chiller efficiency testing

[hinesguy]

Has anyone done a chiller efficiency test. We are getting some weird numbers. Heat balance is supposed to be 5% or less. We are getting 30% to 40%. The machines are running well, tubes have been cleaned. They are carrier low pressure 540 ton. These are my readings I took at this moment:
ref temp: 41
chw sup temp: 44
ret chw temp: 56
cond ref temp: 97
cond wat temp out: 91
ent cond wat temp: 83
capacity: 101%
suction: -16
discharge:7

The main difference from design spec is the condenser delta T which was 14 but now reads around 7 to 8 psi most of the time. Could this be the prob?
We cut back on condenser water flow to it's design spec of 3.4 psi differential. It was at 6psi.
Any ideas?

 

[imok2]

The cooler approach is good at 3*F
The chill water delta T is good at 12*F
You have a good condenser approach at 7*F
You have a good condenser Delta T at 8*F so I don't see a problem

 

[hinesguy]

Neither do I, but the program calls for a 5% heat balance. We tried running 3 condenser pumps for 2 machines today to achieve a 9 psi differential on the condenser water. This worked but it consumes more amperage to do this. The chiller amps did not go down and total amps to run the 2 machines with 3 pumps went up by 50 amps. Seems like a waste. We are being audited next week, can't wait.

 

[imok2]

Please let us know what the results are. :>)

 

[Yorkman]

Not, to be contradictive but, are you mixing terms? You start out by saying the condenser delta "T" was 14: "but now reads around 7 to 8 psi most of the time" do you mean 7 - 8 degrees" or was the 14 delta P not sure. The 6 degree approach could be a bit high I know this sounds like a dumb question but did you verify that the condenser water is connected to the correct nozzles? The only reason I ask is the reduction is condenser flow from 6 delta P to 3.4 delta P should have caused the delta T to increase instead of drop. Something doesn't quit fit.

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[hinesguy]

It was a typo. The design delta P is 3.4 for the condenser. Once we started a second pump we got it to 9 psi. This got our heat balance to spec but it uses an extra 55 amps to do it. Chiller amps remained the same, so to me it's not worth it. The design specs also called for 85 degree water in, 99 out. We have never had these numbers. Maybe a 10 degree spread at best. The test I ran today came up with a 96% effeciency. With 1 cond pump running it went down below 80%. As far as I'm concerned it's just not worth the extra amperage to run a second pump.

 

[hinesguy]

Here's the test I did today:

CONDENSER DESIGN ACTUAL 1
TEMPERATURE IN 85.00 84.00
TEMPERATURE OUT 99.00 92.00
TEMPERATURE DIF 14.00 8.50
PRESSURE DIF 3.40 8.50
Gpm's 1100 1739
TONNAGE 646 615.99
PERCENT LOAD 100.00% 95.35%
EVAPORATOR DESIGN ACTUAL 1
TEMPERATURE IN 58.70 54.00
TEMPERATURE OUT 44.00 42.50
TEMP DIFF 14.70 11.50
PRESSURE DIFF 5.87 6.00
GALLONS PER MIN 1010 1021.12
TONNAGE 541.00 489.29
PERCENT LOAD 100.00% 90.44%
MOTOR DESIGN ACTUAL 1
VOLTAGE L-1 460 475
VOLTAGE L-2 460 474
VOLTAGE L-3 460 474
AMPERES L-1 512 470
AMPERES L-2 512 471
AMPERES L-3 512 467
AMPERAGE TOTAL 512 469
PERCENT LOAD 100.00% 91.67%
CHILLER DESIGN ACTUAL 1
AMPERES PER TON 0.9464 0.9592
KILOWATTS PER TON 0.6617 0.6916
CHILLER EFFICIENCY 100.00% 96.40%
% CHILLER INEFFICIENCY 0.00% 3.60%
HEAT BALANCE DESIGN ACTUAL 1
MOTOR TONS 101.672 96.10337053
HEAT BALANCE -0.52% -5.23%


CORRECTED DESIGN AMPS 512 496.528461
CORRECTED DESIGN AMPS/TON 0.9464 0.9178
ACTUAL AMPS PER TON 0.9464 0.9592
DESIGN KW PER TON 0.6617 0.6617
ACTUAL KW PER TON 0.6617 0.6916
CORRECTED DESIGN DEVIATION % 0.00% -0.75%
CORRECTED DESIGN KW/TON 0.6617 0.6667
DESIGN EFFICIENCY % 100.00% 96.40%


CONDENSER LOAD % 100.00% 95.35%
EVAPORATOR LOAD % 100.00% 90.44%
MOTOR LOAD % 100.00% 91.67%
DESIGN EFFICIENCY % 100.00% 96.40%
HEAT BALANCE % -0.52% -5.23%


POWER FACTOR CALCULATION DESIGN
MOTOR KW RATING 358
POWER FACTOR % 0.8786