TERI

2.6

Research on Flammability and Safety ofLower GWP Refrigerantds

Prof. Dr. Zhao Yang
Thermal Energy Research Institute(TERI) ofTianjin Universityzhaoyang@tju.edu.cn
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ContentsTERIPart I BackgroundPart II Introduction of Research on Flammabilityof Lower GWP Refrigerantds by TERIPart III Summary

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① Montreal Protocol‐2007
1996
12007
2

2010

ForTERI

Developed countries

2015

2020

Year

CFCs have been
completely phased out

Accelerate the phaseout of HCFCs at 19th
Meeting of Parties

Reduce 75%
Reduce 90%
Elimination schedule about HCFCs in Montreal
Protocol Amendment in 2007 for developedcountries in 2007

Allow 0.5% for
maintaining3

①

Montreal Protocol-2007
2007

2013

2015

2020

ForTERI

Developing countries

2025

Amendment toaccelerate the phaseout of HCFCs at the19th Meeting of Parties

2030‐2040 Year

Reduce10%Freeze year,
on the average of2009-2010

Reduce35%

Elimination schedule for developing countries
to accelerate the phase out of HCFCs so wehave to reduce 10% of the HCFCs on theaverage of 2009‐2010

Reduce 67.5%
Allow 2.5% for
maintaining

4② Consumption Distribution of HCFCs in ChinaTERI

Consumption
Production
Production
Consumptionof HCFCsof HCFCs
in 2009in 2009(420(180Kt) Kt)

The most of them is R22
Source: XF,Zhou. Introduction of HCFCs phase-out situation,2010.

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Global warming has been becoming more inportant problem
TERIODPMontreal Protocol

GWP
Copenhagen World Climate Conference

0 ODP: has been basic requirement of newly‐developed refrigerants
Global warming has been becoming more important problem all over the world6

CFCs emissions continue to decline, but other compounds are increasing

From “ Report of the Scientific Assessment Panel
Open‐Ended Working Group Meeting
20 July 2015 ‐ Paris ” –UNEP, WMO

Let’s zoom in20 July 2015

OEWG meeting Paris

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In 2013, the emissions of CFCs, HCFCs, and HFCs were about equal in
G tonnes CO2‐equivalent
From “ Report of the Scientific Assessment Panel
Open‐Ended Working Group Meeting 20 July 2015
‐ Paris ” –UNEP, WMO

20 July 2015

HCFCs and HFCs with higher GWP are increasing these years
1000 million
OEWG meeting Paris

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HCFCs alternatives with zero ODP and lower GWP
HCs

R290

Zero ODP, lower GWP:

R600a
R1270

…

HFCs

TERI

Others

R161

R717

R32

RE170
R1234yf

R152a

R1234ze(E)…

…

…

So developing new generation environmentally acceptable ref. with 0ODP and Lower GWP becomes more and more important and emergency
But at present ,nearly all of the HCFC alternatives with zero ODP andlower GWP are flammable.
Such as:9TERILower GWP

R1150

R290

R600a

R600

R170

R1270

R601a

R601

Alternatives
R744
R161

R152a

R32

RE170

R41

R1234yf

R1234ze

R717

Although they are all flammable, the flammabillties for them are different ,some ofthem are higher such as . And some of them are lower.
10TERI

Application
Flammable refrigerants

GB 7144

There must be some risks in the processof life cycle of these equipments:
production,operation,maintenance,recovery
图片引自百度图片

They will be widely used in air conditioners , heat pumps and cold storages

11Fire Accident Example
TERI

2013‐06‐03 6时6分

The serious fire and explosion accident for NH3 leakage
occurred in Jilin province of china two years ago, led to120 workers passed away. It is reported that the electric
spark caused the fire first and then burnt the NH3khdd hbll

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TERI

Flammability is an inescapable problem on
the process of HCFCs elimination .
Special security arrangement and related
standards should be proposed or updated
ASAP !

13TERI

GB 4706.32-2012

Household and similar electrical appliances- Safety Particularrequirements for electrical heat pumps, air-conditioners and dehumidifiers
2013-05-01•① This standard and IEC 60335-2-40: 2005 are equivalent,•② The flammable refrigerants (accordant with ASHRAE 34-2001, A2 and A3 ) areallowed to be used in heat pumps, air conditioners, and dehumidifiers.

•③ But there are special requirements or suggestions for systems using flammable
refrigerants in the process of transport, storage, label, maintenance, detection, andrecovery.

