Previous in Forum: AC Drive   Next in Forum: Thermal Over Load Relay Setting
Close
Close
Close
7 comments
Rate Comments: Nested
Associate

Join Date: May 2007
Location: Houston, TX
Posts: 39

COP Improvment Meaning

12/07/2010 2:54 PM

I am working with several screw chillers that we have installed new technology on to improve energy efficiency. The data logging equipment is showing an improvement in COP of about 3%, 3.62 from 3.52. Are we seeing savings? The data loggers did not record amps or kw.

__________________
How is it that my measurement of 8" is different than hers?
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21017
Good Answers: 795
#1

Re: COP Improvment Meaning

12/07/2010 3:32 PM

Then how do you know what the COP improvement is?

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Associate

Join Date: May 2007
Location: Houston, TX
Posts: 39
#2

Re: COP Improvment Meaning

12/07/2010 3:43 PM

There was a unit called a ClimaCheck installed that measures COP

__________________
How is it that my measurement of 8" is different than hers?
Register to Reply
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21017
Good Answers: 795
#3

Re: COP Improvment Meaning

12/07/2010 5:40 PM

Usually COP is understood as heat energy moved ÷ energy consumed, in matching units. Without measuring kw (or amps, assuming constant voltage), you don't get a direct measurement of energy consumed. I take it the ClimaCheck scheme measures temperatures and pressures, looks up or calculates what the matching energy usage should be, and then displays this imputed COP. How close this is to the real COP depends on how accurate the sensors and programming are.

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Guru
Engineering Fields - Mechanical Engineering - New Member India - Member - New Member

Join Date: Aug 2008
Location: City of destiny, INDIA
Posts: 775
Good Answers: 67
#4

Re: COP Improvment Meaning

12/08/2010 2:04 AM

A big YES, you are definetely seeing savings. Improvement in COP is direct indicater of improvement in energy efficiency, beacause COP is nothing but 'Refrigeration Effect' acheived per unit of power spent for compession.

Register to Reply
Associate

Join Date: May 2007
Location: Houston, TX
Posts: 39
#5

Re: COP Improvment Meaning

12/08/2010 9:01 AM

If its a "big Yes", how should I calculate the .10 or 3% improvement to mean something in laymens terms?

__________________
How is it that my measurement of 8" is different than hers?
Register to Reply
Guru
Engineering Fields - Mechanical Engineering - New Member India - Member - New Member

Join Date: Aug 2008
Location: City of destiny, INDIA
Posts: 775
Good Answers: 67
#7
In reply to #5

Re: COP Improvment Meaning

12/09/2010 1:22 AM

While agreeing with Mr Aerodeo, I can suggest following simple way to calculate the improvement in laymans terms, considering there are no other changes:

COP = Refrigerating Effect (RE) / Power for Compression (P)

(both shall be in same units, either in kW or in heat units like KCal or kJ)

For previous COP, if I assume 352 kW is RE, then P shall be 100 kW to get COP=3.52

Later COP increased to 3.62 (2.84% increase). Considering RE is same i.e. 352 kW, now revised power requirement shall be 352/3.62 = 97.24 kW which is 2.76% lower than earlier. Hope it is clear.

Register to Reply
Participant

Join Date: Jul 2010
Posts: 3
#6

Re: COP Improvment Meaning

12/08/2010 7:53 PM

In short, YES, you are seeing energy savings, though how much depends on environmental conditions and run time. ClimaCheck calculates COP based on a number of inputs, but, most relevantly to you, it does indeed measure the line voltage and current draw (to calculate power consumption) of the compressor.

If you can read the COP within ClimaCheck, then you can certainly access your kw consumption. Or you can contact ClimaCheck and they will be able to tell you exactly how your system is performing.

Assuming the cooling capacity is the same (not a trivial assumption) then you could use the formula for COP: COP=Qevap/Pcomp do derive the improvement in Pcomp

i.e. : Pcomp = XBtus/0.1

Please note that this is a gross oversimplification and I would still advocate for contacting ClimaCheck so they can tell you how much extra cooling you're getting or how much less energy you're using or (far more likely) some combination of the two.

Register to Reply Score 1 for Good Answer
Register to Reply 7 comments

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

Aerodeo (1); Enersol (2); pritam (2); Tornado (2)

Previous in Forum: AC Drive   Next in Forum: Thermal Over Load Relay Setting

Advertisement