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Thread: R407c
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07-10-2003, 05:27 AM #1
R407c
What are the repercussions of using R 407C for a medium temperature refrigeration application ? I'm aware of the temperature glide of 6-8K and possible fractionation that happens with this refrigerant. How about design and field issues ?
Design : Evaporator and Condensor selection - need to oversize ?
Field : Leakages - how do you manage this ?
Some air-conditioning manufacturers claim that R 407 C is a very efficient refrigerant because of the glide - the compressor suction 'sees' a higher suction temperature and so does not have to 'work ' as hard as say, if R22 is used. But then in the condensor, the condensing temperature also progressively drops and may approach the ambient - so you may need a higher design condensing temperature - and off goes your efficiency advantage , right ?
Any views/assistance appreciated ?
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08-10-2003, 10:25 PM #2
Hi Bersaga
407c works well at high temperature ranges. My most recent experience is on water to water heat pumps with 2 deg C evaporation and 52 deg c condensing, with COP in the range of 3.8, so you could say it works well there. Medium temp is proabably alright, but you would have a little both controlling your evaporator flooding and your sution superheat, I would say leading to less than ideal (high) superheats and some reduction in effeciency.
Regards. Andy
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09-10-2003, 01:54 AM #3
Thanks Andy - but say , on an application that requires -15 C evaporating temp. R407 C has a glide of 6-8 K(or more) at that point. Do I select a TXV rated at -15 evap or look for some sort of average ?
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09-10-2003, 07:59 PM #4
Have a look at this from Copeland http://www.ecopeland.com/Literature/...0100_Glide.pdf
Frank
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09-10-2003, 10:40 PM #5
Hi Bersaga,
from reading Frank's Copeland document I would say use Dew point to set the expansion valve and Mid point when selecting compressors and matching capacities.
Kind Regards. Andy.
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