•.

④ Especially: there is a charge limit requirement for the refrigerating system
This is the new chinese national standard issued 3 years ago. that isSo, safety particular requirement research for flammable refrigerants is very
important and over the past several years we have been engaging in this work.

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Contents

TERI

Part I Background Introduction

Part II Introduction of Research on Flammabilityof Lower GWP Refrigerants by TERIPart III Summary

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Our progress are including

TERI

①

Review of the Chinese standards related to the flammable refrigerantscompared with the ISO and IEC standards②Collection and analysis on the safety measures of using
flammable refrigerants (especially for A2L)③

Investigation on manufacture and application for the usageof flammable refrigerants④

Research on the flammability of lower GWP alternative refrigerants

3) may be , there were twenty-one related companies to participate this investigation,16

④ Our research topics on the flammability and safety of lower TERIGWP alternative

A: Research on theflammablecharacteristics ofnew alternatives

refrigerants in TERI ofTianjin UniversityPartBPartA

B: Flammabilityinhibitory technology
for combustible
refrigerants

TERI of TJU

D: fault tree analysis
for risk assessment
to flammable
refrigerant system.

PartDPartC

C: Research on thepotential fire hazard
by leakage

There are several research topics on the flammable alternatives that we are engaged in,including A,B,C,D.

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TERI

This is the structure of testing system of IERI for the characteristics of flammable alternatives
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Four
Four fundamental
fundamental andand vital
vital parametersparameters
Among them flammable limits including lower flammable limit
and uper flammable limits are very important properties toreflect the flammability of refrigerants

TERI

Ignited concentration;
Maximum allowable charge;
Refrigerants classification;

Flammablelimits

MinimumignitionenergyFlamepropagation
velocity

Heat ofcombustion

LFL/UFL

MIE

Burning velocity

HOC

There are four fundamental flammable characteristics for flammable refrigerants, including:
LFL: means the minimum concentration of flammable gas in air below that the flame does
not propagate to the top of reaction tube on contact with a source of electronic igniter.
UFL: is defined as the maximum concentration of flammable gas in air above that thepropagation of flame does not occur on contact with a source of electronic igniter.
19TERI

Research on the flammable limits of some new alternatives

Lower flammable limit

Samplewith oilIgnition
Energy

LFL
LFL

burningvelocity

Temperature

Humidity

UFL
UFL
Upper flammable limit

The testing research has been focused on the impacts on the flammable limits andburning velocities by surrounding air temperature, humidity, ignition energy andlubricant etc.

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TERI

Some test results of TERIabcde

fgTERI

different molecular component shows flame in different colour and shape
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TERI
0.30

LFLm / kg/m

30.25

0.20

0.15

0.10

0.05

0.00
R32

R290

R600a

RTJU4R161

R1234yf

R717

The LFLm of R32 is near to that of the R1234yf, but much higher than that of
R290, R600a, R161 and R717.

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TERI
5wintersummer
制冷剂可燃下限，%

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2

10

R1150

R600a

R161

R152a

RE170

Test Resulis in summer and winter by IERI
Impact of different season on the LFL ,the red one is in summer and the blue
one is in winter, so the LFLs decrease with the increase of surrounding airtemperature,23TERI
402018

爆炸下限
爆炸上限

302520151050-100102030

环境温度/℃

405060

HFC2 在空气中的燃爆极限浓度, %HC1在空气中所占体积分数/v%

3516141210LFLsUFLs

8642-100102030

405060Fig. flammable limits of the HFCs under the variable temperature conditions by TERI

For the two REFs, the LFLs decrease with the increase of surrounding air temperature,and the UFLs increase oppositely as the surrounding air temperature increases from -5℃
to 55℃,therefore the flammable ranges for this two REFs. will be enlarged with the24
increase of surrounding air temperature

Our research topics on the flammability and safety of lower TERIGWP alternative refrigerants in TERI of Tianjin University

A: Research on theflammablecharacteristics ofnew alternatives

PartBPartA

B: Flammability
inhibitory technology
for combustible
refrigerants

TERI of TJU

D: Research on thepotential fire hazardby leakage

PartDPartC

C: Risk assessment
to flammable
refrigerant system.

There are several research topics on the flammable alternatives that we are engaged in,including A,B,C,D.

