Trane CG-PRC011-EN User Manual
Scroll Liquid Chillers
20 to 60 Tons (60 Hz)
17 to 50 Tons (50 Hz)
Water-Cooled and Condenserless
Built For the Industrial and Commercial Markets
January 2002
CG-PRC011-EN
Features and
Benefits
The Trane 20-60 Ton Scroll Liquid Chiller
More Than Just Another “Improved”
Chiller
— Advanced Design
— Better Reliability
— Superior Efficiency
— Smarter Microprocessor Control
— Better Availability
— Easier To Install and Operate
Control
Panel
Design
The Trane scroll compressor is the most
advanced compressor in the industry.
Reliability
64 percent fewer compressor parts,
compared to reciprocating compressors,
mean long and reliable life.
Efficiency
CGWE scroll chillers meet and exceed
ASHRAE Standard 90.1 full and part load
efficiencies. Part load efficiencies are
simply unmatched by reciprocating
chillers.
Power Supply Monitor Protects
Compressors From Phase Loss, Phase
Reversal, Phase Imbalance, Incorrect Phase
Sequence and Under and Over Voltage
Control
Advanced and complete safety and
control algorithms available.
Availability
Fast ship cycles on both stock and builtto-order specials.
Installation
Small unit size, factory wiring, easy
lifting provisions, and start-up control
logic mean quick and easy setup.
Chillers fit through standard singlewidth door.
Operation
Smart safety features and over 40
diagnostic displays mean easy and
virtually trouble-free operation.
Rugged Trane
Scroll
Compressor
Microprocessor
Operator
Interface
Condenser
Leaving
Water Piping
Condenser
Entering
Water Piping
Evaporator Leaving
Water Piping
CG-PRC011-EN© 2002 American Standard Inc. All rights reserved.
Contents
Features and Benefits
Model Number Description
General Data
Application Considerations
Selection Procedure
Performance Adjustment Factors
Performance Data
Electrical Data
Jobsite Connection
Controls
Dimensional Data
Weights
2
9
10
11
12
13
15
24
26
28
29
34
CG-PRC011-EN
Options
Typical Wiring Diagrams
Features Summary
Mechanical Specifications
35
36
38
39
3
Features and
Benefits
Standard Features
Microprocessor Control
Microprocessor control means the scroll
chiller maintains chilled water
temperature more accurately, resulting in
less temperature drift in the building. The
microprocessor control also incorporates
optimal chiller start-up logic (low and
high ambient), load limiting, compressor
anti-recycle timing, auto lead/lag
function, compressor protection, and
many other safety features. The “smart”
safety features provide complete fault
protection without nuisance tripping.
BENEFIT: consistent, reliable operation,
longer life.
Leaving Chilled Water
Temperature Control
The microprocessor actually monitors
temperature and the rate of change over
time, effectively controlling compressor
loading for efficient chiller operation.
BENEFIT: accurate and efficient building
comfort, less energy wasted.
Diagnostics and Display
The microprocessor’s operator interface
is a menu-driven digital display. The
display provides temperatures,
pressures, setpoints and diagnostics
readouts. Flashing display notifies
operator of fault condition and
diagnostics are saved until manually
reset.
BENEFIT: easy troubleshooting and
control
Compressor Protection
All compressors are individually
protected against starting and running
overload, under and over voltages,
phase loss, phase reversal, high winding
temperature and rapid recycling.
BENEFIT: long unit life and added
reliability.
External Control
Several external contacts are provided
for custom control requirements
including time of day scheduling and kW
demand limiting.
BENEFIT: more standard control and
more flexible owner upgrades.
Other Standard Features
• Control power transformer
• Auto lead/lag (on or off)
• Solid-state motor protection
• Insulation (Armaflex II or equal)
• Evaporator and condenser water pump
interlocks
• Filter-dryer
• Built-in loss of chilled water flow
sensors
• Chillers fit through standard single
width door.
