1Low-GWP Refrigerant Workshop for IEA HPP's Annex 54: Heat Pumps for Low

GWP Refrigerants

Risk assessment of A2L refrigerants implemented in Japan

Eiji Hihara (University of Tokyo)

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Product Category Number of Unitsin 2016FY (x 1,000)

Refrigerant

Residential A/Cs 8,527.5 R410A ⇒ R32(almost 100%)

Commercial A/Cs 793.9 R410A ⇒ R32(only Small-size; 41%)

Gas engine-driven A/Cs 30.5 R410A

Water Chiller 12.9R410A, R134a⇒

R32,R1233zd,R1234ze,R1223yd

Commercial refrigerators 403.7R404 ⇒ R410A,

CO2,R448A,R463A

Refrigeration facility 29.7 R22 ⇒ NH3, (+CO2)

-in Japan-Conversion status for each product

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• Low Toxicity• Low Flammability

S:Safety

• Zero Ozone Depletion Potential (ODP)• Low Global Warming Potential (GWP)

E: EnvironmentPerformance

• High Seasonal Efficiency• Similar performance at high load

cooling

E: EnergyEfficiency

• Low Capital Cost• Low Operating Cost

E: EconomicFeasibility

S+3E

s

Key concept for refrigerant conversion

4Organization of the research committee for risk assessment of A2L refrigerants

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Japan Society of Refrigeratingand Air Conditioning Engineers,JSRAE

University of Tokyo

Tokyo University of Science, Suwa

Kyushu University

National Institute of Advanced Industrial Science and Technology,AIST

Japan AutomobileManufacturers Association, JAMA

Japanese Refrigerationand Air-conditioning Industry Association, JRAIA

Observers -NEDO-METI-KHK

Research on the safety of Mildly Flammable Refrigerants WG

Mini-Split Risk Assessment SWG(Ⅰ)(Ⅱ)

VRF Risk Assessment SWG

Chiller Risk Assessment SWG

Secretary: Fujimoto

Chair: Hihara

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A2L refrigerant risk assessment had difficulty and long period.

2011 2012 2013 2014 2015 2016 2017 2018

●ResidentialA/Cs

●CommercialA/Cs

●VRF

●Chiller

●Built-in Ref. Display Cabinets

●Others(Refrigeration

equipment)

R32 residential models launched.

R32 light commercial models launched.

Schedule of risk assessment for AC and others

New Risk assessmentfor A3 Refrigerant.

HFO centrifugal chillers launched.

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Trade-off relationship between GWP and flammability

R1234yf, R32, and R290 have much lower GWPs than R410A. R410A is nonflammable, but R1234yf, R32, and R290 are flammable.

Refrigerant R410A R32 R1234yf R717 R290Boiling temperature, ºC -51.4 -51.7 -29.4 -33.3 -42.1Critical temperature, ºC 71.3 78.1 94.7 132.4 96.7

GWP (100 years) 2088 675 4 <1 <3Burning velocity (cm/s) - 6.7 1.5 7.2 38.7

LFL [vol %] - 13.3 6.2 15 1.8UFL [vol %] - 29.3 12.3 28 9.5

Minimum ignition energy (mJ) - 15 500 21 0.246

Flammability 1 2L 2L 2L 3

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7Methodology of risk assessment

START

Identify user, intended use, reasonable foreseen misuse.

Estimation of risk

Hazard Identification

Risk Reduction

Evaluation of risk

Tolerable？

１

２

３

４

５

Validation and documentationYes

No

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8Identify products/system and life-stage for study

Residential A/C

Commercial A/C

VRF(multi A/C for commercial bldg..

Chiller

Commercial refrigerator

GHP

Industrial A/C

Identified Product/System

IdentifiedLife-stages

Logistic

Installation

Use(indoor)

Service

Disposal

Use(outdoor)

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Guide 51 ; Safety means freedom from unacceptable risks. Tolerable risk means accepted risk in a given context

based on the current values of society.

Examples of the current tolerable risk in Japan1. Chemical factory : 10-5 [accidents/(year-site)]2. Car : 10-7 [accidents/(year-unit)]3. Home appliance : 10-8 [accidents/(year-unit)]

for one million units in the market (106 unit)

Identify the tolerable risk

START

Identify user etc.

Estimation of risk

Hazard Identification

Risk Reduction

Evaluation of risk

Tolerable？

１

２

３

４

５

Validation and documentation

We concluded that the fire accident during use less than once a century would be acceptable.

