[F1Sub-Annex - 8Appendix 7

Fuel consumption measurement of compressed hydrogen fuel cell hybrid vehicles U.K.

1. General requirements U.K.

Fuel consumption shall be measured using the gravimetric method in accordance with paragraph 2. of this Appendix.

At the request of the manufacturer and with approval of the approval authority, fuel consumption may be measured using either the pressure method or the flow method. In this case, the manufacturer shall provide technical evidence that the method yields equivalent results. The pressure and flow methods are described in ISO 23828:2013.

2. Gravimetric method U.K.

Fuel consumption shall be calculated by measuring the mass of the fuel tank before and after the test.

2.1. Equipment and setting U.K.

2.1.1. An example of the instrumentation is shown in Figure A8.App7/1. One or more off-vehicle tanks shall be used to measure the fuel consumption. The off-vehicle tank(s) shall be connected to the vehicle fuel line between the original fuel tank and the fuel cell system. U.K.
2.1.2. For preconditioning, the originally installed tank or an external source of hydrogen may be used. U.K.
2.1.3. The refuelling pressure shall be adjusted to the manufacturer's recommended value. U.K.
2.1.4. Difference of the gas supply pressures in lines shall be minimized when the lines are switched. U.K.

In the case that influence of pressure difference is expected, the manufacturer and the approval authority shall agree whether correction is necessary or not.

2.1.5. Balance U.K.
2.1.5.1. The balance used for fuel consumption measurement shall meet the specification of Table A8.App7/1. U.K.
Table A8.App7/1

Analytical balance verification criteria

a

Fuel consumption (REESS charge balance = 0) during the test, in mass, standard deviation.

Measurement system Resolution Precision
Balance 0,1 g maximum ± 0,02 maximum a
2.1.5.2. The balance shall be calibrated in accordance with the specifications provided by the balance manufacturer or at least as often as specified in Table A8.App7/2. U.K.
Table A8.App7/2

Instrument calibration intervals

Instrument checks Interval
Precision Yearly and at major maintenance
2.1.5.3. Appropriate means for reducing the effects of vibration and convection, such as a damping table or a wind barrier, shall be provided. U.K.
Figure A8.App7/1 Example of instrumentation U.K.

where:

1

is the external fuel supply for preconditioning

2

is the pressure regulator

3

is the original tank

4

is the fuel cell system

5

is the balance

6

is/are off-vehicle tank(s) for fuel consumption measurement

2.2. Test procedure U.K.

2.2.1. The mass of the off-vehicle tank shall be measured before the test. U.K.
2.2.2. The off-vehicle tank shall be connected to the vehicle fuel line as shown in Figure A8.App7/1. U.K.
2.2.3. The test shall be conducted by fuelling from the off-vehicle tank. U.K.
2.2.4. The off-vehicle tank shall be removed from the line. U.K.
2.2.5. The mass of the tank after the test shall be measured. U.K.
2.2.6. The non-balanced charge-sustaining fuel consumption FC CS,nb from the measured mass before and after the test shall be calculated using the following equation: U.K.

where:

FC CS,nb

is the non-balanced charge-sustaining fuel consumption measured during the test, kg/100 km;

g 1

is the mass of the tank at the start of the test, kg;

g 2

is the mass of the tank at the end of the test, kg;

d

is the distance driven during the test, km.]

Textual Amendments