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ROCKY123
26-06-2016, 05:51 AM
Hi Everyone,

Can I use a pumped overfeed cooler as DX(direct expansion)
The scenario is like this, I have a pumped overfeed cooler but I only have some high pressure liquid connection available at the area. Can I connect it to the high pressure liquid line through a hand expansion valve? or a thermostatic expansion valve?. Do I need a distributer..? the available cooler is bottom feed and its 23kW. If anyone have similar experience please help..

Thanks

Magoo
27-06-2016, 02:14 AM
Hello Rockie.
generally liquid over feed evaps are purpose designed for each application. All to do with circuit lenghts and internal pressure increases and flow rates.
Yes hand expansion valve or electronic pulse expansion valve, by HP liquid do you mean from the existing pump supply?. You should check existing pumping capacity as by adding additional coils you could effect whole system performance, get an engineer to do system re-design calculations first before changing anything.

ROCKY123
27-06-2016, 08:18 AM
Thanks Magoo.
By HP liquid I mean supply from the high pressure receiver. I already have 2 DX coolers in the same area with thermostatic expansion valve. Now we are going to add 2 more coolers(we have 2 pumped overfeed cooler with the same capacity in our service stock) but without TX valve. Instead we will use normal hand expansion valve. Is there any problem with this

RANGER1
27-06-2016, 11:19 PM
Thanks Magoo.
By HP liquid I mean supply from the high pressure receiver. I already have 2 DX coolers in the same area with thermostatic expansion valve. Now we are going to add 2 more coolers(we have 2 pumped overfeed cooler with the same capacity in our service stock) but without TX valve. Instead we will use normal hand expansion valve. Is there any problem with this

Without modification it would be very crude & capacity not guaranteed unless distributor, as well as circuiting modified.
Also possibility of high levels in pumped over feed vessel, as any liquid returning from these units could affect levels if plant on low loads.

Magoo
28-06-2016, 01:31 AM
Hi Rockie.
With the spare coils in stock , do they have surge/ accumulator vessels attached to them ?
What refrigerant are you using? What temperatures are required in chiller area ?
Some photos of stock coils would good.
magoo