Options
• Trane Integrated Comfort
communication
• Generic building automation systems
(BAS) interface
• Chilled water reset (ambient, zone,
return)
• Ice making
• Hot gas bypass
• Remote display/control panel
• Remote running indication and alarm
contact
• Unit-mounted disconnect
• Gauges
• Sound Attenuation
• Neoprene Isolators
• Compressor cycle counter/hour meter
• Water regulating valves
• Condenser water temperature sensors
™
systems
The standard ARI rating condition
(54/44°F and 85°F/3.0 gpm per ton) and
IPLV are ARI certified. All other ratings,
including the following, are outside the
scope of the certification program and
are excluded:
Glycol.
•
50 Hz.
•
Condenserless models CCAD.
•
Water Chiller Systems Business Unit
CG-PRC011-EN4
Features and
Benefits
ASHRAE Standard 90.1
chillers meet and exceed the new
efficiency levels mandated by ASHRAE
Standard 90.1. This new standard
requires higher efficiencies than past
technologies can deliver. In fact, energy
efficiency is so paramount the US
Federal Government has adopted
standard 90.1. Federal Executive Order
mandates energy consuming devices
procured must be in the top 25% of their
class. In the case of chillers, ASHRAE
90.1 is the product standard for
measurement.
Risk.
Not only has ASHRAE 90.1 been
adopted by the US Federal Government,
it’s expected to be adopted domestically,
if not globally, in the future. Make sure
that your chillers as well as your entire
HVAC system complies, or you may be
caught retrofitting your project with new
equipment and paying extra design
dollars if the code changes during
construction.
Trane’s CGWE was designed with the
end user’s requirements in mind.
Efficiency and reliability were primary
design concerns with this latest
generation machine.
Operating Torque
All Trane
Leading in Efficiency and Reliability with State-Of-The-Art
Scroll Compressor Technology
Efficiency
The energy efficiency of the scroll chiller
results in energy costs lower than any
other comparable chiller. Full load
efficiencies are improved beyond
reciprocating chillers, but part load
efficiencies are simply unmatched by any
other manufacturer.
Superior efficiencies are obtained by
combining many of the traditional scroll
chiller energy efficient features with the
Trane scroll compressor technology.
HERE’S HOW:
• Scroll compressor’s positive
displacement design
• Dual refrigerant circuits (40-60 ton units)
• Multiple compressors
• Optimum system design
• Reduced friction
• No valves
• Advanced heat transfer surfaces
Scroll Chiller Energy Usage Savings
Typical Reciprocating
Chiller
Reliability
The Trane scroll chiller with many new
improvements, now brings an exciting
new compressor to the commercial
market — the Trane scroll compressor.
Trane has designed the scroll
compressor to be a leader in reliability.
HERE’S HOW:
• Simple design with 64 percent fewer
parts than equal capacity reciprocating
compressor.
• Scroll compliance allows liquid and dirt
to pass through without damaging
compressor (liquid slugging resistant).
• Advanced microelectronics protect both
compressor and motor from typical
electrical fault conditions.
• Scroll compressors have less than a
third the torque variations of a
reciprocating compressor.
• Years of laboratory testing have
optimized compressor and chiller
systems reliability.
• Water-cooled scroll chillers are factory
tested.
10-20% Annual Energy Savings
Chart illustrates low torque variation of the
Trane scroll compressor vs reciprocating
compressor.
CG-PRC011-EN
Scroll Chiller
Kilowatt Hours
Chiller Load (%)
Graph illustrates Trane scroll chiller’s superior annual energy costs vs typical reciprocating
chillers.
5
General
The scroll compressor has two scrolls.
The top scroll is fixed and the bottom
scroll orbits. Each scroll has walls in a
spiral shape that intermesh.
Inlet-First Orbit
As the bottom scroll orbits, two
refrigerant gas pockets are formed and
enclosed.
