fuel consumption systems guidelines to installation … · fuel consumption systems guidelines to...

Confidential

AVL List GmbH (Headquarters)

Romain LARDET

FUEL CONSUMPTION SYSTEMS

GUIDELINES TO INSTALLATION & APPLICATION

Any unauthorized copying, disclosure or distribution of the presentation is strictly forbidden

Romain LARDET | ITS CONSUMPTION MEASUREMENT | 21 May 2015 | 3Confidential

MAIN GUIDELINES FOR INSTALLATION



SAFETY PRINCIPLES

735S

753C

pressure

control

modules

HC-

Detector

Testbed Standard Layout

UUT

FUEL

REFERENCE

BASEMENT

Ventilation in the testcell prevents an explosive atmosphere to exist permanently.

HC Sensors must be installed at a proper position inside the testcell.



735S

753C

pressure

control

modules

HC-

Detector

temp. influencebubbles

Testbed Standard Layout

UUT

FUEL

REFERENCE

BASEMENT

High sensor accuracy

Temperature

stability

+/- 0.02 °C

Efficient venting

Avoid bubbles, temperature and fuel storage influence

MEASURING WELL : BASIC PRINCIPLES



Sensor EngineFuel

Volume

19 l/h 20 l/h+1 l/h

Changing fuel temperature (ambient, engine impact, external heat impact, conditioning performance)

Elastic elements(Air in the fuel application, soft hoses, pressure regulators, volume buffers)

Pressure pulsations (caused by the engine)

GOAL:

Do a proper setup of the fuel circuit, especially between fuel system and engine to optimize the system performance

BASICS – MEASUREMENT CIRCUIT



FUEL SUPPLY LINE

a ….. Fuel supply from facility

b ….. Fuel System inlet

1 & 3 ….. Pump Module in case of low supply pressure

2 …... Filter unit (coarse & fine)

4 …... Shut-off Valve (controlled by the fuel system in case of overflow)

5 …… Inlet Pressure Reducer if supply pressure > 0.8 bar rel.Any unauthorized copying, disclosure or distribution of the presentation is strictly forbidden


IMPORTANCE OF PIPING DIAMETER

pump capacity inner diameter tube flow velocity

250 l/h 10 mm ~ 0.78 m/s

500 l/h 14 mm ~ 0.8 m/s

Deaeration of Fuel Lines requires

flow velocity : 0.5 m/s … 1.5 m/s

For Diesel engines you must find a compromise between flow

velocity and pressure drop in the return line in order to limit

the backpressure at the engine outlet.

For Gasoline engines, there is usually no return and it is easier

than on diesel engines. Here typical diameter are 8…12 mm

inner diameter depending on the size of the engine.



0

1

2

3

4

5

6

7

8

9

6 8 10 12 14 16 18

Flo

w S

pe

ed

[m

/s]

flow speed [m/s]vs inner diameter[mm] for several pump flow rates [l/h]

50

100

150

200

250

500

800

Internal diameter [mm]

Flow rate

[l/h]



Recommended pipe material

- Stainless steel pipes, seamless (if piping does not have to move)

- Teflon hoses (electric conductive) which are metal braided for connections

which have to be flexible (e.g. between AVL 735S and AVL 753C; between

engine bypass and fuel system)

INSTALLATION PRINCIPLES – PIPE MATERIAL



Recommended pipe material

- For engine connection lines, we recommend to use stiff conductive hoses

- Avoid any material which is „flexible“ – meaning a very

soft material which will behave like a volume buffer

element and can cause „fake“ consumption signals

INSTALLATION PRINCIPLES – PIPE MATERIAL



R > • Avoid sharp curves of tubes / pipes

underpressure can cause bubbles

bending diameter > 3* pipe diameter

• If possible avoid pipe diameter changes

• The fuel flow direction through pumps,

filters, heat exchangers etc. always has to

be from bottom to top

• Installation of „dead ends“ (drain valves,

pressure gauges) below tubes, not above

INSTALLATION PRINCIPLES – DO‘S AND DON‘TS



• Avoid sharp curves of tubes / pipes

underpressure can cause bubbles

bending diameter > 3* pipe diameter




• Safety measures to be considered Use a

flame filter for the device venting line if the

venting line ends in the test cell

• Each AVL Fuel Device has to be connected

to test bed grounding (PE)





- Material used for fuel piping must be electric conductive. Fuel flow through a

pipe causes electric charge separation (ions) and this can be a source of

degradation of the fuel pipes or even a spark.

- Fuel piping (and the fuel systems) must be connected to the test bed

grounding

- Quick coupling connectors have to be over AND under-pressure proof. For

applications where vacuum fuel pressure is required, this is a potential

source of air formation (air is sucked into the fuel pipe!)

