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20-12-2017, 02:35 PM #1
R404A Pressure-Enthalpy Diagram Properties VS Pressure-Temp Chart Properties
Hey guys, I need some clarification between these 2 data sets.
I was studying a refrigeration system that uses R404A. I graphed the refrigeration cycle on a P-H Diagram to get a better idea of what was going on. After that, i looked up a Pressure-Temp Chart for R404 and noticed things were not adding up. On the PH Diagram R404 is at 0*F at a pressure of about 50psia, however according the Pressure-Temp Chart for the same refrigerant, @ 0*F P=33.5 psig. Am i missing something here?
Thanks in advance!
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20-12-2017, 02:49 PM #2
Re: R404A Pressure-Enthalpy Diagram Properties VS Pressure-Temp Chart Properties
Only missing about 2.5 psi so not too bad.
Brian - Newton Abbot, Devon, UK
Retired March 2015
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20-12-2017, 03:11 PM #3
Re: R404A Pressure-Enthalpy Diagram Properties VS Pressure-Temp Chart Properties
haha actually it turns out it was a little more than 2.5, more like 14.7 psi. I think i have found the discrepancy and it all boiled down to units. The Pressure-Temp table is in psig and the P-H graph is in psia.
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20-12-2017, 05:24 PM #4
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20-12-2017, 08:24 PM #5
Re: R404A Pressure-Enthalpy Diagram Properties VS Pressure-Temp Chart Properties
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pH charts are always in absolute.
So they will always be 1 atmosphere
higher than gauge.
1 atmosphere = 1 bar = 14.7 psi
Rob
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20-12-2017, 08:46 PM #6
Re: R404A Pressure-Enthalpy Diagram Properties VS Pressure-Temp Chart Properties
Cool thanks for the help guys! Just one more example of why units are our friends !