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KETTLER
02-05-2006, 12:23 AM
:eek: I would like to use a SOLAR COLLECTOR as an evaporator for an R111 system that would heat water through a chiller.
Thoughts?:confused:

US Iceman
02-05-2006, 02:32 AM
I did a quick search for this fluid.

R-111 = pentachlorofluoroethane
Boiling point = 275F [135C]

My first thought (& question) is: This has chlorine in it, so is it permissible for use? It is listed as a CFC.

Second question: This has ethane also, so you need to be aware of the need for intrinsic safety with electrical devices.

If the collectors generate a sufficient temperature to boil this fluid, why do you need a chiller? The heat sink (the lower temperature you are rejecting heat to) will be low enough to condense the refrigerant at temperatures high enough for space heating.

You could use a refrigerant pump to circulate the fluid.

1) boil the refrigerant in the collectors.
2) the refrigerant vapor travels to the cold heat sink and condenses to a liquid
3) The refrigerant condensation process heats the water
4) the refrigerant pump circulates the condensed refrigerant back to the collectors for boiling again.

The idea is reasonable, but I don't think the fluid is suitable.

Johnny Rod
02-05-2006, 09:05 AM
It is a CFC so won't be flammable - no hydrogen in it (the "ethane" bit only tells you about the backbone of the molecule that the Fs and Cls are attached to). Think you're right, wouldn't a lower boiling point be more suitable? Unless kettler means R11, but then that would be a bit low?

NoNickName
02-05-2006, 11:21 AM
Why not using a water/water heat pump with std solar collector and a more environmental friendly refrigerant?
That type of HP would help in keeping the charge low...

KETTLER
02-05-2006, 11:27 AM
Thanks everybody. I appreciate the information and dialoge.

KETTLER
02-05-2006, 11:30 AM
:) Thanks! I think the refrigerant I picked is incorrect. :confused: Will look into.


I did a quick search for this fluid.

R-111 = pentachlorofluoroethane
Boiling point = 275F [135C]

My first thought (& question) is: This has chlorine in it, so is it permissible for use? It is listed as a CFC.

Second question: This has ethane also, so you need to be aware of the need for intrinsic safety with electrical devices.

If the collectors generate a sufficient temperature to boil this fluid, why do you need a chiller? The heat sink (the lower temperature you are rejecting heat to) will be low enough to condense the refrigerant at temperatures high enough for space heating.

You could use a refrigerant pump to circulate the fluid.

1) boil the refrigerant in the collectors.
2) the refrigerant vapor travels to the cold heat sink and condenses to a liquid
3) The refrigerant condensation process heats the water
4) the refrigerant pump circulates the condensed refrigerant back to the collectors for boiling again.

The idea is reasonable, but I don't think the fluid is suitable.

US Iceman
02-05-2006, 03:13 PM
...the "ethane" bit only tells you about the backbone of the molecule that the Fs and Cls are attached to)

Thanks for that. I am certainly no chemist.;) Can you provide a short explanation why the ethane becomes non-combustible?

If we bypass the CFC issue, the fluid could work if the Pressure/Temperature relationship does not exceed the design pressure limits for the collectors and system.

I think a lot of this depends on the type of collector (flat plate or concentrating and/or tracking capability). If the fluid can evaporate at 275F [135C] at atmospheric pressure it can also condense at the same temperature.

The lower heat sink temperature would be less than 275F [135C], so this could generate hot water (pressurized) or steam at atmospheric pressure. A simple thermosiphon, except the liquid would have to be pumped to the collector panels, if the heat sink is lower than the panels.

R-114 has been used in a similar application except I believe the system did use a compressor to circulate the refrigerant around the system.

Johnny Rod
03-05-2006, 01:32 PM
It's part of the IUPAC naming convention. Ethane means the molecule has a backbone of 2 carbon atoms (methane is 1, propane is 3, butane is 4 but can be straight or T-shaped) and has 6 attachment points. When it's preceded by mono-/di-/tri- fluoro-/chloro-/bromo- etc. then these atoms are attached to the backbone. Any leftover spaces are taken up by hydrogen atoms - in ethane istelf there are only hydrogens attached (it is a HC). More hydrogen atoms means more flammable (HCFCs, HFCs). No hydrogens (CFCs and FCs) means not flammable, except at high temps. Pictures work better but I don't have anything to hand.

KETTLER
09-05-2006, 11:37 AM
I'm looking for a list of REFRIGERANTS and their corresponding BOILING POINTS. Does anyone know where I can obtain the information?

NoNickName
09-05-2006, 11:45 AM
Try coolpack or refpack in the database section above

Josip
09-05-2006, 02:52 PM
Hello Kettler,

you can download this to see:

http://www.airah.org.au/downloads/AIRAH_RSG2003.pdf

maybe you can find something more at: http://www.airah.org.au/

Attached file is not complete (need to extract some pages to reduce file size)

Here at "Andy's HVAC/R Web Page" you can download REFPROP v1.0 Calculator for 38 refrigerants and some other useful things :)

http://users.isp.com//aschoen/

Hope this will help, come back with comments, please ;)

Best regards,

Josip :)

KETTLER
10-05-2006, 12:24 PM
Thanks! I'm looking at the information you provided and will get back to you.