Most Efficent Intake Air Temp?

While doing some research for an industrial application, I came across a device that creates cold air with just appling compressed air (Vortex Cooler System by Vortec). Its used for electronic sytems that are used in hot enviroments.

So, I've started to wonder if it would be worth it(Est. $700 w/compressor)to pipe it into my stock intake system with the use of an air compressor (still debating on electric or engine mounted. Of course I'll have to also engineer a way to keep from injecting the cold air and allow it to be naturally asperated).

So what kind of HP gain could I get if the most efficent air temp is supplied to the 4.0L? And what would that temperature be?  
2001 TJ Sport
- 4.0L I6
- Sport Wheels w/ 30 x 9.50
- Half Steel Doors
- Soft Top
- Daily Driver
- Standard Tranny
- 3:73 Gears

The standard rule of thumb is a 1% increase in power for every 10 degrees in reduction of intake air temperature. So, if you decreased the temperature 30 degrees for the 4.0L, that would be less than 6hp increase.

Your idea has already been tested. It's been a while since I read about it, but Ford and the SVT people (I think) rigged up a little evaporator that was charged by the A/C system and installed into the intake system of a Lightning. It reduced the intake charge by something like 30-40 degrees. But the restriction caused by the evaporator was almost enough to neutralize the gains. I think I read about this in Popular Mechanics, but it's been a long time.

Also, remember that air is heated when compressed, not cooled. That's why superchargers and turbos have intercoolers, to cool the super heated compressed air before entering the intake system.

This cooler air theory is also used by water injection technologies that claim to cool the intake charge for performance and fuel efficiency increases.  

This is a little different than the evaporator method that was used.

A Vortex Tube creates cold air and hot air by forcing compressed air through a generation chamber which spins the air centrifugally along the inner walls of the Tube at a high rate of speed (1,000,000 RPM) toward the control valve. A percentage of the hot, high-speed air is permitted to exit at the control valve. The remainder of the (now slower) air stream is forced to counterflow up through the center of the high-speed air stream, giving up heat, through the center of the generation chamber finally exiting through the opposite end as extremely cold air. Vortex tubes generate temperatures down to 100°F below inlet air temperature. A control valve located in the hot exhaust end can be used to adjust the temperature drop and rise for all Vortex Tubes.

The hot stream, I'll exhaust out to where ever. As for the cold stream I'll exhaust into the intake system, so there won't be any additional restriction like the tested condensor method.

With this being stated, it brings me back to, How cold can we go?  
2001 TJ Sport
- 4.0L I6
- Sport Wheels w/ 30 x 9.50
- Half Steel Doors
- Soft Top
- Daily Driver
- Standard Tranny
- 3:73 Gears

The other part of the equation is what volume of air is produced and at what cost.

Air does not move by itself, it takes energy to move air. No process is 100% efficient. Compressing air is an extremely inefficient process. The biggest indicator of a process's efficiency is heat. If heat is the bi-product and not what you're after, then your process efficiency goes way down.

So knowing more about the energy requiremnets of that process can help evaluate its potential benefits above its generation costs.

The temperature figure that you're asking about would not have "real world" meaning.

Any efficiency calculation would be relative to ambient temperature. Your cool air generation process would have ambient air available at the same temperature as the engine intake system. The amount of energy needed to cool the ambient air to any given temperature would vary with different ambient temperatures.

When it's all said and done, you're talking about one air stream's temperature that you're trying to cool, and that would be relative to the ambient temperature regardless of the optimum intake air temperature of an internal combustion engine. It would have an energy cost associated with the difference in temperature (how much cooling) that you're trying to affect.  

The system will also include a programable thermostat, so i will be able to control the temperature no matter what the ambient temperature is ( The systems are capable of 100 F from incoming air temp. However, the system does require air to be moved at 60 psi to work properly, so I would need to do some more head scratching, because I believe I would need a hell of a compressor to keep up. Do you have a chart that shows the incoming air flow rate to a 4.0L per rpm?  
2001 TJ Sport
- 4.0L I6
- Sport Wheels w/ 30 x 9.50
- Half Steel Doors
- Soft Top
- Daily Driver
- Standard Tranny
- 3:73 Gears

I don't have a chart but Click Here for a calculator. Use 75% ve for a stock engine. Plug in a few rpm values and that will tell you the cfm to support that rpm.  

The more I think about your "cold air generator" the more I'm convinced that it would be a very inefficient way to produce cold air.

So, why does it exist? My guess would be for industry. There are all kinds of processes that happen in industry that have unused bi-products. If these "free" energy sources could be harnessed, then you might get something for "free".

So if there was some process that was shedding heat and that heat could be used to power a pump, either directly or indirectly, then you could get free air flow that could be cooled in the low pressure chamber that you described.

"Ideal Gas Law" tells us the pressure, volume, and temperature of a gas are all related. A lower pressure = a lower temperature. This is regardless of how the pressure is lowered mechanically.

Lets assume that the most efficient way to cool air is with an air conditioner. That's easy to assume because that's what's on your car or in your home.

