User manual | 07/00 6066A WCGA Direct Fired Absorption Chillers 100 through

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Direct Fired
Absorption Chillers
100 through 770 tons
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Form No. 6066A
WCGA
FEATURES
• Multi-shell design
• Advanced proactive microcomputer
• On line purging
• Hybrid system equipped
INTRODUCTION
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Dunham-Bush has a legacy of innovation that
spans most of this century. Since the early
1900’s the company has been providing its
customers with innovative solutions for their
air conditioning, heating and commercial
refrigeration needs.
Dunham-Bush now continues this legacy with
the introduction of a complete line of
absorption cooling products.
Space
Conditioning, later acquired by Dunham-Bush,
was a bit ahead of its time in 1962 when it
introduced a double effect absorption chiller.
2
Although this machine never really caught on,
it was a pioneer in the market place and
continued the Dunham-Bush tradition of
innovation.
Today, Dunham-Bush brings this technology
into the future with a complete line of
Absorption Chillers. This fact allows DunhamBush to have a better, more expansive service
force for our customers. Dunham-Bush
continues to offer complete solutions for our
customers, so choose Dunham-Bush
Absorption Chillers for your future needs.
TABLE OF CONTENTS
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Page
Nomenclature ........................................................................................................................ 3
The Absorption Cycle Basic Principle ...................................................................................... 3
Features, Specifications and Benefits .................................................................................. 4-7
Selection Data & Technical Specifications ............................................................................ 8-9
Application Information.................................................................................................. 10-11
Physical Dimensions ............................................................................................................. 12
Typical Piping Schematic ...................................................................................................... 13
Electrical Wiring Drawing ................................................................................................ 14-16
Engineering Specifications .............................................................................................. 17-20
NOMENCLATURE
W C
G
A
-
100
Water Cooled
Nominal Capacity (TR)
Heat Source
G = Gas
O = Oil
D = Gas or Oil (Dual Fuel)
Absorption
THE ABSORPTION CYCLE
100
120
150
180
210
240
280
320
360
400
450
500
550
620
690
770
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Basic principle
The boiling point of water is directly proportional to
the pressure. At atmospheric pressure water boils at
212°F (100°C). At lower pressure it boils at a lower
temperature.
At 0.24” Hg absolute (6mmHg
absolute) the boiling point of water is 38.7°F (3.7°C).
Further there is a large difference between the vapor
pressure of LiBr and water. This means that if we
heat the LiBr-water solution, the water will vaporize
but the LiBr will stay in the solution and become
concentrated.
Lithium Bromide (LiBr) is a chemical similar to
common salt (NaCl). LiBr is soluble in water. The
LiBr water solution has a property to absorb water
due to its chemical affinity. As the concentration of
LiBr solution increases, its affinity towards water
increases. Also as the temperature of LiBr solution
decreases, its affinity to water increases.
Absorption systems use heat energy to produce a
refrigerating effect. In these systems the refrigerant,
i.e. water, absorbs heat at a low temperature and
pressure during evaporation and releases heat at a
high temperature and pressure during condensation.
3
FEATURES, SPECIFICATIONS AND BENEFITS
The Dunham-Bush Absorption Chillers have a multishell design, consisting of the upper shell which
houses the condenser and low temperature
generator, lower shell which houses the evaporator
and absorber, high temperature generator with a
suitably sized burner, heat exchangers, absorbent
and refrigerant pump, purge pump, purge unit, inter-
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connecting piping and a machine mounted control
panel. Each chiller goes through a series of tests for
leak tightness at the factory including the stringent
helium leak detection test, for achieving highly
reliable operation. Also the number of valves and
gasketed joints is kept to the minimum to ensure
leak tightness.
High Temperature Generator
The high temperature generator has a direct flue type
furnace with a wetback and wetfront to ensure
maximum heat exchange. The shell is made of
carbon steel SA 516 Gr 70 and the seams are welded
by TIG welding. The tubesheet, similarly made of
carbon steel SA 516 Gr 70, has drilled holes to
accommodate the tube and each hole incorporates
a groove so as to enable leakproof locking.
•
Using round tubes means that the tubes can be
evenly expanded and thus need to be welded only
on the outside. These tubes can be removed in
the eventuality of tube leak. Some manufacturers
use elliptical or oblong tubes, which have to be
welded both internally and externally and thus
cannot be removed easily during leakage
problems.
The Dunham-Bush Absorption Chiller uses straight
and plain, round tubes made of boiler quality, with
2" (50.8 mm) diameter and 0.144" (3.66 mm) wall
thickness. Each tube is individually expanded and
seal welded from the outside to the tubesheet. The
advantages of this construction are:
•
This design can accommodate a higher sulfur
content in the fuel as compared to that normally
acceptable to other manufacturers.
•
Heat release rate for the Dunham-Bush
Absorption Chiller is 100,000 Btu/hr (29.3 kW)
as compared to heat flux of 150,000 Btu/hr (41.0
kW) normally used by other manufacturers. A
bigger furnace with lower heatflux reduces the
depletion of corrosion inhibitor at high
temperatures.
•
Access is provided to tubes for cleaning.
•
Flue gas pressure drop is maximum 3.15” H 2O
(80 mm kPa) and the stack temperature is limited
to around 392°F.
•
Reliable burner is used.
•
Large diameter tubes mean less soot deposition,
even when heavier fuels are used.
•
Plain tubes without any spirals/turbulators mean
less cleaning frequency even though it increases
the size of the high temperature generator. Plain
tubes also ensure that soot deposition is limited
and thus problems like increased back-pressure,
improper combustion, burner backfiring and in
some cases even furnace collapse are eliminated.
Burner
The UL listed burner is supplied along with the chiller/
heater unit, capable of firing on one of the following fuels:
a. Natural gas
b. No. 2 fuel oil
The burner supplied meets all major insurance,
military and local codes. The burner is provided with
a burner mounted control panel and is provided with
necessary controls and stand alone safeties to
provide safe and efficient working.
4
With a wide and established network of service
centers throughout the country, the Dunham-Bush
Absorption Chiller has an added advantage of being
the only chiller and burner combination supplied
from one manufacturer. The burner control panel is
designed to interface directly with the
microcomputer based chiller/heater control panel, to
provide integrated burner firing control for the
chiller/heater operation.
FEATURES, SPECIFICATIONS AND BENEFITS (CONT.)
