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21-06-2009, 08:42 AM #1
Pressure drop through the suction line accumulator?
Now I am using a suction line accumulator (R134a) between my evaporator and compressor. I measured that the pressure of evaporator is about 3 bar but the inlet pressure of compressor is about 1bar. That means accumulator caused the pressure drop of 2 bar.
My dear friends, is it normal that accumulator results in such big pressure drop? I am not quite clear about the inner structure of accumulator. Is there any bolck or mesh in the accumulator which could induce the pressure drop?
Thanks a lot!
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21-06-2009, 10:49 AM #2
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Re: Pressure drop through the suction line accumulator?
Pressure drop of suction accumulator is about 0.3°C.
What is make and model # of your accumulator?
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21-06-2009, 03:11 PM #3
Re: Pressure drop through the suction line accumulator?
Full of liquid.
Debris is almost not possible, most don't have mesh filters in it.It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.
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22-06-2009, 03:21 AM #4
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22-06-2009, 03:25 AM #5
Re: Pressure drop through the suction line accumulator?
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22-06-2009, 04:43 AM #6
Re: Pressure drop through the suction line accumulator?
design kw rating of evap & comp at what suction temp would be good to see.sounds to me your suction line is undersized,only accumulator prob ive had is the tube falling off inside.
mmm to beer or not to beer...........lets drink breakfast
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22-06-2009, 07:07 AM #7
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22-06-2009, 07:21 AM #8
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22-06-2009, 07:22 AM #9
Re: Pressure drop through the suction line accumulator?
R-134a @ 0.3'C dP
= (0.3/1.1)*13.3 kPa
= 3.63kPa
= 0.0363 bar
Source 'Application Guide AG 31-011' "Refrigerant piping design guide", McQuayEngineering Specialist - Cuprobraze, Nocolok, CD Technology
Rarefied Technologies ( SE Asia )
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22-06-2009, 09:04 AM #10
Re: Pressure drop through the suction line accumulator?
I don't think that "full of liquid" state could make pressure drop in range of 2 bar.[/QUOTE]
In another thread on this forum, you will find this actual situation which isn't resolved yet. Even a bigger pressure drop Nike of 2 barLast edited by Peter_1; 22-06-2009 at 08:04 PM.
It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.
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22-06-2009, 09:24 AM #11
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22-06-2009, 09:30 AM #12
Re: Pressure drop through the suction line accumulator?
I suspect there is something else between the evap and the compressor. Perhaps a suction drier or an EPR valve... or maybe a kink in the line.
Check the suction line temperature from the evap to the compressor. Where you find a temperature drop you will find the pressure drop.
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22-06-2009, 09:50 AM #13
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22-06-2009, 12:14 PM #14
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22-06-2009, 12:33 PM #15
Re: Pressure drop through the suction line accumulator?
.
Many heat pumps of Far Eastern or Japanese manufacture incorporate a wire mesh filter in the inlet pipe at the top of the accumulator.
These are mostly unmarked, little more than the diameter of the pipe and often block with debris.
You need to cut the whole thing out to locate it.
I have also seen them be fitted the wrong way around (i.e. reversed flow) at the factory.
.
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22-06-2009, 01:15 PM #16
Re: Pressure drop through the suction line accumulator?
Hello Frank.
? Are you speaking about that L'Unite Hermetique from your thread: http://www.refrigeration-engineer.co...ad.php?t=18967
If yes, could you please give other parameters, such as room temp, evap dT, SH, presupposing 3 Bar is evap pressure.
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22-06-2009, 01:15 PM #17
Re: Pressure drop through the suction line accumulator?
gday frank nikes photo depicts the said tube internally,you can hang any size suction line off the fitting ie lets say long pipe run requires larger size piping,size of accumulator ports is only relevant to capacity (kw) of system.5/8" accumulator with 1 1/8" pipe run
mmm to beer or not to beer...........lets drink breakfast
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22-06-2009, 01:40 PM #18
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Re: Pressure drop through the suction line accumulator?
You mean this one?
Pressure drop there is 1,9 Bar.
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22-06-2009, 01:49 PM #19
Re: Pressure drop through the suction line accumulator?
Ciao,
Interesting debate, it appears to be a large pressure drop to be caused by an accumulator full of liquid, what is the pipe temperature at the accumulator inlet/outlet and the compressor inlet?
CheersTutto il Mondo e un Paese
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22-06-2009, 01:50 PM #20
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Re: Pressure drop through the suction line accumulator?
frank721
As Gary already pointed out, when there is pressure drop, there is temperature drop.
Measure accumulator inlet pipe and outlet pipe temperature ((and post your findings here).
If difference is greater than 0,5°C you have restriction in accumulator. If not, your problem is elsewhere.
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22-06-2009, 08:06 PM #21
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22-06-2009, 08:33 PM #22
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22-06-2009, 08:35 PM #23
Re: Pressure drop through the suction line accumulator?
