Chillers in tropical climates

AIRAH 2014
Chiller Plants for Tropical Climates
Today’s Agenda
 Chiller developments
VSD advantages
YMC2 Technology
Chiller plant optimization
Series counter-flow configuration
Opportunities from ‘de-coupling’
Multi CHW loop applications
Efficiency possibilities
Example project
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Despite using more environmentally benign, yet less efficient
refrigerants, chiller efficiency has improved significantly

In recent decades, significant gains in chiller efficiency at full & part load
through advances in HX, compressor, motor, driveline, and economizers.

The biggest single efficiency gain has been at reduced ‘lift’ condition
with the adoption of the variable speed drive.
Rectifier
L1
L2
L3
YK
YMC2
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
DC
L
V1
C
Motor
Inverter
V3
V5
V4 V6
V2
U
U1
V1
Control electronics
Control, monitor, and communication
W
M3
VSD technology benefits
Reduces inrush current to < than FL amps (soft start)
Corrects power factor close to unity
Reduces utility demand
Regulates compressor speed to provide the most
efficient chiller operation, reducing energy consumption
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Recent technology introduction
Variable speed magnetic bearing oil free centrifugal chillers
High efficiency permanent magnet motor
Latest Generation VSD
Frictionless magnetic bearings
Direct drive compressor
Oil free design
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Comparing fixed speed to variable speed technology
At constant conditions
At AHRI “relief “ conditions
YK
CSD
YK
CSD
YK
VSD
YMC2
VSD
YMC2
VS
YK CSD
YMC2
VS
YK VSD
Load%
LWT
EWT
COP
EWT
COP
COP
COP
%
%
100
6.7
29.4
6.46
29.4
6.46
6.28
6.60
2.1
5.0
90
6.7
29.4
6.54
27.2
7.05
7.05
7.43
5.6
5.6
80
6.7
29.4
6.52
25.0
7.55
7.99
8.41
11.5
5.5
70
6.7
29.4
6.44
22.8
7.83
9.09
9.66
22.8
6.2
60
6.7
29.4
6.25
20.5
8.12
10.34
11.23
38.6
9.0
50
6.7
29.4
6.14
18.3
8.18
11.72
13.12
61.1
13.0
40
6.7
29.4
5.75
18.3
7.55
11.31
12.79
89.5
13.0
30
6.7
29.4
5.28
18.3
6.77
10.34
11.96
76.1
15.7
20
6.7
29.4
4.46
18.3
5.55
9.30
10.31
85.9
10.9
15
6.7
29.4
3.96
18.3
4.88
8.25
8.60
75.7
4.0
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
VSD chillers perform best with condenser water “relief”
YK CSD Constant CEFT
YK CSD AHRI Relief
YK VSD AHRI Relief
YMC2 AHRI Relief
14.0
13.0
Chillers operate
for 85% of the
time within this
capacity range
12.0
11.0
COP
10.0
9.0
8.0
7.0
6.0
5.0
4.0
10
20
30
40
50
60
% Capacity
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
70
80
90
100
How to effectively apply high efficiency
VSD chillers to HVAC systems
in tropical climates?
Chiller
58%
Fans
24%
Pumps
13%
Tower
5%
Design Performance
One of the most ‘constant’ tropical climates is Singapore.
What levels of plant efficiency can be achieved
where operating conditions have limited variance ?
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Efficient chillers are a great foundation,
but optimization is a process
Maintain
Measure &
Verify
Operating Decisions
Optimize System
Automate System
Apply components effectively,
optimally
Design
Decisions
Select components effectively, optimally
Design system infrastructure to
maximize efficiency potential
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
The key functional components of chiller plant optimization are
the same irrespective of jobsite location
Apply variable speed drives
Chillers
Pumps
Tower Fans
Reduce “lift”
lower CW temperatures
higher CHW temperatures
Reduce pump energy
wide delta T
variable flow
Efficient chiller staging
energy based vs load based
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
All chillers benefit from reduced “lift”…..especially VSD chillers.
How to achieve reduced ‘lift’ in tropical climates ?
Lower tower water temps
Limited opportunity at design condition.
Some opportunity when at off-design.
AND
Higher chilled water temps
Significant opportunity with HT CHW,
chiller arrangement,and airside design
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
One has to ‘create’ the optimum operating environment
Every 1 deg C of ‘lift’ reduction improves
VSD chiller efficiency by 3-6%
depending on the technology
DC
Rectifier
Motor
Inverter
L
L1
Supply
L2
V1
C
L3
V3
V5
V1
U
V4 V6
V2
Control electronics
Control, monitor, and communication
Every 1 deg C counts !
YMC2
–
YORK®
Johnson Controls - Proprietary & Confidential
State of the Art Magnetic Centrifugal Chillers
