- This topic has 4 replies, 4 voices, and was last updated 9 years, 8 months ago by
.
- Topic
- Replies
They all have different characteristics and regulatory status that makes them suitable for different purposes. The most basic property necessary in a refrigerant is the ability to change states from liquid to to gas at certain temperatures and pressures. Other important physical characteristics are toxicity and flammability (you wouldn’t want a flammable gas to fill the cabin of a car in an accident, for example). From a regulatory perspective issues like supposed damage to the ozone layer or supposed contribution to global warming are important. (I am skeptical about these things.)
So, for example, R12 is by far the best refrigerant for mobile applications, its temperature/pressure characteristics make it very efficient at transferring heat and it is non-toxic and non-flammable and it is extremely stable. However, as you probably know, it is believed to damage the ozone layer so it was banned sometime around 1993. R134a was chosen as a replacement for R12– although it is less efficient, it is non-flammable, non-toxic, is stable and operates within a similar pressure range as R12 making it possible to retrofit a system to R134a. However, with the recent global warming hysteria, governments (especially in Europe) have been looking for an alternative to R134a because it is believed to have a very high global warming potential. There has been some discussion of using CO2 as a refrigerant, but this has been largely found to be impractical because of the extremely high pressures that the system would need to operate in (in the thousands of psi)– that requires a very heavy duty system and specialized service equipment.– to give you a sense of the irrationality of the regulators, it would still be illegal to vent CO2 from an A/C system requiring that millions be spent on specialized equipment to capture and recycle it (even though we all breathe it out). Anyway, the industry has now settled on a new refrigerant, HFO 1234yf that is apparently more practical than CO2, but has the disadvantage of being slightly flammable, since presumably burning up a few people in car accidents has been deemed to have a lower global warming effect than R134a. I saw in the news that the European Union has recently granted a patent on the new refrigerant, so there is also the political advantage of a refrigerant that a large company with lots of money to make donations gets a temporary monopoly. So that should give you some idea of the considerations that go into different refrigerants.
An update of sorts – was looking around DuPont’s website and see that indeed the European Union has adopted a Directive, which stipulates that from 2011 mobile air condition systems (MAC) of new types of vehicles have to be filled with a refrigerant with low GWP (a de facto ban of the use
of refrigerant R134a).One of these is HFO-1234yf, which DuPont calls Opteon® YF.
I guess one could get some of this stuff from one of these DuPont jobbers?
http://www2.dupont.com/Refrigerants/en_US/uses_apps/automotive_ac/SmartAutoAC/where_to_buy_NA.html
If the tree huggers in the EU adopted this, is there any doubt, the tree huggers here might push for it?
Anyone have any idea what it would take to convert an R-1234a system to a HFO-1234yf system? What’s the word from our resident HV/AC experts?
You can use HFC-152a right now, without changing anything, not even the oil. It has been recently approved by the EPA for use as an automotive refrigerant in the US, and has been in other countries as well. Just pull out the R134a, evac, and recharge with the new refrigerant. The chemical in HFC-152a is difluoroethane. It is very inexpensive as well, and it is eco-friendly (does not harm the atmosphere). It is easy to find too. Just look for cans of electronics duster. Look at the back, and see that the ingredient is difluoroethane. Walmart sells it in a three-pack of 10oz cans for like $8. I put it in my Jeep and the A/C has never worked better.
- You must be logged in to reply to this topic.