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Upper Shell Assembly
Condenser and low temperature generator
The low temperature generator and condenser sections
are housed in a common fabricated carbon steel shell,
but with separate compartments for each section. The
condenser and low temperature generator are
separated by a partition plate fitted with stainless steel
(SS-430) eliminators. The Dunham-Bush Absorption
Chiller uses plain DLP (Deoxidized Low Phosphorous)
copper tubes in the condenser section. The
condenser has marine type hinged water headers,
with side exit nozzles for ease of maintenance. The
tubes of the low temperature generator are low
finned copper.
Lower Shell Assembly
Evaporator and absorber (side by side
construction)
The lower shell houses the evaporator and absorber
sections, separated by eliminators of SS-430, to
prevent any liquid carryover. The Absorption Chiller
uses plain DLP (Deoxidized Low Phosphorous) copper
tubes in the evaporator and absorber sections. All
the tubes are subjected to hydrostatic pressure and
eddy current tests.
The advantage of specifically using the more
expensive DLP copper, with phosphorous content of
less than 0.005 ppm, instead of the DHP grade tubes
used in competitive machines is:
Phosphorous content of higher than 0.005 ppm in the
tubes of absorption machines results in “stress
corrosion cracking”. At a microscopic level, stress
corrosion cracking takes place at grain boundaries by
the attack of a salt (e.g. lithium bromide) on the grain
boundary.
The absorber has marine type hinged water headers,
with side exit nozzles for ease of opening during
maintenance. The evaporator has headers with side
exit nozzles. The advantage of using these headers is
that normally the water piping need not be removed/
cut before the headers can be opened for tube cleaning
and other maintenance activities.
Heat Exchangers
There are two heat exchangers - low temperature and
high temperature heat exchanger. Both the heat
exchangers are shell and tube type, designed for
maximum heat exchange between the two circulating
streams of LiBr. The tube material for low temperature
heat exchanger is spiral copper and for high
temperature heat exchanger is spiral cupro-nickel
(90:10).
Overflow Pipe (Auto Decrystalization Line)
An overflow pipe is provided connecting the shell
side of the low temperature generator to the
absorber and bypassing the heat exchanger. The
blockage of the strong solution line from the low
temperature generator to the absorber leads to the
accumulation of concentrated LiBr in the low
temperature generator. This causes the solution level
to rise in the low temperature generator, and the
overflow of hot concentrated LiBr from the low
temperature generator to the absorber directly
begins. The heated weak solution warms up the
crystallized solution on the shell side of the heat
exchanger and hence melts the crystals.
Canned Motor Pumps
The Dunham-Bush Absorption Chiller uses only one
absorbent and one refrigerant pump, thus minimizing
the electrical consumption and reducing the
maintenance, as these pumps are the only moving parts
in an absorption chiller. These pumps are low net
positive section head pumps and are self lubricating
type. These canned motor pumps are cooled by the
fluids they handle. The canning of the stator eliminates
any chances of shorting. Both the pumps have separate
motors and hence are independent of each other. The
absorbent pump has both the over-current and high
temperature protection to prevent motor burnout.
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FEATURES, SPECIFICATIONS AND BENEFITS (CONT.)
These canned motor pumps are provided with an
inbuilt bearing monitoring terminal, which enables
the condition of the pump bearings (TRG reading)
to be evaluated for wear, externally, without stopping
the chiller.
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Further to facilitate the pump maintenance and
repair without breaking the chiller vacuum, specially
fabricated and leak tight isolation valves are provided
at the suction and discharge ends for both pumps.
This drastically reduces the downtime.
Gravity Feed Trays
The refrigerant from the condenser is not directly
sprayed over the chilled water tube bundle. The
water (refrigerant) from the condenser is first simply
allowed to fall into the evaporator section alongside
the shell. This water flashes and self cools itself to
approximately 39°F (3.9°C), and collects at the
bottom of the evaporator from where the refrigerant
pump pumps it to the top of the feed trays. The
Dunham-Bush Absorption Chillers have gravity feed
trays for the spray of refrigerant in the evaporator
and LiBr in the absorber section. These feed trays
are manufactured with utmost precision and have
perforations perfectly aligned with and running
along the entire length of the tubes. Refrigerant
and the LiBr droplets fall on the center of each tube
ensuring maximum area coverage and hence
maximum heat transfer in the respective section.
Purge Pump, Purge Storage Tank And Purging Mechanism
The purging unit consists of a factory mounted and
tested electrical motor driven purge pump, storage
tank and all the necessary piping and valves. Any
non-condensable gas, like hydrogen and oxygen,
generated due to the chemical reaction inside the
chiller, moves toward the low pressure lower shell.
These gases are automatically purged to the purge
tank thereby maintaining the vacuum inside the
chiller.
The purge tank is a double walled cylinder with the
outer cylinder connected to the absorber shell. A
tapping from the absorbent pump running through
the center of the inner cylinder sprays the LiBr
through a nozzle. The high velocity generates a low
pressure area, which sucks the non-condensables
from the absorber section and bubbles through the
LiBr solution to get trapped in the annular space
between the two cylinders. The purge pump can
then be operated to remove these stored gases from
the purge tank.
Solution Level Control
The Dunham-Bush Absorption Chillers use highly
reliable floatless level electrodes for controlling the
level of the refrigerant in the evaporator and the
level of lithium bromide solution in the high
temperature generator and also to prevent the
pumps from cavitation. These floatless level
electrodes ensure that proper signals are transmitted
to the refrigerant and absorbent pumps for starting/
stopping. The use of float valves for level control is
avoided.
Corrosion Inhibitor
A corrosion inhibitor is added to the lithium bromide
solution to minimize the possibility of any corrosion
occurring in the absorption machine. The
Absorption Chillers use lithium molybdate as the
inhibitor. Lithium molybdate has excellent corrosion
inhibition properties. The use of lithium nitrate is
avoided as it desiccates at high temperatures, and
therefore will not protect the absorption machine.
Lithium intrate is also a substance controlled by the
EPA.
Sight Glasses And Service Valves
The Dunham-Bush Absorption Chiller is provided with
an optimum number of sight glasses and service
valves for easy diagnosis, user-friendly operation and
trouble-shooting. The number of sight glasses and
service valves is kept to a minimum to reduce the
6
number of potential leakage points. The sight glasses
are provided at the evaporator absorber shell and
high temperature generator to monitor the
refrigerant and solution levels.
FEATURES, SPECIFICATIONS AND BENEFITS (CONT.)
