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hvacrr
08-10-2011, 04:13 PM
How to calculate the volume of low pressure receiver(seprator)? Scientific Method & Rules of Thumb

Thank you!

NoNickName
10-10-2011, 10:44 AM
ASHRAE chapter R2.30 only indicates the accumulator to be with Length-to-diameter ration of 3/1 to 5/1 with a free height above liquid of about 600-750mm

Magoo
11-10-2011, 04:43 AM
Totally agree with NNN

sterl
08-12-2011, 07:39 PM
Volume is simple to calculate and you will find the tables on the site of any pressure vessel manufacturer....but I think you are really looking for Capacity as in effective separation speed?

hvacrr
15-12-2011, 09:27 PM
Volume is simple to calculate and you will find the tables on the site of any pressure vessel manufacturer....but I think you are really looking for Capacity as in effective separation speed?

Yes, I want know the procedure of sizing the separator for 1) effective separation 2) adequate volume for liquid supply and liquid surge

sterl
01-02-2012, 12:50 AM
Effective separation is in multiple textbooks but the readily available form is:
www.irc.wisc.edu/file.php?id=61

If you look up Evapco on the Web and go to pressure vessels: Is all in US units but its as handy as set of tables as you will find.

As to Hold Up Volume: Your Application, as in evaporator and process establish that.... For instance: If you are going to defrost a big finned coil (think pallet blast freezer) you will have to accumulate all the liquid generated as the hot gas condenses.....and whatever the hot gas pushed out of the coil (the residual cold liquid) as well as that which condensed before the "melt" portion of the defrost got going. This could be as high as 30 minutes of HG flow (before anything comes back) and then that liquid will tend to return to the separating vessel in as little as 3 to 4 minutes, which is why you have to accomodate it: you will never evaporate it or pump it away or transfer it as fast as a big single coil can dump it at you. So the "Surge Volume" can exceed the volume of your largest coil though for suction accumulators, that volume is often used as a "first start, thumb in the air" sort of a number.

Of course, this also effects your high side accumulation because the volume of whats in your suction accumulator is a reduction to the HP receiver level or the content of some other vessel, somewhere. So putting a very large accumulator on the low side and letting the collecting liquid evaporate out over an extended period of time will not work if there is not otherwise liquid stored somewhere to keep the rest of the circuit active.