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26-07-2016, 01:33 AM #1
Liquid Subcooler causing high suction pressure drop
Hello everyone!
Long time just reading you... now I have an issue.
I have a system with several circuits and multiple compresors on a Parallel system, each liquid line has a subcooler (whose return gets into the Rack's suction manifold) to avoid flashing on a long rise to evaporators, but I noticed that when the subcooler is open the pressure drop on Suction line is very high; when I close the liquid subcooler the suction pressure drop lowers to a reasonable digit.
I calculate this in a Danfoss Cool Selector software, and the theoretically efect should be the opposite, with liquid subcooling there should be lower suction pressure drop.
Any idea why this is happening??
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26-07-2016, 09:07 AM #2
Re: Liquid Subcooler causing high suction pressure drop
Georgedvf,
If subcooler suction line returns into suction line then theoretically load should be identical with it on or off.
The sub-cooling only helps system run more efficiently in the superheat control of evaporator.
If you turn off & suction pressure lowers, then maybe evaporators working at lower capacity.
What at type of system, pressures temperatures & refrigerant.
How much subcooling do you achieve?
what type of Tx valves?
What type of compressor?
Also clarify what you mean pressure drop or rise in suction line, is it inhibiting performance or just observationLast edited by RANGER1; 26-07-2016 at 09:10 AM.
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26-07-2016, 01:57 PM #3
Re: Liquid Subcooler causing high suction pressure drop
Hello Ranger1.
Suction pressure rises in evaporator when turn on subcooler. It's R134a, 20°F liquid subcooling, EEV(pulse electronic expansion valves), reciprocant bitzer compressors.
The suction pressure drop I mean evaporator pressure vs compressor suction pressure, the pressure in compressor doesn't change with subcooler on or off, but when turn on subcooler evaporator pressure goes higher about 5-7psig.
The line rise is in liquid line, it is about 40ft vertical line to evaporators.
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26-07-2016, 08:35 PM #4
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26-07-2016, 10:46 PM #5
Re: Liquid Subcooler causing high suction pressure drop
The calculated size for suction manifold is 3-5/8" including subcoolers load. The installed manifold is 8" to use it as acumulator as well.
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28-07-2016, 08:28 PM #6
Re: Liquid Subcooler causing high suction pressure drop
Yes have a look in my first question, i put other photos there...