Series compressors in one stage...

[n00b 0f l337]

If you series'd up two compressors of similar or the same specs in a stage, be it a first or 2nd or anything, and managed to balance the oil, what would happen?

Let's say its two 1/2hp rotary's. Would there be a very large vacuum on the low side with a really low bp?

[star882]

It could work. You'll just increase the pressure ratio. Keep in mind, however, that you'll need a desuperheater between the compressors to avoid overheating. A coil of pipe works great for that.

[n00b 0f l337]

Of course. And you'd need an oil seperator to then balance oil return to both compressors.

[\Karting_freak]

that WONT work
the first compressor needs to be like 10times weaker or smth like that

chilly i think told about it long time ago )

[_HL4E_HalfLife_]

Hes right it won't work adding another compressor in series is NOT going to increase the pumping capacity of the first compressor, however if u had the compressors in parallel than ur idea would work.

[jinu117]

Series... so whats cooling the 2nd compressor?

[n00b 0f l337]

Good point, thats why I asked. I was drinking (not the best time for ideas) and I thought, if you can series compressors to make a ghetto-vacuum pump ...
You know the rest.

[Jort]

you CAN run 2 compressor's in series BUT you need to cool down the gas that enters the 2nd compressor.

THe name for the system you want to make calls "Booster"

i'll take a foto right away

edit: here it is.
there is also another type of this, with a liquidline hx.

imo this aint the best solution out there to build;)

[n00b 0f l337]

So its basically has 3 evaps to limit just a little flow back to compressors and the rest to the evap.

[quintus]

yeah paralel u need them! i ask the same q as u did, but i waz awake :rolleyes: :D
see ya

[Jort]

So its basically has 3 evaps to limit just a little flow back to compressors and the rest to the evap.


no 2, the gas that leaves the liquid line hx cools down the 2nd compressor;-)

[_HL4E_HalfLife_]

It Won't Work!!!!!!!!!!!!!

[jinu117]

Short of not having having oil sep... so... what was the point of going through this complicated process for sub optimal temperature? :)

[Jort]

It Won't Work!!!!!!!!!!!!!


please go elsewhere if don't anything more to say,
ITS BEEN USED IN THE FIELD:)

Short of not having having oil sep... so... what was the point of going through this complicated process for sub optimal temperature? :)

this is actualy like a cascade, with this application you can get a lower pressure proportion compared with a single stage.

cascade is offcourse better then this:)

[Unknown_road]

It Won't Work!!!!!!!!!!!!!

And you base that on what? only looking at a performance chart of a compressor will tell your wrong :slap:

[_HL4E_HalfLife_]

And you base that on what? only looking at a performance chart of a compressor will tell your wrong :slap:

I say this because as i said in my first post adding a 2nd compressor in series with the first is not gonna increase the compressing speed of the first compressor, the only way to do that is to increase the RPM of the first compressor or put them in parallel. Prove me wrong with some cold hard results than ill retract my claim.:fact:

[MaRtIe]

some intense words being said here :p:

[Jort]

I say this because as i said in my first post adding a 2nd compressor in series with the first is not gonna increase the compressing speed of the first compressor, the only way to do that is to increase the RPM of the first compressor or put them in parallel. Prove me wrong with some cold hard results than ill retract my claim.:fact:

thats true, without doing some changes it won't work,
but with some changes on the piping a nice system can be made:toast:

[RussC]

My .02 is that they do this in the automotive aftermarket ie series turbochargers or supercharger/turbo in series. It works there very well. In this case, it may not increase overall refrigerant flow, it can produce higher pressure out of the second stage. That higher pressure can condense lower boiling point refrigerants, right. That in itself can increase cooling. But as it was said earlier, a true cascade is more efficient.

RussC

[Unknown_road]

I say this because as i said in my first post adding a 2nd compressor in series with the first is not gonna increase the compressing speed of the first compressor, the only way to do that is to increase the RPM of the first compressor or put them in parallel. Prove me wrong with some cold hard results than ill retract my claim.:fact:

The discharge pressure of the first compressor wil be much lower because the discharge gas is sucked away by the second compressor. Because of this the first compressor can maitain a much lower suction pressure.

When you look at the spec sheet of a compressor you'll see that the capacity rating is higher with lower condensing temp (pressure).

The efficiency of the compressor increases when the compression ratio lowers.