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10Tolerable risk of each products

Product/System No. of units in market

Tolerable value Use Installation and

service

Residential A/C 1 × 108 1.0 × 10-10 1.0 × 10-9

Commercial A/C 7.8 × 106 1.3 × 10-9 1.3 × 10-8

VRF 1 × 107 1.0 × 10-9 1.0 × 10-8

Chiller 1.34 × 105 7.5 × 10-7 7.5 × 10-7

GHP 4.5 × 105 3.7 × 10-9 3.7 × 10-8

Display cabinet 4.9 × 105 2.0 × 10-8 2.0 × 10-7

Condensing unit 1.46 × 105 6.9 ×10-8 6.9 × 10-7

Tolerable value is dependent on the number of units in the market for each products

During installation and services, the tolerable value was increased by 10 times because the units are handled by trained professionals.

START

Identify user etc.

Estimation of risk

Hazard Identification

Risk Reduction

Evaluation of risk

Tolerable？

１

２

３

４

５

Validation and documentation

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11Methodology of Risk Assessment

[Probability of fire accident] = [Rapid leakage] × [High concentration] × [Ignition source]

Rapid leakage

Ignition

Existence of an ignition source

Concentration higher than lower flammability limit

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1. Rapid gas Leakage

2. Generating of Flammable volume

3. Existence of Ignition Source

and

and

Stove

AC type Residential Package VRF Chiller

Rapid Leak Rate 15kg/h 10kg/h 10kg/h burst 75kg/hProbability of leak 0.023％ 0.0015% 0.0005% burst 0.0010%

market data (some data from IEC)

Stoves, Lighters, Sockets, Switches etc. were researched.

Estimation of incident probability

Ignition incident occurs when following three conditions occur simultaneously.

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Generated flammable volume-time integrationProbability of flammable volume=Space-volume x Total time

13FTA indoor space assumption13．

Flammable region

Floor-standing Indoor unit

Flammable gas region

Wall-mounted indoor unit

- Case of wall-mounted AC and floor-mounted AC -

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R32 Amount：1000 gFlow rate：250 g/min

• The small flammable region existed below the air outlet of indoor unit only.

• The flammable gas volume was small.• After leakage, the flammable region

vanished in less than a second.

Flammable region can only be seen near the unit

14．

- Case of wall-mounted AC -Flammable gas region

by the University of Tokyo Wall-mounted

Unit

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Refrigerant：R32Amount：1000 gFlow rate：250 g/min

• There was a large flammable region spread on the floor.

• The flammable region did not vanish for sometime.

Flammable region appears on the floor.

- Case of floor-mounted AC -Flammable gas region

by the University of Tokyo

Floor-mountedUnit

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16Study of flammability：TUSS16．

■ReferenceTHE INTERNATIONAL SYMPOSIUM on NEW REFRIGERANTS and ENVIRONMENTALTECHNOLOGY 2012

Pneumatic cylinder

Solenoid valve air

R1234yf Flammable

Flame

Flame propagation was not observed in the case of cigarette gas lighter with A2L gas

Result

LighterPush rod

300

1000

Refrigerantmixture

Study of ignition source- Cigarette Lighter -

Cigarette Lighter

by Tokyo University of Science at Suwa

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17Study of ignition：AIST17．Study of ignition source- Contactor, Sockets-

A2L gas did not ignite.But A2 and A3 gases ignited.

A2L

Contactor below 12kVA can be eliminated as ignition source for A2L gas.

by AIST by AIST

Magnetic contactor Hair Dryer

A3 A2

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2.30×10-4 (times/year/unit)by the results of the questionnaire survey

2. Volume and time of flammable gas

3. Ignition source

Flammable space

Indoor unit

1. Provability of rapid leakage

①AC magnetic switch (by AIST)

② Cigarette lighter (by TUS)

Electronic lighter is not a source of ignition.

③heating appliance (by TUS)

Flame propagation in the heating equipment is suppressed by convection.

Time and volume integration of flammable space9.8×10-3～3.7×10-2 m3・min (by U Tokyo)

Refrigerant: R32

When refrigerant leaksfrom a wall-mounted indoor unit, volume of flammable space is very small.

1) In the electromagnetic switch of 12kVA, flame propagation does not occur for R32.2) The possibility of ignition of Electrical components in the air-Conditioners and household appliances is extremely low.

Risk assessment of small split air conditionerSource: JRAIA

19Risk assessment of small split air conditionerTarget value

Results of risk assessment

３．着火源の存在

Ignition probability: 10-10 (times/year/unit) in use; 10-9 in service

Accident scenario

Ignition probability(times/year/unit)

Evalua-tion

At transportation 4.1х10-12 SafeAt installation 2.7х10-10 Safe

In operation Indoor unit：2.1х10-12

Outdoor unit：1.5х10-10SafeAlmost safe

In service 3.2х10-10 SafeAt disposal 3.6х10-11 Safe

Schedule2010～2013 2014 2015 2016

Consideration Fist Second assessmentConst. manual

Overseas operation

1) Wall-mounted split air conditioners are pretty safe in the lifecycle.

2) To improve the safety at the time of service and installation, a construction manual was issued.

