone ran a evap line all around the IC and hooked it all up to the stock HVAC, meaning when he wanted ice he turned on the A/C... only problem he said he was getting incredible amount of sweat from the evap tubing and IC.

 

[Steve93Talon]

Anyone know what temp water their air to water IC's spit out?

Without running ice, and with a 5 gallon reservoir and pretty good size heat exchanger, we usually see about 5F degrees over ambient.

 

[dsm-onster]

Interesting idea. . . Are you talking about the Ford patented SuperCooler found on the Ford Lightnings? This is where the phase change of the compressed freon in the a/c system is used to cool the air going across the intercooler fins.

I've heard of guys fooling w/ this but nothing ever materialized. Keep in mind that enough cooling capacity would require a decent size compressor and it probably would only be useful for a minute or 2. Which is plenty for a 1320 ft run, of course. This compressor would have to run off of your engine and cause a bit of parasitic drag. Just like an a/c compressor. Actually it would be. See the sited Ford product.

I would choose ethanol over water because of it's super low freezing point. Water could be used, but it would take an obscene vacuum to get it to boil at anything close to colder than ambient. Also, if this half assed setup breaks, it will be less likely to harm the engine as the ethanol can evaporate and burn, while water is bad news.

Keep in mind that enough methenol to absorb as much heat as h2o wold requre so much that it would still drown out the engine and probably soak the piston rings causing abnormal wear (just like too much water in the engine). 6 of one, half dozen of the other. Either is too much.

I would not use either water or methenol. I would use what works best: freon (r-134a).

"Hold on guys. If I'm going to the track, I need to charge up my intercooler first."

 

[gixrman]

I had done alot of reading and research into this and after many sleepless nights concluded that 1. the system would only be good for short runs. 2. Would add alot of weight to the car. Overly complicated with more chance of system, complete motor failure. NOS, water, methnol injection is just as effective and simplier and lighter. I read somewere that frost had built up on an intake from methanol inj. don't know if thats true....

 

[Maglin]

With phase change comes 2 components you have to add. You need a evaperator most likely a custom IC and a condenser. Then you don't want to put it into vacuum because once the fluid starts to boil it's going right out the vac source. System has to be closed. So freon would be the easiest route. You have to just make sure the system doesn't go under 32* F or you will turn your IC into a block of ICE which won't do much of anything for you. It's just a heat pump. Where their is cold their is also a hot side along with using engine HP to run a compressor.

Would be cool to run but it's a PITA. You would want to build a IC where every other row was their to form the evaperator.

Best system of this would be a hybrid using cascade cooling. You use a W2A IC and put a tiny evaperator into the water reservoir for the IC. Then you can kept it cool with your A/C system. The heat will just be moved to the condenser which will be in front of your radiator. With this setup you could run a very small IC compared to a A2A IC.

 

[tkelly27]

Good ideas guys!

Yeah, the cooling capacity is why I was going to use ethanol, vs. any regular AC fluid. Much higher latent heat. If I'm reading it right, R-134A is 1/10th that of water, vs. ethanol which is 1/2. Using water would be best, but it would require an obscenely high vacuum.

I was hoping to put the whole system under vacuum then closing it off, a lot like regular AC systems are under pressure then closed off. I might try using a check valve and capping off the engine while it's running to see what kind of vacuum spike I can get.

I was also hoping to get away with using a fuel pump. I've not had huge experience with HVAC, but I was keeping my fingers crossed that I could put the condensor after the evaporator (instead of evap -> pump -> condensor) and use a gravity feed system to go back to the coolant reservour. If there was a big enough volume of condensor the vapor could spend some quality time there exchanging the heat with the air. It would really defeat the whole purpose of the setup to use the 10-20hp A/C motor, and if it comes to that I'll just go back to a regular old water to air system.

I don't see there being any more weight than a regular air to liquid IC, and the only added complexity would be an expansion valve and all the lost sleep I'm getting over trying to figure out how to work it.

I read in a book that ammonia was used way back in the day. I guess it's toxic, but I'm not breathing the stuff, so that might be an easy to get fluid.
http://www.ammonia-safety.com/ammonia.html
bummer, perfect for doing AC, but nasty stuff. Back to the drawing board.

Do you think the interior would get coated with ice? That would be bad news.

Worst case scenario, it fails completely, I can tell people it's a bad idea, and I have a sweet, cheap, air to water setup.

 

[Maglin]

Well Never hurts to try. I just don't know how you are going to attain a vacuum. The expansion of the liquid to a gas will kill a vacuum. And the cooling effect is when the phase changes happens going from a liquid to a gas. latent heat shouldn't be what you are looking at. It only refers to how much energy is required to take a certain volume of liquid and turn it into a gas. It's after it reaches it's boiling point. Once the liquid reaches it's boiling point you can't physically measure any more heat. If you raise the boiling point you could like in an automotive cooling system.

And Yes I do believe the interior and exterior would get coated with ice. It's why an A/C system has to be completely dry. I put all mobile HVAC in a vacuum of 30"hg for 30 minutes to ensure their is no moisture in the system. The vacuum lowers waters boiling point to below ambient around 25"hg causing it to turn to gas and get sucked out by the vacuum. It's why I don't see how you are going to get a vacuum on this system. It's better to use something with a very low boiling point and use pressure.

Best of luck to ya though. If it works you can come on here to say I told you so.

 

[dsm-onster]

Well Never hurts to try. I just don't know how you are going to attain a vacuum. The expansion of the liquid to a gas will kill a vacuum. And the cooling effect is when the phase changes happens going from a liquid to a gas. latent heat shouldn't be what you are looking at. It only refers to how much energy is required to take a certain volume of liquid and turn it into a gas. It's after it reaches it's boiling point. Once the liquid reaches it's boiling point you can't physically measure any more heat. If you raise the boiling point you could like in an automotive cooling system.

