Post on 18-Dec-2015
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Eng. Marco CaldaraFrascold R&D laboratory manager
COMPRESSOR TECNOLOGY FOR THE LOW GWP
REFRIGERANTS
London - 26° April 2012RAC question time
Frascold Research Philosophy
Compressor Technology
Manufacturing and Process Engineering
Material Sciences
Forensic Engineering
Compressor Design
Refrigerants and Application Engineering
Frascold Research Philosophy
Compressor Technology
Manufacturing and Process Engineering
Material Sciences
Forensic Engineering
Compressor Design
Refrigerants and Application Engineering
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Introduction
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• HFO
• R407F
• CO2
Refrigerants
• Design evaluation for drop-in allowance
• Design evolution for performance increasing
• Application envelope extensions
Compressor design
• Suggest refrigerant choice
• Hybrid system
• Field test in different location for seasonal TEWI calculation purposes
Validating application
Current activities
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R1234zeTESTING
EXPERIENCE
R1234zeTESTING
EXPERIENCE 4
R&D case study
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Summary
Testing routine instructionTesting equipment and methodsRefrigerant properties databasesResultsOperationsCurrent state of test programDesign evolutionSelection software update
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TEST PLAN
1. Measure compressor parts2. Assembling compressor3. Tightness test4. Oil charge5. Installing on test rig and evacuate for 12 h6. Test and record time + working condition7. Recover refrigerant and uninstall from test rig8. Taking oil sample for analysis9. Dismantle compressor10.Measure compressor part (500 h).
Each test result contributes to the entire project final result
Testing routine instruction
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TEST RIG: 300kW
Test equipment and methods
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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%
Test equipment and methods
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PERFORMANCE DATA PROCESSING STEP
1. Placing testing point2. Expect limits3. Break-in time (24 h)4. Reproduce conditions5. Go outside limits6. Check results7. Use interpolation software8. Evaluate efficiency curve9. Create performance model
Test equipment and methods
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REFRIGERANT PROPERTIES DATABASE:
NIST refprop 9.0
ILK REFLIB for MS Excel 2.1 10
Refrigerant databases
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Compressor performancePerformance testNumeric simulation
Refrigerant comparison
Oil behavior
Compressor parts wearing
Results – key points
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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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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
Results – Oil behavior
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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
Results – compressor parts wearing
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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
Operations
?
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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
Test program
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Design evolution
• Motor optimized for HFO• New valve
plate
• Reduced clearances • Optimized
bore-strokeratio
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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
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
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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.
Selection software update
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COMPRESSOR TECNOLOGY FOR THE LOW GWP
REFRIGERANTS
Thanks !