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Making the Best Choice:
Optimizing Compressor Applications
Dayton, Ohio
May 10, 2016
System Capacity Modulation Strategies
• Single-compressor condensing unit
• Parallel duo-mate rack
• Even parallel four-by-four rack
• Uneven parallel rack
• Hp limits / extended body racks
• VFD and swing compressor
• Digital Discus™ capacity modulation
Unloader types
Digital
Available Products and Technologies
Hot gas bypass
(Fixed step)
Blocked suction
(Fixed step)
Digital compressor
10–100%
Variable frequency drive
50–100%
Variable displacement
Recip
Scroll
(two-step)
Screw
(25%–100%)
Copeland Discus™with blocked suction
Copeland Scrolldigital
Copeland Discusdigital
Modulation Technologies
Pros Cons
Hot gas bypass • System-based design• Efficiency
• Compressor reliability
Blocked suction
• Efficiency
• Cost
• Reliability
• Ease of service
• Less precise control
• No option on single-bank compressor designs
Digital compressor• Precise control
• Moderate cost
• Minimal efficiency loss on modulated capacity
Variable frequency drive• Precise control
• Modulated capacity efficiency
• Cost
• Electrical noise
• Reliability
Variable displacement• Precise control (with infinitely
variable systems)• Low-capacity efficiency
Variable unloading up to 90%
Excellent load matching
Reduced number of compressors
Lower capital equipment costs
Increased steps of unloading
Better load matching
More compressors needed
Increased equipment costs
Parallel Rack Historical Design Evolution
15 15 8 5 3
6D 6D 4D 3D 2D
Rack A – traditional configuration (actual store)
15 12.5 12.5 6
6D 4D4D 3D
Digital
Rack A – configuration with Digital (actual store)
50% capacity unloading
Poor load matching
Significant compressor cycling
High inrush current
Early rack configurations
23 23
46 Hp
46 Hp
46 Hp
Digital Can Provide Continuous Modulation Over Larger Capacities
• Used in parallel racks with fixed capacity
compressors
– Wider range of capacities
• Acts like a swing compressor
– Without the cost of a VFD
– With extended unloading
• Down to 10% vs. 50%
– Avoids the oil issues associated with VFDs
• One Digital per suction group
– Optimized cycling of existing compressors
– Can be applied with any brand compressor
Fixed
capacity
#1
Fixed
capacity
#2
Digital
Digital
Digital
Fixed
capacity
#1
Ca
pacity (
Hp
)
Copeland Digital Compressor Technology
• Copeland compressor with continuous
capacity control:
– Scroll: 10–100%
– 3D: 10–100%
– 4D: 50–100%
– 6D: 33–100%
• Applicable on new and existing compressors– Scroll P
– Discus P P
• Patented technology
Time
Tem
pera
ture
Tightens temperature control
Digital control
module
Time (sec)
10 10 10 101010
0 20 40 60
50%
capacity
System
needs 50%
capacity
Here is how
to deliver
50% capacity
Results in Narrow Operating
Temperature Range
Copeland Scroll Digital
Copeland Discus Digital
Blocked Suction vs. Copeland Digital Technology
Digital
Control
module
Controller decides 50% or 100% capacity:
100% — both banks loaded
50% — energize unloader
1 bank unloaded / 1 bank loaded
Controller
decides
10–100%
capacity
Here is how to deliver
20% capacity desired
by system
50%
20%
Compressor
Capacity
50
100
0Compressor capacity
50
100
0
Time (sec)
4
20 40 60
20% Capacity
16 4 16 4 16 4 16
80
Discus Digital Provides Continuous Capacity
Modulation From 10% to 100%.
