Risk Assessment of Mildly Flammable Refrigerants

2012 Progress Report

The Japan Society of Refrigerating and Air-Conditioning (JSRAE)

November 22, 2013

Akio MIYARASaga University

Department of Mechanical Engineering

Collaboration of JSRAE and SAME Okinawa Chapter

1 Introduction

2 Legal issues with mildly flammable refrigerant 2-1 Explanation of high pressure gas safety law and legal issues with mildly flammable refrigerant 2-2 Current international trends regarding refrigerant

3 Research on safety of mildly flammable refrigerants 3-1 Progress of the University of Tokyo 3-2 Research and development of low-GWP refrigerants suited to heat pump systems 3-3 Physical hazard evaluation of A2L-class refrigerants using several types of conceivable accident scenarios 3-4 Progress report by research Institute for Innovation in Sustainable Chemistry, AIST 3-5 Physical hazard evaluation on explosion and combustion of A2L class refrigerants

4 Progress of the Japan Refrigeration and Air Conditioning Industry Association (JRAIA) 4-1 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 4-2 VRF risk assessment SWG: The 1st risk assessment of VRF system with A2L refrigerant and future 4-3 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

Contents of the report

File can be downloaded from “ http://www.jsrae.or.jp/info/2012progress_report_e.pdf ”

Combustion

Absorption system

Adsorption system

Vapor compression system

1

Food supply

Medical & Biological fields

Refrigerating

Air-Conditioning

Heat Pump

Comfortable life

Cold storageCold chain

Drying

Food processing

House

BuildingOffice

Cooling Heating

Freezing

Automobile

Industrial process

Hot water

Survive

Sustainable society

Refrigerator

Refrigerator car

Hospital

Industrial fields

3

Data center

Clean room

Background Necessary & Indispensable Technology

Background Need to Build Low-Carbon Society

• Montreal Protocol (1987) • Phase out of ozone depletion gasses, CFCs, HCFCs, etc.

• Developed countries

• CFC: 1995 (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. • Developed countries

• 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. 2013 ~ Oct. 2014

• 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, …

Motivation Next Generation Refrigerants

Introductionby Eiji HIHARA, University of Tokyo

Summary of the proposed regulation of HFCsEU protocol on mobile air-conditioning refrigerants GWP < 150 from January 1, 2011

F-gas Regulation for stationary air-conditioners Reducing leakage, Proper management, Instruction

courses, Labeling, Report by producers/importers/exporters

Revise the Montreal Protocol (US, Canada, Mexico) Restriction of production and sales of HFCs

Proposed phasedown schedule of HFCs

Proposal by EU Commission

Proposal by US, Canada, Mexico

Developed countries

Developing countries

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

Trend in mildly flammable refrigerants

Environment-friendly refrigerants Zero ODP (ozone depletion potential) Low GWP (global warming potential)

HFOs R1234fy ODP=0, GWP=4 R1234ze(E) ODP=0, GWP=6HFCs R32 ODP=0, GWP=675

(note: most of other HFCs: GWP>1000)

Requirement of risk assessment

Mildly flammablerank 2L on ASHRAE Standard 34

Refrigerants for room and package air-conditioners

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)

Research on safety of mildly flammable refrigerants

ByEiji HIHARA, Tatsuhito HATTORI, Makoto ITO

University of Tokyo

Leakage of mildly flammable refrigerants

Simulation conditions of leakage of refrigerants

Room air conditioners (RAC)

Leakage scenariosVariable refrigerant flow air conditioning systems for building (VRF)

Simulation results of leakage of refrigerants

Simulation model

Leak of R32 from wall-mounted indoor unit of RAC

Simulation result

isosurface of concentration at LFL (13.3 vol%)

No Position of leakage Refrigerant Amount[g]

Flow rate[g/min]

1 Wall-mounted indoor unit R32 1000 250

Leakage scenarioCombustion does not occur if the ignition source does not exist inside the indoor unit.

Simulation results of leakage of refrigerants

Simulation model

Leak of R32 from floor-mounted indoor unit of RAC

Simulation resultisosurface of concentration at LFL (13.3 vol%)

No Position of leakage Refrigerant Amount[g]

Flow rate[g/min]

9 Floor-mounted indoor unit R32 1000 250

Leakage scenarioThe leakage of flammable refrigerants from a floor-mounted indoor unit has a high risk of combustion.

Simulation results of leakage of refrigerants

Simulation model

Leak of R32 from outdoor unit of RAC in balcony

Simulation resultisosurface of concentration at LFL (13.3 vol%)

No Position of leakage Refrigerant Amount[g]

Flow rate[g/min]

11 Outdoor unit R32 1000 250

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.

Simulation results of leakage of refrigerants

Simulation model

Leak of R32 from ceiling-mounted indoor unit of VRF

Simulation resultisosurface of concentration at LFL (13.3 vol%)

No Refrigerant Amount[kg]

Flow rate[kg/h]

Forced air[m3/h] Air vent

3 R32 26.3 10 0 exists

Leakage scenarioA 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.

Simulation results of leakage of refrigerantsTime variation of concentration of R32

Research and development of low-GWP refrigerants suitable for heat pump system

ByShigeru KOYAMA, Kyushu University

Yukihiro HIGASHI, Iwaki Meisei UniversityAkio MIYARA, Saga University

Ryo AKASAKA, Kyushu Sangyo University

Flammability Toxicity Thermodynamic properties Transport properties Heat transfer Heat pump cycle

Drop-in experiments of pure HFO and HFO+HFC

Drop-in experiments of pure HFO and HFO+HFC

Drop-in experiments of pure HFO and HFO+HFC