Natural Refrigerants

[baker]

Last month on radio there was a good introduction to natural refrigerants. You can see the transcript at: http://www.abc.net.au/rn/science/ear...s/s1039294.htm

[shogun7]

Baker:
Carbon dioxide was the preferred refrigerant in the early 20th century, only to be replaced by man-made chemicals. Now it appears poised for a comeback so I suppose if man worked with it then he can do it again.
As the article stated the problem with CO2, as it was when it was used years ago, is the extremely high pressure that it is under. It has operating pressures the likes of which air conditioners have not seen , five to seven times more than normal refrigeration used now. And because of this hi pressure the gas tends to leak out easily and quickly I would think. Also the cost would be high, because an entirely new air conditioning system would be needed.
The entire system would be at least schedule 80 pipe and fittings and quite a substantial compressor, as far as efficiency is concerned I think the jury is still out on that (kw/Ton)
Anyway this will be interesting to watch. Remember my post on closed cycle air refrigeration – that also is an alternative and like CO2 it operates with high pressures but you can’t beat it for a safe and nondestructive refrigerant.
Roger

[frank]

Roger

Please consider us mere mortals here in the UK -
What is schedule 80 pipe and fittings?

[shogun7]

Frank sorrry I too have trouble with some of the posts over there. PiPe schedules 5. 10, 20,40, 80 have various wall thicknesses the larger the number the heavier the wall thickness.

ASTM standard specifications covers various types of steel pipes, tubes and fittings for high-temperature service, ordinary use and special applications such as fire protection use. Specifications for steel tubes list standard requirements for boiler and superheater tubes, general service tubes, steel tubes in refinery service, heat exchanger and condenser tubes, mechanical and structural tubing. with what I had reference to it may fall under this application:A179 A179/A179M-90a (1996) e1 Specification for Seamless Cold-Drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes

[shogun7]

I found this interesting reading, thought you might too!
Roger
Fractionation Effects on
System Charge

A system at rest will allow the refrigerant to pool and the vapor to come to an equilibrium concentration. Leaks which occur in vapor areas of the equipment will allow fractionation of the blend. The worst case will occur when about half of the refrigerant charge has leaked.
Small amounts leaked from a system will not change the remaining blend by much. Large leaks will shift the composition, but the majority of the pounds after recharge will be from fresh product at the right composition.
Recharging the system after repair will result in a blend with slightly reduced capacity and operating pressures. In smaller systems, where charge size is critical, it will be best to pull any remaining refrigerant and charge with fresh blend. In larger systems you will need to make a
decision whether the remaining charge should be pulled or not. Note: for Low Fractionation Potential blends you will not see much shift in composition anyway, and therefore the charge can be topped off after repair without loss of properties.
In running systems it has been found that the circulating composition is the bulk blend
composition. In liquid and suction lines there is no second phase, and in the heat exchangers
there is much turbulence so leaks will lose both vapor and liquid. Testing has shown that leaks from a running system do not cause fractionation, and a normally cycling system will not fractionate much on the off cycle.
In other words, in most cases servicing blends does not require full recovery of the charge.

[dude]

What about nitrous oxide which liquefies relatively easily?

[jg/oz]

Friends,
Just for those into " Natural Fluids" an interesting Day for those in the know
go to

http://www.refrigerantsnaturally.com

On a day in June 2004 a few large companies eg MacDonald, Coke and
Unilever (ice division) gave their views and commitments for the future on
Naturals.

Interesting to see what is ahead of us, are you willling to be one of them
in the new technologies or are you keeping your knowledge base closed for the future, you may be at the end of your Trade lige soon.

jg/oz
australia.

http://www.refrigerantsnaturally.com

[ejonesss]

the advantage of co2 is you can then go to your local sports shop and get the co2 for use in paintball guns or to your local soda or beer store and get the co2 used for food and some adaptors to allow connecting the co2 cans to the service nipple on the system.

and even get the stuff legally