ANNEX
METHODOLOGY TO DETERMINE THE CO 2 SAVINGS OF THE SMART DIESEL FUEL HEATER
1. INTRODUCTION
This Annex sets out the methodology to determine the CO 2 emission savings to be attributed to the use of a Smart Diesel Fuel Heater in a vehicle fulfilling the conditions specified in Article 1.
In order to determine these savings, the following elements shall be determined:
(1)
the baseline technology power consumption;
(2)
the innovative technology power consumption;
(3)
the CO 2 savings;
(4)
the uncertainty of the CO 2 savings.
2. METHODOLOGY
The operation of the innovative technology is intended to be controlled by the vehicle electronic control unit (ECU) based on a temperature and pressure signal coming from the fuel filter.
The baseline fuel heater is controlled by the vehicle ECU based on a temperature signal only.
In order to simultaneously determine the power consumption of the baseline and eco-innovative technologies, a vehicle equipped with the innovative technology shall be tested as described in points 2.1 and 2.2 below. Diesel arctic fuel belonging to class 2 to class 4 of the EN 590 classification shall be used for those measurements.
2.1. Determination of P base (power consumption of the baseline technology)
In order to determine the baseline heater power consumption, the diesel fuel heater shall be put into activated state during the entire power consumption test as specified in points (1) to (9) below, and its operation shall not be affected by the filter pressure sensor.
The tool to be used for the read-out of the ECU, as well as the most suitable software to be used for the identification of the pressure threshold calibration label, shall be agreed upon between the manufacturer and the type-approval authority.
The type-approval authority or its designated technical service shall ensure that the power consumption test consists of the following steps:
(1)
a calibration read-out of the production ECU installed on the eco-innovative vehicle;
(2)
the installation on the vehicle of an open ECU that enables to set the threshold for the heater filter pressure sensor;
(3)
a calibration read-out of the open ECU;
(4)
identification, using appropriate software, of the pressure threshold calibration label as specified by the manufacturer;
(5)
setting of the heater pressure threshold to 0 kPa to ensure that the fuel heater is activated during the entire test;
(6)
verification and confirmation, that the only difference between the production and the open ECUs settings is the diesel fuel heater pressure threshold calibration;
(7)
cool down the vehicle, filled to at least 50 % fuel tank volume, until the climatic chamber and fuel temperature are stabilized at – 20 °C;
(8)
at least 30 seconds prior to starting to drive the WLTC, check that the heater is in activated state and start measuring and recording the battery voltage and diesel fuel heater current with an acquisition frequency of at least 100 Hz in order to document the pre-WLTC vehicle status;
(9)
drive a complete WLTC, with the climatic chamber and fuel temperature stabilized at – 20 °C.
Steps (7) to (9) shall be repeated at least five times.
Before starting the first WLTC drive, the manufacturer shall provide to the type-approval authority the operating voltage (U PS ) and current intensity (I PS ) of the pressure sensor of the smart diesel fuel heater, based on its electrical property data or measurement data provided by the supplier of the sensor.
For each WLTC drive completed, the energy consumed by the diesel fuel heater over the cycle (
) and the corresponding power consumption of the baseline diesel fuel heater (
) shall be calculated in accordance with Formula 1 and Formula 2, respectively:
Formula 1
Formula 2
Where:
:
Energy consumption of the diesel fuel heater during the i-th WLTC drive [Wh]
U base (t)
:
Battery voltage measured at time t [V]
I base (t)
:
Diesel fuel heater current intensity measured at time t [A]
t s
:
Starting point in time of WLTC drive, counted from the start of the voltage and current measurements [s]
t e
:
End point in time of WLTC drive, counted from the start of the voltage and current measurements [s]
:
Power consumption of the baseline diesel fuel heater during the i-th WLTC drive [W]
U PS
:
Pressure sensor supply voltage [V]
I PS
:
Pressure sensor supply current intensity [A]
The arithmetic mean of the baseline diesel fuel heater power consumption (
) over all complete WLTC drives performed shall be calculated in accordance with Formula 3.
Formula 3
2.2. Determination of P eco (power consumption of the innovative technology)
Before starting the WLTC drive as set out in the steps (8) and (9) in point 2.1, the manufacturer shall provide to the type-approval authority the heater filter pressure signal(s) to the ECU that would trigger the deactivation of the smart diesel fuel heater during the WLTC test.
Using that ECU signal, for each WLTC drive performed as set out in points (8) and (9) of point 2.1, the type-approval authority or its designated technical service shall determine the earliest time X [s] after which the smart diesel fuel heater would be deactivated.
