EFFICIENCYEFFICIENCYVERMONTVERMONTSuccessful Successful
Cooling SystemCooling SystemEnergy Energy
OptimizationOptimization
Topics for Discussion
Commercial Energy Consumption
Equipment EvaluationFull-load efficiency
Integrated part-load values
Electric utility charges
Power Factor
Help you understand how to evaluate an air-cooledsystem with regard to bottom-line implications.
Commercial Energy Consumption
U.S. DOE Electrical End-Use Estimates“Commercial Buildings Energy Consumption Survey”
Electric Utility Charges
• Customer Charge• Electric Fuel Charge Adjustment
– Fuel Charge Adjustment• Environmental Surcharge• Energy Charge• Kilowatt (kW) Demand/Delivery Charge• Power Factor Adjustment/Penalty
ASHRAE 90.1ASHRAE 90.1--2001 (Mandatory Provisions)2001 (Mandatory Provisions)
• Full Load (FL)– Predicts performance at a single operation point
• Doesn’t anticipate how equipment will respond during off-design conditions
• Equipment with excellent full-load characteristics may have less than satisfactory part-load characteristics
• Integrated Part Load Value (IPLV)– Predicts performance over a defined range of
operating points• Provides a more accurate account of actual
equipment operation
AirAir--Conditioning & Refrigeration InstituteConditioning & Refrigeration Institute• Provides programs to certify manufacturer’s
published equipment data– Verified through random testing
• Equipment labeled when in compliance
Equipment Evaluation
ARI Standard 550/590-98Standard defining the testing and rating requirements for all chillers
Provides an equal baseline for all manufacturers
Defines testing conditions for real-world, chiller performance
ARI Standard 550/590ARI Standard 550/590--9898• Developed through real-world studies
– 1992 U.S. Department of Energy Study
• DOE/EIA-0246(92)
– 1995 Building Owner’s & Managers Assn.
• 1995 BEE Report
• Developed Weighted Average for:– Building types, Buildings with/without economizer, Chiller
operational hours, etc.
• Determined 1% of a chiller’s operating hours spent at full load design conditions.– With such few hours spent at FL operation, an analysis
comparing FL only would be completely inaccurate.
ARI Standard 550/590ARI Standard 550/590--9898
IPLV = .01A + .42B + .45C + .12D
Equipment Evaluation
A = EER @ 100% load (95°F Ambient)B = EER @ 75% load (80°F Ambient)C = EER @ 50% load (65°F Ambient)D = EER @ 25% load (55°F Ambient)
EERtonkW 12/ =
Equipment Evaluation
1.26 FL 1.15 IPLV
kW / TON9.56 FL
10.41 IPLV2.80 FL
3.05 IPLV
EERCOP
A/C Chillers w/Condenser Minimum Efficiencies
IPLV ComparisonA/C Chiller A = 12.5 EER A/C Chiller B = 15.2 EER
kW/ton12.5 = 12/EER= 12/12.5= 0.96 kW/ton
kW/ton15.2 = 12/EER= 12/15.2= 0.79 kW/ton
0.17 kW/TON difference!
Approximate Annual Energy Costs (dollars)
IPLV Comparison
Equipment Evaluation
109109109Avg. Load
$35,003$42,536$50,955AEC0.08130.08130.0813Rate500050005000Op. Hours
0.790.961.15kW / ton15.212.510.41
IPLV (EER)ASHRAE
Minimum Efficiency
$15,952 difference!
System ConsiderationsAir-cooled system• Low maintenance• Low installation and
equipment costs• Higher Energy
Consumption• Water Scarcity
W/C ChillerA/C Chiller
Water-cooled systemHigher maintenance
High-efficiency
High installation costs
Low sound
How do you know How do you know when your when your
cooling system is cooling system is optimized?optimized?
Step 1: Begin with Step 1: Begin with the end in mind.the end in mind.
Decide what components Decide what components you are going to you are going to optimize.optimize.Look at the Look at the systemsystem..
Cooling System Energy:Cooling System Energy:•• ChillersChillers•• Tower fansTower fans•• Primary Chilled Water and Primary Chilled Water and
Condenser Water PumpsCondenser Water Pumps•• Sum of the kWh Sum of the kWh
consumption of the consumption of the above.above.
