The document summarizes a presentation given at the eurammon Symposium 2017 about using R290 and R1270 refrigerants in commercial refrigeration systems. It discusses the properties of R290 and R1270 and their impacts on system design criteria, such as lower pressure drops and mass flows compared to R22 and HFCs. It also addresses the influence of hydrocarbons on compressor lubrication, such as stronger oil dilution, and measures needed for reliable operation like minimum refrigerant charges and suction superheating. Outdoor chiller/heat pump units using R290/R1270 blends are presented as a promising future solution.

1. eurammon Symposium 2017
TITLE
SPEAKER
Schaffhausen, 22nd / 23rd June, 2017
Commercial Refrigeration Systems
with R290 and R1270 −
Criteria for the Selection and Layout of
Components and Pipe Work
Hermann Renz, BITZER GmbH

2. Schaffhausen, 22nd / 23rd June, 2017 Page 2
Contents
• R290 and R1270 properties and their impact
• Resulting design and layout criteria
• Influence of hydrocarbons on compressor lubrication
• Required measures for reliable operation
• Summary
Presentation does not include measures for safety provisions
Commercial Refrigeration Systems with R290 and R1270

3. Schaffhausen, 22nd / 23rd June, 2017 Page 3
• Moderate pressure levels, low
pressure ratio (p/po) due to flat
temperature/pressure characteristics
 p/po far lower than with any HFC
or HFC/HFO alternative
• Volumetric refrigerating capacity
+/-20% vs. R22 and R404A/507A
• High evaporation enthalpy
 @ -10/40°C approx. 1.7 times vs.
R22 // 2.5 times vs. R404A/R507A
R290 and R1270 Properties and Their Impact (1)

4. Schaffhausen, 22nd / 23rd June, 2017 Page 4
Volumetric Refrigerating Capacity / Suction Gas Volume Flow
Volumetric refrigerating capacity of
different refrigerants compared to R290
 Identical suction volume flow
Suction gas volume flow of different
refrigerants compared to R290
 Identical refrigerating capacity
tc 40°C, Dtoh 20 K tc 40°C, Dtoh 20 K

5. Schaffhausen, 22nd / 23rd June, 2017 Page 5
• Low refrigerant mass flow
 @ identical Qo   55..60% vs. R22 //  40% vs. R404A/R507A
• Very low vapour and liquid densities
 Vapour (suction):  35..55% vs. R22 and HFCs
 Liquid:  40..50% vs. R22 and HFCs
 Low pressure drop in heat exchangers (HX) and pipe work
• High superheat enthalpy in relation to volume change
 Rising volumetric refr. capacity with increasing useful superheat
 Increase of capacity and COP with liquid/suction line HX
R290 and R1270 Properties and Their Impact (2)

6. Schaffhausen, 22nd / 23rd June, 2017 Page 6
Refrigerant Mass Flow / Liquid Volume Flow
Mass flow of different
refrigerants compared to R290
 Identical refrigerating capacity
Liquid volume flow of different
refrigerants compared to R290
 Identical refrigerating capacity
tc 40°C, Dtoh 20 K
tc 40°C, Dtoh 20 K

7. Schaffhausen, 22nd / 23rd June, 2017 Page 7
Relative Compressor COP – R22, HFCs vs. R290 and R1270
20
30
40
50
60
70
80
90
100
110
120
130
140
150
R22 R404A/R507A R407F (Dew) R448A/R449A (Dew) R290 R1270
RelativeCOP[%]
to +5°C, tc 50°C
to -10°C, tc 45°C
to -35°C, tc 40°C
Dtoh 20 K
hc (+5°/-10°C): 0.7
hc (-35°C): 0.65
Compressor type: Semi-hermetic Recip (isentropic efficiency includes motor losses)
COP does not reflect system bahaviour

8. Schaffhausen, 22nd / 23rd June, 2017 Page 8
• Low discharge gas and oil temperatures (low cp/cv)
 Moderate thermal load even with high pressure ratio (LT single stage)
• High critical temperature (96.7 / 91.1°C)
 Favorable compressor and system COP also at high condensing
temperatures and lift conditions
R290 and R1270 Properties and Their Impact (3)

9. Schaffhausen, 22nd / 23rd June, 2017 Page 9
• Good heat transfer due to intensive boiling and excellent solubility
and miscibility with oil
 Single fluids  no temperature glide
 Good oil transport, low viscosity also in superheat section of
evaporators
• Material compatibility similar to R22 and HFCs
 Elastomers/plastics  some stronger limitations with R1270
(see also “Forschungsrat Kältetechnik“ Research Report FKT61_99)
R290 and R1270 Properties and Their Impact (4)

10. Schaffhausen, 22nd / 23rd June, 2017 Page 10
0
20
40
60
80
100
120
140
160
180
200
R22 R404A/R507A R407F (Dew) R448A/R449A (Dew) R 290 R 1270
DischargeGasTemperature[°C]
to +5°C, tc 50°C
to -10°C, tc 45°C
to -35°C, tc 40°C
Dtoh 20 K
hc (+5°/-10°C): 0.7
hc (-35°C): 0.65
Comparison of Discharge Gas Temperatures
with Single Stage Operation
Compressor type: Semi-hermetic Recip (isentropic efficiency includes motor losses)

