Info Carrier 30GX-358

[rooboy]

Gday Fellas

I wonder if someone could possibly give me some background on a Carrier Chiller that I am currently working on. The model is a 30 GX - 358 - AO290.

It is a two circuit , 4 screw system.

I originally understood it to be an economised system, however having requested a schematic from the manufacturer I found that the economised 30 GX is nothing like this model. The non economised version of the same model also gives a schematic that is similar but missing vital parts.

The liquid line, after passing through the sight glass and dryer then passes through a plate heat exchanger. Prior to this liquid is picked up from the liquid line and expanded through an EXV then passed through the other side of the plate heat exchanger and subsequently to the compressors via a temp controlled solenoid valve.

My issue is, is this expanded ' cool gas' being used to simply cool the motor windings , or is it actually entering the screw chamber at some point and hence acting as an economiser.

I have been told that this system is French built.

I am not very familiar with screws. Any thoughts would be appreciated.

Thanks

[Gibbo]

You have a French made Pro Dialog Plus Phase 3 Chiller and yes it is econimised, normal chiller doesn't have the plate heat exchanger.
The diagram that was sent probably from a earlier design whihc had a different style of econimiser.

[rooboy]

Thanks Gibbo

Ok that would make sense that the design and style of the economiser has been updated.

Can you tell me what sort of pressure we should expect on the cool gas line prior to entering the screws ?

Cheers

[Grizzly]

Hi rooboy
Below is a link to the manuals you may need .
I hope they help?
Grizzly

http://www.mediafire.com/?9c15xjzytdn

http://www.mediafire.com/?9c15xjzytdn

[Gibbo]

Your econimiser pressure will be a bit higher than your suction pressure.

[Dimitris]

Hi Rooboy, the system with the plate heat exchanger is an economiser and cools the motor winding as well as a being a subcooler. If you need more info, I'll be happy to explain.
Dimitris

[rooboy]

Grizzly - thanks for the links to the manuals.
Dmitris - I will check out the manuals and get it right in my head and then get back to you.

Thanks to you both

Rooboy

[rooboy]

Grizzly

I checked out your link and the manual provides some good info, but unfortunately not quite what I am after.

Can you or Dimitri tell me about the plate heat exchanger on the liquid line and whether it is specifically used for motor cooling or for economising - knowing they are not one and the same.

Thanks

[Grizzly]

Grizzly

I checked out your link and the manual provides some good info, but unfortunately not quite what I am after.

Can you or Dimitri tell me about the plate heat exchanger on the liquid line and whether it is specifically used for motor cooling or for economising - knowing they are not one and the same.

Thanks

Hi rooboy.
Just doing my bit for the forum, as I knew where to look for the manuals.
And I hoped they might help you?

Sadly in this case I cannot advise as I have not worked on these particular units.
Maybe Dimitri, Gibbo or one of the other Guys may be able to help?

Maybe these comps have what other manufacturers term side load injection?
Where the refrigerant is injected part way down the rotor loabs giving increased duty for the size of the rotor?
Just a thought?
Good Luck Grizzly

[Gibbo]

The econimiser can do both

[Dimitris]

Hi Rooboy,
The thermal expansion valve controls the refrigerant flow through the plate heat exchanger. The temperature of the compressor's winding controls the thermal expansion valve. When refrigerant flows in the plate heat exchanger it:
a) subcools the refrigerant in the liquid line which passes through the other side of it the plate heat exchanger
b) cools down the compressor's winding
c) is drawn into the intermediate compressor stage after passing through the compressor's winding

a + c = economiser

I hope this helps.

Dimitris

[rooboy]

Hi Rooboy,
The thermal expansion valve controls the refrigerant flow through the plate heat exchanger. The temperature of the compressor's winding controls the thermal expansion valve. When refrigerant flows in the plate heat exchanger it:
a) subcools the refrigerant in the liquid line which passes through the other side of it the plate heat exchanger
b) cools down the compressor's winding
c) is drawn into the intermediate compressor stage after passing through the compressor's winding

a + c = economiser

I hope this helps.

Dimitris

Gday Dimitris

Can you tell me , as there is a solenoid at the motor , is this also controlled by the temp of the motor windings or is this just for shutdown,with the temp of the windings only controlling the thermal expansion valve ?


Thanks

[Dimitris]

Hi Rooboy,
The solenoid of the model with the plate heat exchanger, is turned on every time the compressor is. It turns off only when the compressor is off.

[rooboy]

Dimitris

Thanks , that is exactly what I needed to know. Now I understand where we've been going wrong.

Cheers

Rooboy