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Other Features
• The unit is charged with a positive charge of
• The crossover piping from the absorber to the
nitrogen gas, to avoid any ingress of air inside
the unit during shipping. Shipment of chiller
under vacuum is not recommended.
condenser is a standard feature of the DunhamBush Absorption Chiller. This feature saves the
installing contractor both labor and material.
• The Dunham-Bush Absorption Chiller is provided
with a factory-mounted, wired and tested
microcomputer-based control panel.
Optional Features
• On-line standby canned motor pumps
• Three piece shipment
On-line standby absorbent and refrigerant pumps can
be offered for extremely critical operations where
continuous operation is required.
The Dunham-Bush Absorption Chiller can be shipped
in three sections, comprising of lower shell assembly,
upper shell assembly and high temperature
generator, for convenience of rigging the chiller
inside the existing building structure.
• On-line bearing monitoring for canned motor
pumps
As a special option Dunham-Bush can provide a TRG
meter for on-line bearing monitoring of the pumps.
By continuously measuring the bearing clearance,
through eddy currents, the TRG reading proactively
lets the user know the condition of the bearings at
any given instant.
• Special tube material for evaporator/
absorber/condenser
The selection of tube material is done purely on the
basis of the water quality available. Dunham-Bush
can offer the following special tube material
depending on the available water quality:
Cupro-nickel (90:10)
Cupro-nickel (70:30)
SS-316 L
Titanium
• Cooling water flow switch
As an optional feature, paddle type flow switch is
available for the absorber- condenser water circuit.
The chilled water flow switch is a standard supply.
• Inverter drive for absorbent pump
A microprocessor-based inverter drive can be offered
on the Dunham-Bush Absorption Chiller. The inverter
drive suitably varies the flow of the dilute solution
from the absorber to the high temperature generator,
thus limiting the input steam to the generator. This
assists the chiller to obtain superior part load
performance.
Double Effect Direct Fired
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SELECTION DATA & TECHNICAL SPECIFICATIONS
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Selection Data: Double Effect Gas Fired Absorption Chiller
All double effect gas/oil fired chillers are rated for the following standard parameters:
Chilled water temperature in / out
Cooling water temperature in / out
Chilled water / cooling water fouling factors
Minimum gas pressure at the inlet of the gas train
Maximum working pressure in the water system
Calorific value of natural gas
:
:
:
:
:
:
54 / 44°F
85 / 95.4°F
0.00025 ft2-hr-°F/Btu
.66 ft H2O
113.8 psi
1084.4 Btu/ft3
(12.2 / 6.7°C)
(29.4 / 35.2°C)
(0.000044 m2- /kW)
(2.0 kPa)
(784.5 kPa)
(9650 Kcal/Nm3)
Burner is supplied with the chiller.
For conditions other than mentioned here, please contact the nearest Dunham-Bush Office / Sales
Representative
Technical Specification Sheet Gas Fired Absorption Chiller
Model: WCGA
100
120
150
180
210
240
280
320
93
112
140
167
195
223
260
298
kW
327.4
394.2
492.8
587.8
686.4
785.0
915.2
1049.0
gpm
224.8
271
338.8
403.9
471.7
539.4
629.2
720.7
L/S
14.2
17.1
21.4
25.5
29.8
34.0
39.7
45.5
Ft H 2O
16.1
18
17.1
16.4
18.4
18.7
24.3
24
kPa
48.0
53.9
51.0
49.0
54.9
55.9
72.5
71.5
4
4
4
4
5
5
5
6
102
102
102
102
127
127
127
152
6
6
4
4
4
4
4
4
gpm
409.2
492.8
616
739.2
862.4
985.6
1148.4
L/S
25.8
31.1
38.9
46.6
54.4
62.2
72.4
82.7
Ft H 2O
12.5
13.1
17.7
20.3
16.7
18.7
26.2
24
kPa
37.2
39.2
52.9
60.8
50
55.9
78.4
71.5
5
5
5
5
6
6
6
8
127
127
127
127
152
152
152
203
No. of passes (Absorber)
3
3
2
2
2
2
2
2
No. of passes (Condenser)
1
1
1
1
1
1
1
1
1977.4
2330.5
2813
3072
56
66
74
87
Chilled water circuit
Capacity
Flow rate
Pressure drop
Connection diameter
Tons
in
mm
No. of passes (Evaporator)
Cooling water circuit
Flow rate
Pressure drop
Connection diameter
in
mm
1311.2
Fuel circuit
Gas Consumption
8
ft3/hr
1095
m 3/hr
31
1341.7 1624.3
38
46
3460.4
98
SELECTION DATA & TECHNICAL SPECIFICATIONS (CONT.)
Model: WCGA
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360
400
450
500
550
620
690
770
335
372
419
465
512
577
642
716
1636.8
1802.2
2031.0 2259.8
2520.3
1395.7 1553.2
1734.5
Chilled water circuit
Capacity
Tons
kW
Flow rate
Pressure drop
Connection diameter
1179.2
1309.4 1474.9
gpm
810.5
899.8
1013.8
1124.2
1238.6
L/S
51.1
56.8
64.0
70.9
78.1
88.1
98.0
109.4
Ft H2O
23.3
24.9
24
23.3
27.9
28.9
21.3
23.3
kPa
69.6
74.5
71.5
69.2
83.3
86.2
63.7
69.6
6
6
8
8
10
10
10
10
152
152
203
203
254
254
254
254
4
4
4
4
4
4
3
3
2046
2186.8
2464
2741.2
3058
in
mm
No. of passes (Evaporator)
Cooling water circuit
Flow rate
gpm
1474.0
1636.8 1843.6
L/S
93.0
103.3
116.3
129.1
138
155.4
172.9
192.9
Ft H2O
21.3
23
20.3
20.3
24
25.3
34.8
36.4
kPa
63.7
68.6
60.8
60.8
71.5
75.5
103.9
108.8
8
8
10
10
12
12
12
12
203
203
254
254
305
305
305
305
No. of passes (Absorber)
2
2
2
2
2
2
2
2
No. of passes (Condenser)
1
1
1
1
1
1
1
1
5437.1
5826.2
6744.2
7521
155
165
191
213
Pressure drop
Connection diameter
in
mm
Fuel circuit
Gas Consumption
ft3/hr
3707.6
m 3/hr
105
4237.2 4943.4
120
140
8227.2
233
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APPLICATION INFORMATION
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Location And Space Requirements
The Dunham-Bush Absorption Chillers have
negligible noise and vibration and may generally be
located at any level in a building. The chiller plant
room should be sufficiently ventilated to provide
enough circulation of air and also to ensure that the
burner gets the required quantity of air for efficient
combustion. The unit should be placed on a level
foundation. Sufficient space at either end of the
unit should be provided for tube cleaning/removal.
