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1 |
Emerging Oil Free Technologies
Ray Good
Global Director of Application Engineering
Danfoss Turbocor Compressors, Inc.
2 |
Agenda
•Chiller Overview
•Benefits of Oil Free
•Oil Free Compressors Today
•Next Generation Oil Free Compressors
•Oil Free Future
3 |
Learning Objectives
•Obtain an overview of new compressor technologies using magnetic, ceramic, and gas (foil) bearings, which can operate without oil.
• Introduce advances in compression technology, which enable oil-free systems for more demanding air-cooled applications.
• Explore the current and expanding opportunity for oil-free technologies in air conditioning systems.
4 |
Background
What is a Chiller?
• A chiller is a machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle
• The liquid is circulated through a heat exchanger to cool air, equipment or process application as required
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Background
Four basic components of a vapor compression chiller
• Evaporator
• Compressor
• Condenser
• Expansion Valve
44oF
54oF
2
1
3
4
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Two Major Types of Chillers
Heat from application load is rejected into the atmosphere in 2 ways:
• Air Cooled
• Water Cooled – Cooling Tower
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Compressor Types Used in HVAC
Capacity
Reciprocating Scroll Screw Centrifugal
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Oil – A Critical Component
• Lubricate bearings
• Form seal during compression
• Open drive compressor shaft seal
• Lubricate gears
• Lubricate ancillary system components
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Oil Management – A Critical System
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Oil Management
Risks with oil management system
• Complexity and cost of additional components
• Maintenance
Required Maintenance FrequencyCheck Oil Pressure Daily
Check Oil Level Daily
Inspect Oil Pump Operation Weekly
Inspect Oil Sump Heaters Weekly
Oil Analysis (Acidity, Moisture, Viscosity, etc.) Quarterly
Oil Filter Change Semi-Annual
Oil Change Annual
Inspect Oil Sump Strainers Every 5 years
ComponentOil Sump
Oil Sump Strainers
Oil Pump
Oil Filter
Oil Heater
Oil Separator
Oil Cooler
Oil Pressure Transducer
Oil Piping and Valves
Oil Sightglass
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Risks with oil management system
• Added components can increase risk for failure
• Possible alarms or faults for chillers with oil management systems:
AlarmsLow Oil Pressure
High Oil Pressure
Low Oil Temperature
High Oil Temperature
Loss of Oil Flow
Oil Pressure Transducer Failure
Oil Temperature Sensor Failure
Oil Pump Failure
Oil Pump VFD Failure
Oil Filter Clogged
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Other Negative Impacts of Oil
• Performance degradation
•Environmental impact of low efficiency
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• A two year project with data collecting spanning over 6 years
• 24 Buildings in study
• 36 Well maintained chillers analysed
• 26 Centrifugals
• 10 Screw
• Project team was headed by Mr Wang Baolong
Tsinghua University Study - 2014
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Tsinghua University Study ConfirmsChiller Efficiency Loss Over Time
-0.10
0.00
0.10
0.20
0.30
0.40
0 2 4 6 8 10 12 14
Degra
dation ra
tio o
f CO
P
Operation Time/year
> 10% after 5 years
> 20% after 10 years
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Sources of Performance Degradation
45%
30%
25%
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
CompressorPerformance
Excess Oil Water Fouling
• Excess oil accounted for 30% of the performance degradation
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Oiled Compressors
Oil Free Compressors
There is an Alternative!!