11. Schaffhausen, 22nd / 23rd June, 2017 Page 11
• Reduced cross sections in HX, suction and discharge lines vs. R22 / HFC
 Due to far lower vapour density / pressure drop
• Identical dimensions of liquid line as with R22
 Higher liquid volume flow but less pressure drop  lower density
• Potential for minimum refrigerant charge
 mass 40..60% vs. R22 / HFCs
Resulting Design and Layout Criteria (1)

12. Schaffhausen, 22nd / 23rd June, 2017 Page 12
• Select HX and line components according to mass and volume flow
 Evaporator: e.g. injection distribution, pipe length and pipe geometry
 Danger of uneven distribution and liquid overfeed in part load
 TXV / EXV  capacity* vs. R22 − same nozzle (bulb charge adapted):
 R290  HT / MT: 0..+5% // LT: -2..+2.5%
 R1270  +13..18%
Higher numbers with lower condensing temperatures (15 K < reference tc)
Resulting Design and Layout Criteria (2)
* Source: Danfoss / Honeywell calculation methodology

13. Schaffhausen, 22nd / 23rd June, 2017 Page 13
• Preferred use of liquid/suction line HX  target Dtoh  20 K (HT, MT)
 Benefit in capacity, COP and reduced oil dilution  higher oil temp
Resulting Design Criteria and Measures (3)
71°C
-5°C
43.0°C
w/o IHX w/ IHX  COP  +7%
Examples of Cycle Configuration (R290)
-5°C
43.0°C
84°C
33.8°C
10°C

14. Schaffhausen, 22nd / 23rd June, 2017 Page 14
• HC‘s have exceptionally good solubility/miscibility behaviour in oil
especially with lubricants of low polarity like MO
 Strong oil dilution / reduced viscosity / solvent effect
 Strong degassing and foaming with pressure fluctuation
• Operating temperatures (discharge gas, oil) remarkably low
 Increased amount of dissolved HC in oil especially at small pressure
ratios, high evaporating temperatures and low superheat
Influence of Hydrocarbons on Compressor Lubrication (1)

15. Schaffhausen, 22nd / 23rd June, 2017 Page 15
• Solubility (oil/refrigerant) usually measured in “mass %“
 With MO no severe difference in mass % vs. R22
or HFC‘s w/ POE − however …
 Low liquid density of HC‘s (40 – 45% vs. R22) leads to more than
double volume of dissolved refrigerant in oil
 Far stronger oil dilution than with R22 and HFC‘s
Influence of Hydrocarbons on Compressor Lubrication (2)

16. Schaffhausen, 22nd / 23rd June, 2017 Page 16
Operation @ to +5°C
Oil temp R22 10 K higher than with R290 (55° vs. 45°C)
Pressure / Temperature / Solubility Relation
Example MO Oil / R290 vs. R22
Standstill @ 20°C
MO VG 68 cSt − R290 MO VG 68 cSt − R22
~ 16% R290
~ 8% R290
~ 7% R22
~ 17% R22
vapourpressure(bar)
vapourpressure(bar)
Temperature (°C)
Temperature (°C)

17. Schaffhausen, 22nd / 23rd June, 2017 Page 17
Solubility / Viscosity Relation
Example MO Oil / R290 vs. R22
MO VG 68 cSt − R290 MO VG 68 cSt − R22
Standstill @ 20°C
Oil temp 40°C
40°C 55°COperation @ to +5°C
Oil temp R22 10 K higher than with R290 (55° vs. 45°C)
45°C
Far lower viscosities!
Temperature (°C)Temperature (°C)
Temperature (°C)

18. Schaffhausen, 22nd / 23rd June, 2017 Page 18
• Best suitable lubricant − acc. to compressor manufacturer specification
 Usually higher basic viscosity and/or lubricants with higher viscosity
index (Vi) or high polarity (lower solubility)
• Minimum refrigerant charge
• Generously sized crankcase heater
• High suction pressure during standstill periods?
 Pump down cycle may become necessary
• Possible insulation of compressors in case of outdoor installation
Lubricants: Required Measures for Reliable Operation (1)

19. Schaffhausen, 22nd / 23rd June, 2017 Page 19
• Superheat in MT & HT should be 20 K or higher, LT > 10 K
 Liquid/suction line heat exchanger  especially AC & Heat Pumps
• Measures against ”wet operation“ during start and operation
 Avoid refrigerant migration to suction side during standstill
 Maintain sufficiently high suction gas superheat
Lubricants: Required Measures for Reliable Operation (2)

20. Schaffhausen, 22nd / 23rd June, 2017 Page 20
• The extended use of R290 and R1270 in commercial RAC systems
can be seen as one of the promising future solutions
• High system efficiency and reliability can be reached with component and
system design precisely matched to the specific refrigerant properties
• This as well includes to consider the necessary measures with regard to
lubricant related issues
Summary

21. Schaffhausen, 22nd / 23rd June, 2017 Page 21
• Outdoor Units with a cooling
capacity range up to 190 kW
 Reversing cycle
chiller / heat pump unit
 3-pipe water loop
• Refrigerant: R290/1270 blend
Example of Chiller / Heat Pump Unit
Source: Unichemie NL

22. Contact:
Hermann Renz
Eschenbruennlestr. 15, D-71065 Sindelfingen
Germany
+49 7031 932 240
+49 7031 932 5240
hermann.renz@bitzer.de
Thank You for Your Attention!