Also sufficient clearances should be provided on the
remaining sides of the unit for the necessary access
and maintenance. Refer to the physical dimensional
table for space and clearance requirements.
Since water is the refrigerant, the unit must be
located where the ambient temperature does not fall
below the freezing point.
Water Circuits
Water Piping: All chilled water and cooling water
piping should be designed and installed in
accordance with the accepted piping practice. The
piping should be adequately supported to avoid any
strain on the chiller components. All water piping
should be thoroughly flushed clean before
connecting to the unit. A suitably sized expansion
tank should be provided in the chilled water line.
Pressure gages should be installed at the inlet and
outlet water lines of the unit. Air vents should be
located at all high points in the water piping system.
All drain points should be located at low points to
facilitate complete system drainage. Both the chilled
and cooling water pumps should be located to
discharge a positive pressure and required flow
through the unit. Shut-off valves should be provided
to allow unit isolation during maintenance. The
chilled water piping should be insulated to minimize
heat gain, and to prevent condensation of moisture.
Water Quality: Proper quality of water should be
monitored and maintained to ensure long life, and
trouble free and efficient operation of the entire
cooling system. Impurities in water can cause scale
formation, thereby causing a reduction in heat
transfer and affecting the performance of the unit.
The impurities can also be a potential for mechanical
damage to the unit and the system. The use of
properly sized water strainers and water treatment
may be necessary to maintain the required water
quality. It is desirable to set the appropriate water
quality control values under the guidance of a water
processing specialist who will periodically control it.
Suggested Guide Of Cooling And Chilled Water For The Dunham-bush Absorption Chiller
Items
pH at 77°F (25°C)
Electrical
conductivity
at 77°F(25°C)
M alkalinity
Total hardness
Chloride ion
Sulfuric acid ion
Total iron
Sulfur ion
Ammonium ion
Silica ion (SiO2)
Free carbonic acid
Unit
Micro S/cm
ppm
ppm (CaCO3)
ppm (Cl)
ppm (SO4)
ppm (Fe)
ppm (S)
ppm (NH4)
ppm SiO2
ppm (HCO3)
Cooling Water
One-pass or
Make-up Water
circulating
6.5~8.0
6.5~8.0
Chilled Water
800 or less
100 or less
200 or less
200 or less
200 or less
1.0 or less
Not detected
1.0 or less
50 or less
-
500 or less
100 or less
100 or less
100 or less
100 or less
1.0 or less
Not detected
0.5 or less
50 or less
0
200 or less
50 or less
50 or less
50 or less
50 or less
0.3
Not detected
0.2 or less
30 or less
-
Circulating
6.5~8.0
If such water conditions exist which cannot be corrected by proper water treatment, it may be necessary to
provide a larger fouling/scaling allowance and/or choose special tube material suitable for the water quality.
10
APPLICATION INFORMATION (CONT.)
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
Fuel And Exhaust Piping
The Dunham-Bush Absorption Chiller utilizes natural
gas or oil no. 2 as the fuel source. Depending on
the requirement, the chiller is equipped with a
suitable burner, capable of firing either one, or both
fuels. The dual-fuel firing capability gives the user
more flexibility. The fuel and the exhaust piping
should be designed and installed in accordance with
the standard engineering practice and conforming
to the local codes. The site erected exhaust gas duct
should have a removable section above the unit, to
facilitate the duct and the machine maintenance. For
multiple units, it is important to provide separate
ducts from the unit to the main chimney (stack) and
also each duct should be provided with a suitable
damper. This damper should be shut-off for the unit,
while the unit is not in operation.
Cooling And Heating Modes
The Dunham-Bush Direct Fired Absorption Chiller can
be utilized to meet both heating and cooling
requirements of a building. For hot water temperatures
below 140°F (60°C), a two-pipe system is utilized. Thus
the same set of piping, pumps, etc. can be used for
either cooling or heating purposes. If the required
temperature of hot water is higher than 140°F (60°C),
then a four-pipe system can be utilized, by the addition
of an optional heat exchanger on the unit. This feature
assists the owner to eliminate any additional heating
equipment, and also saves the plant room space and
reduces the maintenance. An optional heat exchanger
is also added onto the unit if the requirement is for
simultaneous heating and cooling.
11
PHYSICAL DIMENSIONS
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
Direct Oil/Gas Fired Absorption Chiller
Model: WCGA
Length:
Width:
Height:
Clearance for
tube cleaning:
100
120
150
180
210
240
280
320
in
148.2
144.3
157.1
149.0
162.0
169.5
172.4
175.2
mm
3765
3665
3990
3785
4115
4305
4380
4450
in
100.8
103.1
106.3
109.3
110.0
110.0
113.0
119.5
mm
2560
2620
2700
2775
2795
2795
2870
3035
in
93.1
94.7
94.7
95.5
104.8
99.3
109.1
109.1
mm
2365
2405
2405
2425
2661
2521
2772
2772
in
94.5
94.5
133.9
133.9
133.9
133.9
161.4
161.4
mm
2400
2400
3400
3400
3400
3400
4100
4100
Max shipping
weight:
lb
15212
16314
19401
24692
26676
29983
36376
kg
6900
7400
8800
9300
11200
12100
13600
16500
Total shipping
weight:
lb
15212
16314
19401
20503
24692
26676
29983
36376
A
Shipping method
ONE SECTION
20503
kg
6900
7400
8800
9300
11200
12100
13600
16500
lb
16094
17196
20503
21605
26235
28439
31967
38581
kg
7300
7800
9300
9800
11900
12900
14500
17500
360
400
450
500
550
620
690
770
in
175.2
181.3
175.2
187.2
228.7
228.7
277.2
277.2
mm
4450
4605
4450
4755
5810
5810
7040
7040
in
121.5
121.5
129.3
129.3
132.7
133.9
133.9
133.9
mm
3085
3085
3285
3285
3370
3400
3400
3400
in
113.0
113.0
116.4
120.7
120.7
123.9
128.2
130.4
mm
2870
2870
2956
3067
3067
3147
3257
3312
in
161.4
161.4
161.4
161.4
209.4
209.4
258.3
258.3
mm
4100
4100
4100
4100
5320
5320
6560
6560
Max shipping
weight:
lb
38360
47085
46738
48501
60627
65036
74736
78704
kg
17400
18500
21200
22000
27500
29500
33900
35700
Total shipping
weight:
lb
38360
47085
46738
48501
60627
65036
74736
78704
kg
17400
18500
21200
22000
27500
29500
33900
35700
Operating weight:
lb
40785
43431
49824
51808
64154
68784
78925
83334
kg
18500
19700
22600
23500
29100
31200
35800
37800
Operating weight:
Model: WCGA
Length:
Width:
Height:
Clearance for
tube cleaning:
A
ONE SECTION
HEIGHT
Shipping Method
CLE AR AN CE FOR
TU B E R EMO VA L
A
A
12
LE NG TH
WID TH
TYPICAL PIPING SCHEMATIC
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
13
ELECTRICAL WIRING DRAWINGS
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
WCGACTAA.DWG
14
ELECTRICAL WIRING DRAWINGS (CONT.)