Example of good fittings and

connectors suppliers




- The venting line of the fuel system / meter

(AVL 733S, AVL 735S, KMA4000, AVL

FuelExact) must be free and never blocked.

- There must never be residual fuel in the

venting line or in the hoses leading e.g. to

the overflow vessel.




- Hoses leading to a pressure sensor which is mounted above the fuel piping

(e.g. in the cable boom) MUST BE COMPLETELY FILLED WITH FUEL




- Fuel pressure measurement can also be done by directly connecting

pressure sensors to the engine bypass and using inclining hoses



AIR IN THE TEFLON TUBE TO FEM-P (PRESSURE SENSOR)



ZERO CONSUMPTION WITH AND WITHOUT AIR IN THE SYSTEM (735S/753C)




- Avoid any elements in the fuel application which cannot be deaerated (e.g. fuel

filter with the filter cap on top, heat exchangers wrong mounted, dead ends)




- Do not install components / parts which are not needed for engine testing

(because the engines requirements are met by the mere AVL Fuel System).

each additional component (like pressure regulators, auxilliary fuel

pumps) is a potential source of fuel consumption signal noise.

KEEP IT SIMPLE




- Keep the fuel pipes away from any heat source (e.g. other conditioning

units) or hot/cold pipes from other medias

- Keep the fuel pipes away from blowers or fans which can cool down the fuel

in the pipework

- Try to maintain a stable test cell temperature

- Fuel pressure modules have to be installed as close to the engine as

possible!

- The engine bypass has to be installed as close to the engine as possible!

- Try to avoid „fuel locks“, meaning fuel is trapped e.g. between two valves.

Due to heat impact and thermal expansion, components might be destroyed

due to overpressure. Expansion vessels can help.



THEORETICAL IMPACT OF THE TEMPERATURE STABILITY ON FUEL CONSUMPTION MEASUREMENTS

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%

0.01 0.1 1 10 100

Re

lati

ve E

rro

r [%

]

Actual Engine Fuel Consumption [kg/h]

Relative Errors in Fuel Consumption Measurementfor different temperature gradient in °/min

0.025°/min

0.05°/min

0.1°/min

0.3°/min

0.5°/min

Calculation based on a typical

testbed setup:

2 liters of diesel fuel between

the sensor and the injectors



Engine inlet temperature measurement

(T_FUEL_I)

CHECK OF THE ENGINE FUEL FEED TEMPERATURE DURING A WHTC CYCLE

Controlled fuel temperature

At the beginning and at the end of the test run,

the fuel temperature at the engine inlet differs

from set temperature of the fuel system.

If there is no fuel flow to the injection system,

the temperature of the fuel in the engine line will

be influenced by ambient temperature



CHECK OF THE ENGINE FUEL FEED TEMPERATURE

DURING A WHTC

The measurement uncertainty in transient cycles is very influenced by the

temperature stability of the fuel over time. With an AVL FuelExact, we achieve on

this demanding WHTC a temperature stability of about +/-0.1°C around 34.6°C.

This value is not a specification but the result of a good installation combined with

the heating/cooling capabilities and temperature regulation strategy of the system.



INSTALLATION PRINCIPLES – PIPE THERMAL INSULATION

Why the need for pipe insulation?

- The fuel temperature is usually conditioned at the device outlet and

well controlled. To minimize any heat transfer (impact from outside and

/ or heat loss to ambient), it is strongly recommended to insulate the

fuel piping between the fuel system up to the engine bypass

- Optimization of the measurement accuracy by minimizing the influence

of non stable environmental conditions

- Fuel temperature at the engine inlet will be approximately the same

like at the fuel system outlet (no need to change the set temperature

for the fuel conditioning system)



Results

(1) without insulation: CT 74,0

(2) with insulation 10 mm:CT 26,0

(3) with insulation 20 mm:CT 22,0

Calculated for a tube

length 5m

NW 10mm (inner diameter)

Flow rate 250l/h

Fuel Diesel

Fuel Temperature 50°C

Air Temperature 20°C

Temperature loss of a fuel pipe with and without thermal insulation

10 mm insulating material already

shows improvement on thermal stability




Conditions:

- engine stand still

- conditioning of 753C

- no venting

- 733S + 753C

Influence of changing ambient air temperature


Temperature

of fuel return [°C]

Temperature at

753C outlet [°C]

Temperature of

ambient air

[°C]

Consumption variation [kg/h]

(FB_VAL)



SUMMARY

Optimize fuel piping between Fuel System

Piping material & fittings material

Piping length

Piping diameter (=> flow speed & pressure drop)

Piping insulation

Bypass close to engine

Do not trap air between fuel system and engine

Keep it simple and limit the fuel volumes

Manage safety :

Ventilation

HC Sensors

Overflow / venting line


fuel consumption systems guidelines to installation … · fuel consumption systems guidelines to...

Documents