Simple Answer needed

[munesh]

Which is better refrigerant R407C or R134a? Please guide? Why?
I have gone through much of the sites searching for the same and I could find myself more confused. Can anyone help me on this

[NoNickName]

There is no such thing as the "best refrigerant". There is a more suitable refrigerant for a specific application. If you are in India and are looking for air conditioning appliances, then R134a is better for you.

[fridgey]

"There is no such thing as the "best refrigerant". There is a more suitable refrigerant for a specific application."

True, I agree. Theres no simple answer to which is better either. In my opinion R134a is a lazy gas, it was made as a replacement for R12, but has been wildley used in many applications because of its zero ODP and lower GWP. There are better preforming refrigerants R407C one of them but it's not as friendly as R134A in GWP. R407C is also a blend and has a high temperature glide which is not always favourable. But it all comes back to your application. What application are you looking at?

[Samarjit Sen]

As stated above, there is nothing as best refrigerant. It depends on what your application is. You have to study the properties of the refrigerants and then depending on your application find the suitable one.

[munesh]

"There is no such thing as the "best refrigerant". There is a more suitable refrigerant for a specific application."

True, I agree. Theres no simple answer to which is better either. In my opinion R134a is a lazy gas, it was made as a replacement for R12, but has been wildley used in many applications because of its zero ODP and lower GWP. There are better preforming refrigerants R407C one of them but it's not as friendly as R134A in GWP. R407C is also a blend and has a high temperature glide which is not always favourable. But it all comes back to your application. What application are you looking at?

I want to use Screw Chillers for Air Conditioning. The major players out here differ in refrigerants. Some use R134a (Carrier, Trane) and some are using R407c (Hitachi). I am preparing a comparative for all of them. From whatever I have gathered I came to know that R407c is better refrigerant but have not come across the exact comparative for the two. I would verymuch like to have a comparative of the two. I checked Dupont site but it lacks on comparatives. If possible you could guide on some site for the same.

[Samarjit Sen]

Considering the application and with high ambient in our country, I feel choosing R 134a would be more suitable.

It is not possible to make any comparision and nor will you find any comparitive charts. The refrigerant shall depend completely on the application. In this case it is for air conditioning.

Further you have to see the avaibility of the refrigerant and the cost. R 134a is easily available and people in our country are now more used to it. Costwise too it is cheaper than R 407c.

[narkom]

It is not possible to make any comparision and nor will you find any comparitive charts. The refrigerant shall depend completely on the application. In this case it is for air conditioning.

I guess ASHRAE handbook will help us . Lets look at table 7. I think ""Net refrigerating effect"" is the point we need. One can see that R407 is 162.28/149.95=1.08 more efficient at this working conditions.
But if we use flooded evaporator/condenser, R134 will gain an advantage because of its low working pressure

[US Iceman]

narkom has a good point to think about. Look at the refrigerant properties also but think about the overall impact and other aspects.

In the ASHRAE table R-134a requires 0.814 liters/second for the compressor displacement and requires 0.217 kW for power. The compression ratio is 4.69:1.

If you look at R-507a it requires 0.461 liters/second for the compressor displacement and 0.239 kW for the power. For this refrigerant the compression ratio is 3.84:1.

Now before anyone gets excited....

Think of this. Yes, the power use for R-507a is approximately 10% higher . However, the compressor is almost 50% smaller in displacement!

If you can design the system to operate with a slightly lower condensing temperature the energy use could be equal to R-134a, plus the compressor is smaller. However, the pipe sizes may be slightly larger for the R-507a system rather than R-134a system for the same capacity.

You have to look at everything and all operating conditions, not just the mass flow or COP.

[munesh]

Thanks every one your answers were of great help.
Also special thanks for the comparatives.