8
49
~
REFRIGERANT
LEVEL
50
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
~
(1DI/OB)
2
2LS
51
9
3
1
10
52
5
53
6
7
54
56
RE1 RE2
57
13H
13DI
13N
85
84
83
55
32
4
RE3
4SN
58
59
4C
4CP
9C
9CP
4NO
33
2CR
9NO
ALARM OUTPUT
2LT
R
60
SEE NOTE 11
61
100
62
3CR
5SN
101
5CP
6C
5NO
34
6CP
6NO
35
7C
7CP
7NO
8C
8CP
10C
10CP
102
64
2CR
104
66
4CR
SEE LINE 48
105
COOLING WATER
CONTROL
19
CONTROL POWER
36
68
69
40
70
71
HIGH TEMP GENERATOR
PRESSURE SWITCH
42
RIBBON CABLE
72
1PS
TO DIGITAL I/O BOARD
73
J3
75
MICROCOMPUTER
(MCB)
J2
76
J5
DISPLAY
J6
77
RS485
J7
79
82
PRESS HELP KEY FOR BASIC
OPERATION INSTRUCTIONS.
83
TO DISPLAY CONTROL VALUE
87
89
89
NAME
TLW °F
PWR LOSS
CWR MAX
FREEZE
SET POINTS
A
OPEN
39 °F
730 mmHG
2TAS
1PS
3TS
COOLING
WATER
OUTLET
TEMP
RED
59
CLOSE
760 mmHG
AI BOARD #1
(1AIB)
BLK
52
WHT
51
RED
59
BLK
53
WHT
51
RED
59
BLK
54
WHT
51
92
GND
NAME
SET POINTS
A
TLW °C
TLW
PWR LOSS
CWR MAX
FREEZE
OPEN
39.0 °F
(3.9 °C)
730mmHG
1
4AI
4RES
250
55
(4TB)
2
BLK
1
81
5 AI
8RES
250
2
BLK
0.0
0.0
4.0°C
CLOSE
(+)
1ZD
0-5VDC
(-)
GND
CHILLED
WATER
RESET
OPTIONAL
GND
93
SEE NOTE 8
94
RIBBON
CABLE
1SC
98
99
100
101
8
11
ANALOG OUTPUT
BOARD (AOB)
AO1
12VAC
AO3
GND
12
102
760mmHG
STACK
TEMP
3 63
97
B
5TS
GND
6AI
51
1 61
2 62
GND
(3TB)
HIGH TEMP
GENERATOR
TEMP
3
5TSI
(3TB) 50 WHT
GND
+5
4TS
SH
GND
2AI
3AI
1
2
+5
96
FURNISHED
NOT FURNISHED
4TSI
(3TB) 50 WHT
1AI
95
METRIC DISPLAY OPTION
16N
7CPR
+5
91
0.0
0.0
39.2 °F
14N
15N
6CPR
GND
90
B
TLW
16DI
TO BURNER CONTROL
2
2TS
COOLING
WATER
INLET
TEMP
FOR MORE INFORMATION
SEE OWNERS MANUAL.
88
15DI
41
RIBBON CABLE
1TS
LEAVING
CHILLER
TEMP
1) PRESS MENU KEY TO DISPLAY
MENU ITEM.
2) USE UP OR DOWN ARROW TO
MOVE TO DESIRED MENU ITEM.
3) PRESS ENTER KEY TO SELECT
DESIRED MENU ITEM.
4) USE UP OR DOWN ARROW TO
DISPLAY DESIRED CONTROL VALUE.
86
16H
10NO
MACHINE ON/OFF
12VAC
INSTRUCTIONS
85
44
12
KEYBOARD
84
15H
RS232
80
81
43
8N0
37
5CPR
BURNER FAULT
11
78
14DI
14H
BURNER ON
8
74
1PS
4CR
19
COOLING WATER CONTROL
67
2TAS
CHILLED WATER
INTERLOCK
6SN
103
ALARM CONTACTS
65
1
2
3
4
3CR
CHILLED WATER PUMP CONTACTS
63
1
2
3
4
5C
JUMPER ON
ADDRESS #4
103
67
(+)
0-10VDC
68
(+)
REMOTE TLW
SIGNAL
69
(-)
1
4
7
2
115VAC
9
(+)
4-20mA
6
10
(-)
TO
BURNER
CONTROL
GROUND
SH
104
105
106
107
108
NOTES
1- FUSES SHALL BE TIME DELAY TYPE.
2- ALL FIELD WIRING SHALL COMPLY WITH LOCAL, STATE AND NATIONAL CODES.
3- USE COPPER CONDUCTORS ONLY. CONTROL WIRING 14AWG WITH MAX. 15A OVERCURRENT PROTECTION.
USE TERMINAL 2 FOR NEUTRAL CONNECTIONS.
4- DISCONNECT MEANS AND BRANCH CIRCUIT PROTECTION SHALL BE PROVIDED BY INSTALLER IF NOT SUPPLIED.
109
110
111
112
113
7- CUSTOMER CONTROL CONTACTS MAY BE WIRED BETWEEN TERMINALS 16&17.
8- IF 0-5 VDC CWR IS USED, SET SETPOINT 3B TO RESET DESIRED
AT +5VDC INPUT.
CAUTION: DO NOT SUPPLY OVER 5.0VDC TO ANALOG INPUT.