Compression-Second Orbit
The refrigerant gas is compressed as the
volume is reduced closer to the center of
the scroll.
Discharge-Third Orbit
The gas is compressed further and
discharged through a small port in the
center of the fixed scroll.
Features and
Benefits
Trane Scroll Compressor
— Maximum Efficiency with Enhanced Reliability
Scroll Principal Components
This is a cutaway view of a hermetic,
scroll compressor, showing the relative
positions of the principal components.
Shown is a Trane 10-ton, 3600 rpm, 60 Hz
[3000 rpm, 50 Hz] scroll compressor as
an example.
The principle of operation of this
example compressor is as follows: The
suction gas is drawn into the compressor
at A. The gas then passes through the
gap between the rotor and stator, B,
cooling the motor, before it enters the
compressor housing, C. Here, the
velocity of the gas is reduced, causing a
separation of the entrained oil from the
gas stream. The gas then enters the
intake chamber, D, that encircles the
scrolls.
Finally, the suction gas is drawn into the
scroll assembly where it is compressed
and discharged into the dome of the
compressor. The dome of this example
compressor acts as a hot gas muffler
which dampens the pulsations before the
gas enters the discharge line, E.
CG-PRC011-EN6
Features and
Benefits
Trane Value Means Fast Availability,
Easy Installation and Quality Service
Packed Stock For Fast Delivery
When your project is a fast-track job,
Trane can help. A wide range of chillers
are stocked and can be shipped soon
after receipt of your order.
Build To Order
Need a special chiller fast? Think Trane
scroll chillers. New manufacturing
technology and inventory control means
the fastest delivery schedule in the
industry. Wide array of standard options
provides the right chiller for the job fast.
Installation
• Only one power connection hook-up —
for fast and inexpensive installation.
• Integrated Comfort™ system means
only single pair connections are
required for control interfaces and
therefore, lower total installation costs.
• Factory refrigerant and oil charged
units help speed installation.
• All units easily fit through a standard
single width door.
• Built-in chilled water flow sensors
mean no field-installed flow switches
are required.
• Microprocessor displays both entering
and leaving chilled water temperatures.
No chilled water thermometers are
required.
Easy Serviceability
Trane 20 through 60 ton scroll chillers
are designed with service personnel in
mind. All major components are
replaceable without complete unit
disassembly. Plus, the microprocessor
control panel provides diagnostic
capability to aid service personnel in
analyzing problems. Therefore, if a
problem does occur, the chiller can be up
and running in a shorter period of time.
Quick and Complete Submittals
The Trane commitment to value-added
products doesn’t stop at just the
products, we are committed to total
customer satisfaction. Part of this
commitment is to provide quick,
complete, readable and accurate
drawings.
Single-Source Responsibility
A wide range of products designed for
complete compatibility are available with
the scroll chillers. Your entire building
comfort system can be completed using
components from Trane.
The Added Value of Applications
Expertise
With the scroll chiller you get
applications expertise and know-how
from a Trane sales engineer. Trane has
more than 1500 sales engineers across
the country — each one a degreed
engineer. Trane sales engineers have
creative ideas and solutions to difficult
building comfort system design
problems. You can take full advantage of
their knowledge in designing a quality,
dependable comfort system.
There’s more. Your Trane sales engineer
is backed by the Trane world
headquarters staff of applications
experts, regarded as the best in the
industry. The C.D.S. Network provides
Trane sales engineers — and many
independent design and consulting firms
— direct access to many comfort system
application, selection and design
programs.
You get a quality chiller, properly
selected and applied in a properly
designed system. That means a comfort
system that works, the first time!
CG-PRC011-EN
7
Features and
Benefits
No Other Microprocessor Does More So
You Can Do Less
The new microprocessor control system
enhances the Trane scroll chiller by
providing advanced technology to
control chiller operation and associated
sensors, actuators, relays and switches.
