challenges in retrofitting r-404a with lower gwp refrigerants · challenges in retrofitting r-404a...
TRANSCRIPT
Challenges in Retrofitting R-404Awith Lower GWP Refrigerants
Sarah Kim, Laurent Abbas, Wissam Rached
Arkema
2015 ASHRAE Summer ConferenceAtlanta, GAJune 30th, 2015
Seminar 37 - Lower GWP Alternatives for R-404A in Commercial and
Transport Refrigeration
Learning Objectives
1. Understand recent and proposed changes in regulations, such as the EU F-Gas Regulations and EPA SNAP, which will drive the transition from R-404A to lower GWP alternatives.
2. Explain options to replace R-404A in commercial and transport refrigeration systems and condensing units.
3. Describe the performance and efficiency of refrigeration systems with lower GWP refrigerants (GWP<2500), in low- and medium-temperature applications.
4. Describe how the behavior of these replacement refrigerants differs from R-404A and other azeotropes and how to manage these differences (i.e., temperature glide, discharge temperature, etc.) in design, construction and commissioning.
2
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.
Regulatory Policy on refrigerants
European Union F-gas : Reduction of HFC emission by 2/3 by 2030
● Main measures – Cap and Phase Down – Selected use bans
EPA Proposal
● Notice of Proposed Rulemaking (NOPR) issued in Summer 2014 to change the status (delist) materials
● Propose to ban the use of some high GWPs refrigerants like R-404A in applications for commercial refrigeration. Lower targets for stand alone and vending machines
ApplicationsDate of
ban
Refrigerators & Freezers for commercial use (Hermetically sealed) with GWP > 2500 2020
Stationary refrigeration with GWP>2500 2020
Multipack centralized refrigeration systems for commercial use with
CAP>40kW : GWP>150 (GWP>1500 in the primary refrigerant circuit of cascade systems)
Refrigerators & Freezers for commercial use (Hermetically sealed) with GWP>150
2022
Global regulatory policy on HFCs picking up momentum3
Regional Regulatory Programs- commercial refrigeration
USA
4
Europe
Stationary refrigeration with GWP>2500
Refrigerators & Freezers for commercial use (Hermetically sealed systems) with GWP > 2500
Servicing/maintenance of refrigerating equipment with charge size > 40t CO2 eq. with GWP>2500
Ban on some high GWP refrigerants. Supermarket Systems, field charged Condensing
Units
National regulations under
discussion in other countries like
Japan and Canada.
2016 + (?) 2020 2022
CA EPA
R-449B*, Others
R-407A
R-407A, Others
R-449B, Others
Cascade system with charge size > 40t CO2
eq. with GWP>1500
*Pending final approval from ASHRAE BOD
**GWP value for 100-year time horizons according to IPCC 2007 4th Assessment Report
5
R-404A Substitutes with Reduced GWP - Non-flammable
R-404A R-449B R-448A R-449A
ASHRAE Safety Rating Class A1 Class A1 Class A1 Class A1
GWP Reduction
vs R-404A (%)*- 64% 65% 64%
HFO Content (%) - 23.2% 27% 25.3%
Normal Boiling Point- 51.2˚F/ -46.2˚C
-51.0˚F/ -46.1˚C
- 50.6˚F/ -45.9˚C
- 50.7˚F/ -46.0˚C
*GWP value for 100-year time horizons according to IPCC 2007 4th Assessment Report
Thermodynamic Cycle Performance
6
GWP~1500 blends showed superior performance compared to R-404A
Mean Evaporator Temperature
Mean Condenser Temperature
Evaporator Outlet Superheat
Compressor Suction Superheat
= -25˚F/-31.7˚C= 105˚F/40.5˚C
= 10˚F/-12.2˚C= 40˚F/4.4˚C
0
20
40
60
80
100
120
COP CAP CondenserPressure
EvaporatorPressure
% w
ith R
esp
ect
to R
-404A
R-407A R-449B R-448A R-449A
Test Unit – Walk-in Freezer with External Evaporator
“Drop-in” tests
R-404A, 1 HP, Walk-in Freezer
with matching evaporator
● Reciprocating Compressor
● No liquid injection
1 ton capacity TXV
2 Outdoor Box Temperatures :
60˚F (15.5˚C) and 85˚F (29.4˚C)
7
PP
TT
T
P
T
P
P
T
T
P
Adjustable
Expansion
Valve
Over 20 feet of line
with several 90º
angles
Outdoor Chamber Indoor Chamber
