1. Risk Assessment of Mildly Flammable Refrigerants
Collaboration of JSRAE and SAME Okinawa Chapter
Risk Assessment of Mildly Flammable Refrigerants
2012 Progress Report
The Japan Society of Refrigerating and Air-Conditioning (JSRAE)
November 22, 2013
Akio MIYARA
Saga University
Department of Mechanical Engineering

2. Contents of the report
1 Introduction
2 Legal issues with mildly flammable refrigerant Explanation of high pressure gas safety law and legal issues with mildly flammable refrigerant Current international trends regarding refrigerant
3 Research on safety of mildly flammable refrigerants Progress of the University of Tokyo Research and development of low-GWP refrigerants suited to heat pump systems Physical hazard evaluation of A2L-class refrigerants using several types of conceivable accident scenarios Progress report by research Institute for Innovation in Sustainable Chemistry, AIST Physical hazard evaluation on explosion and combustion of A2L class refrigerants
4 Progress of the Japan Refrigeration and Air Conditioning Industry Association (JRAIA) Mini-split air-conditioner risk assessment SWG: The risk assessment result of the residential air-conditioner, and the study of the mini-split air-conditioner for small business use VRF risk assessment SWG: The 1st risk assessment of VRF system with A2L refrigerant and future Chiller risk assessment SWG: Risk assessments policy of the chiller and guideline planning taking IEC60079 into consideration
5 Deregulation activities in Japan for the introduction of mobile air conditioning refrigerant R1234yf
File can be downloaded from “ ”

3. Background Necessary & Indispensable Technology
Comfortable life
Refrigerating
Sustainable society
Survive
Cold storage
Freezing
Cold chain
Refrigerator car 1
Vapor compression system
Food supply
Food processing
Absorption system
Medical & Biological fields
Refrigerator
Industrial process
Data center
Industrial fields
Drying
Clean room
House
Hot water
Automobile
Office
Hospital
Heat Pump
Building
Adsorption system
Air-Conditioning
Combustion
Cooling
Heating

4. Background Need to Build Low-Carbon Society
Montreal Protocol (1987)
Phase out of ozone depletion gasses, CFCs, HCFCs, etc.
Developed countries
CFC: (Phase out was completed in Japan)
HCFC: 2020 (Production is being reduced)
Developing countries
CFC: Phase out in 2010 (start from 1999)
HCFC: Phase out in 2040 (start from 2016)
Alternative refrigerants: HFCs (R134a, R410A, etc. )
Successful replacement
Kyoto Protocol (1997)
Reduction of greenhouse gases, CO2, HFCs(R32, R410A, etc.), etc.
Average reduction of 5.2% reduction from 1990 level by the year 2012
6% reduction for Japan, F-gas regulation in Europe
IPCC Fifth Assessment Report: Sep ~ Oct. 2014

5. Motivation Next Generation Refrigerants
Natural refrigerants
HC in refrigerator, CO2 in HP water heater, NH3 in industrial …
Tentative continuous use of HFCs for midway
Refrigerant management
Refrigerant leakage, Refrigerant tracking, Engineers skill, …
R32 is now being promoted.
Low GWP synthetic refrigerants: HFOs
R1234yf for mobile AC, R1234ze(E) for turbo chiller,　R1234ze(Z) for heat pump in high temperature range … other HFOs, R1234ye, R1233zd, R1243zf, R1225
Study on Properties, Heat transfer , Drop-in test, …
Refrigerant mixtures
Limitation of pure refrigerant properties
Suitable properties such as pressure, flammability, …
Property measurements, Cycle simulation, Drop-in test, …

6. Summary of the proposed regulation of HFCs
Introduction
by Eiji HIHARA, University of Tokyo
Summary of the proposed regulation of HFCs
EU protocol on mobile air-conditioning refrigerants
GWP < 150 from January 1, 2011
Revise the Montreal Protocol (US, Canada, Mexico)
Restriction of production and sales of HFCs
F-gas Regulation for stationary air-conditioners
Reducing leakage, Proper management, Instruction courses, Labeling, Report by producers/importers/exporters

7. Proposed phasedown schedule of HFCs
Proposal by US, Canada, Mexico
Developing countries
Developed countries
Proposal by EU Commission