• Operator interface is improved and
easy to use. Panel displays all operating
and safety codes with complete
diagnostic information. Over 40
diagnostics are included.
• Smart safety features shut down
cooling only if absolutely necessary,
preventing nuisance safety trip outs.
• Microprocessor easily interfaces with
Trane Tracer
computer for Integrated Comfort
system benefits; all with a single
twisted pair wire!
™
building management
Trane Integrated Comfort
System
The Future Is Now!
Simple
• Factory packaging for smooth start-up.
• Easy to install with only a single twisted
wire pair to the central Tracer building
management system.
• Constant, comprehensive monitoring
tracks equipment operation and takes
control to keep tenants comfortable.
• Optional override buttons on each floor
allow tenants to have control after
hours. After-hours use is automatically
logged to allow tenant billing.
• Review building performance at a
glance with automatically generated
reports and logs.
• Enhanced service and building
management capability through remote
diagnostics and control.
• Trane Building Management Network
allows control from across town or
across the country.
A Dependable System From A Single,
Reliable Source
• System design, equipment supply and
service support all available from Trane.
• Factory testing of all Trane equipment
ensures the system works.
The Trane Difference —
™
The Integrated Comfort
Twisted Pair
Communications
Connects To:
Trane Integrated
Comfort Systems
(No System Control Panel
(SCP) is necessary)
At A Lower Cost
• Factory packaged controls and sensors
reduce jobsite labor costs while
assuring proper installation.
• Single twisted pair wire
communication technology
dramatically simplifies installation and
reduces jobsite installation costs.
• Because the unit has been factory
tested, there are no system problems;
allowing smoother start-up, reducing
follow-up costs.
• Building block approach allows you to
change your system without
redundancy and wasted cost.
System
No Bad Jobs
There is another benefit from singlesource responsibility and the Trane
Integrated Comfort systems. With Trane
ICS, you get a single-source supplier of
the system — from the chillers to the air
handlers to the controls. Trane is the
only HVAC manufacturer which can
provide the entire system.
For more information on how Trane
scroll chillers and an Integrated Comfort
system can benefit your next HVAC
project, contact your nearest Trane sales
office.
CG-PRC011-EN8
Model Number
Description
Model Number Description
CGW E 020 4 C XX H A T 1 0 0 0 0 0 L A
1,2,3 4 5,6,7 8 9 10,11 12 13 14 15 16 17 18 19 20 21 22+
Digits 01, 02, 03, – Chiller Series
CGW = Water-Cooled Scroll Chiller
CCA = Scroll Compressor Chiller
Digits 04, – Development Sequence
Digits 05, 06, 07 – Nominal Capacity
020 = 20 Tons (Simplex Circuit,
2 Compressors)
025 = 25 Tons (Simplex Circuit,
2 Compressors)
030 = 30 Tons (Simplex Circuit,
2 Compressors)
040 = 40 Tons (Duplex Circuit,
4 Compressors)
050 = 50 Tons (Duplex Circuit,
4 Compressors)
060 = 60 Tons (Duplex Circuit,
4 Compressors)
Digit 08 – Unit Voltage
D = 380/60/3
G = 200-230/60/3
N = 400/50/3
S = Special Customer Option
4 = 460/60/3
5 = 575/60/3
Digit 09 – Cooling Type
C = Standard Cooling
S = Special Customer Option
Digit 10, 11 – Design Sequence
XX = Factory Assigned
Digit 12 – Condenser Configuration
H = High Efficiency Condenser
0 = No Unit Condenser
(CCA, CUA Units)
Digit 13 – Control Interface
A = Standard Microprocessor Interface
B = Multi-Wire Interface (GBAS)
C = Chilled Water Reset Return Water,
No Comm.
D = Chilled Water Reset – Zone Air,
No Comm.