Normal system condensing @ 15bar and 1 bar suction == compression ratio 1:15
compound(series) intermediate pressure, say 3-4 bar. So 1st compressor has a discharge pressure of only 3-4 bar! Compression ratio isn't linear but I suspect that 0.6-0.7 bar is achieveble with the same heat load as the normal system with 1 bar suction.

[Jort]

The discharge pressure of the first compressor wil be much lower because the discharge gas is sucked away by the second compressor. Because of this the first compressor can maitain a much lower suction pressure.

When you look at the spec sheet of a compressor you'll see that the capacity rating is higher with lower condensing temp (pressure).

The efficiency of the compressor increases when the compression ratio lowers.

Normal system condensing @ 15bar and 1 bar suction == compression ratio 1:15
compound(series) intermediate pressure, say 3-4 bar. So 1st compressor has a discharge pressure of only 3-4 bar! Compression ratio isn't linear but I suspect that 0.6-0.7 bar is achieveble with the same heat load as the normal system with 1 bar suction.

http://www.firevictor.co.th/chillmatch/images/bitzer_rec_2stage_01.jpg

this is a compoundsystem;)

In compound compression, the work of compression is divided into two or more stages or cylinders. In two-stage compression, air is compressed in the first or low-pressure cylinder to a certain point, then forced into an intercooler where it is cooled to approx. its original temperature, then passes into the second or high-pressure cylinder, in which it is compressed to the final or delivery pressure. The ratio of compression in each cylinder of a two-stage compressor is equal to the square root of the overall ratio of compression, i.e., the square root of the final absolute pressure divided by the absolute atmospheric pressure. In three-stage work, the ratio of compression in each cylinder is the cube root of theoverall ratio of compression. Also called stage compression.

:cool:

[wdrzal]

a 2 stage or even 3 stage compressor just uses a progessivly smaller diameter piston in each stage to raise the pressure. Say the 1st stage has a 1-1/2" diameter piston with a 3" stroke this is compressed and discharged to the second stage which may have a 3/4" diameter piston with a 3" stroke. this is 2 stage compression,not a 2 stage cascade.

[Jort]

hey wdrzal where not saying its a 2stage cascade;)

btw someone needs to test this out, if this works quite good it can make some real low numbers.

unknown_road and me are open for trail:slap: :banana:

[pocketbikeuk]

hey wdrzal where not saying its a 2stage cascade;)

btw someone needs to test this out, if this works quite good it can make some real low numbers.

unknown_road and me are open for trail:slap: :banana:

how about a try with 2 small compressors say 1/10th will that make ppl happy it would be a laugh might do it this wknd for some fun. btw do i really need a oil balancing line that means drilling into the little babies

[Jort]

the oil will travel all true afaik, no need for balance:)

[Unknown_road]

how about a try with 2 small compressors say 1/10th will that make ppl happy it would be a laugh might do it this wknd for some fun. btw do i really need a oil balancing line that means drilling into the little babies

adding an oil balancing line will destroy the first compressor in 2 seconds :D The intermediate pressure will push all the oil in the first compressor, so the first compressor suck up oil and the second compressor wil run dry.

you need 2 oil seps for this kind of system to work properly!!!

@jort: no oil will not just flow through. Even if you use 2 exactly the same compressors the suction pressure of them is different so the oil output of them isn't the same. Maybe it will take some time but after a while 1 compressor will be out of oil and 1 full.

[Jort]

adding an oil balancing line will destroy the first compressor in 2 seconds :D The intermediate pressure will push all the oil in the first compressor, so the first compressor suck up oil and the second compressor wil run dry.

you need 2 oil seps for this kind of system to work properly!!!

@jort: no oil will not just flow through. Even if you use 2 exactly the same compressors the suction pressure of them is different so the oil output of them isn't the same. Maybe it will take some time but after a while 1 compressor will be out of oil and 1 full.

so where going to think about it? :buddies: :hehe:

[Unknown_road]

I'm up for the challenge ;)

[Jort]

allright, lets do it, lets dance ... LOL:D

[Jort]

just called with my classm8, who i am going to build the cascade with for the schoolproject.

our teacher said it's no problem too add the 2stage to the cascade.
so this means there is going to be a killer cascade soon.

i know what you think about it unknown but w'll see about that,
we have plenty experienced people around us:D

beside that, w'll try to make one for ourself's, w'll see about that very soon ;)