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lowtempref
03-10-2006, 05:09 PM
Can we use electronic expansion valve for flooded chiller without level transmitter or level cotroller. Can we control of chiller level with super heat measurement/super heat controller?

Andy
03-10-2006, 10:20 PM
Can we use electronic expansion valve for flooded chiller without level transmitter or level cotroller. Can we control of chiller level with super heat measurement/super heat controller?

Hi Lowtempref:)

yes and no. I have one site where I used danfoss controllers, just the ordinary electronic superheat control type. WhatI do is allow the controller to control the level on superheat with a thermistor imersed in the liquid, if the thermistor circuit senses a high level I force close the electronic valve. So what happens is the chiller is normally controlled on supheat heat but if the level creeps up during low load the thermistor level control allows the chiller to pump out a little.

Hope this helps.

Kind Regards Andy:)

TXiceman
10-10-2006, 02:54 AM
Sporland made a valve named a Sporlan Levelmaster. I don't know if it is still available or not.

On a flooded evaporator, you normally run with all of the tubes submerged or wetted and a staurated suction. The only way to get superheat will be to uncover some of the tubes, which will reduce you capacity.

It is simple enough to use a low side float control or if it is critically charged, a high side float control.

ken

taz24
10-10-2006, 04:33 PM
Can we use electronic expansion valve for flooded chiller without level transmitter or level cotroller. Can we control of chiller level with super heat measurement/super heat controller?


You should be able to. The danfoss valve controls to about .2 of a deg on superheat, which means your evap is nearly flooded.

Cheers taz.

Dimitris
13-10-2006, 08:03 PM
Hi lowtempref, I think that the best way to use an EXV on flooded type chillers is monitoring and controlling the DISCHARGE superheat with a thermistor.
(low discharge superheat=high level refrigerant)
Hope this helps. Dimitri

Andy P
15-10-2006, 04:27 PM
Hi lowtempref, I think that the best way to use an EXV on flooded type chillers is monitoring and controlling the DISCHARGE superheat with a thermistor.
(low discharge superheat=high level refrigerant)
Hope this helps. Dimitri

Woah there! The only way you get low discharge superheat from a flooded evaporator is by putting liquid through your compressor - this is just what he's trying to avoid. If the compressor is a semi-hermetic you might get away with it provided the motor heat can keep the suction dry. If it is an open drive - especially an open drive recip then you are asking for trouble!

cheers
Andy P

US Iceman
15-10-2006, 11:36 PM
You can certainly monitor the discharge superheat as a means of detecting the presence of "liquid", but by no means should you be using this as a control point for a flooded chiller.