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2020

1818

B/R152a在 空 气 中 的 体 积 分 数 /%A/R152a在 空 气 中 的 体 积 分 数 /%

Flame retardant efficiency comparison of two inhibitors to R152a by TERI

161412LFLUFL

1086
40.0

TERI

1614LFL12UFL10
8
64

0.2

0.4

0.6
A/R152a

0.8

1.0

0.00

0.05

0.10

0.15

0.20

0.25

B/R152aSome kinds of inhibitors can be mixed with the flammable refrigerant to make themixture become non‐flammable or weak‐flammable. This is the LFL and UFL for R152a
mixed with A and B.It could reduce the upper flammable limt and increase the LFL.

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Our research topics on the flammability and safety of lower TERIGWP alternative refrigerants in TERI of Tianjin University

A: Research on theflammablecharacteristics ofnew alternatives

PartBPartA

B: Flammabilityinhibitory technology
for combustible
refrigerants

TERI of TJU

D: Research on thepotential fire hazard
by leakage

PartDPartC

C: Risk assessment
to flammable
refrigerant system.

There are several research topics on the flammable alternatives that we are engaged in,including A,B,C,D.

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TERI
Risk assessment for the units charged with the flammable refrigerant

Possibility ofleakagePossibility offault tree analysis for risk assessment to 28
ignition sources flammable refrigerant system by TERIOur research topics on the flammability of lower GWP
alternative refrigerants
in TERI of Tianjin University
A: Research on theflammablecharacteristics ofnew alternatives

PartBPartATERIB: Flammability
inhibitory technology
for combustible
refrigerants

TERI of TJU

D: Research on thepotential fire hazard
by leakage

PartDPartC

C: Risk assessment
to flammable
refrigerant system.

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TERI
Research on the refrigerant leakage and fire hazardous prevention by TERI

Stop Model

50s20sconcentration distribution of flammable gases escaping from the air-conditioner by TERI
The higher concentration area of refrigerant locates near the wall below an air conditioner;
The risk can be reduced partly by increasing the outlet wind speed of A/C properly;
Once leakage occurs at the stop model, it is much more dangerous than that of runningmodel .
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Experimental Research on the flammability of the lower GWP refrigerants
leakaging from the heat pump

TERI

Tong Fang artificial environment co.

Experiments were carried out under theconditions of varying temperature andhumidify with computer-aided control

Tianjin University

A small-sized commercial air source heat pumpwas used to sample at the outlet of compressor
at the running model.
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TERI

Some typical projects on in CHINA• Project on refrigerant converting Freon to hydrocarbon for room
air conditioners- by GREE Company• Demonstration sub-project for conversion of room A/Ccompressor manufacturing from HCFC-22 to propane –by
Guangdong Meizhi Co.Supported by Multilateral Fund for theImplementation of the Montreal Protocol• Demonstration sub-project for conversion from HCFC-22 topropane at room air-conditioner -by Midea Manufacturing
Company Supported by Multilateral Fund for theImplementation of the Montreal Protocol• …

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Ministry of Environmental
Protection , MaldivesHC290
P Han. Ozone2Climate industry roundtable on
alternatives to HCFCs, Beijing, Apr.2012

Application
http://digi.163.com/

Production line

Prototype conditioner

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Contents

TERI

Part I Background Introduction

Part II Introduction of Research on Flammabilityof Lower GWP Refrigerants by TERIPart III Summary

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TERI

Summary
1\Some standards need to be updated, and some others should becomplemented, especially concerning the special requirements on using
flammable refrigerants.
2\Related scientific research including risk assessment , flammabilityinhibitory, simulation and charge reduction technologies sould becontinued deeply.
3\flammable limits and burning velocities will be influenced bysurrounding air temperature, humidity, ignition energy and lubricant
etc.
4\The LFLs of the flammable refrigerants decrease with the increase ofsurrounding air temperature, and the UFLs increase oppositely,
therefore the flammable ranges will be enlarged with the increase ofsurrounding air temperature.
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TERI
5\Some kinds of inhibitors can be mixed with the flammable
refrigerant to make the mixture become non-flammable or weakflammable
6\The higher concentration area of refrigerant locates near the wall
below the air conditioner; The risk can be reduced partly byincreasing the outlet wind speed of A/C properly;Once leakage
occurs at the stop model, it is much more dangerous than that ofrunning model.
Note: Some of the details above research could be foundon the following published papers in these 3 years:

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1.

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2.

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3.

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4.

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5.

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6.

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Prof.Dr.Zhaoyangzhaoyang@tju.edu.cn

天津大学热能研究所
Thermal Energy Research Institute of Tianjin
University43