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Rfcont
14-11-2005, 05:36 PM
Hi all!

If you need to remove heat loading, for example 500 KW, what way you prefer:
1. install one remote condenser 500 KW
2. install two remote condensers on 250 KW each in parallel
3. install 5 remote condensers on 100 KW each in parallel
What decision is better and why?
:)
Thanks!

RSFN1974
14-11-2005, 06:09 PM
That depends!

Is it a constant heatload?

If it's constant you might as well use one condenser with fan control. Preferrable with speedcontrol on the fans instead of on/off control. And in Moscow you might need some condensing pressure reg. during the wintertime.

If it's a variable load you should consider more condensers with some kind of condensing pressure reg. valve. combined with fan control and some solenoid valves so you can cut off some condensing capacity.

R. Nielsen

chemi-cool
14-11-2005, 08:00 PM
You should check the size of the area, is it big enough?
The cost of the project.

all of your ideas will do the job.

Chemi:)

Brian_UK
14-11-2005, 10:31 PM
I would modify option 2 and install 3 x 250kW. You now have some capacity control, albeit coarse, and some spare capacity for overload, breakdown or maintenance.

Rfcont
15-11-2005, 06:21 PM
to me I'd prefer the first way and that is why:
I think, that dividing of heat loading into some parts will lead to serious lowering presure drop in condenser system and at work during hot time of summer, whole condenser system can be a disbalancing.
Also regulation of head pressure by cycling of the fans can be more complicated ;)

Regards,

Peter_1
15-11-2005, 07:12 PM
One 500 kW condenser with fan cycling control to regulate pressure.
When you cut off a condenser with a SV, you first have to pump it down so that no liquid remains in the condenser. And you will need 2 SV's (in and out), otherwise the not working part of the condenser can fill up backwards with liquid. In my opinion, not such a good idea.
If very low part load associated with low ambient is a possibility, install a condensing pressure regulator, a differential pressure flow valve (NRD of Danfoss) so that liquid is stored in the condenser to decrease condenser surface area and make sure that your receiver is big enough.
Or even better, use a EEV so that you can use all the benefits of a low HP and let it run on a low HP.

Connecting parallel different condensers, even from different size (different DP across the condenser) is not that difficult, as long as you use the proper rules to do this.

zerodegreec
30-11-2005, 03:55 AM
Whats the load? Constant? variable like a rack?
If constant I would recomend single cond due to price and ease of setup/install.

Variable load would come down to how much of a load variable are we talking about. Multiple condensers are great in low amb conditions like up here in Canada where -30c is common. Its quite allot more money to put in a multiple condenser system but you are able to keep a good handle on the design liquid pressure. Var speed fan on the condensers are expensive and not really needed unless the amb temps will fall down to the -30 range for long periods of time.
Ever think about split coils? One condenser with multiple headders. Best of both worlds :)

To give you and example of a typical multi condenser setup for a variable load would be the systems used in some supermarkets around my area. 200+ HP rack with 2 condensers. First condenser is split in half and the second condenser is the same size but non split.
So what we have is 100%,50% and 25% split ability. We also use a variable speed fan on the lead fan on the full time 25% condenser that allows us to run low condensing temps year round without having liquid logging problems.

clear as mud?
their is NO hard fast rule, never is, the best way to approach is to look at each individual application and ballance price and function.

Andrew Pribora
06-12-2005, 12:44 PM
it depends on ambient temp - if you choose as amb.temp. +28 - you can find this condenser.

if +34 - you simply can not find such condenser!

plus - size of condenser, sound.

and you must have KVR+NRD for winter. In our country it is usual run of things - temp minus 20 Grad C in winter.