Risk Assessment of Gas Engine Driven Heat Pump（GHP） Working Group for Risk Assessment of Lower Flammability Refrigerant
Conclusion

Introduction
Philosophy

High Risk Cases and Guide Line for Safety

GHP is similar to electric air-conditioning systems (EHP), except it
has a gas engine to drive compressors instead of electric motors.

Guide line, GL-16 and JRA 4070 should be applied forGHP, because the evaluated risk was equal to the risk ofEHP as the result of the risk assessment.

Procedurei) Evaluation of the risk assessment of EHPii) Abstraction of items to be re-evaluatediii) Abstraction of regions in GHP to be evaluatediv) Implementation of risk assessment reflectingthe results of ii) and iii) on the results of i)

Risk assessment result of GHP charged R32

outdoor Unit

Compressor

Outsideheat
exchanger

Indoorunit

Conditioned air issupplied to rooms

Indoor Unit

Gas
engineConditioned air issupplied to rooms

Heat exchanger

Exhaust gas

Electric air-conditioning systems (EHP)

OutdoorUnit

outdoor Unit

ElectricMotor

Compressor

Outsideheatexchanger

allowable

A.Transportation
E. Repair/
C. Usage(indoor)
Life stage
B. Instalation
F. Disposal
Installation CaseD.
Usage(outdoor)/Storage
Service-9＜3.7X10(indoor),
Allowable-8-8＜3.7X10＜3.7X10-82probability(Chargedrefrigerantkg)
2.2X10(outdoor)<Floor area m , Height m
MeasureNYNYNYNYN
Y>
1. Ceiling
Office-9-12-11-13
1.90X10
3.58X10
1.70X10
5.63X102(26.3 kg)<40.6m 2.7m>
2. Floor
Restaurant-9-7-9-9-11
1.90X10
2.95X10 3.47X10 2.40X10
6.57X102(52.8 kg)<9.7m 2.5m>
7.57X10-163. Ceiling
Karaoke-6-11‐～≃0
1.17X10
1.70X102(110 kg)<4.0m 2.4m>
1.74X10-16
4. Open space‐‐
1.90X10-9 - 3.41X10-9
2.80X10-10 - 4.62X10-9 (110 kg)
5. Each floored‐-9-9-10-9‐
1.90X10
3.78X10
6.28X10
9.38X102(110 kg)<4.2m 4m>

Gas engine driven air-conditioning systems (GHP)

Indoorunit[time/(umit/year)] Not allowable

SystemInstallation

Cooling capacity: 14.0 ～ 170ｋW
Charge amount of refrigerant: 11.0 ～ 110.0kg
Type: Variable refrigerant flow system for buildings (Indoor units are same as EHP)

Total number : Approx. 450 thousands outdoor units in Japan
Others (OfficeUser:etc.), 24%

School, 35％

Restaurant, 1%
Hotel, 1%

Indoorunit

Indoorunit

Indoorunit

Super market,3%
Public Office,7%Store, 13%

Indoorunit

Outdoor unit

Hospital,
Welfare, 16%

Industry Classified Capacity Ratio of GHP

Focused Items of outdoor unit
Difference with EHP (outdoor
排気ガス unit)

Exhaust heat
Exchanger

EngineCompartment

Heat Exchanger

Belt

Belt

Generator

Compressor

ElectricityGasEngine

Rubber Mounts

Fuel Gas

RegionMain Components in GHPIgnition SystemCompressor Drive
Exhaust Path
Fuel Gas System
Power SupplyGenerator Drive
Refrigerant Circuit
Cooling Water Circuit
Housing

Ignition coil, Ignition plugBelt, Engine, Electromagnetic clutch
Muffler, Exhaust heat exchanger
Gas regulator, Shut off valve
Generator, Convertor
Belt, Engine
Open type compressor, Exhaust heat exchanger
Water pump, Radiator
Sealed engine compartment, Air vent

Flammable volume-time integration in Engine Compartment (A)i) Refrigerant concentration was calculated by formula (a), because the Engine compartment is forcibly ventilated.
ii) Refrigerant concentration was calculated under each conditions of Cooling/Heating mode, outside temperature andrefrigerant leak rate (10kg/h or 75kg/h). See Figure 1 and 2.
iii) Flammable volume-time integration in the engine compartment was calculated.
Figure 1. Cooling Mode
Figure 2. Heating Mode120

UFL160<Open type compressor>
Leakage from the mechanical seal is 30 g/year.
SuctionDischarge

Low pressure

Stationary part

ClutchHigh pressure

Mechanical seal
Low pressure

Rotating part

80706010050804060

Refrigerant Leakage Risk

9030

Flammable Region

10060

40000＋Refrigerant
Leakage Risk（Open type compressor)

252321

Flammable Region

40202770501029808020319060

UFL

2033

Refrigerant Concentration(Leak Rate 10 kg/h)
Refrigerant Concentration(Leak Rate 75 kg/h)
LFL

120

4035100

Duration

140

Duration (h)140Refrigerant Concentration(Leak Rate 75 kg/h)
Refrigerant Concentration(Leak Rate 10 kg/h)
LFL

160

1930
20

Refrigerant Concentration (%)

100

Duration

180

Duration (h)K：Refrigerant concentration
M: Refrigerant leakage rate (m3/h)
Q: Ventilation flow ofeach outside temperatures (m3/h)
R: Engine compartment volume (m3)
T: Leakage duration (h)200Refrigerant Concentration (%)

K＝M（１－e-QT/R)/Q ‥・(a)1001210864
20-2
Outside Temperature (Degree C)

Outside Temperature (Degree C)-4Flammable volume-time integration in the engine compartment wascalculated

Leak rate (kg/h)
Flammable volume-time in the engine
compartment (m3-min)
Refrigerant leakage frequency (%/y)*Main Components in EHP
Not Applicable
Inverter, Motor
Not Applicable
Not Applicable
Not Applicable
Not Applicable
Hermetic type compressor
Not Applicable
ExposedIgnition Risk
No good
No good
No good

No good
No good

The probability of the presence of specific ignition
source of GHP per unit time and volume (B)X: Cannot be denied the possibility to be an ignition source- ：No possibility to be an ignition source(not reach to the ignition energy nor ignition temperature)
RegionPossibility of sparkNon-operational orIn operationor highStarting up
temperature
NormalAbnormal
NormalAbnormalXX
1. Ignition Leakage of spark toSystemoutside6.28X10-11
6.28X10-11
2. Clutch

Spark by slipping

Overheating byslipping
3. Exhaust Overheating bypathheat of exhaust gas
Total

Ignition Risk

1107500

3.82X101

Installation

8.14X10-3

1.78X10-3

1.82X10-4

Open space
Each floored*Refrigerant leakage frequency : Calculated by the actual value in 2014, 1.01% / year

Refrigerant
Leakage Risk------

6.28X10-11

X
X
1.48X10-6 3.41X10-9
X
5.98X10-11
X
1.79X10-10
1.49X10-6

Ignition risk ≒ (A) x (B) x Refrigerant leakage rate

Ignition risk inoperation
3.41X10-9
3.78X10-9

Criteria
Less than 2.20X10-8
Less than 2.20X10-8

Evaluation
resultOKOK

Documentation
1.Guideline of design construction for ensuring safety against refrigerant leakage from commercial air conditioners using lower flammability (A2L) refrigerants
JRA GL-16：2016
2.Requirements for ensuring safety against refrigerant leakage from commercial air conditioners using lower flammability (A2L) refrigerants JRA 4070：2016