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yorkie
22-09-2007, 03:07 AM
Hello all,
I have a project for a medium pressure refrigeration system that requires a cooling capacity up to 15kW.

The customer is paramount on the use of hydrocarbons.
At the moment i am looking into changing all the electical components to make it safe but not sure if the compressor would be suitable. I have looked into the oil and that is ok although i am adding a crank case heater.

Does anyone know of any compressors that would do the job. Evap at 7C condense 50C probally R290 (propane) as the compressor manufacturer at the moment does not offer any solution.

Its a friday night and i am googles up to the eye balls.

750 Valve
30-09-2007, 09:07 AM
Good luck, I know bitzer are hesitant to warrant use on r290. Have seen small danfoss comps - under 1 kw on r290 at sydney olympics - none since though.

taz24
30-09-2007, 02:21 PM
Hello all,
I have a project for a medium pressure refrigeration system that requires a cooling capacity up to 15kW.

Its a friday night and i am googles up to the eye balls.

The comp needs to be intrinsicly safe.
All conections need to be sealed and no sparks possible.
The comp internals will be ok as long as it is compatible with the oil.
Pure refrigerant in the system is safe, as long as there is no Oxygen in there with it. Even if there is oxygen in the system, the pressures involved almost negate any chance that you will achieve the correct partial pressure to cause a problem. The risk is almost negligable.

Cheers taz.

Pooh
30-09-2007, 02:30 PM
Yorkie
the only difference between Hydrocarbon compressors and normal is that the internal protection is elecrtronic not Klixon typre as you do not want any sparks internally. I know Danfoss/Manuerop do HC comps. The question as to changing the electrics is a difficult one as on most systems I have worked on normal electrics are used as the refrigerant is inside the system so why protect against it and to be honest with the quantities used and the dillution factor in normal areas where the plant is installed you would never get to an explosive concentration anyway. If it is AC why not use a HC water chiller outside and just pump glycol into the area to be cooled. Looking at the loading this may not be feasable on this occasion. If you keep the runs short you should not have a problem.

Ian

Brian_UK
30-09-2007, 11:33 PM
It can also depend on the size of the charge to go in the system as to whether you can use HCs or not.

Have a read here, on page 7, for starters.

http://www.bbc-consultancy.com/Hydrocarbon_Refrigerants_Guidelines.pdf

Pooh
01-10-2007, 12:02 AM
Brian
the regs look similar to ammonia and we all know how dangerous that is. Realistically taking that you usually need only 60 to 70 percent of an equivilant HFC charge for a given cooling capacity with HC's a 15kw duty aslong as the pipe run is short or you use two systems there should not be a problem.

Ian

US Iceman
01-10-2007, 01:16 AM
...similar to ammonia and we all know how dangerous that is.


Booo!:(

How dangerous are other refrigerants?

NH3LVR
01-10-2007, 01:32 AM
Booo!:(

How dangerous are other refrigerants?

The Diamond mall in Anchorage 15 years ago. Two people dead, numerous to the hospital-Refrigerant=R-502.
You cannot smell it. You just get a bit dizzy, and then die!

Pooh
01-10-2007, 01:28 PM
Guys
as an ammonia engineer I was being sarcastic in my comment. The big problem with ammonia and HC is the perceived danger not the actual danger.

Ian

750 Valve
03-10-2007, 01:12 PM
Yorkie
The question as to changing the electrics is a difficult one as on most systems I have worked on normal electrics are used as the refrigerant is inside the system so why protect against it and to be honest with the quantities used and the dillution factor in normal areas where the plant is installed you would never get to an explosive concentration anyway.
Ian

If you install leak detection and ventilation system and can guarantee that no part of the environment where the unit is stored can get to the low flammability limits of the refrigerant used then sure its safe not to use flame proof switchgear.

yorkie
07-11-2007, 08:43 PM
Thank you all for the comments to date and sorry for the long reply

The system is going to be on the primary side (on roof)(2 circuits) with a secondary refrigerant supplying some AHU's via a Heat Exchanger.

Its a fully ventilated system with an external control panel located about 2m away.

I know to increased the viscocity of the oil as well due to miscibility of the refrigerant/ oil.

I need to get the job done asap.

Customer getting a bit twitchy.

Not sure to say sorry and go back to a system with R410A.


My old boss used it many years ago and i think he would be proud for me to use it again but safer than the really old stuff.
?

Yorkie