Liebert HPC-S 006 - Correction Factors; Performance Adjustment Factors

7
Performance Adjustment Factors
7--1
Liebert HPC---S 006---022---PD---273571---01.03.2012
Perf orm ance A djustm ent Fact ors
Correction Factors
Glycol mixture correction factors
The water glycol mixtures are used as a thermal carrier fluid, in very cold climates with temperatures be-
low 0 ° C. The use of low freezing point mixtures causes a modification in the main thermodynamic prop-
erties of the units.
The main parameters affected by the use of glycol mixtures are the following:
D Cooling capacity
D Mixture volumetric flow
D Pressure drop
D Compressor power input
In the table below are reported correction factors referred to the most common ethylene glycol mixtures.
Ta b . 7 a --- C h i l l e r Ta b l e --- C B 0 --- C G 0
Ethylene glycol [% in weight] 0 10 20 30 40 50
Freezing temperature
Refrigeration capacity correcting factor
Mixturevolumeflowratecorrectingfactor
Mixture side pressure d rop correcting factor
Compressor power input correcting factor
°C
F3
F4
F5
F6
0
1
1
1
1
--- 4 , 4
0,998
1,046
1,053
0,998
--- 9 , 9
0,993
1,080
1,109
0,997
--- 1 6 , 6
0,987
1,098
1,168
0,995
--- 2 5 , 2
0,977
1,150
1,234
0,992
--- 3 7 , 2
0,969
1,210
1,311
0,990
Ta b . 7 b --- F r e e c o o l i n g Ta b l e --- F B 0 --- F G 0
Ethylene glycol [% in weight] 0 10 20 30 40 50
Freezing temperature
Refrigeration capacity correcting factor
Mixturevolumeflowratecorrectingfactor
Mixture side pressure d rop correcting factor
Compressor power input correcting factor
°C
F3
F4
F5
F6
0
1,013
0,911
0,856
1,005
--- 4 , 4
1,007
0,926
0,902
1,003
--- 9 , 9
1,002
0,956
0,950
1,002
--- 1 6 , 6
1
1
1
1
--- 2 5 , 2
0,990
1,048
1,056
0,997
--- 3 7 , 2
0,982
1,102
1,122
0,995
W eindicate as R0, V0, P0 respectively the unit capacity, volumetric flow rate and compressor power input
with 0% ethylene glycol on Chiller models or 30% ethylene glycol on Freecooling models; when we use
glycol mixtures with different % with the same inlet and outlet temperatures at the evaporator, the per-
formance will vary as follows:
D Refrigeration capacity = R0 x F3
D V o lumetric flow rate = V0 x F3 x F4
D Mixture pressuredrop = DP1 x F5, where DP1 is the unit water pressuredrop forthe new volumetric
mixture flow rate
D Compressor power input = P0 x F6
Fouling correction factors
Tab. 7c --- Fouling correction factors
Fouling factors [10
--- 4
m
2
°C/W] Correction factors
F1a refrigeration capa city
correction factor
F2a compressor power input
correction factor
0,18
0,44
1,32
1
0,996
0,984
1
0,999
0,994
Unit performance reported in the tables are given for the condition exchanger with fouling factor corres-
ponding at 0,18 x 10
--- 4
m
2
° C / W. For different fouling factor values, performances should be corrected
with the correction factors shown above. For optimum unit operation, proper water treatment must be
maintained. Scaling and dirt in a system will vary significantly depending on local water conditions.Water
treatment should be based on characteristic s of the area’s water. Improper or untreated water can lead
to scale build up, erosion and corrosion in the evaporator.
Emerson will not accept responsibility for poorly or improperly treated water.
Sea level correction factors
Tab. 7d --- Sea level correction factors
Elevation above sea level [meters] Correction factors
F1b refrigeration capacity
correction factor
F2b compressor power input
correction factor
0
600
1200
1800
1
0,997
0,993
0,988
1
1,004
1,007
1,015
Unit performance reported in the tables are given for sea level conditions.
For different altitude, performances should be corrected with the correction factors shown above.