View Full Version : Cop

24-12-2004, 05:30 PM
Hi All and Marry Christmas :)

I want to calculate the COP of a cooling unit.

The Unit cools a 40000 L milk tank.

The info I can collect is:

KW/H per 24 hours.
Entering temp and leaving temp of milk.
Amount of milk per 24 hours.

Do I need any anything else?

Marc? Peter? Anyone else?

I will wait until you are all sober :D

Chemi :)

24-12-2004, 10:20 PM
Hi Marc.

What I know now, is the cost per liter.

What I want to know is to clculate the unit COP.
If you think that I need more details, let me know and I will get them.

Chemi :)

25-12-2004, 06:55 PM
Also a Merry Christmas for you and all the other members.

Hey Chemi, I forgot to ask: Kristien says she always can use some pictures of Israeli cows. So, take you Sony with you the next time.

Jeez, 40.000 l of milk. The biggest I saw was 4 or 5.000 liters!!
The biggest trailer in Belgium can only carry 25.000 liters or 30.000 liters of milk.

What you definitely need Chemi is evaporating pressure, condensing pressure, superheat and subcooling.
But calculating will be not that easy because you start with high evaporating temperatures and as soon the milk temperature drops, also the working conditions will drop: evaporating and condensing temperature will decrease.

So the curve will not be a straight one and the measurement you will take is only valid for that moment.

What you can do is take a sample each 5 or 15 minutes and calculate then afterward an average value. This will be in my opinion reasonable correct.

I think that if you will do it correct, you need to log evaporating and condensing pressure and the current from the motor.

And then in fact you have to put in in some sort of spreadsheet or in a more complicated integral math functions and calculate the average COP.

Do you need to calculate for your COP also the power of the stirring motors?

25-12-2004, 08:41 PM
Hi Peter.

I have KW/H meters installed so I know the power consumption.
Every two days when the milk is taken, I write down the amount.
This way I can calculate the cost of cooling per liter.
This is done for the ministry of agriculture and they pay (not enough) for my time.

For my ego I want to calculate the Cop of the cooling units.
Its 7 Maneurop condensing units based on MT64 compressors with a small modification.
I think that I have data but I do not no how to use it to get the COP.

Also the agitating motors are in the count as it is a part of the milk cooling.

Chemi :)

25-12-2004, 10:08 PM
If you go to
http://cc.danfoss.com/SW/Foresee/en/index.htm?click=i_{C6B8FB6E-6797-4888-B35C-376614FDB524} then you can download their for free the selection software for Maneurop.
You give in the measured values and the program gives you automatically the COP.
You will notice that changing SH or SC will change dramatically the COP.
You only have to look then for the appropriate compressor.
A second control is the AMPs that the program gives you. Corresponds this with the AMP you measured?


30-12-2004, 10:15 PM
Surely you just need to log the system on a ph chart and the cop is then quite easily determined by dividing the power input h into the evaporator h :confused: nothing hard about that ?

Sorry, I've been away for christmas and just catching up.