Investigation of New Low-GWP Refrigerants for Use in Two-Phase - - PowerPoint PPT Presentation

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Aug 05, 2023 432 likes •652 views

Investigation of New Low-GWP Refrigerants for Use in Two-Phase Evaporative Cooling of Electronics Alexis Nicolette-Baker, Elizabeth Garr, Abhijit Sathe, and Steve O'Shaughnessey Precision Cooling Systems Parker Hannifin Corporation Background

SLIDE 1

Investigation of New Low-GWP Refrigerants for Use in Two-Phase Evaporative Cooling of Electronics

Alexis Nicolette-Baker, Elizabeth Garr, Abhijit Sathe, and Steve O'Shaughnessey Precision Cooling Systems Parker Hannifin Corporation

SLIDE 2

Parker Precision Cooling Systems www.parker.com/pc 2

 Global warming from refrigerants a major

environmental concern

 Kyoto Protocol  AHRI Low-GWP Alternative Refrigerants Evaluation

Program identifies several candidates for replacement

f R134a

 Four fluids – R1234ze, R1234yf, N-13a and N-13b are

among 12 candidates identified by AHRI for R134a replacement

Background

SLIDE 3

Parker Precision Cooling Systems www.parker.com/pc 3

Candidate Fluid Overview

Name R134a R1234ze R1234yf N-13a N-13b Type Pure fluid Pure fluid Pure fluid Blend Blend Composition (% Mass) R134a: 42 R1234ze: 40 R1234yf: 18 R134a: 42 R1234ze: 58 Enthalpy of Vaporization 182.28 170.50 149.29 168.71 173.51 GWP (100 Years) 1430 6 4 604 604

SLIDE 4

Parker Precision Cooling Systems www.parker.com/pc

Vapor Pressure vs. Temperature

0.5 1 1.5 2 2.5 3 3.5 4 4.5 150 200 250 300 350 400

Pressure (MPa) Temperature (K)

R134a R1234yf R1234ze N‐13a N‐13b

SLIDE 5

Parker Precision Cooling Systems www.parker.com/pc

Saturated Pressure vs. Enthalpy

100 1000 10000 150 200 250 300 350 400 450

Pressure (kPa) Enthalpy (kJ/kg)

R134a R1234yf R1234ze N‐13a N‐13b

SLIDE 6

Parker Precision Cooling Systems www.parker.com/pc 6

Parker 2-Phase Cooling System

Microchannel Heat Sink Cooling Unit Condenser Accumulator Pump Inverter Drive

SLIDE 7

Parker Precision Cooling Systems www.parker.com/pc 7

Parker 2-Phase Cooling System

50 100 150 200 250 300 500 1000 2000 5000

Enthalpy [kJ/kg] Pressure [kPa]

70°C 50°C 30°C

0.2 0.4 0.6 0.8

1 2 3

System schematic P-h diagram with R134a

SLIDE 8

Parker Precision Cooling Systems www.parker.com/pc

Testing Goals

 Determine what system changes need made for

alternative refrigerants

» Refrigerant line sizes

– Tubing – Hosing – Inter connects

» Refrigerant flow rates

– Pump – Condenser – Heat sink

SLIDE 9

Parker Precision Cooling Systems www.parker.com/pc 9

Experimental Setup

T – Thermocouple (9) P – Pressure sensor (6)

SLIDE 10

Parker Precision Cooling Systems www.parker.com/pc 10

Test Procedure

 Heat load to heat sink was controlled by adjusting

input voltage to electric heaters

 Refrigerant subcool of 2 °C was maintained by

adjusting condenser fan speed

 Refrigerant exit quality was calculated by energy

balance on heat sink

 Exit quality was varied by changing the liquid pump

speed which in turn varied refrigerant volume flow rate

SLIDE 11

Parker Precision Cooling Systems www.parker.com/pc 11

Test Matrix

Q (W) 500 550 600 650 700 750 800 850 900 950 1000

Heat load

X (%) 30 40 50 60 70 80

Refrigerant exit quality

 Uncertainties for pressure, temperature and volume

flow rate are ± 1 %, ± 1 °C and ± 3 %, respectively.

(g/s)

5.5 7 8.5

Refrigerant mass flow rate

SLIDE 12

Parker Precision Cooling Systems www.parker.com/pc 12

Data Reduction

 Refrigerant quality

Q

 Heat transfer coefficient
, ∙ ∆
∆

∆ 2 ∆ 1

∆

SLIDE 13

Parker Precision Cooling Systems www.parker.com/pc 13

Refrigerant Flow Rate vs. Heat Load

70% exit quality

5 10 15 20 25 30 35 400 500 600 700 800 900 1000 1100 R134a R1234ze R1234yf N‐13a N‐13b

Volume flow rate [LPH] Heat load (W)

SLIDE 14

Parker Precision Cooling Systems www.parker.com/pc 14

Refrigerant Flow Rate vs. Exit Quality

500 W heat load

5 10 15 20 25 30 35 40 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 R134a R1234ze R1234yf N‐13a N‐13b

Volume flow rate [LPH] Exit quality

SLIDE 15

Parker Precision Cooling Systems www.parker.com/pc 15

Refrigerant Flow Rate Comparison

5 10 15 20 25 30 35 40 0.3 0.4 0.5 0.6 0.7 0.8

% Increase in volume flow rate over R134a Exit quality

R1234ze R1234yf N‐13a N‐13b

% change in required volume flow rate of candidate fluids compared with R134a

 R1234yf required ~ 34%

more flow than R134a

 N-13b required ~ 8%

more flow than R134a

SLIDE 16

Parker Precision Cooling Systems www.parker.com/pc 16

Pump Pressure Rise vs. Exit Quality

Mass flow rate = 0.007 kg/s

5 10 15 20 25 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 R134a R1234ze R1234yf N‐13a N‐13b

