Blue is better

1

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

Blue is better

2

Introduction

Blue is better

3

• 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

Blue is better

R1234zeTESTING

EXPERIENCE

R1234zeTESTING

EXPERIENCE 4

R&D case study

Blue is better

5

Summary

Testing routine instructionTesting equipment and methodsRefrigerant properties databasesResultsOperationsCurrent state of test programDesign evolutionSelection software update

Blue is better

6

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

Blue is better

7

TEST RIG: 300kW

Test equipment and methods

Blue is better

8

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

Blue is better

9

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

Blue is better

REFRIGERANT PROPERTIES DATABASE:

NIST refprop 9.0

ILK REFLIB for MS Excel 2.1 10

Refrigerant databases

Blue is better

11

Compressor performancePerformance testNumeric simulation

Refrigerant comparison

Oil behavior

Compressor parts wearing

Results – key points

Blue is better

12

Results – performance test

Blue is better

13

Results – Numeric simulation

Blue is better

14

Results – Refrigerant Comparison

Blue is better

15

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

Blue is better

16

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

Blue is better

17

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

?

Blue is better

18

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

Blue is better

19

Design evolution

• Motor optimized for HFO• New valve

plate

• Reduced clearances • Optimized

bore-strokeratio

Blue is better

20

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

Blue is better

21

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

Blue is better

22

COMPRESSOR TECNOLOGY FOR THE LOW GWP

REFRIGERANTS

Thanks !