Blocked Suction Unloader Offers Only 100%, 50% or 0%
Capacity Options; Limited to 10 Cycles per Hour
Copeland Digital Technology Benefits
• Precise control of suction pressure and temperature– Longer shelf life and less food shrink because of minimal food temperature fluctuations
– More consistent TXV operation
• Reduced cycling of compressors– Extends contactor life
– Extends compressor life
• Reduced defrost cycle time– Tighter temperature control minimizes formation of frost on evaporator
• System efficiency improvement– Eliminates over/under shooting of suction pressure setpoint
– Allows increasing suction pressure setpoint
– Reduces inrush current / power usage
• Paradigm shift in parallel system design– No need for uneven paralleling for compressor staging
– Using common compressor selections simplifies replacement needs
Copeland Digital Technology Applications
• Temperature ranges
– High-temp — Medium-temp — Low-temp
• Refrigerants
– R-22, R-404A and R-507, R-407A and R-407C, R-448A and R-449A
• Floating head pressure capability
– Low temperature down to 40 °F condensing
– Medium temperature down to 50 °F condensing
• System configurations
– Single-compressor condensing units
– Even parallel racks
– Uneven parallel racks
– Parallel racks with satellite compressors
– Split-suction parallel racks
– Secondary fluid-cooling systems
Discus Digital Field Experience
Canadian supermarket in Halifax, Nova Scotia
Medium-Temp., Rack-Suction Pressure
Rack suction pressure range narrows significantly with Discus Digital
Product degradation
Excessive operating costs
39 p
si
6 p
si
Suction pressure:
85% tighter
control
Before Digital After Digital
Dairy Case With Discus Digital Activated
Case temperature range narrows significantly with Discus Digital
Product degradation
Excessive operating costs
15 °
F
1.2
5
°FCase temperature:
Before Digital After Digital
92% tighter
control
Meat Case With Discus Digital Activated
Case temperature range narrows significantly with Discus Digital
Product degradation
Excessive Operating Costs
17 °
F
2 °F
Case temperature: 88% tighter
control
Before Digital After Digital
Five-Compressor Rack With Discus Digital Activated
Compressor cycling reduced by 56% with Discus Digital
3DS3R17ML-TFE-A23
(08E03844R)
3DB3R12ML-TFE-A23
(08E01922R)
3DB3R12ML-TFE-A23
(08E03087R)
3DB3R12ML-TFE-A23
(08E03088R)
3DSDR17ML-TFE-A23
(08E03845R)
Digital retrofit
Before Digital After Digital
Comp 1
Comp 2
Comp 3
Comp 4
Comp 5
Compressor Cycling:
56% reduction
Discus Digital Upgrade in Atlanta, GA
Rack 3 MT (R-22) 300 MBTU
• 4 Compressors
1. 2DA3-075L-TFD 7.5 Hp
2. 3DB3A100L-TFD* 10 Hp
3. 3DF3A120L-TFD 12 Hp
4. 3DS3A150L-TFD 15 Hp
Rack 4 LT (R-22) 160 MBTU
• 5 Compressors
1. 2DF3-030L-TFD 3 Hp
2. 3DB3A075L-TFD* 7.5 Hp
3. 3DF3A090L-TFD 9 Hp
4. 3DS3A100L-TFD 10 Hp
5. 4DL3A150L-TSK 15 Hp
• 40,000 sq. ft. supermarket; HillPHOENIX racks constructed in 2003
• Clean machine house with plenty of space
• Retrofit (1) compressor per rack
• Plenty of space available in control panels
• One knowledgeable technician (26 years of experience)
- Familiar with store prior to project
• CTs installed to monitor energy consumption for the rack, condensers and compressors
• ESRs present for case temperature control
*Compressor upgraded to Discus Digital
Rack 3 MT +10
Before After (Discus Digital Enabled)
0
10
20
30
40
50
60
Comp 1Comp 2Comp 3Comp 4 Comp 1 DGTL Comp 3Comp 4A
ve
rag
e D
ail
y C
yc
les
80% Avg Cycle Reduction!
