Dunham-Bush WCFX-E Series, Руководство пользователя

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UNIT FEATURES
PART LOAD PERFORMANCE
Through the use of economizer and multiple compressors,
Dunham-Bush Water Cooled Screw Flooded Chillers
some of the best part-load performance characteristics in
the industry when measured in accordance with AHRI
Standard 550/590-2011.
In most cases, actual building system loads are
significantly less than full load design conditions, therefore
chillers operate at part load most of the time.
Dunham-Bush Rotary Screw Water Chillers combine the
efficient operation of multiple rotary screw compressors
with economizer and controller control to yield the best
total energy efficiency and significant operating savings
under any load.
When specifying air conditioning equipment, it is important
to consider the system load characteristics for the building
application. In a typical city, the air conditioning load will
vary according to changes in the ambient temperature.
Weather data compiled over many years will predict the
number of hours that equipment will operate at various
load percentages.
The Air Conditioning and Refrigeration Institute (AHRI)
has established a system, in AHRI Standard 550/590-
2011, for measuring total chiller performance over full and
part-load conditions. It defines the Integrated Part-Load
Value (IPLV) as an excellent method of comparing diverse
types of equipment on an equal basis. The IPLV is a
single number estimate of a chiller's power use weighted
for the number of hours the unit might spend at each part-
load point. IPLV's are based on Standard Rating
Conditions.
The formula for calculating an IPLV is:
IPLV =
where: A= kW/ton at 100% load point
B= kW/ton at 75% load point
C= kW/ton at 50% load point
D= kW/ton at 25% load point
GLYCOL FREEZE PROTECTION
If the chiller or fluid piping may be exposed to
temperatures below freezing, glycol protection is
recommended if the water is not drained. The
recommended protection is 15°F below the minimum
ambient temperature in the equipment room and around
piping. Use only glycol solutions approved for heat
exchanger duty. DO NOT use automotive anti-freezing.
If the equipment is being used for applications below
38°F, glycol should be used to prevent freeze damage.
The freeze protection level should be 15°F lower than the
leaving brine temperature.
Table 1 and 2 are to be used to calculate performance
and power input with the addition of glycol. Table 3 and 4
are to be used to calculate performance and power input
with different fouling factor.
Table 1 : Ethylene Glycol
% E. G.
By Weight
Freeze
Point
C1
Capacity
Factor
K1
kW
Rate
G1
Flow
Factor
P1
P.D.
Factor
°F °C
10 26.2 -3.2 0.995 0.998 1.019 1.050
15 22.4 -5.3 0.991 0.997 1.030 1.083
20 17.8 -7.9 0.988 0.996 1.044 1.121
25 12.6 -10.8 0.984 0.995 1.060 1.170
30 6.7 -14.1 0.981 0.994 1.077 1.219
35 0.0 -17.8 0.977 0.992 1.097 1.275
40 -10.0 -23.3 0.973 0.991 1.116 1.331
45 -17.5 -27.5 0.968 0.990 1.138 1.398
50 -28.9 -33.8 0.964 0.989 1.161 1.466
Table 2 : Propylene Glycol
% P. G.
By Weight
Freeze
Point
C2
Capacity
Factor
K2
kW
Rate
G2
Flow
Factor
P2
P.D.
Factor
°F °C
10 26.1 -3.3 0.988 0.994 1.005 1.019
15 22.8 -5.1 0.984 0.992 1.008 1.031
20 19.1 -7.2 0.978 0.990 1.010 1.051
25 14.5 -9.7 0.970 0.988 1.015 1.081
30 8.9 -12.8 0.962 0.986 1.021 1.120
Table 3 : Evaporator Fouling Factor
Fouling Factor Capacity
Correction
Factor
kW
Correction
Factor
hr.ft².°F/BTU m².°C/kW
0.00010 0.018 1.000 1.000
0.00025 0.044 0.995 0.998
0.00050 0.088 0.985 0.995
0.00075 0.132 0.975 0.991
0.00100 0.176 0.964 0.987
Table 4 : Condenser Fouling Factor
Fouling Factor Capacity
Correction
Factor
kW
Correction
Factor hr.ft².°F/BTU m².°C/kW
0.00025 0.044 1.000 1.000
0.00050 0.088 0.998 1.007
0.00075 0.132 0.996 1.010
0.00100 0.176 0.995 1.014
1
0.01 + 0.42 + 0.45 + 0.12
A B C D