10- SHIELDED CABLE IS RECOMMENDED FOR CUSTOMER SUPPLIED CONTACT WIRING. GROUND ON SUBPANEL.
11- CONTACT RATING IS 10A AT 125 VAC AND 5A AT 250 VAC (1/2 HP).
WCGACTBA.DWG
15
ABSORBENT PUMP #2
OVERLOAD
6L2
6L3
2L1
2L2
2L3
6CR
90
21
91
SEE AFD OPTION
118
120
11CP
4H
11NO
2
20DI
4N
7SN
93
92
SEE AFD OPTION
ABSORBENT
PUMP #2
CONTACTOR (13)
4M
1M-2
6LT
W
(#4 ON 2DIOB)
REFRIGERANT
PUMP #2
OVERLOAD
5MOL
26
5MOL
121
~
~
119
5M
4M
1M
11C
3N
94
~
~
6L1
117
~
~
116
HMT
1TAS-2
19DI
(#3 ON 2DIOB)
~
~
FURNISHED
NOT FURNISHED
3H
~
~
DUAL ABSORBENT AND
REFRIGERANT PUMP OPTION
~
~
115
~
114
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
~
ELECTRICAL WIRING DRAWINGS (CONT.)
12CP
12C
12NO
8SN
96
95
122
REFRIGERANT
PUMP #2
CONTACTOR (14)
5M
2M-2
4-MTR
ABSORBENT
PUMP #2
5-MTR
REFRIGERANT
PUMP #2
7LT
W
~
124
~
1-MTR
ABSORBENT
PUMP #1
123
125
TEMPERATURE SENSOR OPTION
126
FURNISHED
NOT FURNISHED
127
128
129
8TSI
NOT FURNISHED
6TS
RS232
ENTERING
CHILLER
WATER
TEMP
J6
131
132
MODEM
134
GND
LINE
136
BLK
60
WHT
51
GND
8TS
LOW TEMP
HEAT EXCHANGER
TEMP
3
SH
(4TB)
GND
2
BLK
9TSI
(3TB) 50 WHT
1
1
9TS
2
3 2
BLK
SH
POWER
OUTLET
137
57
2
LOW TEMP
GENERATOR
TEMP
WHT
1
2
11AI
(#3)
6RES
250
9AI
(#1)
WHT 50 (3TB)
1
1
+5
7TSI
1
7TS
2
BLK
59
TELEPHONE
133
7
RED
(3TB) 50 WHT
AI BOARD #2
(2AIB)
FURNISHED
130
135
RIBBON CABLE TO MCB
MODEM OPTION
10AI
(#2)
2RES
250
56
(4TB)
12AI
(#4)
7RES
250
2
BLK
CONDENSED
REFRIGERANT
TEMP
3
SH
(4TB)
GND
GND
138
58
139
ADJUSTABLE FREQUENCY DRIVE (AFD) OPTION
141
FURNISHED
142
NOT FURNISHED
24
143
1L1
144
REMOVE
1M & 1MOL
145
146
R
1L2
1AFD
S
1L3
T
2
5CR
REMOVE 1M UNLESS
DUAL PUMP OPTION
IS SUPPLIED
U
V
W
1L1
6L1
ABSORBENT
PUMP
6L2
REMOVE
1M & 1MOL
6L3
1AFD
R
1L2
1L3
T
71
149
TB2-6
TB2-7
8
TB2-8
150
72
151
152
TB2-11
5CR
ANALOG
OUTPUT
BOARD
~
155
AO2
156
GND
~
154
TB2-10
73
0-10VDC
74
157
TB2-2
1H
13
SEE LINE 13
TB2-9
8
66
NOTE: TO RESET FAULT,
REMOVE POWER
FROM DRIVE (OPEN 1CB)
22
TB2-3
6CR
70
TB2-6
71
TB2-7
TB2-8
FAULT
OUTPUT
6CR 2
TB2-12
153
18AWG
5CR
23
72
TB2-11
8
TB2-9
FAULT
OUTPUT
6CR 2
TB2-12
~
70
6L3
W
ANALOG
OUTPUT
BOARD
AO2
GND
66
TB2-10
~
5CR
ABSORBENT
PUMP
6L2
V
GND
~
18AWG
148
6L1
U
S
GND
147
~
140
73
NOTE: TO RESET FAULT,
REMOVE POWER
FROM DRIVE (OPEN 1CB)
TB2-2
0-10VDC
TB2-3
74
SEE LINE 28
158
159
LEGEND
160
AE
AFD
161
DOOR LATCH
SOLENOID OPTION
165
AI
C
CB
CO
CP
CPR
CR
CTR
CWDP
166
CWFS
162
FURNISHED
NOT FURNISHED
163
164
167
1
1SOL
2
CWP
CWR
DI
FU
GND
I/O
LS
LT
M
MTR
NC
NO
OL
ABSORBENT ELECTRODE
ADJUSTABLE FREQUENCY
DRIVE
ANALOG INPUT
SHORTING CONTACTOR
CIRCUIT BREAKER
CONVENIENCE OUTLET
CONTROL POINT
CAPACITOR
CONTROL RELAY
CONTACTOR
CHILLED WATER DIFF.
PRESSURE
CHILLED WATER FLOW
SWITCH
CHILLED WATER PUMP
CHILLED WATER RESET
DIGITAL INPUT
FUSE
GROUND
INPUT/OUTPUT
LEVEL SENSOR
LIGHT
CONTACTOR
MOTOR
NORMALLY CLOSED
NORMALLY OPEN
OVERLOAD
PWR
RE
RES
RLY
S
SC
SCR
SH
SN
SOL
T
TAS
TB
TLW
TR
TS
TSI
UVR
VM
ZD
*
[]
POWER SUPPLY
REFRIGERANT ELECTRODE
RESISTOR
RELAY
SWITCH
SIGNAL CONDITIONER
SPEED CONTROL
SHIELD
SNUBBER
SOLENOID
TRANSFORMER
THERMOSTAT
TERMINAL BLOCK
TEMP LEAVING WATER
TIMER
TEMP. SENSOR
TEMP SENSOR INTERFACE
UNDERVOLTAGE RELAY
VOLTMETER
ZENER DIODE
MANUAL RESET
FACTORY TERMINAL
FIELD WIRING
FIELD SUPPLIED
STANDARD COMPONENT
8
2
ABSORBENT
LOW LEVEL
3LS
3
10
11
5
DIGITAL I/O
BOARD #2
(2 D I/O B)
9
45
1H
17DI
(#1)
1N
4
GND
82
86
AE5
AE3
ABSORBENT
LOW-LOW LEVEL
4LS
3
9
1
10
5
46
2H
18DI
(#2)
2N
4
12VAC
88
82
AE4
JUMPER ON
ADDRESS #3
AE5
RIBBON CABLE TO
MICROCOMPUTER J2
WCGACTCA.DWG
16
11
12
ENGINEERING SPECIFICATIONS
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
Provide ................no.(s) factory assembled, leak tested
Natural Gas/Fuel oil no.2 Fired Double Effect DunhamBush Absorption Chiller. Each chiller shall have a
capacity of ................. TR, cooling ................. gpm of
chilled water from .................ºF to .................. ºF, when
supplied with condenser water at a temperature of
............ºF. The unit selection shall be based upon a
fouling factor of ................ for the evaporator and
................ for the condenser/absorber circuit. Natural
gas/fuel oil no. 2 at a pressure of ................. psi shall
be provided before the inlet of burner. The supply
power characteristics shall be ................Volts,
.............Phase, ..............Hz.