• Tighter suction pressure• Higher average suction pressure• Tighter case temperature
Rack 4 LT -20
Before After (Discus Digital enabled)
0
5
10
15
20
25
Comp 1
Comp 2
Comp 3
Comp 4
Comp 5
Comp 1
DGTLComp 3
Comp 4
Comp 5
Av
era
ge
Da
ily C
yc
les
12% Avg Cycle Reduction
•Tighter suction pressure•Higher average suction pressure•Tighter case temperature•Reduced defrost time
Standard unloading Digital unloading
Copeland Discus Digital Field Testing Experience
A. Carmel, IN 63% 67%
B. Grove City, OH 91% 64%
C. Middletown, OH 95% 50%
D. Nova Scotia, CN 56% 85%
E. Statesville, NC 78% 33%
Average = 77% 60%
Suction pressure
changeReduction in
compressor cyclingDigital benefit
Copeland Digital Compressor Selection Guideline
• For optimum suction pressure control, the following guideline is recommended in the selection of digital and fixed compressors, per suction header:
– D ≥ F1
– F2 ≤ D + F1
– F3 ≤ D + F1 + F2
– ……
– FN ≤ D + F1 + F2 + ….+ FN-1
• In the above equations,
– D is digital capacity or horsepower
– F1, …FN are fixed speed compressor capacity
or horsepower
Example:
• Assume five-compressor system
• Pick Digital as D = 10 Hp
• Per rule, one fixed compressor, F1 , should be 10 Hp or less
• Pick F1 = 10 Hp
• Per rule, second fixed compressor, F2 , should be 11 Hp or less
• Pick F2 = 7.5 Hp
• Per rule, third fixed compressor, F3 , should be 18.5 Hp or less
• Pick F3 = 7.5 Hp
• Per rule, fourth fixed compressor, F4 , should be 36 Hp or less
• Pick F4 = 7.5 Hp
• Final compressor selections should total up to max capacity needed
to match load
Note! For Best Results, the Digital Compressor Should Be the Lead Compressor.
It Should Be the First Compressor on and the Last Compressor off!
Copeland Discus Digital Selection Example 1
• Consider the following MT suction group:
1. 3DB3R12ME-TFD
2. 3DF3R15ME-TFD
3. 3DS3R17ME-TFD
• Before selecting the compressor to upgrade to Digital, verify that it will cover the “gaps” in
between capacity steps
– 3DB3R12ME-TFD 120,000 BTUH
– 3DF3R15ME-TFD 150,000 BTUH
– 3DS3R17ME-TFD 170,000 BTUH
Copeland Discus Digital Selection Example 1
• Apply the compressor selection guideline:
– D ≥ F1
– F2 ≤ D + F1
– F3 ≤ D + F1 + F2
– ……
– FN ≤ D + F1 + F2 + ….+ FN-1
• For 3DBDR12ME:
– 120,000 (3DBD) > 150,000 (3DF3) X
– 170,000 (3DS3) ≤ 270,000 (3DF3 + 3DBD) P
Selecting the 3DB3 as a Digital would NOT satisfy the guideline!
• For 3DFDR15ME:
– 150,000 (3DFD) > 120,000 (3DB3)P
– 170,000 (3DS3) ≤ 270,000 (3DB3 + 3DFD) P
Selecting the 3DF3 as a digital will satisfy the guideline!
Resulting Capacity Staging With 3DBD
Compressor Capacity (Btu/hr)
3DF33DB3 3DS3 3DF3 3DBD3DS3
Gaps in
capacity
steps
Staging with standard compressors Staging with Digital compressor
Confidential
Resulting Capacity Staging with 3DFD
Compressor Capacity (Btu/hr)
3DF33DB3 3DS3
Gaps In
Capacity
Steps
3DFD3DB3 3DS3
No gaps!
Staging with standard compressors Staging with Digital compressor
Confidential
Copeland Discus Digital Selection Example 2
• Consider the following MT suction group:
1. 3DA3R10ME-TFD
2. 3DF3R15ME-TFD
3. 3DS3R17ME-TFD
4. 4DE3R18ME-TSK (one-bank unloader compressor)
• Before selecting the compressor to upgrade to Digital, verify that it will cover the “gaps” in between
capacity steps
– 3DA3R10ME-TFD 100,000 BTUH
– 3DF3R15ME-TFD 150,000 BTUH
– 3DS3R17ME-TFD 170,000 BTUH
– 4DE3R18ME-TSK 180,000 (90,000) BTUH
Copeland Discus Digital Selection Example 2
• Apply the compressor selection guideline:
– D ≥ F1
– F2 ≤ D + F1
– F3 ≤ D + F1 + F2
– ……
– FN ≤ D + F1 + F2 + … + FN-1
• For 3DADR10ME:
– 100,000 (3DAD) > 90,000 (4DE3* unloaded) P
– 150,000 (3DF3) ≤ 190,000 (4DE3* unloaded + 3DAD) P
– 170,000 (3DS3) ≤ 340,000 (4DE3* unloaded + 3DF3 + 3DAD) P
Resulting Capacity Staging
Compressor Capacity (Btu/hr)
4DE3
4DE3 (Unl)
3DF3 3DS3 3DA3 4DE3
4DE3 (Unl)
3DF3 3DS3 3DAD
Staging with standard compressors Staging with Digital compressor
No gaps!