This took the words right out of my mouth. You're pretty much done after getting to a gas state for all practical purposes. After that. Cooling the environment is all about how slow the gases are moving. Not much more.

It's better to use something with a very low boiling point and use pressure.

This is why the suggestion of freon.

This is not to discourage you, but rather to send you in the right direction. He!! if a Ford engineer can do it . . . It can work. AND it can work well.

The idea of submersing the evaporator in the water reservoir is not half bad either. GEtting the water to below ambient is plenty. Let the h2o do what it does best soak up heat in a liquid state. Then send it to a fridge like sending warm air through an a/c evaporator. The air comes out nice and cool. So will the h2o.

Keep in mind that water doesn't like to GIVE UP heat as much as other fluids. That's why I don't prefer w/a ICs over a/a ICs. It takes a pretty much a good radiator or a d@mn good refrigeration system to take the heat out of water. It doesn't take as much time to bring water to a boil then it does for it to cool down to it's original temp.

 

[tkelly27]

From wikipedia

"This device then passes the low pressure, barely liquid (saturated vapor) refrigerant to another heat exchanger, the evaporator where the refrigerant evaporates into a gas via heat absorption."

http://upload.wikimedia.org/wikipedia/commons/f/f7/RefrigerationTS.png

In a conventional air to liquid heat exchanger, you're right, pretty much all you can do is heat up the cooling medium and pass it along. With a phase change, instead of heating it up, you're getting it to convert states. This is the concept behind chemical intercooling, the latent heat of the ethanol and water is what is required of the intake gas to give up in order to boil those fluids. The latent heat of water is massive, and is actually how it removes heat the best, which is why they use it in steam turbines to extract the most energy possible from the heat source.

Check out latent heat (or heat of evaporation) vs. the specific heat, the difference is astounding!
http://www.physchem.co.za/Heat/Latent.htm
even to take it from 0*C to 100*C takes 1/6th the energy it takes to boil it.

As Maglin helpfully pointed out, you can direectly control the temperature of a boiling fluid by placing it under higher or lower pressure. Pressure cookers cook faster because they place the water under higher pressure, forcing the temperature up. Up in Colorado your food takes longer to cook because the boiling temperature is lower due to the lower pressure. Also like he mentioned, if you've got a super gnarly vacuum pump you can get water to boil at 32*F. I figure if I have a modest vacuum going on I can get ethanol to boil at near to sub ambient temps, I've not found a steam table for it yet though. The thing is, with the pressure in the system, you set what temperature you want your IC fluid to be at. Theoretically, until 100% of it boils of the whole thing is at that temperature. Try it with boiling water, it will be 100*C when the pot is full, and 100*C when nearly empty. If I can't get it to work with ethanol, I may try gasoline, but that's where the experiment will end.

Why not put a regular coolant in there? First, I don't trust my welds to take 200psi. I'm simply not that good. Second, the latent heat (again, the only thing we care about in a phase change heat exchanger) of R-134A is significantly less than that of ethanol or water. I've screwed around with R-134 a little bit before and it's not something I want to do again All the rest of the common chemicals used to this end really don't thrill me either. I'll stick with regular convection (standard air/water setup) at that point.

How to keep a vacuum? It will be like a vacuum canister. The same way you can contain and maintain pressure levels in the standard AC system, you can contain and (hopefully) maintain a lower pressure inside this system. You are right, vapor pressure is one of the things I am concerned about, and that will be a big part of this experiment. I may be able to use vapor pressure to drive the system, which would be less efficient and may not work for beans when it comes to cooling, but kinda cool to see in action.

That water likes to take heat more than it likes to give it off is incorrect. It's more a matter of what you're using to heat it up or cool it down. It certainly likes to take the heat in the charge pipes at 200-300* much better than it likes to give it off to the 65* atmosphere. As far as I know, there's no chemical property of water that reduces it's ability to give off it's heat energy. If you don't think it wants to give off it's heat better, put your hand in a pot of boiling water, and then put it into an oven at the same temp... eek! I'd also encourage you to have the same temperature difference while boiling your water (instead of a 1000* burner, use one at a boiling temp) and see how long it takes to bring it to a boil. You'll be waiting all day!

That cycle diagram kinda screws up my plans for switching around the pump and the condensor. Maybe... I dunno, I need it liquid to pump it with a cheap fuel pump.

Also, I don't want anyone to think I'm telling them they are wrong, but these are my understandings of the situations and how I'll be approaching this. I'm meerly putting them out the for discussion and brainstorming. Your opinions are always welcome as it seems a few people at least have dealt with some of this stuff in the real world.

 

[Maglin]

Yes. As with your boiling water example. You can not measure latent heat. It was what I was trying to say up above. Only thing that can be measured is how many btu's it takes to be able to completely boil off a set volume of liquid which is where you get your latent heat index. I'm still thinking that since you don't want to run temps under 0*C that a cascade cooling solution would be best. Use a small ac system to cool the liquid of a W2A IC. You could regulate it pretty easily. The HP loss running the compressor would be made up 2x by the reduction of air temps. instead of having say 110*F inlet air temps you could get them down to say 50-60*F. That would be roughly a 5% increase in HP. So if you are outputting 400HP then you would see a 20 HP gain. Takes 10HP to drive the small A/C compressors on imports. So you make your HP gains. But is it worth it? It's just easier to run methanol injection.

If you want to try this get a vacuum pump. Don't use engine vacuum. The discharge for the pump would need it's own tank as I'm positive you will be pumping your fluid out in a gas state. Once it leaves the pump it should condense back into a liquid state. If you use the engine it will just go through it. Just remember that once you go below freezing you will ice up the IC and it will become ineffective as ice is a very good insulator.