The chiller shall be of multi-shell design consisting of
lower shell assembly, upper shell assembly, high
temperature generator mounted with a suitably sized
burner, heat exchangers, absorbent pump, refrigerant
pump, purge pump, purge unit and inter-connecting
piping & accessories.
The unit shall operate on Water-Lithium Bromide cycle.
All tubes in the condenser shall be individually
replaceable from either end of the chiller. The condenser
shall have marine type hinged water headers with side
nozzles for easy opening and access to the tube bundle.
All the tubes shall be fitted in the respective tube sheets
expanded into grooved holes.
4. High temperature generator
The high temperature generator shall have straight and
plain, circular carbon steel boiler quality tubes,
adequately sized and 0.144" wall thickness. All the
tubes shall be fitted in the respective tube sheets duly
expanded for a tight fit and welded. Inside welding of
the tubes shall be avoided to facilitate the removal of
tubes at the site, if required. A suitably sized burner
for firing natural gas/fuel oil no. 2 shall be mounted
on the high temperature generator.
Burner:
The chiller unit shall be supplied with a UL listed burner,
capable of firing on one or both of the following fuels:
1. Mechanical description
All the heat exchangers shall be of shell and tube type
welded construction. The material of shell, tube sheets
and water boxes shall be as per SA 515/516 Gr 70/60
or IS 2002 Gr 2 or IS 2062.
a. Natural gas
b. No. 2 fuel oil
The burner shall be provided with a burner mounted
control panel, necessary controls and stand alone
safeties to provide safe and efficient working.
2. Lower shell assembly
5. Heat exchangers
The evaporator and absorber sections shall be housed
in a common fabricated carbon steel shell, but with
separate compartments for each section. The
evaporator and absorber shall be separated by rows of
stainless steel (SS-430) eliminators. Material for
evaporator and absorber tubes shall be plain DLP
(Deoxidized Low Phosphorous) grade copper. All the
tubes shall be fitted in the respective tube sheets duly
expanded for a tight fit. All the tubes shall be
individually replaceable from either end of the chiller.
The absorber shall have marine type hinged water
headers with side nozzles for easy opening and access
to the tube bundle. The evaporator water headers shall
have side nozzles for easy opening and access to tube
bundle.
3. Upper shell assembly
The low temperature generator and condenser sections
shall be housed in a common fabricated carbon steel
shell, but with separate compartments for each section.
The condenser and low temperature generator shall
be separated by a partition plate fitted with stainless
steel (SS-430) eliminators. Material for condenser tubes
shall be plain DLP (Deoxidized Low Phosphorous) grade
copper. The tubes of the low temperature generator
shall be low finned copper.
The heat exchangers shall be of shell and tube type
welded construction. There shall be three heat
exchangers - low temperature, high temperature and
drain heat exchanger. The tube material for low
temperature heat exchanger shall be spiral copper, for
high temperature heat exchanger shall be spiral cupronickel (90:10) and for drain heat exchanger (heat
reclaimer) shall be stainless steel (SS-430) titanium
stabilized, for maximum heat transfer between the
circulating fluids.
6. Refrigerant and absorbent pump
The unit shall be provided with two motor-pump
assemblies - a refrigerant pump for even distribution
of refrigerant on the evaporator tube bundle through
gravity feed arrangement and one absorbent pump to
deliver the dilute solution to the generator. Both the
pumps shall be canned motor, self lubricating type and
shall be cooled by the fluid being pumped. The
absorbent pump shall be provided with both overcurrent and high temperature protection safeties to
prevent the motor from burnout. Both the pumps shall
be provided with isolating valves at both the suction
and discharge ends for ease of removal of the pumps
for maintenance, without breaking the vacuum inside
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the chiller. Both the pumps shall have a external bearing
monitoring system to enable the user to check the
condition of the bearing, without dismantling the
pumps.
7. Purge recovery unit
The purge unit shall be sized to automatically and
continuously remove the non-condensable gases from
the shell to the storage tank, when the chiller is in
operation. The purge unit shall be provided with a
factory mounted and tested electrical motor driven
purge pump to remove these gases from the storage
tank. The unit shall be provided with a solenoid valve
or a non-return valve to avoid air from entering the
absorption chiller, in case the power fails while the
purge pump is in operation.
8. Gravity feed trays
The chiller shall be provided with stainless steel (SS430) gravity-feed trays for even distribution of
refrigerant and absorbent over the respective tube
bundles. The gravity feed trays shall be located just
above the top of the respective tube bundle and shall
have perforations perfectly aligned with and running
along the entire length of the tube bundle. The gravity
feed arrangement enhances the machine life by
eliminating the chances of erosion of spraying nozzles
and disruption of flow due to clogging of nozzles with
impurities.
12. Liquids
The absorption chiller shall operate on water-lithium
bromide cycle. A suitable charge of both the refrigerant
and a suitably inhibited lithium bromide shall be
supplied by the manufacturer. The inhibitor used shall
be environment friendly and shall not be chromate or
nitrate based. Also a suitable quantity of heat transfer
additive shall be charged in the unit.
13. Controls and safeties
Each unit shall be equipped with a factory mounted
and pre-wired control system. The chiller shall be
equipped with two panels - a combined power and
control center, and a burner control panel.
