Frascold NRQT
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Transcript Frascold NRQT
COMPRESSOR TECNOLOGY
FOR THE LOW GWP
REFRIGERANTS
London - 26° April 2012
RAC question time
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Eng. Marco Caldara
Frascold R&D laboratory manager
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Introduction
Compressor
Technology
Refrigerants
and Application
Engineering
Manufacturing
and Process
Engineering
Frascold Research
Philosophy
Material
Sciences
Compressor
Design
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Forensic
Engineering
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Current activities
Refrigerants
• HFO
• R407F
• CO2
Compressor design
• Design evaluation for drop-in allowance
• Design evolution for performance increasing
• Application envelope extensions
Validating application
• Suggest refrigerant choice
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• Hybrid system
• Field test in different location for seasonal
TEWI calculation purposes
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R&D case study
R1234ze
TESTING
EXPERIENCE
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Summary
Testing routine instruction
Testing equipment and methods
Refrigerant properties databases
Results
Operations
Current state of test program
Design evolution
Selection software update
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Testing routine instruction
TEST PLAN
1. Measure compressor parts
2. Assembling compressor
3. Tightness test
4. Oil charge
5. Installing on test rig and evacuate for 12 h
6. Test and record time + working condition
7. Recover refrigerant and uninstall from test rig
8. Taking oil sample for analysis
9. Dismantle compressor
10.Measure compressor part (500 h).
Each test result contributes to the entire project final result
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Test equipment and methods
TEST RIG: 300kW
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Test equipment and methods
TEST RIG: 300kW
Built by ILK Dresden in 2004.
Test according to EN13771-1
Two Coriolis mass flow meter
LP side, method D1
HP side, method D2
Oil separator
Power supply from stabilized grid
Four independent PID controllers
Pressure measurement uncertainty lower than 1%
Temperature measurement uncertainty lower than 0,3 K
Power measurement uncertainty lower than 1%
Water cooled condenser and subcooler
Performance uncertainty lower than 5%
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Test equipment and methods
PERFORMANCE DATA PROCESSING STEP
1.
2.
3.
4.
5.
6.
7.
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9.
Placing testing point
Expect limits
Break-in time (24 h)
Reproduce conditions
Go outside limits
Check results
Use interpolation software
Evaluate efficiency curve
Create performance model
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Refrigerant databases
REFRIGERANT PROPERTIES DATABASE:
NIST refprop 9.0
ILK REFLIB for MS Excel 2.1
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Results – key points
Compressor performance
Performance test
Numeric simulation
Refrigerant comparison
Oil behavior
Compressor parts wearing
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Results – performance test
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Results – Numeric simulation
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Results – Refrigerant Comparison
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Results – Oil behavior
EVALUATED OIL:
POE 68 cst
PAG 68 cst
POE 170 cst (screw)
POE 68 cst
Oil level was regulated at half of the sight glass on compressor
crankcase by an optical level switch.
LUBRICATION AT COLD START UP
SUDDEN PRESSURE DECREASE (FOAM)
FORCED LUBRICATION – PUMP
DIFFERENTIAL PRESSURE
GAS TRAPPING WHEN DISCARDED
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Results – compressor parts wearing
EVALUATED COMPONENTS:
PISTON AND PISTON RINGS
SHAFT
RODS
BUSHES
VALVE PLATE REEDS
LIGHT WEARING (NORMAL)
NO OVERHEATING SIGN ON VALVE
REEDS AND ROTATING PARTS
ABSENCE OF DIRT OR PARTICLES
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Operations
NEEDING ADDITIONAL CARE FOR:
LOADING – UNLOADING OF THE REFRIGERANT
FLAMMABILITY ISSUE: VENTILATION OF AREA
STOCK AND HANDLING
VACUUM OPERATION
?
No difference in loading operation, but
lower pressure at given temperature
Same ambient condition
Same stock area and procedure
Additional vacuum time to sample oil
after test
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Test program
1° step: drop in of refrigerant in standard model
2° step: Evaluated R134a model
range
3° step: HFO dedicated model to enhance
favorable behavior
4° step: field test running and confirmation test
99% compatible with standard model
(dedicated oil)
different performances requires
technology adaption
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Design evolution
•New valve
plate
•Reduced
clearances
•Motor optimized
for HFO
•Optimized
bore-stroke
ratio
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Design evolution
Different motor size tested to
catch higher efficiency
different bore-stroke solutions
will be evaluated in future.
New design of valve plate
under evaluation
Thanks to lower power consumption
motor
efficiency
improvement
is
possible and necessary
Shorter stroke compression helps with
low density refrigerant in suction stage
Valve plate for higher specific volume
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Selection software update
Refrigerant model available
Compressor efficiencies available for tested models
Other models could be calculated having tested
performaces with HFC and conversion tools
Models need confirmation test on oher sizes
Thanks to similarity with R134a
conversion is plausible and tested to
define accuracy
Performance calculation in progress.
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Thanks !
COMPRESSOR TECNOLOGY
FOR THE LOW GWP
REFRIGERANTS
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