Practical Differences in Working With Low & High Glide Blends, and Implications for Retrofitting. Stephen V. Spletzer

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1 Practical Differences in Working With Low & High Glide Blends, and Implications for Retrofitting Stephen V. Spletzer 2014 ASHRAE Winter Conference New York, NY January 22, 2014

2 Learning Objectives 1. Describe a high glide refrigerant blend 2. Explain how to use bubble and dew point to evaluate superheat and subcooling. 3. Identify when an oil change may or may not be required. 4. Describe when a new refrigerant may require modifications to valves or controls. 5. Acknowledge that the EPA has recently aggressively increased the phase-out of R Explain applications where one of the refrigerant manufacturer s blends would be most preferred over another s. ASHRAE is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to ASHRAE Records for AIA members. Certificates of Completion for non-aia members are available on request. This program is registered with the AIA/ASHRAE for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. 2

3 Thank You Disclaimer The statements, technical information and recommendations contained herein are believed to be accurate as of the date hereof. Since the conditions and methods of use of the information referred to herein are beyond our control, Arkema expressly disclaims any and all liability as to any results obtained or arising from any reliance on such information; NO WARRANTY OF FITNESS FOR ANY PARTICULAR PURPOSE, WARRANTY OF MERCHANTABILITY, OR ANY OTHER WARRANTY, EXPRESS OR IMPLIED, IS MADE CONCERNING THE INFORMATION PROVIDED HEREIN. The user should thoroughly test any application before commercialization. Nothing contained herein constitutes a license to practice under any patent and it should not be construed as an inducement to infringe any patent, and the user is advised to take appropriate steps to be sure that any proposed action will not result in patent infringement Arkema Inc. 3

4 4 Phase-out of R-22

5 Refrigerant Blends Blend a mixture of 2 or more refrigerant components Blend Types Azeotropes (500 series) Zeotropes (400 series) Blend Behaviors Fractionation Vapor vs. Liquid Charging Leaks Glide 5

6 Fractionation Fractionation: preferential separation of a refrigerant blend s components that occurs during phase change due to differences in component volatilities, which may affect performance / safety 6

7 Blends Vapor vs. Liquid Charging = High Volatility = Low Volatility 7

8 Vapor Charging Low Glide R-410A Vapor Charging Simulation Liquid Level R-32 Mass % R-125 Mass %

9 Vapor Charging High Glide R-427A Vapor Charging Simulation Liquid Level R-32 Mass % R-125 Mass % R-143a Mass % R-134a Mass %

10 Understanding Glide INLET OUTLET Refrigerant Temperature T5 T4 T3 T2 T Evaporator Position = High Volatility = Low Volatility Refrigerant Glide: a temperature gradient produced by different blend component volatilities. With a high glide blend, the inlet of the evaporator may be noticeably colder than the outlet 10

11 Low Versus High Glide Blends Question What is Low / High Glide? ASHRAE # Evap. Glide ( o F) ASHRAE # Evap. Glide ( o F) R-507A 0.0 R-417A 5.0 R-428A 0.5 R-421A 5.5 R-404A 0.7 R-422B 5.5 R-422A 2.4 R-424A 5.6 R-434A 2.7 R-438A 7.0 R-422C 3.0 R-407A 7.7 R-421B 3.2 R-427A 7.8 R-417B 3.5 R-407F R-422D 4.8 R-407C 8.5

12 R-427A Quaternary HFC Refrigerant Blend Mol. Weight (g/mol) R R-427A 90.4 N. Boiling Point ( o F) % 25% 10% R-32 R-125 R-143a Critical Temp. ( o F) Safety Rating A A1 50% R-134a ODP GWP 1,810 2,138 Evap. Glide ( o F)

13 Leaks with High Glide Blends R-427A Charge / Recharge Simulation* (Liquid Composition) R-32 R-125 R-143a R-134a Mass % Mass % Mass % Mass % Start st Recharge nd Recharge rd Recharge th Recharge th Recharge *15% Liquid Fill - 20% Mass Vapor Leaks

14 Leaks with High Glide Blends R-427A Charge / Recharge Simulation* (Liquid Composition) Capacity COP Mass Flow HS Pressure (%) (%) (%) (%) Start st Recharge nd Recharge rd Recharge th Recharge th Recharge *15% Liquid Fill - 20% Mass Vapor Leaks

15 Leaks with High Glide Blends Fractionation effects from leaks on actively running systems tend to be small Supermarkets Vapor leaks on dormant systems with high glide blends pose a concern AC systems during winter Topping off refrigerant (after repairing all leaks!!!) Commonplace and usually acceptable May come down to judgment call for certain scenarios Pressure checks may help indicate extent of fractionation 15

16 Other Impacts of High Glide High glide blends Produce range of pressures / temps during phase change Bubble / Dew points used to describe ends of phase change Bubble Point All Liquid End (Used for Subcooling) Dew Point All Vapor End (Used for Superheat) Superheat adjustments Decrease in superheat at evaporator outlet (relative to R-22) common Adjustment of TXV / Charge likely For R-427A, may need to close down TXV slightly ( ¼ - ½ turn) Both Bubble / Dew Point may be used for calculating coil temperatures / pressures and adjusting pressure controls 16

17 Environmental Chamber Testing Evaporator Unit Condensing Unit 1-½ HP R-22 condensing unit / evaporator assembly Horizontal line-set sloped down from evaporator compressor Optimized refrigerant charge / adjusted TXV superheat setting Used MO for R-22 baseline, changed to POE with R-427A 17

18 Testing Results * R-22 R-422D** R-427A R-438A Charge Weight (%) Capacity (%) COP (%) Suction Pressure (psi) Discharge Pressure (psi) Discharge Temp ( o F) Mass Flow (%) TXV Adjustment N/A 1-¼ turn ¼ turn ¼ turn Oil Type MO POE POE POE 18 * 100 o F Ambient, 50 o F Box Temperatures **Distributor Nozzle Undersized

19 Field Trial Food Prep Room (HT R) Compressor Amperage (A) Suction Pressure (psi) Discharge Pressure (psi) Oil Type 55 o F Cold Room Temperature R MO R-427A POE Validates lab testing similar operating pressures Equipment changes filter-drier & elastomers No TXV or pressure control adjustments required 19

20 Field Trial Supermarket (MT & LT R) R 22 R-427A W32 R-427A W Consumed energy (kwh) Mineral oil replaced with POE, elastomers, filter-driers changed 20 Similar operating parameters 18 o F lower discharge temps Energy consumption equivalent or lower than R-22

21 Flooded Evaporators (FEs) Float Valve To Compressor Surge Tank Retrofit of FE systems typically not recommended for high glide blends Pooling = High Volatility = Low Volatility EU ban on use of virgin / reclaimed R-22 leaves few options for existing system owners Flooded Evaporator Retrofits happening on limited basis 21

22 Modeling / Simulation of FE Systems Charge distribution critical to retrofit success with high glide blends 22 Not all systems / geometries will be viable candidates

23 Conclusions The phase-out of R-22 is driving retrofits Use of high glide blends will become more common Understanding fractionation / glide vital Blend Charging Handling leaks Setting pressures Adjusting controls R-427A is high glide retrofit blend option, but Closely matches R-22 s pressures and flow rates Requires minor adjustment to controls High glide blends typically not recommended for flooded evaporators Retrofit experience in EU shows it is possible on a limited basis 23

24 24 Stephen V. Spletzer