Evaporative Pre-Cooling Condenser Air Developing Performance Standards

Jay Madden Southern California Edison

Emerging Technologies Summit October 22, 2014

Evaporative Pre-Cooling Technologies

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Direct Spray on Coil

Spray on Media

Spray Evaporation w/Media Drip-down Evaporative Media w/sump

How Does One Objectively Compare Performance?

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ASHRAE Standards Project Committee (SPC)-212

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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

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•  Equipment Manufacturers •  Electric Utilities •  Independent Laboratories

SPC-212 Goal

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To provide test methods for gathering performance data for use in calculating: •  design and seasonal energy savings •  water-use performance

SPC-212 Results

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•  AC Unit Cooling Capacity Improvement •  AC Unit Power Usage Improvement •  C.O.P. Improvement •  Water Consumption

Ambient Design Conditions

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Test Condition

Ambient Temperatures

(oF DB/ oF WB) A 115/76 B 105/73 C 95/70 D 85/67

Measuring Evaporative Efficiency

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•  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

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Condenser Discharge

Ambient Air

Condenser Air Intake (not always measurable)

Measuring Evaporative Efficiency using incoming and outgoing air conditions

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•  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

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*

* Performance = Input Power Output Capacity or COP

Measuring Evaporative Efficiency using measured performance map

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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

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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

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𝑊𝑈𝐸↓     = 𝑚 ↓𝑤𝑎𝑡𝑒𝑟  𝑒𝑣𝑎𝑝𝑜𝑟𝑎𝑡𝑒𝑑 /𝑚 ↓𝑤𝑎𝑡𝑒𝑟  𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑   ↓    

Where: WUE = Water Use Effectiveness

Accounts for: •  Water Bleed •  Overspray

Test Results- Water Use Effectiveness

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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

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•  Tested on four manufacturers •  Different Technologies Tested

ASHRAE SPC-212 Next Steps

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• Submit First Draft to ASHRAE at Winter 2015 Meeting

• Reviewed – Summer 2015 • Final Approval – End of 2015

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Q & A