That's true... but with this much restriction I'm thinking we can assume a liquid/vapor mixture before the restriction... especially if it has a liquid filled accumulator.
But then, we don't have enough information about the system.
Is this a cooler or a freezer?
Is it a cap tube system or a TXV system?
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22-06-2009, 08:36 PM #24
Re: Pressure drop through the suction line accumulator?
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22-06-2009, 09:07 PM #25
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22-06-2009, 11:02 PM #26
Re: Pressure drop through the suction line accumulator?
why not fit shreader tails into inlet/outlet sides of accumulator,if anything it will tell you if it is the problem.dont like them myself as they ushally just become large oil traps on our old hot gas systems.
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23-06-2009, 06:55 AM #27
Re: Pressure drop through the suction line accumulator?
That's also what I'm thinking about it.
Give us some more information.
What's your SH on the evaporator? What's the pressure inside your accumulator and what's its shell temperature? That's how we found out it was full of liquid.
Install schraeders as Fowlie suggested and share this readings
Nike, at least no noticeable temperature drop, perhaps you can see it with an IR imaged scanner, perhaps..
A pressure reduction of a gas can be perfectly isothermicLast edited by Peter_1; 23-06-2009 at 07:15 AM.
It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.
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23-06-2009, 10:45 AM #28
Re: Pressure drop through the suction line accumulator?
My believe is any gas pressed, then cooled down to ambient, during sudden expanding will always consume SOME heat (insufficient however at all for refrigeration). And using nitrogen, we deal with a huge expansion - from 200Bg down to 20-30Bg (then to 0 Bg). But not so huge gas transition is here - only from 3B to 1B.
Frank meanwhile, is not giving the whole picture, having drawn onto the scene only that partricular part of his system.
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25-06-2009, 07:12 AM #29
Re: Pressure drop through the suction line accumulator?
is the accumulator to small?a reply from the original poster would be good
mmm to beer or not to beer...........lets drink breakfast
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01-07-2009, 11:47 AM #30
Re: Pressure drop through the suction line accumulator?
dear freinds. sorry for late reply, since i was on leave in this period. it was not convenient for me to use internet.
now, let's continue. i feel so warm here because you are so kind.
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01-07-2009, 11:50 AM #31
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01-07-2009, 11:59 AM #32
Re: Pressure drop through the suction line accumulator?
Thanks for your suggestion. there is no other device between the accumulator and compressor. But you bring a good point: kink in the line. In fact, the diameter of outlet of accumulator is 7/8" and diameter of inlet of compressor is 5/8", but they are connected with a smaller tube of 1/4"
is it the reason that cause the big pressure drop?
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01-07-2009, 12:02 PM #33
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01-07-2009, 12:07 PM #34
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01-07-2009, 12:10 PM #35
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01-07-2009, 12:14 PM #36
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01-07-2009, 05:41 PM #37
Re: Pressure drop through the suction line accumulator?
Hi Frank.
What temp air off evap ?
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01-07-2009, 05:44 PM #38
Re: Pressure drop through the suction line accumulator?
And what the RH of the 31C air by the way?
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01-07-2009, 06:11 PM #39
Re: Pressure drop through the suction line accumulator?
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01-07-2009, 06:53 PM #40
Re: Pressure drop through the suction line accumulator?
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02-07-2009, 07:15 AM #41
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02-07-2009, 02:45 PM #42
Re: Pressure drop through the suction line accumulator?
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02-07-2009, 04:56 PM #43
Re: Pressure drop through the suction line accumulator?
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07-07-2009, 03:50 AM #44
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07-07-2009, 03:54 AM #45
Re: Pressure drop through the suction line accumulator?
yes, it is 1/4" really.
there is a needle valve between the evap and accumulator. but it is fully open. pressure drop is not significant when fully open.
it seems that we have found the cause of the 2 bar pressure drop:7/8" to 1/4"
thanks a lot, my friends
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07-07-2009, 04:05 AM #46
Re: Pressure drop through the suction line accumulator?
For discussing conveniently, i post the schematic of the evaporator. i measured the pressures at Point 1 and 2.
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07-07-2009, 04:14 AM #47
Re: Pressure drop through the suction line accumulator?
frank if suction line diameter is fixed by size of accumulator port,what the hell happened.when anyone has a vague out i call it the autoduhh syndrome it can happen any time.
mmm to beer or not to beer...........lets drink breakfast
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07-07-2009, 04:17 AM #48
Re: Pressure drop through the suction line accumulator?
interesting picture whats it of frank
mmm to beer or not to beer...........lets drink breakfast
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07-07-2009, 06:59 AM #49
Re: Pressure drop through the suction line accumulator?
I think your compressor is going to suffer the world of pain, sooner, rather than later...
Engineering Specialist - Cuprobraze, Nocolok, CD Technology
Rarefied Technologies ( SE Asia )
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07-07-2009, 09:00 PM #50
Re: Pressure drop through the suction line accumulator?
That's a flooded evaporator... and a whole different ball game.
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