Test procedure development

Mobile Air Conditioning (MAC)

Stakeholder meeting,

Brussels, 07-10-2010

2

Contents

• Project overview• Draft of the test procedure

• Chassis dynamometer tests• Influence of glazing quality• Test Evaluation

• Preliminary results• Next steps

Fonts: blue = Optiongreen = suggestet

3

Project overview

Goal: To develop test conditions and procedures for MAC

• Main evaluation parameter: impact on fuel consumption

• Procedure should be clearly discriminative of different systems

• Target accuracy and repeatability need to be clearly established

4

Project overview

• Test conditions based on typical European:• Climatic conditions (temperature, humidity)• Operational conditions• Consumer habits

• Three basic operational modes:• Cool down

• To simulate vehicle interior cool-down after heat soak• Constant temperature

• To simulate operation with a constant temperature interior• Simulation based or HIL (Hardware in the Loop)

• E.g. COP map with duty cycle

5

Project overview

• Definition of a test procedure(s) for MAC performance at type approval

• Focus on physical testing:• Cost efficiency• Realistic representation of MAC efficiency• Use previous experience (ADAC 2007)

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• Simulation of “Seasonal Performance” of MAC system to determine most important ambient conditions

• Analysis of Weather Data• Simulations by means of “Seasonal Performance” (LCCP)

MAC test conditions

Results presented in last meetings for Athens, Frankfurt, HelsinkiSummary:

•main share in additional fuel consumption between 20°C and 30°C ambient temperature 25°C at 50% RH defined.

•21°C interior temperature defined as representative.

•700 W/m² suggested as solar radiation (higher than EU average to consider heat up during parking, which is not part of the test procedure).

7

Factors to be considered in test procedure

1. Test cycle („easy to drive” for repeatable results at small fuel consumption effects)

2. Ambient temperature and humidity

3. Interior temperature to be reached with MAC

4. Mass flow of the MAC system

5. Simulation of heat from sun radiation

6. Evaluation method for test results

Option for test procedure: Test vehicle on the chassis dynamometer with and without MAC.Difference is the additional fuel consumption from the MAC system.

Define following settings:

8

Chasis dyno tests

Test cycle: Options tested = 2-step, 3-step, NEDC

Selected: 3-Step cycle (developed by ACEA)

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Time [s]

km/h

0

1

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5

Gea

r

Velocity

Gear

Bag 165 km/h ~ average speed of (NEDC+real world cycles)

Bag 2idling (long duration for

repeatibility)

Ti = const -> start test

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0 200 400 600 800 1000 1200Time [s]

velo

city

[km

/h]

BAG 1(UDC)

BAG 2(EUDC)

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Time [sec]

Vel

ocity

[km

/h]

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7

Gea

r [-

]

Velocity [km/h]

Gear [-]MAC test cycle

Advantages:Covers 3 speed ranges (different rpm for compressor)

Tests MAC-on and MAC-off within same analysers calibration less uncertainty

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Chassis dyno test

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Time [sec]

Vel

oci

ty [

km/h

]

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Gea

r [-

]

Velocity [km/h]

Gear [-]MAC test cycle

1960 - 2220

2320 - 2580

2710 - 2970

3090 - 3350

3450 - 3710

3840 - 4100

Evaluation periods suggested:

MA

C o

nM

AC

off

MAC onmeasurement

MAC offmeasurement

1) Preconditioning as defined in EC 692/2008 for emission tests2) Soak >8h at 25°C (+/-2°C) at 50% RH (+/-5%RH)3) start MAC test, until second 1400 the MAC setting shall be found for 21°C cabin temperature (alternative 15°C vent outlet)

MAC on, m >230 kg/hPre conditioning (ti = 21°C)

Additional MAC FC = Weighted average [kg/h] MAC on

- Weighted average [kg/h] MAC off

10

TC3

Ta, a

To CVS, exhaust gas analyser g CO2/km

Chassis dynamometer

blower

Positions of sensors

“ambient temperature” 25°C and 50% RH measured at testbed-blower inlet

Vehicle temperature measured in the cabin (details see next slide)

ma

ml

330 mm to roof

30 mm

Chassis dyno tests

airstream

11

Option a): weighted average of 3 positions for cabin temperature This avoids special optimisation of vent(s) for one temperature sensor position. Sensors position in the vehicle as shown in the picture:

Chassis dyno tests

≈1145 mm

TC1

TC2

TC3

TC1, TC2, TC3330 mm to roof

30 mm

Option b): highest vent outlet temperature shall be <15°C.

Effect of option b): vehicle size has nearly no influence on test results.No effort necessary to optimise flow in vehicle for the sensors positions.Not guaranteed that this setting would reach 21°C in the cabin.

What we suggest: option c = a+bgain experience in pilot phase where temperatures are recorded for both options

Positions of sensors for cabin temperature

12

4 x „vent outlet temperature

Chassis dyno tests

Set up of option „vent outlet“

13

Chassis dyno tests

Other options to be discussed:

Conditioning of the state of charge (SOC) of the batteryBackground: basically air conditioning could be driven electrically only from battery no additional fuel consumption if battery not charged during test.

Option a): measure energy flow and correct for difference kWh in/out with constant efficiency (e.g. 50% hel at 230 g/kWh).

Option b): as a) but with measured efficiency.

Option c): start one test with minimum SOC and a second test with maximum SOC.

In actual tests SOC differences were small, future technologies may behave different.

