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November 2004
Low Hanging FruitLow Cost Energy Efficiency Opportunities in Cleanrooms
Free Cooling
Psychrometric Chart for San Jose
San Jose, CAWYE Psychrometric Chart
RH = 20%
RH
= 4
0%
RH
= 6
0%
RH
= 8
0%
h = 20 Btu/lb ¾ ¾ ®
h = 30 Btu/lb ¾ ¾ ®
h = 40 Btu/lb ¾ ¾ ®
h = 50 Btu/lb ¾ ¾ ®
0.0000
0.0020
0.0040
0.0060
0.0080
0.0100
0.0120
0.0140
0.0160
0.0180
0.0200
0.0220
0.0240
0.0260
0.0280
0.0300
30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Dry Bulb Temperature (F)
Hu
mid
ity
Rat
io (
lbs
H2O
per
lb
s d
ry a
ir)
50°F Wetbulb Line
3,200 Hours Minimum
Free Cooling Configuration #2 - Series PCW Only
M
M
M
Comparison of Low Temperature and Medium Temperature Chillers
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
200 300 400 500 600 700 800 900 1000
Tons
Eff
icie
nc
y (
kW
/to
n) 1000 Ton Chiller operating at 42 F
CHWS Temp and 70 F CWS Temp
1000 Ton Chiller operating at 60 F CHWS Temp and 70 F CWS Temp
An Innovative Layout Possibility
1100 BELL CHILLED WATER PLANT
VFDCHILLER
NON-VFDBACKUPCHILLER
VFDCHILLER
40-45°F LOOP 50-55°F LOOP
Dual Temperature Chilled Water Plant
Pumping Problems
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Existing Best Practice
Eff
icie
nc
y k
W/t
on Cooling Tower
Condenser Water PumpChilled Water PumpChiller
Current Primary - Secondary Pumping
VFD Chillers
High Efficiency Chillers with and without Variable Speed Drives
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0% 20% 40% 60% 80% 100%
Percent Load
Ch
ille
r E
ffic
ien
cy
(k
W/t
on
)
Chiller without VSD
Chiller with VSD
Data Provided by York for 1000 ton Chillers Running at 42 deg F CHWS and 65 deg F CWS
Impact of Varrying Condenser Water Temperatures for 1000 Ton Chiller without VFD (CHWS = 42 Deg F)
0.4
0.5
0.6
0.7
0.8
0.9
1
200 300 400 500 600 700 800 900 1000
Load (Tons)
Eff
icie
nc
y (
kW
/To
n)
85F
80F75F
70F65F60F
Lower Chiller Condenser Water Temperatures
Impact of Varrying Condenser Water Temperatures for 1000 Ton Chiller with VFD (CHWS = 42 deg F)
0
0.2
0.4
0.6
0.8
1
1.2
0 200 400 600 800 1000 1200
Load (Tons)
Eff
icie
nc
y (
kW
/To
n)
85F
80F
75F70F65F60F
Use Variable Speed Drives
0
20
40
60
80
100
0 20 40 60 80 100
Air Flow (%)
Fan
Po
wer
(%
)
Inlet Guide Vanes
Variable Frequency Drive
Theoretical Minimum FanPow er
Good for fans, even better for pumps, which are typically controlled and balanced by throttling
Remove Booster Pumps and close bypasses
Close 3-way Valves
B8 has a highly variable load due to air washer capacity, yet a constant flow
878 Flow
0
500
1000
1500
2000
2500
3000
5/17/0216:33
5/17/0217:02
5/17/0217:31
5/17/0218:00
5/17/0218:28
5/17/0218:57
5/17/0219:26
5/17/0219:55
5/17/0220:24
GP
M
878 Building Load, Tons
0
100
200
300400
500
600
700
5/17/0216:33
5/17/0217:02
5/17/0217:31
5/17/0218:00
5/17/0218:28
5/17/0218:57
5/17/0219:26
5/17/0219:55
5/17/0220:24
Aim for Highest Possible CHW Delta T
Pumping Energy Is Dramatically Reduced as Coil Temperature Rise Is Increased
-
50
100
150
200
250
300
350
400
450
500
4 6 8 10 12 14 16 18
Chilled Water Temperature Rise Through Coil
Re
lati
ve
Pu
mp
ing
En
erg
y (
10
0 a
t 1
0 d
eg
F)
Exhaust Optimization
Exhaust Reduction Amount
Annual Electricity Savings (kWh)
Annual Gas Savings (Therms)
Annual Energy Cost Savings ($)
5,000 cfm 223,400 24,350 $20,800
10,000 cfm 440,000 48,700 $41,200
20,000 cfm 854,000 97,400 $81,300
Tool exhaust can be optimized via tracer gas or other accepted test methods
In most cases tool exhaust can be reduced 10 – 50% Fume containment testing required for optimization also verifies
worker safety
Case Study Savings Opportunity:
When replacing broken or worn out equipment Select the most efficient option
Efficiency often has little relationship to cost of equipment E.G. -----
Pumps Electric Motors Fans etc.
