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Evaporative Pre-Cooling Condenser Air Developing Performance Standards
Jay Madden Southern California Edison
Emerging Technologies Summit October 22, 2014
Evaporative Pre-Cooling Technologies
1
Direct Spray on Coil
Spray on Media
Spray Evaporation w/Media Drip-down Evaporative Media w/sump
How Does One Objectively Compare Performance?
2
ASHRAE Standards Project Committee (SPC)-212
3
Method of Test for Determining Energy Performance and Water-Use Efficiency of Add-On Evaporative Pre-Coolers for Unitary Air Conditioning Equipment
SPC-212 Members
4
• Equipment Manufacturers • Electric Utilities • Independent Laboratories
SPC-212 Goal
5
To provide test methods for gathering performance data for use in calculating: • design and seasonal energy savings • water-use performance
SPC-212 Results
6
• AC Unit Cooling Capacity Improvement • AC Unit Power Usage Improvement • C.O.P. Improvement • Water Consumption
Ambient Design Conditions
7
Test Condition
Ambient Temperatures
(oF DB/ oF WB) A 115/76 B 105/73 C 95/70 D 85/67
Measuring Evaporative Efficiency
8
• Direct measurement of condenser entering air conditions not always possible
• Direct water spray on coil • No space between pre-cooler and condenser
Measuring Evaporative Efficiency using incoming and outgoing air conditions
9
Condenser Discharge
Ambient Air
Condenser Air Intake (not always measurable)
Measuring Evaporative Efficiency using incoming and outgoing air conditions
10
• Wasn’t always accurate in lab tests • When water was in direct contact with condenser coil • Poor air/water mixture
• Exhaust air sometimes measured lower humidity ratio than incoming air
Measuring Evaporative Efficiency using measured performance map
11
*
* Performance = Input Power Output Capacity or COP
Measuring Evaporative Efficiency using measured performance map
12
𝐸𝐸(%)= 𝑇↓𝐷𝐵,𝑇𝑒𝑠𝑡 − 𝑇↓𝐷𝐵,𝐸𝑞𝑢𝑖𝑣𝑎𝑙𝑒𝑛𝑡 /𝑇↓𝐷𝐵,𝑇𝑒𝑠𝑡 − 𝑇↓𝑊𝐵,𝑇𝑒𝑠𝑡
Where: EE = Evaporative Effectiveness TDB,Test = Incoming Temperature, Dry Bulb TDB,Equivalent = Equivalent Temperature, Dry Bulb TWB,Test = Incoming Temperature, Wet Bulb
Test Results Evaporative Effectiveness
13
0%
10%
20%
30%
40%
50%
60%
70%
80%
80.0 85.0 90.0 95.0 100.0 105.0 110.0 115.0 120.0
Eva
pora
tive
Effe
ctiv
enes
s (%
)
Outdoor Air Temperature (°F)
Pre-cooler 1 Pre-cooler 2 Pre-cooler 3 Pre-cooler 4
All tests performed at constant outdoor air humidity ratio 0.010 lbw/lba
Measuring Water Use Effectiveness
14
𝑊𝑈𝐸↓ = 𝑚 ↓𝑤𝑎𝑡𝑒𝑟 𝑒𝑣𝑎𝑝𝑜𝑟𝑎𝑡𝑒𝑑 /𝑚 ↓𝑤𝑎𝑡𝑒𝑟 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑 ↓
Where: WUE = Water Use Effectiveness
Accounts for: • Water Bleed • Overspray
Test Results- Water Use Effectiveness
15
0% 10% 20% 30% 40% 50% 60% 70% 80% 90%
100%
80.0 85.0 90.0 95.0 100.0 105.0 110.0 115.0 120.0
Wat
er U
se E
ffect
iven
ess
(%)
Outdoor Air Temperature (°F)
Pre-cooler 1 Pre-cooler 2 Pre-cooler 3 Pre-cooler 4
All tests performed at constant outdoor air humidity ratio 0.010 lbw/lba
SPC-212 Robustness
16
• Tested on four manufacturers • Different Technologies Tested
ASHRAE SPC-212 Next Steps
17
• Submit First Draft to ASHRAE at Winter 2015 Meeting
• Reviewed – Summer 2015 • Final Approval – End of 2015
18
Q & A
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