Possibly also consider: Possibly also consider: secondary pumps, AHU secondary pumps, AHU fan energyfan energy..
2A: The Chiller: 2A: The Chiller: Do you know your Do you know your
chiller matrix?chiller matrix?
Chiller Efficiency MatrixPercent
LoadCapacity
Tons 55 60 65 70 75 80 85
10%20%30%40%50%60%70%80%90%100%
Entering Condenser Water Temperature
kW/ton usage
Const Speed Chiller Effy MatrixPercent Load
55 F 65 F 75 F 85 F
10% 1.140 1.180 1.22020% 0.700 0.740 0.810 0.90030% 0.547 0.587 0.653 0.74740% 0.470 0.515 0.585 0.67550% 0.428 0.476 0.544 0.63260% 0.400 0.450 0.517 0.60770% 0.383 0.437 0.503 0.59180% 0.375 0.425 0.493 0.58090% 0.371 0.420 0.484 0.573100% 0.368 0.416 0.482 0.564
Entering Condenser Water Temperature
kW/ton usage
Const Speed Chiller Effy Curves
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
1.100
1.200
10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Pct Load
kW/to
n 55 F65 F75 F85 F
Entg CondWtr Temp
VAR SPEED Chiller Efficiency Matrix
Percent Load55 F 65 F 75 F 85 F
10% 0.520 0.680 1.10020% 0.320 0.430 0.660 0.90030% 0.260 0.353 0.527 0.75340% 0.235 0.320 0.475 0.67050% 0.220 0.308 0.444 0.61260% 0.210 0.303 0.420 0.57770% 0.209 0.311 0.423 0.56980% 0.233 0.325 0.428 0.55890% 0.249 0.340 0.442 0.560100% 0.270 0.360 0.460 0.576
Entering Condenser Water Temperature
kW/ton usage
VAR SPEED Chiller Efficiency Curves
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
1.100
1.200
10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Pct Load
kW/to
n
55 F65 F75 F85 F
Entg CondWtr Temp
Cooling tower entering condenser Cooling tower entering condenser water bin hours for Burlington Vt.:water bin hours for Burlington Vt.:
•• 85F ECWT = 10 hrs85F ECWT = 10 hrs•• 75F ECWT = 1000 hrs75F ECWT = 1000 hrs•• 65F ECWT = 1450 hrs65F ECWT = 1450 hrs•• 55F ECWT and below = 6300 hrs55F ECWT and below = 6300 hrs
Chiller Performance Chiller Performance GeneralitiesGeneralities::•• Lower lift = less compressor Lower lift = less compressor
energy (Compressor lift is the energy (Compressor lift is the difference between the suction and difference between the suction and discharge pressure).discharge pressure).
•• Capacity has less affect on Capacity has less affect on compressor performance than lift.compressor performance than lift.
•• Different chillers have different Different chillers have different minimum lifts due to design minimum lifts due to design differences…differences…
Orifice: 13# differential pressure
Condenser
@ 85F ECWT
Refrigerant pressure= 19.1 psia
Compressor
Flooded Evaporator
@ 44F leaving
chilled water
Refrigerant pressure =
6.1 psia
Orifice : 4.3 # differential pressure
Condenser
@ 55FECWT
Refrigerant pressure= 10.4 psia
Compressor
Flooded Evaporator
@ 44F leaving
chilled water
Refrigerant pressure =
6.1 psia
Orifice : 4.3 # differential pressure
Condenser
@ 55F ECWT
Refrigerant pressure= 10.4 psia
Compressor Flooded Evaporator
@ 44F leaving
chilled water
Refrigerant pressure =
6.1 psia
Tubes not covered by
liquid
“stacking” phenomenon
Orifice : 4.3 # differential pressure
Condenser
@ 55F ECWT
Refrigerant pressure= 10.4 psia
Compressor Flooded Evaporator
@ 44F leaving
chilled water
Refrigerant pressure =
6.1 psia
Tubes not covered by
liquid
Motor cooling and oil loss problems stem from the same phenomenon; low internal differential pressure for systems which rely on a differential pressure to operate.
2B: The Tower: 2B: The Tower: •• Raising the tower setpoint Raising the tower setpoint
will save fan energy but will save fan energy but penalize the chiller.penalize the chiller.