Air Compressors - (One minute data 10/12-10/13)Compressor 1 and 3 are Cycling Excessively
0
10
20
30
40
50
60
70
12:2
3
12:3
5
12:4
7
12:5
9
13:1
1
13:2
3
13:3
5
13:4
7
13:5
9
14:1
1
14:2
3
14:3
5
14:4
7
14:5
9
15:1
1
15:2
3
15:3
5
15:4
7
15:5
9
16:1
1
16:2
3
16:3
5
16:4
7
16:5
9
17:1
1
17:2
3
17:3
5
17:4
7
17:5
9
18:1
1
18:2
3
Po
wer
(kW
)
Compressor 1(75 hp)
Compressor 3(50 hp)
Standby power consumption is almost 20% of peak power
Variable Speed Drive Compressors and waste heat regen dryers
VSD Compressors address the cycling problem
Commissioning / Retrocommissioning
Retrocommission - on a regular basis commission key components of system
E.G. - Develop standard tests for key control loops
Effect - Supply Air Temperature is Deficient
AMAT AH-A2 AIR
Deg
F
AHU-A2.PL1
55.0
57.5
60.0
62.5
65.0
2 FriJul 99
3 Sat 4 Sun 5 Mon 6 Tue
SUPPLY AIR TEMP :DEG F
Design Supply Air Temp is 55 deg Fwith no SAT reset
Cause
AMAT AH-A2 COOLING COIL
De
g F
CHWTEMP.PL1
40.0
42.5
45.0
47.5
50.0
52.5
55.0
57.5
2 FriJul 99
CHW Supply CHW Return
Chilled Water Temperatures
Heating Boiler Measurement1,400 kBtu Boiler Was Unable to Produce More than 500 kBtu
0.0
100.0
200.0
300.0
400.0
500.0
600.0
700.0
800.0
4/1/99 0:00 4/2/99 0:00 4/3/99 0:00 4/4/99 0:00 4/5/99 0:00 4/6/99 0:00 4/7/99 0:00 4/8/99 0:00 4/9/99 0:00
Time
kBtu
/h
Tower #2 Cell B Power
0
10
20
30
40
0:00 0:10 0:20 0:30 0:40 0:50 1:00
Time: Hour; June 16, 2000
Po
we
r (k
W)
Tower #2 Cell B Power
0
10
20
30
40
13:156/15
13:156/16
13:156/17
13:156/18
13:156/19
13:156/20
13:156/21
Time: Hour, Day; June 2000
Po
we
r (k
W)
Commission to avoid cycling
Control Optimization
0
STEP CHANGE DUE TO EXTRA PUMPS, COOLING TOWERS, AND 50% LOADED CHILLERS
1. Delayed start-up of next chiller saves substantial kW and running hours on cooling plant.
2. "Stretching" cooling capacity can be done by : a) Accepting a small CHW setpoint drift; e.g.
4.5°C to 5.3°C in winter. b) Unlimiting current timer on chillers; e.g.
FLA=300a, but motor rating=355a, so move Current Limiter to 355a.
c) Provide cooler condenser water; drive all cooling fans to 50 Hz.
d) Push more water through condenser tubes, such as running two pumps for one chiller,with upper limit set by chiller manufacturer.
e) Use tube cleaners on certain chillers.
THANK YOU!
Rumsey Engineers, Inc.
99 Linden Street
Oakland, CA 94607
(510) 663-2070
www.RumseyEngineers.com