The power consumption of the innovative technology [P eco ] shall be determined in accordance with Formula 4:
Formula 4
Where:
P eco
:
Power consumption of the innovative technology [W]
:
Arithmetic mean of the baseline technology power consumption as determined under point 2.1 [W]
:
Average value, across all WLTC drives performed, of the earliest time after the start of the WLTC drive when the smart diesel fuel heater would be deactivated [s]
U PS
:
Pressure sensor supply voltage [V]
I PS
:
Pressure sensor supply current intensity [A]
In case the diesel fuel heater is turned off by default at the start of each WLTC drive, the value
will be zero and Formula 4 becomes P eco = U PS . I PS
3. CALCULATION OF THE CO 2 SAVINGS
The CO 2 savings of the innovative technology shall be calculated in accordance with Formula 5:
Formula 5
Where:
CF D
:
Conversion factor, which is 2 640 for diesel [gCO 2 /l]
:
Power consumption of the baseline technology as determined in point 2.1 [W]
P eco
:
Power consumption of the innovative technology as determined in point 2.2 [W]
UF
:
Usage Factor, which is 0,2
v
:
Mean driving speed of the WLTC, which is 46,5 [km/h]
V Pe_D
:
Consumption of effective power, which is 0,220 for diesel [l/kWh]
η A
:
Efficiency of the alternator, which is 0,67 ( 1 )
4. CALCULATION OF THE UNCERTAINTY OF THE CO 2 SAVINGS
The uncertainty of the CO 2 savings shall be determined as follows.
The standard deviation of the baseline technology power consumption
shall be calculated in accordance with Formula 6:
Formula 6
Where:
:
Power consumption of the baseline technology as determined in point 2.1 [W]
:
Power consumption of the baseline technology during the i-th WLTC drive as determined in point 2.1 [W]
:
Standard deviation of the power consumption of the baseline technology [W]
n
:
number of WLTC drives performed for determining the power consumption of the baseline technology [-]
The uncertainty of the CO 2 savings (
) is then calculated in accordance with Formula 7. This uncertainty shall not exceed 30 % of the CO 2 savings.
Formula 7
Where:
CF D
:
Conversion factor, which is 2 640 [g CO 2 /l]
:
Uncertainty of the CO 2 savings [g CO 2 /km]
:
Standard deviation of the power consumption of the baseline technology as determined in accordance with Formula 6 [W]
UF
:
Usage Factor, which is 0,2
v
:
Mean driving speed of the WLTC [km/h], which is 46,5 km/h
V Pe_D
:
Consumption of effective power which is 0,220 for diesel [l/kWh]
η A
:
Efficiency of the alternator, which is 0,67 ( 2 )
5. ROUNDING
The CO 2 savings (
) calculated in accordance with Formula 5 and the uncertainty of CO 2 savings (
) calculated in accordance with Formula 7 shall be rounded to a maximum of two decimal places.
Each value used in the calculation of the CO 2 savings can be applied unrounded or must be rounded to the minimum number of decimal places which allows the maximum total impact (i.e. combined impact of all rounded values) on the savings to be lower than 0,25 gCO 2 /km.
6. CHECK AGAINST THE MINIMUM CO 2 SAVINGS THRESHOLD
The type-approval authority shall ensure for each vehicle version fitted with the innovative technology that the minimum threshold criterion as specified in Article 9(1)(b) of Implementing Regulation (EU) No 725/2011 and Implementing Regulation (EU) No 427/2014 is met. When verifying whether the minimum threshold criterion is met, the type-approval authority shall take into account, in accordance with Formula 8, the CO 2 savings as determined in point 3 and the uncertainty as determined in point 4 .
Formula 8
Where:
:
is the CO 2 savings as determined in point 3 (Formula 5) [g CO 2 /km]
MT
:
is 0,5 g CO 2 /km as specified in Article 9(1)(b) of Implementing Regulation (EU) No 725/2011 and Commission Implementing Regulation (EU) No 427/2014
:
is the uncertainty of the CO 2 savings as determined in point 4 (Formula 7) [g CO 2 /km].
7. CERTIFICATION OF THE CO 2 SAVINGS
The CO 2 savings to be certified by the type-approval authority in accordance with Article 11 of Implementing Regulation (EU) No 725/2011 and Implementing Regulation (EU) No 427/2014 (
[g CO 2 /km]) are those calculated in accordance with Formula 9.
The CO 2 savings shall be recorded in the type approval certificate for each vehicle version fitted with the Smart Diesel Fuel Heater.
Formula 9
Where:
:
is the CO 2 savings to be certified by the type-approval authority [g CO 2 /km]
:
is the CO 2 savings as determined in point 3 (Formula 5) [g CO 2 /km]
:
is the uncertainty of the CO 2 savings as determined in point 4 (Formula 7) [g CO 2 /km]
( 1 ) In case an efficient 12V alternator, 12V motor-generator or 48V motor-generator plus 48V/12V DC/DC converter is applied, which has been approved as an eco-innovation in accordance with Commission Implementing Decision (EU) 2020/174, (EU) 2020/1232, (EU) 2020/1167 or (EU) 2021/488, the type-approval authority shall use the alternator efficiency determined in accordance with that Decision.
( 2 ) In case an efficient 12V alternator, 12V motor-generator or 48V motor-generator plus 48V/12V DC/DC converter is applied, which has been approved as an eco-innovation in accordance with Commission Implementing Decision (EU) 2020/174, (EU) 2020/1232, (EU) 2020/1167 or (EU) 2021/488, the type-approval authority shall use the efficiency determined in accordance with that Decision.