U1
W
M3
Conventional design @ “ASIA” conditions
Pressure
32 ° C
95° F 37°
35°C
C
Lift
12° C
6° C
Enthalpy
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Can we lower tower water temps ?
The cooling tower is the most effective
heat transfer device in the system
250 ton tower super low noise tower
Energy efficiency ratio
=
7.5 kW / 875 kWr
=
117
Conventional design = approach 5-7 deg C
Design Condition
32 - 37 deg C
OR
30 - 35 deg C
Optimized design = approach 3-4 deg C
Tower water does not have to be held constant
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Singapore Building Operation Profiles can
take some advantage of ambient wet bulb relief
ASHRAE 32.8db / 27.3wb
Source: ASHRAE IWEC Weather Bin Data
Singapore tower water will achieve 3 deg C of relief
with 5 deg C of relief available for 24/7 systems
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Can we raise CHW temps ?
Chiller HX approach
temperatures <= >1 deg C
Conventional coil design = 2.5 m/s Face velocity & approach 6-7 deg C
Optimized coil design = < 2.0 m/s Face velocity & approach 3-4 deg C
13 deg C air off coil = 9 deg C CHW @ 4 deg C approach
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Can we widen the CHW temperature range to 8-10 deg C?
12.5 / 7.0 deg C
13.5 / 6.0 deg C
14.5 / 5.0 deg C
Design delta T
% Flow reduction
5.5C
0
7.5C
2/7.5 =27%
9.5C
4/9.5 = 42%
Wide delta T chilled water systems save significant pump energy,
but to use ‘similar’ CHW coils, the chillers must work harder.
Using 9 deg C CHW & 10 deg C delta T will need different AHU CHW coils
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
air ON db
air ON wb
air OFF db
Air Qty l/s
25
18.5
13
5,000
What is the impact to the AHU CHW coil with
9 deg C CHW temp and 10 deg C delta T ?
Increasing face area and reducing coil velocity is key to equivalent energy performance
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
1st cost economics of a 9 /19 deg C CHW system
Savings
 Smaller CHW pipes
 Smaller CHW valves and fittings
 Reduced thermal insulation area
 Smaller CHW pumps, motor kW, and VSD’s
 Smaller CHW pump electrical requirements
 Smaller chiller electrical requirements
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Costs
 Larger AHU coil HX areas and
rows to achieve equivalent
energy performance
 If the additional coil area cannot be
accommodated in AHU height, the
AHU footprint will increase
Wide CHW delta T best suits Series Counter-flow chillers
VPF = variable primary
CHW flow & fixed delta T
VPF
9 deg C
30 deg C
Lift is reduced 2.5 degrees C
14.0 deg C
19 deg C
32.5 deg C
35 deg C
Lift is reduced 5.0 degrees C
Series Counter-Flow chillers further reduce lift
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Series counter flow YMC2 performance at Singapore conditions (office hours)
9
1520kWr
14
1645 kWr
32.5
30
19
35
Load%
CHW in
CHWint
CHWout
CWin
CWint
CWout
UP
COP
DN
COP
SYS
COP
100
19
13.8
9
30
32.4
35
8.75
7.83
8.29
90
19
13.8
9
29.4
31.6
33.9
9.33
8.14
8.70
80
19
13.8
9
28.8
30.7
32.8
9.96
8.49
9.20
70
19
13.8
9
28.2
29.9
31.7
10.56
8.79
9.63
60
19
13.8
9
27.6
29.1
30.7
10.95
8.92
9.88
50
19
13.8
9
27
28.2
29.5
11.42
8.92
10.07
40
19
13.8
9
27
28
29.1
10.95
8.43
9.58
30
18.5
13.6
9
27
27.7
28.5
10.02
7.46
8.60
20
15.4
12.1
9
27
27.5
28.1
6.83
5.38
6.04
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
How does optimized series counter flow YMC2 efficiency
compare to conventional Singapore design with YK CSD ?
YK CSD
at AHRI
constant CW
YMC2 S/C at 9 deg C & 30 deg C
with 3 deg C CW relief
Load%
YK
YMC2 S/C
100
6.46
8.29
28%
90
6.54
8.70
33%
80
6.52
9.20
41%
70
6.44
9.63
50%
60
6.25
9.88
58%
50
6.14
10.07
65%
40
5.75
9.58
66%
30
5.28
8.60
48%
20
4.46
6.04
35%
The bulk of
operating
hours
Chiller energy reduced on weighted average by 55% !
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
How has performance improved over conventional design ?
YK CSD Constant CEFT
YMC2 SCF Office
12.0
11.0
10.0
COP
9.0
8.0
7.0
6.0
5.0
4.0
10
20
30
40
50
60
% Capacity
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
70
80
90
100
Energy economics of a 9 /19 deg C S/C CHW system
Savings
 Compared to constant speed chillers
Costs
 Marginally higher design flow
pump pressures with series HX
at AHRI constant condenser water
conditions
Note : pressures are reduced at
.
part load with variable flow
 CHW pump energy savings 35 %
 Marginally greater tower fan energy
to leverage the 3 deg C reduction in
CW temperature