Pump pressure rise [kPa] Exit quality

SLIDE 17

Parker Precision Cooling Systems www.parker.com/pc 17

Heat Transfer Coefficient vs. Exit Quality

Average heat transfer coefficient at mass flow rate of 0.007 kg/s

19 20 21 22 23 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 R134a R1234ze R1234yf N‐13a N‐13b

Average heat transfer coefficient [kW/m2‐K] Exit quality

SLIDE 18

Parker Precision Cooling Systems www.parker.com/pc 18

Average Heat Transfer Coefficient Comparison

% change in average heat transfer coefficients

f candidate fluids

compared with R134a

‐10 ‐9 ‐8 ‐7 ‐6 ‐5 ‐4 ‐3 ‐2 ‐1 0.3 0.4 0.5 0.6 0.7 0.8

% change in heat transfer coefficiens compared to R134a Exit quality

R1234ze R1234yf N‐13a N‐13b

SLIDE 19

Parker Precision Cooling Systems www.parker.com/pc

Conclusions

 R1234ze, R1234yf, N-13a, N-13b were experimentally

tested for possible replacement of R134a in Parker’s two phase liquid cooling system

 R134a performed the best in terms of volume flow rate,

pressure drop and heat transfer coefficient

 All candidate fluids exhibited significant drop in system

performance

 No clear alternative to replace R134a

» Selection of alternate fluid depends on design criteria

SLIDE 20

Parker Precision Cooling Systems www.parker.com/pc

Conclusions

 Important system design parameters and suitable

refrigerant(s)

Criteria Importance Candidate GWP Environment R1234yf and R1234ze Volumetric Flow Rate Pump Sizing N-13b Pressure Drop Pump Power Consumption R1234yf Heat Transfer Coefficient Heat Sink Thermal Resistance R1234yf

Investigation of New Low-GWP Refrigerants for Use in Two-Phase Evaporative Cooling of Electronics

Alexis Nicolette-Baker, Elizabeth Garr, Abhijit Sathe, and Steve O'Shaughnessey Precision Cooling Systems Parker Hannifin Corporation

 Global warming from refrigerants a major

environmental concern

 Kyoto Protocol  AHRI Low-GWP Alternative Refrigerants Evaluation

Program identifies several candidates for replacement

 Four fluids – R1234ze, R1234yf, N-13a and N-13b are

among 12 candidates identified by AHRI for R134a replacement

Background

Candidate Fluid Overview

Name R134a R1234ze R1234yf N-13a N-13b Type Pure fluid Pure fluid Pure fluid Blend Blend Composition (% Mass) R134a: 42 R1234ze: 40 R1234yf: 18 R134a: 42 R1234ze: 58 Enthalpy of Vaporization 182.28 170.50 149.29 168.71 173.51 GWP (100 Years) 1430 6 4 604 604

Vapor Pressure vs. Temperature

Saturated Pressure vs. Enthalpy

Parker 2-Phase Cooling System

Microchannel Heat Sink Cooling Unit Condenser Accumulator Pump Inverter Drive

Parker 2-Phase Cooling System

System schematic P-h diagram with R134a

Testing Goals

 Determine what system changes need made for

alternative refrigerants

» Refrigerant line sizes

– Tubing – Hosing – Inter connects

» Refrigerant flow rates

– Pump – Condenser – Heat sink

Experimental Setup

T – Thermocouple (9) P – Pressure sensor (6)

Test Procedure

 Heat load to heat sink was controlled by adjusting

input voltage to electric heaters

 Refrigerant subcool of 2 °C was maintained by

adjusting condenser fan speed

 Refrigerant exit quality was calculated by energy

balance on heat sink

 Exit quality was varied by changing the liquid pump

speed which in turn varied refrigerant volume flow rate

Test Matrix

Q (W) 500 550 600 650 700 750 800 850 900 950 1000

Heat load

X (%) 30 40 50 60 70 80

Refrigerant exit quality

 Uncertainties for pressure, temperature and volume

flow rate are ± 1 %, ± 1 °C and ± 3 %, respectively.

5.5 7 8.5

Refrigerant mass flow rate

Data Reduction

 Refrigerant quality

Q

∆

∆

Refrigerant Flow Rate vs. Heat Load

70% exit quality

Refrigerant Flow Rate vs. Exit Quality

500 W heat load

Refrigerant Flow Rate Comparison

% change in required volume flow rate of candidate fluids compared with R134a

more flow than R134a

more flow than R134a

Pump Pressure Rise vs. Exit Quality

Mass flow rate = 0.007 kg/s

Heat Transfer Coefficient vs. Exit Quality

Average heat transfer coefficient at mass flow rate of 0.007 kg/s

Average Heat Transfer Coefficient Comparison

% change in average heat transfer coefficients

compared with R134a

Conclusions

 R1234ze, R1234yf, N-13a, N-13b were experimentally

tested for possible replacement of R134a in Parker’s two phase liquid cooling system

 R134a performed the best in terms of volume flow rate,

pressure drop and heat transfer coefficient

 All candidate fluids exhibited significant drop in system

performance

 No clear alternative to replace R134a

» Selection of alternate fluid depends on design criteria

Conclusions

 Important system design parameters and suitable

refrigerant(s)

Criteria Importance Candidate GWP Environment R1234yf and R1234ze Volumetric Flow Rate Pump Sizing N-13b Pressure Drop Pump Power Consumption R1234yf Heat Transfer Coefficient Heat Sink Thermal Resistance R1234yf

Acknowledgements

 We thank Honeywell, Inc. for supplying the fluids for

testing.