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PaulL
23-04-2014, 11:11 AM
Hello there

I am having more and more request of systems no more utilizing R404A but R407F and R404A.
I would stay stick on R404A, or R507, nonetheless the request of systems with these two refrigernts is increasing.

Therefore I have started to analyze these two new refrigerants, reading threads and googling it

Basically what I have noticed is :
- performance of the two new refrigerants (R407A, R407F) are basically equivalent.
- condenser capacity is lower than R404A around 15%, according to the td considered
- evaporator capacity is higher than R404A around 10% according to the td considered.
- R407F has high discharge temperatures, so that it seems that low temperature applications are difficoult.


What really worries me in utilizing these two refrigerants is that they have glide (4-6K)

are they suitable to freezing application ?

I can see some potential problems, for example: in the coil there are colder parts where frost can form faster.

Please may I ask you if you have an experience on this ?


Many thanks

Sandro Baptista
23-04-2014, 04:28 PM
PaulL see my answers below


Hello there

I am having more and more request of systems no more utilizing R404A but R407F and R404A.
I would stay stick on R404A, or R507, nonetheless the request of systems with these two refrigernts is increasing.

Therefore I have started to analyze these two new refrigerants, reading threads and googling it

Basically what I have noticed is :
- performance of the two new refrigerants (R407A, R407F) are basically equivalent.
- condenser capacity is lower than R404A around 15%, according to the td considered
- evaporator capacity is higher than R404A around 10% according to the td considered.
- R407F has high discharge temperatures, so that it seems that low temperature applications are difficoult. No problem, just take take in consideration you will need additional cooling like fan at the compressor head, CIC system (like Bitzer) has it...It will be as you had use R22


What really worries me in utilizing these two refrigerants is that they have glide (4-6K). No problem if you use dry-expansion feed

are they suitable to freezing application ?

I can see some potential problems, for example: in the coil there are colder parts where frost can form faster. If you are worry about that use a medium evaporating temperature, between the bubble and dew point

Please may I ask you if you have an experience on this ?


Many thanks

coolman
23-04-2014, 09:22 PM
Recently modified a large supermarket from 404a to 407F as it is claimed to have a beter cop and less energie use.
Thsi supermarket has to cooling installtions, both 85 Hp each.
regulation is done with danfoss akm equipment all cabinets have electronic danfoss expansion valves.

After a few weeks after initial retrofit high pressure cut out was noticed and client complained that all cabinets started to leak water.
Ambient was nice but not extreem.

so I was called out to investigate and correct.
at site first had a climb to condensor as at that moment hp was tripping, arriving at condensor to check if it was dirty, i noticed that liquid return was within normal range, warm but not hot (old trusty hand check)
so in my opinion no reason for hp trip.

Than went into shop to check cabinets and water problem.
Noticed that all eveporators and driptray where fully iced up, so took out the trusted gauges and went to check all pressures on sets.

here i noticed that in control units refrigerant was set to R22, so started to compare with trusted refslide as my testo does not support r407F.

so refering to presure and temperture noticed thas suction temp was at about -19-20 C actual and liquid at 43C

In the and regulation was calibrated to adjust for the glide and pressure was set to proper setting af -8 suction and hp at 52

installtion is now running fine, no problems, perfect cabinet temperatures, and no more hp tripping.

so when retrofitting make sure proper adjustment are made so suction an discharge as within proper settings.

btw there also is a energie monitoring and energie savings are within 12%