E = Ice-Making Control
F = Remote Display
G = Chilled Water Reset – Outside Air
S = Special Customer Options
T = Bi-Directional Interface (Tracer)
Digit 14 – Panel Connections
D = Disconnect Switch
S = Special Customer Option
T = Terminal Block
Digit 15 – Evaporator Leaving
Temperature
1 = Standard 40-60 F
2 = Low Temperature 25-39 F
3 = Low Temperature 10-25 F
4 = Icemaking 20-60 F
S = Special Customer Option
Digit 16 – Remote Alarm Contacts
0 = No Remote Alarm Contacts
R = Remote Alarm Contacts
Digit 17 – Condenser Entering
Temperature
0 = Remote Condenser
1 = Standard Temperature 60-90 F
4 = High Temperature 90-130 F
S = Special Customer Option
Digit 18 – Evap Tube Type
F = Standard Finned Tubes
S = Special Customer Option
Digit 19 – Cond Tube Type
0 = Remote Cond
F = Standard Finned Tubes
S = Special Customer Option
Digit 20 – Hot Gas Bypass
0 = Without Hot Gas Bypass
B = With Hot Gas Bypass
Digit 21 – Water Box Orientation
L = Left Hand
R = Right Hand
S = Special Customer Option
Digit 22+ – Add-on Options
A = Unit Sound Attenuator
C = CSA Listing
G = Unit Gauges
H = Hour Meter and Cycle Counter
L = Low Ambient Lock-Out Thermostat
P = Phase Reversal Protection
R = Remote Display
T = Tracer Monitoring Package
U = UL Listing
CG-PRC011-EN
9
General Data
Table GD-1 — General Data — CGWE Water-Cooled Chiller
Size 20 25 30 40 50 60
Compressor
Quantity (1) 2 2 2 2/2 2/2 2/2
Nominal Size (tons) (2) 10/10 10/15 15/15 10-10/10-10 10-15/10-15 15-15/15-15
Steps of Unloading (%) 100,50 100,60 100,50 100,75,50,25 100,80,60,30 100,75,50,25
Evaporator
Water Storage (Gallons) 12 11 16 13 21 40
Min. Flow (GPM) 24 30 36 48 60 84
Max. Flow (GPM) 72 90 108 144 180 252
Condenser
Water Storage (Gallons) 8.9 8.0 11.7 19.9 18.2 23.5
Min. Flow (GPM) 30 36 50 60 72 90
Max. Flow (GPM) 90 108 146 180 216 325
General Unit
Refrigerant R-22 R-22 R-22 R-22 R-22 R-22
No. of Independent
Refrigerant Circuits 1 1 1 2 2 2
Refrigerant (lb) 50 50 90 50/50 50/50 75/75
Charge (kg) 22.7 22.7 40.8 22.7/22.7 22.7/22.7 34/34
Oil Charge (Pints) 16 22 28 16/16 22/22 28/28
Notes
1. Data containing information on two circuits shown as follows: CKT 1/CKT 2
2. Nominal compressor sizes based on 69 Hz.
(Liters) 45 42 61 49 80 151
(L/Sec) 1.5 1.9 2.3 3.0 3.8 4.7
(L/Sec) 4.5 5.7 6.8 9.1 11.4 17.3
(Liters) 33.7 30.3 44.3 75.3 68.9 88.9
(L/Sec) 1.9 2.3 3.2 3.8 4.5 5.7
(L/Sec) 5.7 6.8 9.2 11.4 13.6 20.5
(L) 7.6 10.4 13.2 7.6/7.6 10.4/10.4 13.3/13.3
Table GD-2 — General Data — CCAD Compressor-Chiller
Size 20 25 30 40 50 60
Compressor
Quantity (1) 2 2 2 2/2 2/2 2/2
Nominal Size (tons) (2) 10/10 10/15 15/15 10-10/10-10 10-15/10-15 15-15/15-15
Steps of Unloading (%) 100,50 100,60 100,50 100,75,50,25 100,80,60,30 100,75,50,25
Evaporator
Water Storage (Gallons) 12 11 16 13 21 19
Min. Flow (GPM) 24 30 36 48 60 84
Max. Flow (GPM) 72 90 108 144 180 252
General Unit
Refrigerant R-22 R-22 R-22 R-22 R-22 R-22
No. of Independent
Refrigerant Circuits 1 1 1 2 2 2
Refrigerant (lb) 6 8 12 6/6 8/8 12/12
Charge (kg) 2.7 3.6 5.4 2.7/2.7 3.6/3.6 5.5/5.5
Oil Charge (Pints) 16 22 28 16/16 22/22 28/28
Notes:
