Cold store Bad operation

[Noori]

Dear friends.
Hear under the main head lines for the cold store operation , so my grate thanks for any help to understand the reason for this bad operation.
1- The system has a condenser with one refrigerant circuit and two <O:p</O:p
semi hermetic Bock compressors working in parallel
2- There are three evaporators each one installed in a single room with dimension 10m*6m*2.8.<O:p
3- Room temperature reading for the first one ( the nearest to the condenser) is 12 c with a high temp. signal ( Danfoss microprocessor EKC 201)
4- Room temperature reading for the second store is fluctuated between 7.2 c to 6c.
5- Room temp. for the the rid store ( the far one and located with 40m from the condenser) is fluctuated between 6.5c till 4.3c)
6- Low pressure reading is 2.5bar and the unit shut down by low pressure cut out .( Low pressure cut in set is 2 bar).
7- High pressure reading is 9 bar with one compressor in operation and 12 bar with the lag compressor in operation.
8- The unit has liquid receiver vertically installed with two inspection glass and I see the liquid flow from the upper glass like the rain.
9- The main sight glass on the mean liquid line is fully with liquid refrigerant .
Again I will be thank a lot for any feed back to solve this problem.
Note . A-The liquid refrigerant flow rate for each evaporator can be manually controlled by manual valve which is located down stream the LLSV. For each evaporator.
B- All reading at outside Temp. 10c

[Brian_UK]

What is the refrigerant ?

What should the cold store temperatures be at ?

Have the manual control valves been adjusted recently ?

[nike123]

Noori, do you have diagram of refrigerant circuit. Could you post it or send by mail?

[Noori]

Dear Brian.
Thank u for your feed back.
1-The refrigerant is R22.
2-The temperatures as I posted.
3-The maual valves are fully opend for the three stores.

[Noori]

Noori, do you have diagram of refrigerant circuit. Could you post it or send by mail?

Dear Nike.
Thank u with my best whish for u and your family.
Unfortunately I have no refrigerant circuit diagram and also electrical drawing .
This stores are installed by a Tunisian company. I will explain for u the main head lines for the refrigerant circuit and if necessary I will send u more details by e mail
1-The two compressors working in parallel one is lead and the second is lag .
2- compressor No1 working as Delta/ YY while the second working as Y/YY.
3-the capacity control is Danfoss- EKC331- working according to suction pressure.
4-The compressors with the oil separator and the accumulator and the LL receiver are installed in side the machine room while the condenser are installed on the floor for this room.
5- the stores are installed in face to the machine room all in one roof .
6- the main liquid line pass on the stores roof and feed each evaporator via the LLSV and manual valve and the same locution for the main suction line.
7- please if u have the document for the EKC331 send it by email since I did not find it in danfoss website.
Best regard

[nike123]

7- please if u have the document for the EKC331 send it by email since I did not find it in danfoss website.




This (http://www.haphillips.com/uploads/files/EKC_331_Capacity_Controller_Manual_RS8AG202.pdf) is your manual!

You did not answered at Brian question "What should the cold store temperatures be at ?"!
Does your fluctuations of temperatures corresponds with fluctuations in suction pressure ? What is evaporators superheat for each cold store?
Also what is time frame for these fluctuations? What is thermostats set differential?
How is condensation pressure controlled? It looks to me that you have over-condensation.

[Peter_1]

What exactly is now the problem?

[nike123]

What exactly is now the problem?
3- Room temperature reading for the first one ( the nearest to the condenser) is 12 c with a high temp. signal ( Danfoss microprocessor EKC 201)

[Noori]

What exactly is now the problem?

Dear peter
Thank u for this fed back .
The problem now is that the temperature for the two stores are fluctuated while the first room is running very well and reach to the set point – zero c-

[Noori]

This (http://www.haphillips.com/uploads/files/EKC_331_Capacity_Controller_Manual_RS8AG202.pdf) is your manual!

You did not answered at Brian question "What should the cold store temperatures be at ?"!
Does your fluctuations of temperatures corresponds with fluctuations in suction pressure ? What is evaporators superheat for each cold store?
Also what is time frame for these fluctuations? What is thermostats set differential?
How is condensation pressure controlled? It looks to me that you have over-condensation.

Dear Nike.
First I would like to send u my thanks for the document.
1-all the stores are fully loaded with apples with temperature set point is zero for all the rooms.
2-Suction pressure does not fluctuated with temperature.
3-I will inform u the super heat for each evaporator in my next post.
4-time fluctuation is 10 minutes approximately with decreasing fluctuation is more than increasing.
5-thermostat set differential is 4c for all the stores.
6- condenser pressure controlled by pressure switch to start and stop the two fans-one for each fan- 12 bar cutout and 15 bar cut in ,on fan is lead and the other is lag.
7- I found an electrical bad connection to the LLSV for the first store( the nearest one to the condenser) while its led signal is on in the temperature controller. So that now its running well and reach to the zero temperature( the set point). At this point the LLSV for this store closed by the controller causing rapid decreasing in the suction pressure and the compressors stopped by low pressure cut out while the temperature for the other stores are still between 6c and 5c.
8-I order the costumer to re arrange the apples box so that a good air movement should take place.
Best regard.

[Noori]

Dear Nike.

First I would like to send u my thanks for the document.
1-all the stores are fully loaded with apples with temperature set point is zero for all the rooms.
2-Suction pressure does not fluctuated with temperature.
3-I will inform u the super heat for each evaporator in my next post.
4-time fluctuation is 10 minutes approximately with decreasing fluctuation is more than increasing.
5-thermostat set differential is 4c for all the stores.
6- condenser pressure controlled by pressure switch to start and stop the two fans-one for each fan- 12 bar cutout and 15 bar cut in ,on fan is lead and the other is lag.
7- I found an electrical bad connection to the LLSV for the first store( the nearest one to the condenser) while its led signal is on in the temperature controller. So that now its running well and reach to the zero temperature( the set point). At this point the LLSV for this store closed by the controller causing rapid decreasing in the suction pressure and the compressors stopped by low pressure cut out while the temperature for the other stores are still between 6c and 5c.
8-I order the costumer to re arrange the apples box so that a good air movement should take place.

Best regard.

Dear Nike
Thank u again for this document since these 8 poges solved the probelem and I will send u more details in my nexet post.
best regard

[Noori]

Dear Nike.
<O:p</O:pOnce again thank u for your attention to my posts

Actually I solved the problem by using the instruction manual for the EKC33<O:p</O:p
Here under u will fined the following steps to let the unit running well<O:p</O:p
1- pump down the system and cleans the expansion valve orifice for store 2 &3
2- reset the reference pressure from 2 bar to 1.5 bar. Since the weather is cold
3- reset the offset value from 0.1 bar to o.2 bar
4- And last sep I don’t hesitate to told u that u r very clever and your analysis is right since I found the unit is over charged
Best regard<O:p</O:p

[nike123]

Thank you for compliments!

Another one thing. You should check when outdoor temperature is high (or simulate that condition by covering portion of condenser) that you have enough subcooling in that case, since you removed some charge.

[Noori]

Thank you for compliments!

Another one thing. You should check when outdoor temperature is high (or simulate that condition by covering portion of condenser) that you have enough subcooling in that case, since you removed some charge.
Dear Nike.
yes u are right and I will do it.
best regard.

[samygold]

hi there
please i would like to know since the cold store suction temperature is very low ,what would be the adjustment of the low pressure setting in bars?and where would the bulb be placed , and if the temperature is very low why wouldnt the low pressure switch cut out?