oil free compressor

[Lc_shi]

I've heard that Danfoss have the oil free small capacity centrifugal compressor for HVACR application. As we know ,the oil lubrication is very important for refrigeration system but affect the efficiency and bring up problems at the same time,if the system is oil free ,it would be better ,i believe. How about the oil free tech for other types compressor,e.g. is it possible for piston\scroll\screw etc?

rgds
LC

[US Iceman]

Hi LC,

You always bring up interesting topics to discuss.

Here is a link to the Danfoss site for the centrifugal compressors.

http://www.turbocor.com/applications/

The manufacturer I used to work for did manufacture a large piston compressor that was oil-free. There were many problems and the compressor was eventually discontinued.

Some of the large manufacturers of twin screw compressors build oil-free compressors currently. However, normal (refrigeration and some gas compression applications) screw compressors are oil injected.

A portion of the oil is for lubrication, a greater portion of oil is used to cool the gas compression process.

Dry screw compressors run fairly hot, therefore additional requirements become important. In this case, you might need liquefied refrigerant to be injected into the compression process to maintain a reasonable discharge temperature.

At the same time, if liquid refrigerant is injected into the compression process, the overall power use increases due to the additional mass flow of refrigerant through the compressor.

High temperature applications like HVAC might be OK if R-134a is used, or other refrigerants having a low specific heat ratio. High specific heat ratio refrigerants like ammonia would be very interesting to solve.

Good question!

US Iceman

[johnyfreon]

McQuay has been using the turbocor compressor in some of their chillers, check their web-site tons of good info there.

[knighty]

what about hydrovane compressors as used for compressed air ?

[TXiceman]

Problem with the Turbocor is a rather limited range of capacities from what I have seen. Company I had wowrked for looked and tried to apply some Turbocor machines, but found very few fits.

Ken

[old gas bottle]

i can only compare the likes of reclaim units that need the oil mixed in with the refrigerant to survive and they dont last that long just in ocassional use,if you were to use one on virgin refrigerant its life expectancy is reduced even more,i have a yellow jacket R100 twin with ceramic internal componants that will do the job but they are three times the price of standard machines, so maybe the technoliges there but not the market pricing.

[Andy]

Hi:)
the Turbocor compressors are oil free, and run on R134a only. No bearings or sealing surfaces that require oil. Magnetic bearings.

Used for chilled water operation 6 and 12 deg c with a capacity of 200kw each, if you want 1000kw use 5:D

Very efficient at low speed or part load, not so at high speed, but then chillers run part loaded mostly, so their Seasonal Energy Efficiency ratio is good:)

Knightly:)

vane compressors were used for low stage compression on booster large low temperature systems for years. But their efficency was vey poor:( very few plants running on these now, I know one another mothballed.

Kind Regards Andy:)

Kind Regards Andy