1. Data containing information on two circuits shown as follows: CKT 1/CKT 2
2. Nominal compressor sizes based on 69 Hz.
(Liters) 45 42 61 49 80 72
(L/Sec) 1.5 1.9 2.3 3.0 3.8 4.7
(L/Sec) 4.5 5.7 6.8 9.1 11.4 17.3
(L) 7.6 10.4 13.2 7.6/7.6 10.4/10.4 13.3/13.3
CG-PRC011-EN10
Application
Considerations
Unit Location
Units should be installed indoors where
exposure to rain or water splash is
minimal. A level foundation or flooring
must be provided which will support at
least 150 percent of the operating weight
of the unit. The chiller foundation must be
rigid to reduce vibration transmission to a
minimum. Use of vibration isolators is
recommended for applications with
sensitive vibration and noise criteria.
Allow service clearance for compressor
removal as well as evaporator and
condenser tube removal.
Condenser Water Limitations
Water-cooled scroll chillers start and
operate satisfactorily over a range of load
conditions with uncontrolled entering
water temperature.
Reducing the condenser water
temperature is an effective method of
lowering the power input required.
However, by reducing the condenser
water temperature beyond certain limits,
the effect causes a reduction in the
pressure drop across the thermal
expansion valve to a point when system
instability may occur.
In general, continuous machine operation
with entering condenser water
temperature below 60°F [15.5°C] is not
recommended. When the condenser
water temperature is expected to drop
below 60°F [15.5°C], it is recommended
that some form of condenser water
temperature control be used to ensure
optimal machine performance.
Water Treatment
Use of untreated or improperly treated
water in chillers may result in scaling,
erosion, corrosion, algae or slime. It is
recommended that the services of a
qualified water treatment specialist be
engaged to determine what treatment, if
any, is advisable. Trane assumes no
responsibility for the results of untreated,
or improperly treated water.
Water Pumps
Avoid specifying or using 3600 rpm, 60
Hz [3000 rpm, 50 Hz] condenser water
and chilled water pumps. Such pumps
may operate with objectional noise and
vibration. In addition, a low frequency
beat may occur due to the slight
difference in operating rpm between
water pumps and scroll compressor
motors. Where noise and vibration-free
operation is important, Trane
encourages the use of 1750 rpm, 60 Hz
[1450 rpm, 50 Hz] pumps.
Remote Condenser
Remote condensers should be located
as close as possible to the chiller to
ensure minimum pressure drops of
discharge refrigerant. If non-Trane
condensers are provided, a subcooling
circuit must be provided in order to
achieve cataloged performances
(16°F [-8.9°C] subcooling).
CG-PRC011-EN
11
Selection
Procedures
The chiller capacity tables on the
following pages cover the most
frequently encountered leaving water
temperatures. For temperature drops
other than 10°F [5.6°C], refer to Table
SP-1, Performance Adjustment Factors,
shown below.
Additional chiller selections and
performance information can be
obtained through your local Trane sales
office.
To select a Trane water-cooled scroll
chiller, the following information is
required:
1. Design load in tons of refrigeration
2. Design chilled water temperature drop
3. Design leaving chilled water
temperature
4. Entering condenser water temperature
Evaporator flow rate (gpm) can be
determined by using the following
formula:
gpm = Tons x 24
Chilled Water DT (°F)
Condenser flow rate (gpm) can be
determined by using the following
formula:
gpm =
24 x (tons + (0.285 x compressor kW)
Condenser Water DT (°F)
Table SP-1 – Performance Adjustment
Fouling Water Evap. Cond.