Your car's a/c system will move 75-100 cfm of air at 47-55 degrees when ambient temperature is 100f. So if that air was directed to the engine intake, that would be cooling your intake charge by 40 degrees. That would represent a 6-8hp improvement. Your a/c compressor requires 5 hp to operate. But that's less than half of the cfm required for the 4.0L at 4000 rpm. So if you double the capacity of your a/c system, it would then consume 10hp but only produce 6-8hp. That's a net loss of 2-4hp.  

Interesting stuff...  
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nitrous or co2 system would be a hell of alot cheaper and most likely more effective with that stuff leaving the bottle @ way below sub zero temps  
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JLayne,
I'm basically focusing on a continuos "natural" supply type of setup where you don't have to keep refilling tanks(thats where it starts getting expensive). Plus, isn't Nitrous and CO2 system momentary, used in drag racing or hill climbing?
If the vortex tube works out, it'll be a continuos supply of "free" air and there will be no need to modify the motor.

Giles,
Vortex Tubes are used to:
-Cool machining operations
-Dehumidify gas samples
-Set solders and adhesives
-Cool heat seal operations
-Cool plastic injection molds
-Cool cutter blades
-Dry ink on labels on bottles
-Temperature cycle parts
-Provides cool dry air to electrical
enclosures

The company I work for, we use them to cool electrical enclosures for our contol systems and sensors that are used in steel mills.

Vortec's website is: http://www.vortec.com/vortex_tubes.php
They have a graphic that shows how the tubes work. The only mechanical items that would be involved is the compressor suppling the air to it and a solenoid to control the air to the system.  
2001 TJ Sport
- 4.0L I6
- Sport Wheels w/ 30 x 9.50
- Half Steel Doors
- Soft Top
- Daily Driver
- Standard Tranny
- 3:73 Gears

Thanks for the calculator link. I may have to look into building my own, so far the largest industrial I've been able to locate, produces 150 SCFM. There's plans I've come across for Home Built ones, but of course they nowhere get close enough to producing as well as a industrial built ones.  
2001 TJ Sport
- 4.0L I6
- Sport Wheels w/ 30 x 9.50
- Half Steel Doors
- Soft Top
- Daily Driver
- Standard Tranny
- 3:73 Gears

Here's some quick numbers for you. On that site, it lists the cooling capacity of the Vortex tubes in BTU. That's a number that can be used for comparison.

1 watt is approximately 3.413 BTU
1 horsepower is approximately 2,544 BTU
1 horsepower is 745.7 watts
1 "ton of cooling" is 12,000 BTU
8000 BTU required for 200 cfm of air flow or approximately 3.1 horsepower

The largest Vortex tube they list is 5000 BTU. That would be equivalent to almost 2hp and support a maximum air flow of 125 cfm.

Now these are just energy equivalents and don't allow for the efficiency loss associated with all processes, especially mechanical. Most compressors are only about 40% efficient, diabatic, which means the heat generated is not reused in the process or is wasted. Adiabatic means the heat generated is stored. A Supercharger for example is 40% efficient (diabatic), but 70% efficient with an intercooler (adiabatic).

So if a simple compressor is only 40% efficient, then that more than doubles the horsepower needed to supply the cooling BTU's.

That gets right back to my previous example that states 5hp is needed to produce a 40 degeee drop for 75-100 cfm of airflow. That leaves very little if any in the form of available "work".

Sorry, this is definitely not something worth pursuing.  

wouldn't it be easier to figure out a way to plumb into an air to water incooler?  My friend and I are trying to figure out how to make it work.  If you look at the inside of a Vortech intercooler you will see a series of fins much like a radiator. Our assumption is to find a way use this as a way to plumb the A/C from the car and cool the fins inside the intercooler.  No loss of pressure or any other issues I could think of.  Any suggestions?  

Did you read my second post in this thread? Ford has already tried using the a/c to cool the intake air. Without successful gains.

And remember, turbos and superchargers compress air, which makes the air much hotter than ambient air temps. Intercoolers reduce super heated air to a temp that is still much hotter than ambient air. Intercoolers only make performance sense for compressed air, not normally aspirated air.

The whole cold air concept is so overblown by companies that have something to sell, it's just ridiculous.

There is a 1% increase in power for every 10 degrees of cooling. Plumb in a temp probe into your intake system, and you'll see that your intake air temp is not more than 15 degrees higher than the ambient air temp. So if you have a 200hp 4.0L, that would be a loss of 3hp. When you're driving down the road, the intake charge air is often the same as ambient.

If there was something to the "cold air" hysteria, don't you think the engineers that work for the auto mfgs would be all over it instead of spending millions on R&D for things like variable valve timing and direct injection; things that really do give more power and improved fuel efficiency.  

I agree on the power needed to run it.  So you gain 6hp.... How much does hp does it draw from the motor?  
Tripping over a dollar to pick up a penny comes to mind.
I personally would go with a turbo or supercharger setup.
One oddball thought comes to mind...  A large intercooler with water spray.  I don't know if restriction would overcome gain.  Even with ambient air and ambient water, the water will evaporate on the intercooler, thus reducing temperature.  How much? I'm not an engineer.  Keep a tank w/ ice water and use a wiper pump and you may gain.  Momentary, but a hell of a lot less expensive and longer lasting than nitrous.  The Subaru STI's used this on their intercoolers, but that was to cool the intake after the turbo.  
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