~~Hey yo, help me on this crap please ASAP whatever...

[ironizer]

all right, so first of all, if you're reading this thread, thank-you, you're really cool, and even better if you can help...

 

ok, so let's say we got ourselves a turbocharger thing, such as the one in the picture here:

 

http://en.wikipedia.org/wiki/Turbocharger

 

I wanna (really bad) know the efficiency of one of these (doesn't have to be the same type as the wikipedia picture one). You can think of it this way:

 

You put 100KW of energy into compressing air.

You pipe the air to the inlet part of the turbocharger, so that it works... compressing air into another tank.

Given that everything in the system (except the turbo itself) is ideally (100%) efficient, (so no friction or nothing), then how much air would you get back into the second tank... or, if you used that air to generate electricity (again, generator and all that crap 100% efficient), how many KW could you pump out of it? Would be cool if you could hit me with some %-ege.

 

I tired google but didn't work for me. Maybe my googling skills just blow @$$, i dunnno...

 

Thanks if you can help!

[Jacques]

0 KW

Pratically it's impossible to 100% efficiency so you will lose energy for nothing

[insane_alien]

well, would need to know the pressure in and pressure out then i could give you some numbers.

 

The efficiency will depend on how well its machined, the manufacturer will probably have some info on it

 

EDIT: needs to read posts fully before answering. gah

[Klaynos]

it is not practically impossible, it is not allowed by the laws of thermodynamics...

 

As for working out the maths for this question you'd need to know the sizes and pressures of all the compartments and work them out from the basics.

[ironizer]

it is not practically impossible, it is not allowed by the laws of thermodynamics...

 

As for working out the maths for this question you'd need to know the sizes and pressures of all the compartments and work them out from the basics.

 

I don't want any math or anything, just need an idea of how efficient those things are, that's it.

 

I realize the question was too complex for some of you (no offense)

I'll put it this way: You feed the turbo a flow of air, and, on the other side, you get another flow of air OUT. My question is, if you put in 100UNITS of air in, then how many UNITS of air would you ~apporximately~, ~roughly~ get out on the other end? Don't try to get too complicated on this...

[Klaynos]

Well the net flow is one way, so the same amount out as you put in, would leave it, it has nowhere else to go...

 

As for efficiencies as their rate of flow and energy required I can probably find out within a week or two, my best mate is an aston tech who's had to learn alot of theory about such things...

[ironizer]

hey, i think you're getting on the right track. I guess I didn't explain myself right using words, so this picture should help. I should have done this from the beginning.

 

I don't want any exact math, I'm clueless to how efficient these are. Is it 25%? 30%? 50%? 75...80%?

 

image at imageshack:

http://img54.imageshack.us/my.php?image=turbopartskw3.gif

[Klaynos]

oh yes I was being dumb.

 

Well I don't know off the top of my head, I shall ask around...

[ironizer]

thanks a ton man... if you could give me an idea on this that would be so sweet, because I don't know anything about this stuff, and I REALLY REALLY need to know. muchas gracias!

[Ndi]

It's very inefficient because it was not supposed to work that way. It's supposed to push air through at a certain pressure and a certain flow, not compress. Thus, several million liters of air on one side will unlikely go over 2-3 atmospheres before the turbo actually exploded, throwing blades everywhere.

 

If you lower the pressure to keep it from shaking, it will deliver as designed, around 2 bar. The turbo doesn't work that way, it's meant as an energy recycling pump, not a transformation tool. If you want to move compressed air, you'd have better shots with a compressor, either automotive (roots, centri, etc) or a custom design (I'd go for a piston). That's why a 7 HP compressor on a Mercedes gets .5 bar in an engine and a 12 volt, 0.005 HP compressor fills a wheel with air up to 4 bar.

 

It's like using an airplane propeller to blow air. While it's quite good at doing just that, it's all about flow. Freely, it can move may cubic meters at 500 km/h. Use it to fill a balloon and as soon as it reaches a certain stage the pressure will escape back through the blades. For a balloon, you need a pump.

 

* If you are looking to use it as a compressor, bad choice.

 

* If you are trying to compute engine efficiency, it doesn't work that way, you compute relative to engine capacity. The efficiency listed in various docs are rated relative to other parameters. That's why it can go from +10% to over 100% (a cascading model can give a +300%), but that it's not the air flow relative movement.

 

* If you are trying to use an automotive turbo in another project it's quite complex and demanding (high-spin, sensitive oiling, cooling, etc). A real life turbo spins in excess of 120.000 RPM and the blades are quite different for intake/exhaust, something that does not show in the schematic. It converts slow-moving, high-pressure gas into fast-moving, lower pressure gas.

 

Perhaps if your project is a little clearer we can give you a better explanation. Air tanks is not a good application.