Factor Delta T Capacity GPM kW GPM
0.00010 10 1.000 1.000 1.000 1.000
Note:
This selection procedure is for water only as the
solution.
Factors
8 0.997 1.231 1.000 0.997
12 1.007 0.829 1.001 1.006
14 1.012 0.714 1.001 1.010
16 1.017 0.628 1.002 1.014
Scroll Liquid Chiller — (CGWE) —
Selection Example:
Given:
System Load = 40 tons
Leaving Chilled Water Temperature
(LCWT) = 44°F [6.7°C]
Entering Condenser Water Temperature
(EWT) = 85°F [29.4°C]
Leaving Condenser Water Temperature
(LWT) = 95°F [35°C]
Chilled Water Temperature Drop
= 10°F [5.6°C]
1. From Table PD-2 (Performance Data), a
CGWE 40 at the given conditions will
produce 39.4 tons with a compressor
power input of 30.3 kW and a unit EER
of 15.6.
2. To determine the evaporator and
condenser water pressure drops, the
flow rates (gpm) must be determined.
Using the formula above, this unit
would require an evaporator flow rate
of 95 gpm and a condenser flow rate
of 115 gpm. (Compressor kW is found
in the same table as the capacity.) The
Evaporator Pressure Drop Curve,
Figure PD-1, indicates that 95 gpm
through a 40 ton evaporator results in
a pressure drop of 13.8 feet of water.
The Condenser Pressure Drop curve,
Chart PD-2, indicates 115 gpm through
a 40 ton condenser results in a
pressure drop of 14 feet of water.
3. The final unit selection is:
— Qty (1) CGWE 40
— Cooling Capacity = 39.4 tons
— Entering/Leaving Chilled Water
Temperatures = 54/44°F [12.2/6.7°C]
— Chilled water flow rate = 95 gpm
— Evaporator water pressure drop =
13.8 feet
— Cooling water flow = 115 gpm
— Condenser water pressure drop =
14 feet
— Compressor power input = 30.3 kW
— Unit EER = 15.6
Compressor Chiller – (CCAD) – Selection
Example:
Select the unit for the following
conditions:
A compressor chiller is required to
produce 45 tons when matched with an
air-cooled condenser. The leaving chilled
water temperature is 44°F [6.7°C]. The
evaporator temperature differential is
10°F [5.6°C]. The ambient temperature is
95°F [35°C].
1. Select the nominal unit size. The
performance data is tabulated by
leaving chilled water temperature. For
example, the standard unit capacities
at 44°F [6.7°C] leaving chilled water
temperature are found on page 21.
The system that best meets the
tonnage requirement is a CCAD 50
matched with a CAUC C50. The unit
capacity is 47.1 tons with a kW input of
56.3. The compressor chiller EER is
10.0.
2. Calculate the required chilled water
flow rate.
3. gpm = Tons x 24
Chilled Water DT (°F)
From this example,
47.1 x 24 = 113
gpm =
10
4. Determine the evaporator water
pressure drop. The evaporator water
pressure drop is located on page 22.
Entering the evaporator chart at 113
gpm, the pressure drop for a CCAD 50
evaporator is 7.9 feet.
5. Unit Selection
The above procedure shows the
proper selection for this example is a
CCAD 50 with a CAUB C50 condenser
operating as follows:
— Capacity = 47.1
— Entering/leaving chilled water
temperature = 54/44°F [12.2/6.7°C]
— Chilled water flow rate = 113 gpm
— Evaporator water pressure drop =
7.9 feet
— Compressor power input = 56.3
— Unit EER = 10.0
CG-PRC011-EN12
Loading...