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Oil Free Bearing Types
Magnetic Bearing Ceramic Bearing Gas Bearing
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Rotor Magnets
Bearing Sleeve
Magnetic Bearing Compressor
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Full and Hybrid Ceramic Bearings
Ceramic BallsSteel or Ceramic Races
Rotor
Condenser
Evaporator
Refrigerant Pump
Heat Exchanger
Refrigerant Filter
Refrigerant Lubrication Support System
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Gas Bearing (plain journal bearing illustrated)
Gas CushionBearing Sleeve
Rotor
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Foil or Leaf Foil
Leaf FoilBearing Sleeve
Rotor
Gas Film
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Bump Foil Bearing
Top Foil Bearing Sleeve
Rotor
Gas Film
Bump Foil
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Mesh Pad Bearing
Metal Mesh Pad Bearing Sleeve
Rotor
Gas Film
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Oil Free Compressor Technology Comparison
Characteristic Magnetic Ceramic Gas(foil)
High Speed Capability
Load Capability
Friction Losses
Complexity
Cost
Reliability
High Capacity Cooling
Bearing Type
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Required Maintenance FrequencyCheck Oil Pressure Daily
Check Oil Level Daily
Inspect Oil Pump Operation Weekly
Inspect Oil Sump Heaters Weekly
Oil Analysis (Acidity, Moisture, Viscosity, etc.) Quarterly
Oil Filter Change Semi-Annual
Oil Change Annual
Inspect Oil Sump Strainers Every 5 years
Benefits of Oil Free Compressors
ComponentOil Sump
Oil Sump Strainers
Oil Pump
Oil Filter
Oil Heater
Oil Separator
Oil Cooler
Oil Pressure Transducer
Oil Piping and Valves
Oil Sightglass
• Simple design
• Reduces maintenance
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AlarmsLow Oil Pressure
High Oil Pressure
Low Oil Temperature
High Oil Temperature
Loss of Oil Flow
Oil Pressure Transducer Failure
Oil Temperature Sensor Failure
Oil Pump Failure
Oil Pump VFD Failure
Oil Filter Clogged
Alarms associated with oiled management systems or no longer needed
Reduced Risk of Failure
27 |
Applications for Oil Free Compressors
• Water cooled chillers
• Comfort cooling
• Process applications
• Vertical Market applications
• Schools
• Data centers
• Office buildings
• Healthcare
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Benefits of Air Cooled Chillers
• Lower system installation cost
• Faster design cycles
• Smaller mechanical footprint
• Reduces water consumption
• Lower maintenance – no cooling tower
• Reduce risk of legionella
29 |
Challenges for Air Cooled Chillers
•Size
30 |
Challenges for Air Cooled Chillers
•Outdoor Application
31 |
Challenges for Air Cooled Centrifugal Chillers
•Cost/Efficiency
32 |
Standard Chiller – Heat Rejected to Atmosphere
33 |
Heat Reclaim/Heat Recovery/Heat Pumps
• Heat Recovery / water-water heat pump
• Energy savings by utilizing waste heat
• Can help downsize or eliminate boiler
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Thermal Storage
•Shifts energy consumption to less expensive off peak hours
• Lower utility rates
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75 --
70 --
65 --
60 --
55 --
50 --
45 --
40 --
35 --
30 --
25 --
20 --
15 --
10 --
-- -- -- -- -- -- -- -- -- -- -- --
-30 -25 -20 -15 -10 -5 0 5 10 15 20 25
Satu
rate
d D
isch
arg
e T
em
pera
ture
(deg C
)
Saturated Suction Temperature (deg C)
High Lift Operating Map Requirements - By Application (incr. comp.)
High
Temp
Evap
Air-to-Water Heat Pump
Air-Cooled Low-
Temp Process
Air-Cooled
Thermal Storage
Air-Cooled Chiller
Water-to-Water
Heat Pump
Next Generation Oil Free Compressors
Expanded operating map
• Higher lift capability
• Better unloading
36 |
Oil Free Compressor Current State
Capacity (Tons)
Lift
(Pre
ssure
Ratio)
Capacity (kW)
100 1000
3500350
1
6
9
3
0
Current Oil Free Compressor Range (All Types)
37 |
Oil Free Compressor Future
Capacity (Tons)
Lift
(Pre
ssure
Ratio)
Capacity (kW)
100 1000
3500350
1
6
9
3
0
Current Oil Free Compressor Range (All Types)
Commercial and Light Commercial Packaged Products and VRF