[ironizer]

is it efficient in transforming the airflow into rotary motion, or is it the other side, the comrpessor, that sucks? ...because if that's the case, you can just use a centrifugal compressor for it, because those can get some serious pressures if used in multi-staging (that's what wikipedia says)

 

if it's the other part (the one that takes in the exaust flow) that sucks, then couldn't you use muli-staging for that?

 

What i'm trying to use this for is to take any airflow, and use it to compress air into another tank. It sounds retarded, but that's just how it is.

[Ndi]

you can just use a centrifugal compressor for it, because those can get some serious pressures if used in multi-staging (that's what wikipedia says)

 

In cars, yes, multi-staging can get serious pressures. In automotive applications, where exhaust air has to escape at a certain rate, restriction is limited and the "serious" pressure is never over 3 bar.

 

To "move" pressure, I'd go for a piston setup, like steam train systems. The pressure in the tank can move a piston which in turn moves a heavy wheel that acts as stabilizer. That same wheel can move a pump on the other end. Just two pistons, a wheel, bearings and valves. You can copy the piston off a steam train or a car piston.

 

I remember a Discovery junkyard thing when they linked two engines together. One turned and they used the other to pump water (I think they modified the exhaust valves or camshaft to avoid compression stage. Something like that).

 

You can redesign it as 2-piston so that one piston is driven by compressed air and the other pumps. You'll find the actual concept is the same as the turbine, except it uses linked pistons instead of linked blades. You can copy most of the design from a boxer engine. Perhaps even refine it to a 4-piston (doesn't need speedup and heavy flywheel).

[ironizer]

To "move" pressure, I'd go for a piston setup, like steam train systems. The pressure in the tank can move a piston which in turn moves a heavy wheel that acts as stabilizer. That same wheel can move a pump on the other end. Just two pistons, a wheel, bearings and valves. You can copy the piston off a steam train or a car piston.

 

You can redesign it as 2-piston so that one piston is driven by compressed air and the other pumps. You'll find the actual concept is the same as the turbine, except it uses linked pistons instead of linked blades. You can copy most of the design from a boxer engine. Perhaps even refine it to a 4-piston (doesn't need speedup and heavy flywheel).

 

 

Thanks man, you don't know how much this means to me...

 

but aren't piston compressors like.. really unefficient, because here i'm shooting for the highest effieciency possible, and i think turbines (just like any steam/water/gas/whatever turbines) are more efficient than pistons.

[Ndi]

Turbines *might* be more efficient, less friction (air, only one joint), etc. I'm not sure. But they suck at compressing air tanks. However, there are setups where turbines are less-than-efficient: turbulence in air flow, very high spin, very low spin, etc.

 

Pistons are not inefficient, but they can pump incredible pressures at any rate needed. Thus they are found in high-pressure, low flow applications, usually backed up by a pressurized container that acts as a buffer. Like the turbine in a dentist's office, water - CO2 applications (don't know the English name, it's when you make tap water into a fizzy drink), tank refills, etc.

 

You find turbines in high-flow applications, like blowers, fans, etc where sustained flow at low(er) pressure is needed.

 

You simply can't blow up a basketball with a vacuum cleaner, in spite of the fact it uses 2 KW. You can blow it up by hand, however. That's why a car has a fan for cooling and a compressor for AC.

 

Not to mention turbines lose their effectiveness if the blades were designed for a different flow. A car turbine (e.g. GT25, IIRC) comes rated for a 1.5-2.2 liter engine. Any lower it doesn't spin. Any higher and it starts spitting blades. And this is the highest quality manufacturing available, oil film axle, etc. So if you have 2.2 bar in the tank, as soon as the pressure drops below 1.5 you're in quite some trouble. (I know I mashed bar in tank and engine capacity, ignore it). You could have adapting blades but it gets really, really complicated.

[ironizer]

given the info you gave me (thanks) and what wikipedia says:

 

Centrifugal compressors — use a vaned rotating disk or impeller in a shaped housing to force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser (divergent duct) section converts the velocity energy to pressure energy. These are for continuous, heavy industrial uses and are usually stationary. Their application can be from 100 hp (75 kW) to thousands of horsepower. With multiple staging, they can achieve extremely high output pressures greater than 10,000 lbf/in² (69 MPa).

 

 

... i came up with this design:

 

http://img184.imageshack.us/img184/9850/designjh4.jpg

 

tell me what you think. thanks a ton!

[Rocket Man]

a scroll compressor gives high pressure, low volume. a single stage turbine, generally gives high volume low pressure.

you can use multi staged turbine on either side, just make sure you have stators between stages and run it fast.

a piston compressor is about the simplest, cheapest compressor you're going to find.

 

you'd do well to consider the working rpm of both sides and select compatible engines and compressors, a turbine running a scroll compressor is a bit ridiculous

 

if you really wanted to get fancy, you could purchase a quaziturbine, a sort of rotary engine/compressor. it has much the same uses as a piston compressor but with less working inertia/vibration.