 Note: tower efficiency is an order of
magnitude greater than chillers
YMC2
S/C chillers 28-66 % more efficient
YMC2 S/C chillers 28% more efficient at design
YMC2 S/C chillers up to 66% more efficient at reduced load & lift
YMC2 S/C chillers 55% more efficient on weighted average
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
.
Typical system = CHW VAV AHU’s
HT CHW loop
9C
19 C
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
14 C
VPF
Are there more efficiency gains to be found ?
Can we go higher than 9 deg C CHW ?
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
The most efficient HVAC systems treat
the latent loads separately
Cooling Load Component
Conduction thru walls, roof etc
Solar radiation
Lights
People
Equipment (some…most is sensible)
Infiltration
Ventilation
System heat gains
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
“De-coupling”
Latent
Sensible
A typical application that de-couples
loads is a chilled beam system
Chilled Beam
DOAS
+
One HVAC system performs
all dehumidification
One HVAC system performs
only sensible cooling
De-coupled
Typically @ 6 degrees C CHW
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Typically @ 14 degrees C CHW
What can a CHW system look like for a chilled beam application ?
ACB HT CHW loop
DOAS supplies dry cool primary
O/A to the active chilled beams
LT CHW loop
(S/C chillers)
6C
14.0 C
11 C
VPF
16 C
Plant room
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
VPF
18 C
Plant room
Efficiency is improved further where a % of O/A load is removed by the HT loop
ACB HT CHW loop
DOAS with cascade reduction in primary air temp
LT CHW loop
(S/C chillers)
14.0 C
6C
VPF
18 C
Plant room
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
11 C
VPF
16 C
Plant room
Similar methodology applied to a VAV system
With a VAV system space dew point control is not as critical.
VAV AHU(s)
DOAS pre-conditions the O/A
supplied to the zone VAV AHU’s
CHW loop
14 C
9C
VPF
14 C
19 C
19 C
VPF
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
What efficiency levels can the HT loop chiller deliver ?
YK CSD
at AHRI
constant CW
YMC2 S/C at 9 deg C
Office profile
YMC2 at 14 deg C
Office profile
Load%
YK
YMC2 s/c
YMC2
100
6.46
8.29
28%
9.20
42%
90
6.54
8.70
33%
9.77
49%
80
6.52
9.20
41%
10.37
59%
70
6.44
9.63
50%
10.95
70%
60
6.25
9.88
58%
11.38
82%
50
6.14
10.07
65%
11.68
90%
40
5.75
9.58
66%
11.20
95%
30
5.28
8.60
48%
10.34
95%
20
4.46
6.04
35%
8.45
89%
HT YMC2 delivers weighted average 79% improvement over base design
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
With dual loops, plant performance can be further improved
YK CSD Constant CEFT
YMC2 Evap 14/18C
YMC2 SCF Office
12.0
11.0
10.0
COP
9.0
8.0
7.0
6.0
5.0
4.0
10
20
30
40
50
60
70
80
90
100
% Capacity
Where 30 % load is transferred to the HT loop , cooling efficiency is improved a further 8%
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Example of Dual CHW loop project
JEM Project
Singapore
Multi stage
fresh air
treatment
Dual CHW
loops
Elevated
CHW temps
Series
counter-flow
LT chillers
Wide delta T
LT loop
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
Low temp loop = 9/18 deg C with 2 S/C York YK CSD chiller pairs
High temp loop = 15/20 deg C with 2 x York YK VSD chillers
Greenmark ‘Platinum’ rating @ 0.55 kW/Ton = 6.4 plant COP
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
What about Australia ?
Source : YorkCalc Energy Analysis Database
Cairns 24Hrs Weather Bin Profile
% Operation Hours
30.0%
66% hrs
25.0%
20.0%
15.0%
10.0%
5.0%
0.0%
24-26
22-24
20-22
18-20
16-18
< 16
o
Wet-bulb Temperature C
Cairns has a greater potential for condenser water relief
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
What efficiencies can a YMC2 HT
loop chiller deliver in Cairns ?
YMC2 performance at 14C CHW
Constant ECWT 29.4C
Constant ECWT26C
Constant ECWT 24C
Constant ECWT 22C
Constant ECWT 20C
22.0
21.0
20.0
19.0
18.0
17.0
16.0
COP
15.0
14.0
13.0
12.0
11.0
10.0
9.0
8.0
With a 14 deg C HT loop YMC2 chiller
7.0
66% of the run hours can be at 12-21 COP !
6.0
5.0
20
30
40
50
60
% Capacity
36
Johnson Controls PowerPoint Guidelines | February 8, 2008
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
70
80
90
100
Very few chillers can operate continuously with 14 deg C CHW & 20 deg C CW
Refrigerant level control
YMC2
Motor cooling technologies
Variable orifice expansion
YK
For Consideration
 High Efficiency VSD or VSD magnetic bearing chillers
 Raise CHW supply temperatures
 Wide delta T CHW with series counter-flow chiller arrangement
 Re-evaluate design approach temperatures
cooling towers are efficient and low cost
lower face velocity coils
 De-couple and condition outside air loads separately
 Dual HT & LT CHW loops with cascade coils & ‘low lift’ VSD chillers
YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers
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YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers

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