The burner control panel shall be designed to interface
directly with the microcomputer-based chiller control
panel, to provide integrated burner firing control for
the chiller operation. The control system shall provide
for modulation of the burner based on the desired
chilled water leaving temperature, control and
monitoring of absorbent, refrigerant and purge pumps
and control interlocks for chilled water and cooling
water pumps.
The control equipment shall be enclosed in a NEMA 1
type sheet metal enclosure mounted on the chiller. The
safety and control circuit shall consist of the following:
•
9. Sight glasses and service valves
The unit shall be provided with a minimum yet sufficient
number of sight glasses and service valves for easy
diagnosis, user-friendly operation and troubleshooting. The number of sight glasses and service valves
shall be kept to a minimum to reduce the number of
potential leakage points. The use of threaded type sight
glasses shall be avoided. The sight glasses shall be
provided at the following locations to monitor the
refrigerant and solution levels:
•
•
•
•
•
•
Evaporator shell, absorber shell and high
temperature generator shell.
•
10. Piping
•
The various sections of the chiller shall be interconnected by suitably sized seamless steel piping. All
piping shall be of welded construction complete with
necessary valves and fittings. The absorber to the
condenser crossover piping shall be suitably welded
by the supplier.
•
•
•
11. Auto-decrystalization line
The unit shall be provided with an overflow pipe
connecting the low temperature generator to the
absorber and bypassing the heat exchanger, to enable
the hot solution to flow directly from the low
temperature generator to the absorber and hence
decrystalize the unit.
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•
•
•
Terminal blocks for control and power
connections
Microcomputer based control system
Individual circuit breakers for each pump and
the burner
Ambient compensated overloads for all pumps
Control transformer
Level controller and electrodes for evaporator
refrigerant level control and first stage
generator (high temperature) solution level
control. The use of a float valve for level
controls shall be avoided.
High motor temperature cutout for absorbent
pump
Interlock terminals for chilled and cooling water
pumps
On/off/remote selector switch for unit control
Purge pump control switch
Indicator lights for control power, absorbent
pump, refrigerant pump, purge pump and
alarm
Temperature sensors and digital display for the
following:
Chilled water leaving temperature, cooling
water entering and leaving temperature and
first stage (high temperature) generator
temperature
Freeze protection thermostat
Factory mounted flow switch & differential
pressure switch for chilled water
Burner control and monitoring
Information display
The computer shall have a simple keyboard accessed
input system and shall be complete with a two line 80
character alphanumeric display. The input shall be
accomplished through simple menu driven display
screens, with on-line help available by pressing a help
button at any time during operation. The information
shall be in the English language with numeric data
provided in English units. The following information
shall be provided on the computer:
•
•
•
•
•
•
•
•
Leaving chilled water temperature
Entering and leaving cooling water
temperatures
First stage (high temperature) generator
temperature
Operating hours of the chiller
Indication of refrigerant, solution and purge
pump's manual/auto operation
Burner firing rate (in %)
Number of starts of the chiller
Number of purge cycles (Cumulative)
The computer shall be complete with all hardware and
software necessary to enable remote monitoring of all
data through the addition of only a simple, optional,
phone modem and terminal. The microcomputer shall
be complete with an RS232 “local” communications
port and an RS485 long distance differential
communications port. The microcomputer shall also
accept a remote start and stop signal, and a 0 - 5 VDC
chilled water temperature reset signal.
The microcomputer shall be able to transmit all the
operating, setpoint and shutdown information to a
remote terminal. This transmission occurs as needed
and can be printed. The microcomputer shall store a
history data of the last eight safety shutdowns.
Chilled water limit - If the leaving chilled water
temperature reduces below the low setpoint value, the
microcomputer shall shut off the refrigerant pump. The
pump shall be restarted automatically when the chilled
water temperature rises above the high setpoint value.
Shutdown controls
1. Safety shutdown :
The microcomputer shall be preprogrammed to shut
down the unit when any one or more of the following
conditions occur:
•
•
•
•
•
•
•
•
•
•
•
•
Refrigerant or absorbent pump current
overload
High motor temperature cut-out for absorbent
pump motor
Burner alarm/failure
High stack temperature
Chilled water flow switch trip
Chilled water differential pressure switch trip
Freeze protection thermostat trip
Low cooling water entering temperature
First stage (high temperature) generator high
temperature
First stage (high temperature) generator high
pressure
Sensor failure monitoring
Power failure (when “automatic restart after
power failure” setting is not utilized)
In case of safety shutdown controls, a manual
operation to restart the unit is required. Whenever a
safety shutdown occurs, the computer shall record the
following information and store it in its memory:
• Day and time of shutdown
• Reason for shutdown
2. Cycling shutdown:
Capacity control
The computer shall automatically vary the burner firing
rate in order to maintain the leaving chilled water
setpoint for variable cooling loads. The following
parameters shall be programmable directly from the
keypad using a security access code, for safe operation:
•
•
•
•
Chilled water leaving temperature in
increments of 0.1°F
Chilled water leaving temperature reset based
on 0 - 5 VDC signal
Package control based on 7 day weekly
schedule with up to 8 holiday schedules
Ramp-up of unit capacity on start-up
Proactive controls for unit protection
Cooling water limits - The microcomputer shall restrict
the burner firing rate in case the cooling water entering
temperature exceeds lower or upper limits.
In case of a cycling shutdown, automatic restart of the
unit occurs. The following conditions are included
under the cycling shutdown condition:
• Low leaving chilled water temperature
• Power failure (when automatic restart setting
is utilized)
• Loss of condenser water flow (Optional)
• Scheduling of unit operation set for shutdown
1. In addition to the standard temperatures, the
Microcomputer can monitor the following
temperatures:
• Entering chilled water temperature
• Condensed refrigerant temperature (at the
U-tube)
• Strong solution leaving temperature from
the heat exchanger
2. Optional modem can be provided for remote
monitoring of the unit with a terminal or
personal computer.
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3. Under voltage and phase sequence protection relay.
4. Unit disconnect switch with external handle.
5. Inverter drive for absorbent pump: A fully
microprocessor-based inverter drive can be offered
on the Dunham-Bush Absorption Chiller. The
inverter drive suitably varies the flow of the dilute
solution from the absorber to the high temperature
generator, thus limiting the input energy to the
generator and assisting in achieving superior part
load performance.
Specifications subject to change without notice.
July 2000
101 Burgess Road, Harrisonburg, VA 22801
Phone: (540) 434-0711 Fax: (540) 434-4595
www.dunham-bush.com
Printed in U.S.A.
Form No. 6066A

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