Measures for safety

Source: JRAIA

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1.50×10-5 (times/year/unit)

2. Volume and time of flammable gas

3. Ignition source

Flammable space

1. Provability of rapid leakage

Risk assessment of floor-standing split air conditioner

Category Ignition source R32 Propane

Electric appliance

FireElectric equipmentAC switchLighting switch

△－××

〇〇〇〇

Smoking supplies

MatchOil lighterElectronic lighterFlame

○○×○

〇〇〇〇

Industrial tool

Metal sparkElectric toolRefrigerant recovery machineBrazing burner

○××

○

〇〇〇

〇

Body Spark of static electricity × 〇

Combustion appliance

HeaterWater heaterBoilerCooking device

△△△△

〇〇〇〇

Evaluation of ignition source for R32

When refrigerant leaksfrom a floor-standing indoor unit, volume of flammable space is notsmall.

Source: JRAIA

Refrigerant: R32

Time and volume integration of flammable gas1.43～1.55 m3・h (by U Tokyo)

21Risk assessment of floor-standing split air conditionerTarget value

Results of risk assessment

３．着火源の存在

Accident scenarioIgnition probability

(times/year/unit) Evalua-tion

At transportation 1.1х10-9 Safe

At installation 9.0х10-9 Safe

In operationIndoor unit：4.7х10-10

Outdoor unit：1.1х10-9SafeSafe

In service 4.3х10-9 Safe

At disposal 4.1х10-10 Safe

Schedule2013 2014 2015 2016

Consideration 1st 2nd assessmentConst. manual

Overseas operation

Source: JRAIA

Ignition probability: 10-9 (times/year/unit) in operation; 10-8 in service

・Mixing of leaked refrigerant with indoor air by a fan installed in indoor unit is required.

Measures for safety

22Risk assessment of VRF

2. Volume and time of flammable space

3. Ignition source

1. Provability of rapid leakage

Category Ignition source R32 Propane

Electric appliance

FireElectric equipmentAC switchLighting switch

○×××

〇〇〇〇

Smoking supplies

MatchOil lighterElectronic lighterFlame

○○×○

〇〇〇〇

Industrial tool

Metal sparkElectric toolRefrigerant recovery machineBrazing burner

○××

○

〇〇〇

〇

Body Spark of static electricity × 〇

Combustion appliance

HeaterWater heaterBoilerCooking device

○○○○

〇〇〇〇

○：Ignition,×：No ignition

(1) Evaluation of ignition source for R32

(2) Dangerous ignition source

In operation In service

Indoor Heater, cooking device, oil lighter Brazing burner

Outdoor Boiler, combustion heater Brazing burner

Ceiling cassette(0.8～10Hp)

Floor standing unit(1～20Hp)

Outdoor unit(5～56Hp)

Mechanical ventilation1.5 (times/h)

Natural ventilationClearance under Door: 10mm

No ventilation

Flammable volume [m3]

Time[min]

4.4E-03 5.3E-03 1.1E-02

158 ← ←

【Condition】Office：6.5*6.5*2.7mRefrigerant： 26.3kg (20Hp)

Indoor unit：5×10-6 (times/year/unit)Outdoor unit：1.48×10-3 (times/year/unit)

Refrigerant: R32

23Risk assessment of VRFTarget value

Results of risk assessment

３．着火源の存在

Accident scenarioIgnition probability

(times/year/unit) Evalua-tion

At transportation 7.8×10-17～1.8×10-16 Safe

At installation 1.9×10-9 Safe

In operation3.5×10-12 (Indoor）

1.9×10-11 (Outdoor）Safe

In service 8.7×10-11 Safe

At disposal 2.9×10-14 Safe

Measures for safety

Schedule2010～2013 2014 2015 2016

Location Safety measureRestaurant Leak detection, mechanical

ventilationKaraoke

(1) Indoor unit

Location Safety measure

Semi-underground Detector carrying, leak

detection, mechanical ventilationMachine

room

(2) Outdoor unit

In severe cases, safety measure is required.

1st 2nd assessment 3rd assessmentSafety guidelineAdd R1234yf, ze(E)

Ignition probability: 10-9 for indoor unit in use; 4×10-9 for outdoor unit in use 10-8 in service (times/year/unit)

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Conclusion

1. In Japan, the research committee was established in 2011 with collaboration of government, academia, and industry to initiate risk assessment of A2L. In March 2016, the research committee dissolved after concluding its research.

2. Based on the risk assessment, a new guideline of mildly flammable refrigerants for refrigerating equipment was drafted in 2016. R&D based on this guideline was conducted by each company.

3. The risk assessment for the safe use of flammable gases such as hydrocarbons are under study.

4. The final report on risk assessment of mildly flammable refrigerants can be freely downloaded from the following website.

http://www.jsrae.or.jp/jsrae/committee/binensei/risk_eng.html

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Thank you for your attention!