8. Emissions of HFCs in Japan -present situation-
Total CO2 emission of HFCs[million-t]
others
Ref. & AC
In dispose
In use
Small refrigerator
Large refrigerator
Medium refrigerator
Package AC for building
Other business use
Room AC
Show case (split-type)
million-t CO2
Leakage

9. Trend in mildly flammable refrigerants
Environment-friendly refrigerants
Zero ODP (ozone depletion potential)
Low GWP (global warming potential)
Refrigerants for room and package air-conditioners
HFOs
R1234fy ODP=0, GWP=4
R1234ze(E) ODP=0, GWP=6
HFCs
R ODP=0, GWP=675 (note: most of other HFCs: GWP>1000)
Mildly flammable
rank 2L on ASHRAE Standard 34
Requirement of risk assessment

10. Methodology of risk assessment
Burning characteristics of flammable refrigerants
Mechanism of ignition
Probability of ignition
= (Leakage) X (High concentration) X (Ignition source) X (Low air velocity)

11. Research on safety of mildly flammable refrigerantsBy
Eiji HIHARA, Tatsuhito HATTORI, Makoto ITO
University of Tokyo
Leakage of mildly flammable refrigerants

12. Simulation conditions of leakage of refrigerants
Leakage scenarios
Variable refrigerant flow air conditioning systems for building (VRF)
Room air conditioners (RAC)

13. Leak of R32 from wall-mounted indoor unit of RAC
Simulation results of leakage of refrigerants
Leak of R32 from wall-mounted indoor unit of RAC
Simulation model
Simulation result
isosurface of concentration at LFL (13.3 vol%)
Leakage scenario No
Position of leakage
Refrigerant
Amount
[g]
Flow rate
[g/min] 1
Wall-mounted indoor unit
R32
1000
250
Combustion does not occur
if the ignition source does not exist inside the indoor unit.

14. Floor-mounted indoor unit
Simulation results of leakage of refrigerants
Leak of R32 from floor-mounted indoor unit of RAC
Simulation model
Simulation result
isosurface of concentration at LFL (13.3 vol%)
Leakage scenario No
Position of leakage
Refrigerant
Amount
[g]
Flow rate
[g/min] 9
Floor-mounted indoor unit
R32
1000
250
The leakage of flammable refrigerants from a floor-mounted indoor unit has a high risk of combustion.

15. Leak of R32 from outdoor unit of RAC in balcony
Simulation results of leakage of refrigerants
Leak of R32 from outdoor unit of RAC in balcony
Simulation model
Simulation result
isosurface of concentration at LFL (13.3 vol%)
Leakage scenario
The leakage of flammable refrigerants from an outdoor unit has a high risk of combustion.
Note: Drains and under cuts shorten the presence of the gas. No
Position of leakage
Refrigerant
Amount
[g]
Flow rate
[g/min] 11
Outdoor unit
R32
1000
250

16. Leak of R32 from ceiling-mounted indoor unit of VRF
Simulation results of leakage of refrigerants
Leak of R32 from ceiling-mounted indoor unit of VRF
Simulation model
Simulation result
isosurface of concentration at LFL (13.3 vol%)
Leakage scenario No
Refrigerant
Amount
[kg]
Flow rate
[kg/h]
Forced air
[m3/h]
Air vent 3
R32
26.3 10
exists
A combustion gas region only exists just below the air outlet and the suction of the VRF, even if the entire quantity of refrigerant is discharged.

17. Time variation of concentration of R32
Simulation results of leakage of refrigerants
Time variation of concentration of R32

18. Research and development of low-GWP refrigerants suitable for heat pump systemBy
Shigeru KOYAMA, Kyushu University
Yukihiro HIGASHI, Iwaki Meisei University
Akio MIYARA, Saga University
Ryo AKASAKA, Kyushu Sangyo University
Flammability
Toxicity
Thermodynamic properties
Transport properties
Heat transfer
Heat pump cycle

19. Drop-in experiments of pure HFO and HFO+HFC

20. Drop-in experiments of pure HFO and HFO+HFC

21. Drop-in experiments of pure HFO and HFO+HFC