Confidential
Copeland Discus Digital Upgrade Requirements
• Copeland’s guideline:
– Best choice: install new Discus Digital compressor
– If compressor is less than four years old, then valve plate upgrade retrofit kit is available
• Discus Compressor produced with a serial number of 99C (March 1999) or older are NOTphysically capable of being upgraded
– Also indicated in the model nomenclature
• Old nomenclature: “A” in the fifth character (e.g., 3DS3A150E-TFD-200)
• New nomenclature: all compressors (e.g., 3DS3R17ME-TFD-200)
• System controller with variable capacity control
– Controller must be capable of directly cycling the digital solenoid or provide a variable voltage output
• Copeland recommends the E2 system controller (version 2.3 or later)
• More information in Application Bulletin AE4-1373
Digital Technology Support Material
Overview presentationMarketing bulletin
Press release
Website
Brochure
Animation
Field upgrade
installation video Application engineering
bulletinsCut sheet
Questions?
DISCLAIMER
Although all statements and information contained herein are believed to be accurate and reliable, they are presented without guarantee or warranty of any kind, expressed or
implied. Information provided herein does not relieve the user from the responsibility of carrying out its own tests and experiments, and the user assumes all risks and liability for
use of the information and results obtained. Statements or suggestions concerning the use of materials and processes are made without representation or warranty that any such
use is free of patent infringement and are not recommendations to infringe on any patents. The user should not assume that all toxicity data and safety measures are indicated
herein or that other measures may not be required.
Thank You!
30
Backup
31
Discus Digital Refrigerant Gas Flow
1. Enters compressor
2. Passes through body
3. Into valve plate
4. Compressed by pistons
5. Exits compressor
Loaded
Unloader pistons allow suction gas
flow into valve plate
Valve assembly routes suction gas
above unloader pistons
Discus Digital Refrigerant Gas Flow
Unloader pistons block suction gas
flow into valve plate
Valve assembly routes discharge gas
above unloader pistons1. Enters compressor
2. Passes through body
3. Unloader pistons block gas before entering valve plate
Unloaded
Copeland Discus Product Lineup (MT R-404A, 20/120/65/0 °F, 60 Hz)
Digital: Not applicable P P P P P P P P P P P P
Copeland Discus Product Lineup (LT R-404A, -25/105/65/0 °F, 60 Hz)
Digital: Not applicable P P P P P P P P P
Copeland Scroll Digital
• Scroll compressor with digital modulation capability that
offers continuous capacity control from 10% to 100%
• Unloading and loading is accomplished by separating the
scroll sets axially
• Indicated by a “D” in the third character of the compressor
model number
– e.g., ZBD45KCE-TFD-200
Copeland Scroll Digital
Copeland Scroll Digital Compressor Operation
• Capacity modulation is achieved by axially
separating scrolls
– When “separated”, no gas compression and
~10% power usage
• Varying the amount time the scroll sets are
separated, capacity from 100% down to 10%
can be achieved
• Separation is accomplished by bypassing a
controlled amount of discharge gas to the
suction through a solenoid valve
Unloaded(No compression)
Loaded
Copeland Scroll Product Lineup (MT R-404A, 20/120/65/0 °F, 60 Hz)
Digital: P P P P P P P
Copeland Discus Product Lineup (LT R-404A, -25/105/65/EVI SC °F, 60 Hz)
Digital: P P P P P P
0
20
40
60
80
100
120
140
ZB10 ZB15 ZB19 ZB21 ZB26 ZB29 ZB30 ZB38 ZB45 ZB50 ZB58 ZB66 ZB76 ZB95 ZB114
Expanding MT Product Portfolio
Supermarket
Me
diu
m-t
em
pera
ture
cap
acit
y (
BT
U)
Fixed capacity models Digital modulated and fixed capacity models
Frozen carbonated beverage
Process chiller
2 2.5 3 3.5 4 5 6 7 8 9 10 13 151.5HP
Model
Walk-ins
New MT Digital models
Emerson Confidential
