AC refrigerant in cars,greenhouse effect reasoning

[marellasunny]

I'm a mechanical engineer and am learning about the different refrigerants used.
2 of them seem to be the most popular- R134a(C2H2F4) and R1234yf(C3H2F4).

Why is it that R134a is rated at a Greenhouse effect(GWP) of 1430 where R1234yf is rated at a GWP of 4?

Both refrigerants produce CO2,I assume.Won't R1234yf produce more of it considering it has more carbon atoms?

 

[Yanick]

It seems you are misunderstanding the concept of a GWP. I wasn't aware of how this rating is measured/calculated but a quick Google/Wikipedia excursion revealed that GWP is not related to the production of CO₂ by a given compound, but is a measure of how much EM energy a given compound will absorb in a certain amount of time relative to the same mass of CO₂. The CO₂ appears to be arbitrarily set to 1 as a reference.

See the Wikipedia for more information: http://en.wikipedia.org/wiki/Global-warming_potential