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Andrew Pribora
11-04-2005, 09:45 AM
The question is about multycompressor-Rack. We can install receiver under condenser ("scandinavian scheme"). In such case we could spare money for KVR-NRD-System (Danfoss).

But I've heard there are problems for this variant of installation.
May be it is because if out temp is too low (-35 Grad C), f.E.?

Could you explain me?

SNi
11-04-2005, 11:24 AM
It`s possible but You should insulate the receiver. In any case price for Danfoss kit not so critical.

Andrew Pribora
12-04-2005, 06:42 AM
condenser+receiver must be at the same out temperature - in other case all R404A (f.E.) will be in condenser.

SNi
12-04-2005, 09:01 AM
You can install check valve. You should be carefull then you selecting expansoin valve if outside temperature falls to -35 liquid will be very subcooled.

chemi-cool
12-04-2005, 03:43 PM
Hi Andrew,

You can use a heating tape 30W/M around the reciver to maintain the temp in it.

Chemi :)

Andrew Pribora
13-04-2005, 06:35 AM
Hi Chemi,

I'm interested very subcooled liquid - if we have so subcooled liquid - in evaporator we have ...

BR

Andrew

PS In Israel you have not such problems? Out temp in Russia can be very low!

chemi-cool
13-04-2005, 03:39 PM
In Israel you have not such problems?

Hi Andrew,

-35? in Israel? Never.
It can go as low as -5c.
Weather in general warm to hot and some times' very hot.
It was yesterday 37c and today 33 , :) good for business ;)

You have to maintain pressure differential between the receiver and the TEV.
If the differential is too low, the TEV will not function well.

Heating tape is a good solution, it has to be controlled by a pressure control though.

Chemi :)

SNi
14-04-2005, 06:07 AM
Hi Chemi

+37C (but +33C not so bad too :) ) it`s almost perfect weather for our business!
In my mind most suitable solution is flexible heater with variable impedance and insulation on receiver.

chemi-cool
14-04-2005, 03:57 PM
Look here for examples.



http://www.labkorea.com/lab/heatingacce.html


Chemi :)

Andrew Pribora
23-05-2005, 12:01 PM
Thanks to all for answers!

I thought about this problem - we have to do such scheme for our customer and it is not solved.

I understand the situation - if outer temp is -40 Grad C and we have in condenser+receiver liquid with temp -40 Grad C. And no gas - we can use p-s diagramm and we see - 100% liquid.
For TX Ventil it is very bad - we have very low pressure and compressor will not work.

The question - how can we get gas in system - or how can we make the system workable? In compressors are not working for long time - all R404A will be in condenser+receiver in liquid stand. Or not?

SNi
23-05-2005, 02:05 PM
In my mind you shoud use KVR+NRD or similar. :)