Turbocor compressors

[sgrmarley]

Hi all I was wondering if any of you have seen/worked with Turbocor compressors before.

Reason I ask is I am likely to be working on some soon and have not seen them before.

We are going to get some training soon, but I would be interested to get some feedback about potential problems/and good points especially on air cooled machines.

Thanks guys

[Ian B]

What do you want to know? We have about 25 Turbocor chillers in our area, all on R134a and all aircooled.

regards

Ian

[sgrmarley]

Just general stuff really. I work on air cooled chillers a lot so that side is no problem. Centrifugal compressors on the other hand are new to me. Am I right in thinking they are not positive displacement and would therefore not like it if the load is fluctuating, or is that wrong?

Also the controls look very complicated do they seem reliable??

Any info, no matter how basic would be appreciated as I have never worked on a centrif before and am not at all familiar with these machines.

[Tesla]

You can get technical pdf from the danfos website. I seen one on r22 aircooled. They have high COP at reduced loads.

[Ian B]

Sorry for the delay in writting back, really busy.
basically the compressor is a two stage centrif driven by a DC motor.
They are incredibly reliable and very efficent at part load.
The controls are quite complex but that because theres alot being contoled.
The rotor levitates on two magnetic bearings, these bearings energise and de-energise to keep the rotor true, radially and axially.
The compressor has large capacitors on the side to keep the rotor levitated until stop in the event of a power interuption.
The compressor also needs a dedicated liquid supply to cool the inverter and other controls.

initially we had a number of hardware failures but that has all been ironed out and as i said before these compressors are very efficient and defiatley the way forward.
Just be carefull theres a number of bad examples out there.

Hope this is of some help

regards

Ian

[sgrmarley]

Yes thanks Ian.

I've actually just got the full technical manual for these comps, they do look very clever and rather specialized.

Initially I was sceptical, but perhaps it's a good thing and will probably scare off some "engineers" who like to play with things that they shouldn't be playing with.

[Plank!]

Erm, Ian you must have missed a few pages in the manual

Its 5 electromagnetic bearings - not 2.
The bearing position is positioned by four radial and one axial bearing magnets each being controlled proportionally from sensors around the rotor, this happens around 1000 times every second. The bearings are driven by amplifiers that work exactly like digital audio amplifiers - the electromagnets in the bearings even have similar impedance characteristics to loudspeaker voice coils.

The motor is AC driven, via an inverter that runs from 0 - 800Hz. (0 - 48000rpm)

The capacitors are used to aid in keeping the rotor levitated, but also form an essential part of the DC supply that feeds the invertor along with the bearings.
During unexpected power downs the invertor switches into generator mode and actually charges the capacitors - in the process acting as a shunt brake on the motor - this ensures the rotor stops spinning before the bearinng magnets lower it into the parked position.

Regards
Plank!

ps. there is a thread about magnetic bearing compressors somewhere with more info.

[Plank!]

You can get technical pdf from the danfos website. I seen one on r22 aircooled. They have high COP at reduced loads.

Danfoss does not supply turbocor compressors for R22 ONLY R134a.

Do you have any more info on the R22 machine?

Regards
Plank!

[Plank!]

Just general stuff really. I work on air cooled chillers a lot so that side is no problem. Centrifugal compressors on the other hand are new to me. Am I right in thinking they are not positive displacement and would therefore not like it if the load is fluctuating, or is that wrong?

Also the controls look very complicated do they seem reliable??

Any info, no matter how basic would be appreciated as I have never worked on a centrif before and am not at all familiar with these machines.

The compressors do indeed prefer a stable load, very sudden changes in condensing or suction pressure can cause erratic behaviour in the rotor position, sometimes seen as a bearing fault by the compressor. Close control of head pressure and liquid control is essential.

The comp is not positive displacement, but has enough computational power to figure out optimal running conditions and calculate its Stall and Choke points - ie the minimum and maximum rotor speeds to allow efficient pumping. It also means the comp can be run with very low superheat, we've run them as low as 1.5K with no problems. All this helps add up to a very efficient machine.

[nike123]

Danfoss does not supply turbocor compressors for R22 ONLY R134a.

Compressor is compressor, regardless of gas type.

[Plank!]

Compressor is compressor, regardless of gas type.

True, but in this case the elctronics calculate the superheat, choke and stall points etc based on temperature and vapour density curves for R134a

[nike123]

True, but in this case the elctronics calculate the superheat, choke and stall points etc based on temperature and vapour density curves for R134a

Yet again, you only need to change firmware/software, not hardware.

[Plank!]

Yet again, you only need to change firmware/software, not hardware.

That may well be the case, however the technical guys at danfoss made it very clear they do not want the compressor used on anything other than R134a - could be a restriction in the patent for all i know, but none the less, it was said with enough weight that I'll not be the one to try it with R22

[Andy]

That may well be the case, however the technical guys at danfoss made it very clear they do not want the compressor used on anything other than R134a - could be a restriction in the patent for all i know, but none the less, it was said with enough weight that I'll not be the one to try it with R22

Hello

pressure or compression ratio R134a is a low compresion ratio gas, which suits centrif compressors.

You could use Butane but limited uses.

Kind Regards Andy

[Plank!]

Hello

pressure or compression ratio R134a is a low compresion ratio gas, which suits centrif compressors.

You could use Butane but limited uses.

Kind Regards Andy

Cheers Andy.

That makes a lot of sense, the turbocor unit has a compression ratio of 2.5.

TBH I have zero experience on centrif's except for the turbocor. Not too old to learn tho