Mass Flow Meter
System Set-Up
8
-6
-4
-2
0
2
4
6
15˚F/-9.4˚C
0˚F/-17.7˚C
-20˚F/-28.9˚C
-6
-4
-2
0
2
4
6
15˚F/-9.4˚C
0˚F/-17.7˚C
-20˚F/-28.9˚C
R-449B R-449A
Test Results – Efficiency
9
Outdoor Box Temperature = 60ºF/15.5ºC
% C
hange R
ela
tive
to R
-404A
Experimental uncertainty = +/- 2%
Both refrigerants show similar efficiency within uncertainty
Efficiency of lower GWP options noticeably lower for low temperature (-20˚F)
Outdoor Box Temperature = 85ºF/29.4ºC
% C
hange R
ela
tive
to R
-404A
-10
-8
-6
-4
-2
0
2
4
-12
-10
-8
-6
-4
-2
0
2
4
R-449B R-449A
Test Results – Volumetric Capacity
10
Outdoor Box Temperature = 60ºF/15.5ºC
% C
hange R
ela
tive to
R-4
04A
Experimental uncertainty = +/- 2%
R-449B showed slightly higher volumetric capacity
For most conditions, the blends tested have comparable or lower volumetric capacity than R-404A
Outdoor Box Temperature = 85ºF/29.4ºC
% C
hange R
ela
tive
to R
-404A
15˚F/ 0˚F/ -20˚F/
-9.4˚C -17.7˚C -28.9˚C
-9.4˚C -17.7˚C -28.9˚C
15˚F/ 0˚F/ -20˚F/
Test Results – Mass Flow
11
% R
ela
tive t
o R
-404A
Average Mass Flow Rate
Refrigerant15˚F/
-9.4˚C
0˚F/
-17.7˚C
-20˚F/
-28.9˚C
R-449B 4 ¼ 3 ½ 2 ¼
R-449A 4 ½ 4 3 ½
Change in TXV setting for each Indoor Temperature
60ºF/15.5ºC Outdoor
85ºF/29.4ºC Outdoor
100
90
80
70
60
95
85
75
65
55
R-449B R-449A
0
5
10
15
20
-25 -20 -15 -10 -5 0 5 10 15 20
ΔT D
ischarge(°F)
TIndoor(°F)
R-449B R-449A
Test Results – Temperature Management
12
Both blends showed higher discharge temperature compared to R-404A but remains within the R-404A compressor limit
Figure. Difference in Discharge Temperature versus R-404A (˚F )
Outdoor Box Temperature = 85ºF/29.4˚C
Vapor pressure
13
P (Psia)
T (ºF)
0
50
100
150
200
250
300
-40 -20 0 20 40 60 80 100
R-449B
R-404A
R-448A
R-449A
Lower GWP refrigerants showed lower vapor pressure ranging from 7 to 23%
0
0.4
0.8
1.2
1.6
2
15ºF/-9.4ºC
R-449B R-449A
0
0.4
0.8
1.2
1.6
2
15ºF/-9.4ºC -20ºF/-28.9ºC
R-449B R-449A
Pressure Ratio
14
Outdoor Box Temperature = 60ºF/15.5ºC
Va
lue
rela
tive
to R
-404A
Both refrigerants showed higher pressure ratio than R-404A ranging up to 16%
Outdoor Box Temperature = 85ºF/29.4ºCV
alu
e re
lativ
e to
R-4
04
A
-20˚F/-28.9˚C
Oil management
Reduced liquid and vapor line velocity compared to R-404A
No oil return issues during experimental testing
15
40
50
60
70
80 % w
ith R
esp
ect to
R-4
04A
R-449B R-449A
15˚F/ 0˚F/ -20˚F/-9.4˚C -17.7˚C -28.9˚C
Outdoor Box Temperature = 85ºF/29.4ºC
Vapor line velocityLiquid line velocity
40
50
60
70
80
90
100
% w
ith R
esp
ect to
R-4
04A
R-449B R-449A
15˚F/ 0˚F/ -20˚F/-9.4˚C -17.7˚C -28.9˚C
Summary of Experimental Results*
16
Efficiency Superior to R-404A at medium
temperature
Capacity Comparable or lower volumetric
capacity than R-404A
Mass Flow ~70% of R-404A
Discharge Temperature
Higher than R-404A but below limit of the compressor
Pressure ratio Slightly higher pressure ratio
Oil return No operational issue without oil
replacement
*This is not a retrofit guideline
17
Efficiency Capacity
Superior efficiency and similar or higher volumetric capacity at high condensing temperature
R-449B vs R-404A – Different condensing temperatures
-8
-6
-4
-2
0
2
4
6
8
10
-20°F/-28.9°C 30°F/-1.1°C
% c
hange r
ela
tive t
o R
-404A
Tindoor(ºF)
60°F/15.5°C 105°F/40.5°C
-8
-6
-4
-2
0
2
4
6
8
10
-20°F/-28.9°C 30°F/-1.1°C
% c
hange r
ela
tive t
o R
-404A
Tindoor(ºF)
60°F/15.5°C 105°F/40.5°C
Conclusion
R-407A is available for R-404A retrofits
Non-flammable alternative options to R-404A have been tested in a commercial Walk-in Freezer
Lower GWP HFO/HFC blends offer new opportunities to replace R-404A
● R-449B and R-449A showed comparable performance to R-404A with
GWP~1500
● Trade-off to lower GWP options are likely a higher discharge temperature
and reduced flow
● Same POE oil can be used*
*Always consult with compressor OEM for recommended lubricant
18