•• TwoTwo--speed fan motors speed fan motors better than single speed.better than single speed.
•• Variable speed is best for Variable speed is best for energy and control.energy and control.
2C: The pumps: 2C: The pumps: •• Condenser water flow: Condenser water flow:
Reducing the condenser water Reducing the condenser water flow will save on the pump flow will save on the pump energy but penalize the chiller energy but penalize the chiller (similar to holding up the (similar to holding up the entering condenser water entering condenser water temperature). temperature).
Performance Matters
First Cost Advantage of Air Cooled ChillersEasy Installation – 20% less than Water Cooled Equivalent
No Cooling Tower, Tower pumps, Tower and Pump Starters
No equipment room required for the chillers
Multiple Circuits for redundancy – not multiple chillers
Mounted starters
Maintenance Advantage of Air Cooled ChillersEasy Maintenance – vs. Water Cooled
No on site Systems Engineer required
No water treatment or make up water required
No leaks on the roof
No cooling tower, condenser pumps, associated starters
Performance –The Traditional Trade-off for Air Cooled Chillers
Energy
Full Load typically 65% more than Water Cooled system
9.6 EER = 1.25 kW/TR (ASHRAE 90.1 Tier 1 requirement)
10.2 EER = 1.17 kW/TR (ASHRAE 90.1 Tier 2)
Part Load typically 100% more than Water Cooled system
12.5 EER = .96 kW/TR
Performance –The Traditional Trade-off for Air Cooled ChillersSound
Multiple Compressors and Condenser fans
Typical full load sound levels often 100+ dBA
Lower nighttime sound regulations can be limiting factor
Required acoustical treatments drive up first costSound blankets (-1 dBA) = 2-3% of first cost
Unit enclosures (-3 to 5 dBA) ~$10 K
How Latitude changes the balance• All the best of today’s air cooled chillers
– ASHRAE 90.1 energy level compliance up to 10.3 EER– R-134a environmentally sound HFC refrigerant– Compact single package design (150 – 260 TR)– Simple maintenance requirements– Dual Circuit design for redundancy
New
NewNew
NewNew
PLUS YOU NO LONGER COMPROMISE ON PERFORMANCE…World class IPLV performance – real world savings during the other 98% of the operating time vs. 90.1 requirements
15.2 EER
Part load sound levels 5-6 dBA lower than competitors
load shedding software for noise level management
Soft Start Capabilities for increased motor life
Reduced Full load amps for a reduction in wire sizing
Performance matters
Latitude delivers 15-25% Real World kWh Savings
The power of off design on Energy - 98% of operating hours are at off design conditions
Performance matters
– ARI IPLV part load points
– 12.5 vs 15.2 IPLV– $.0813/kWh
(2003 DOE National Average)
Latitude’s part load performance is tested & ARI certified
Annual Energy Savings due to part load efficiency
$-
$2,000
$4,000
$6,000
$8,000
$10,000
$12,000
$14,000
2000 2500 3000 3500 4000 4500 5000 5500 6000
Operating Hours
Ann
ual S
avin
gs
150 TR 180 TR 200 TR 250 TR
180 TR Chiller
5000 hours$7500/year savings
180 TR Chiller
5000 hours$7500/year savings
3000 hours$4500/year savings
• Soft Start• Power factor• First Costs – Electrical
installation– Wire and circuit breakers
reduced by 1-2 sizes– 5-15% Generator cost
savings• Operating Costs
– .95 Power Factor throughout operating range
Electrical Characteristics
Performance through Technology
• 25 years of real world experience with varying compressor motor speeds
• Logical Extension of Variable Speed Drive technology for compressor motor applications
• Eliminates Slide valve and associated inefficiencies, and reduces compressor moving parts by 50%
• Solid State unit mounted starter
Lowest Total Cost of Ownership
• First Cost savings = 10-15%– Electrical Savings– Elimination of sound attenuation equipment
• Operating Costs Savings = 15-25%
– 15 Year equipment life– 5000 hours per year operation – National Average $$/kWh ($0.0813)
Performance that delivers real world Performance that delivers real world savings every year of operationsavings every year of operation
Latitude can save you 10% of the cost of the chiller…….
Every year it operates!