Suggestion:default = Option a), alternative = Option b) on OEM demand

14

Chassis dyno tests

Other options to be discussed:

Test of low ambient temperature behaviour

Background: According to (Weilenmann et.al., 2010) “two-thirds of CO2 and fuel consumption from MAC activity could be saved without discomfort by switching off the MAC below 18 °C.

Option: First preconditioning before soaking at <18°C with MAC in automatic position. If MAC is not activated with engine start a “bonus” for the MAC fuel consumption could be granted (20% to 50% of the MAC fuel consumption measured later?)

Question: any important disadvantages) MAC activation for de-fogging, defrosting etc. shall not be prohibited.

Ambient conditions need to be specified to avoid condensation issues

15

Glazing

Tests with solar lamps are expensive

In-Use tests are not repeatable

laboratory tests of glazing quality according to ISO 13837 & Simulation

Good glazing quality can save MAC energy demand

Incentive for good quality shall be given in test procedure

•Simulation of heat entrance into the vehicle cabin

•Consider this heat entrance by

Option a) with a correction value in the evaluation

Option b) during tests by adapting the MAC mass flow or

Option c) during tests by adapting the test cell temperature

16

Glazing: simulation of heat entrance

Energy balance from radiation and convection

Te Ti

he

Eabsorbed

EtransmittedEreflected

Ere-emitted, i

Ere-emitted,eexteriour interiour

hi

TG, i

E interior = TTs x E total sun radiation in [kW/m²] for defined solar radiation (700W/m²)

E total sun radiation= E absorbed + E transmitted + E reflected

100% = e + TDs + R Ds

Measured according to ISO 13837

Share of re-emission into cabin from heat transfer coefficients hi and he

Heat entrance to cabin = E transmitted + to cabin re-emitted part of E absorbed

Details see presentation from Volkmar Offermann (Saint-Gobain Sekurit)

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Calculation of heat entrance into the cabin due to sun radiation

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Variant 1 Variant 2 Variant 3 Variant 4 Variant 5

Glazing quality

Su

n r

adia

tio

n e

ner

gy

entr

ance

[W

/m²]

Estate

Van

SUV

Specific energy entrance

Options for application of the approach

discussed with Saint-Gobain Sekurit and NSG, calculation tool provided by Saint-Gobain Sekurit (V. Offermann and F. Manz)

Option a): Application of calculation tool. Complex validation of tool necessary before it becomes standard.

Option b): Provide look up table for W/m² as function of glazing (TTs value and angle of installation).Interpolation from table and multiplication with pane m².

We suggest option b. Draft table could be veryfied by all stakeholders. Eventually diverging results may need further discussion.

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Summary on suggested procedure for glazing

RearAngle [°] 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

2030405060708090

TTS [%]

W/m²

rear door side lite

Angle [°] 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 802030405060708090

TTS [%]

W/m²

front door side lite

Angle [°] 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 802030405060708090

TTS [%]

W/m²

windscreenAngle [°] 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

2030405060708090

TTS [%]

W/m²

sun energy entrance Additional FC

[kW] [kg/h]

1 0.157

0.75 0.118

0.5 0.078

0.25 0.039

0 0

kW

Additional fuel

consumption

[Kg/h]

m²

windscreen

front door side lite

rear door side lite

rear

m²

1. Heat entrance from solar radiation [kW] from look up table

2. Additional fuel consumption calculated from other look-up table [kg/h] as function of [kW]

y = 0.1568x - 4E-17

R2 = 1

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Total heat uptake from sun radiation [kW]A

dd

itio

na

l fu

el c

on

sum

ptio

n [k

g/h

]

1.

2.

k

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Test evaluation

)(6.3 offACMeasuredonACMeasuredPeiCOPMAC iiiiFCFCCCFC

i….single speed steps (0, 50, 100 km/h)

Additional MAC fuel consumption in [kg/h]

Idling = 15%

50 km/h = 65%

100 km/h = 20%

Total result = weighted average according to real world shares:

CPei, CCOPi….Correction factors (details next slide)

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0 km/hAC-on

50 km/hAC-on

100 km/hAC-on

0 km/hAC-off

50 km/hAC-off

100 km/hAC-off

Fu

el c

on

su

mp

tio

n [

g/s

]Basic problem of MAC tests:

Small value is gained from difference of 6 large values

Accurate measurements and affective correction for deviations in settings necessary

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Test evaluation

iSpeedOffAC

iSpeedOnAC

B

B

iPe P

PC

__

__

Suggested correction factors:

Correction for variations in vehicle speed during the test (according to ratio of chassis braking power)

31 TCiCOPRHiCOPTiCOPiCOP CCCC

Correction for variations in test cell temperature, humidity and cabin temperature (according to ratio of variation in cooling capacity)

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Temperature in test cell [°C]

C_C

OP

i [-]

RH = 50%

RH = 45%

RH = 55%

Constant vehicle cabin temperature TC3 = 21°C

CCOPi-T1

Test bed temperature

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40% 45% 50% 55% 60% 65% 70%

Relative humidity in test cell [°C]

C_C

OP

i [-]

T test cell = 25°C

T test cell = 23°C

T test cell = 27°C

Constant cabin temperature TC3 = 21°C

CCOPi-RH

Test bed RH

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Cabin temperature TC3 [°C]

C_C

OP

i [-]

RH = 50%, Ta=25°C

RH = 45%, Ta=25°C

RH = 55%, Ta=25°C

RH = 50%, Ta=27°C

RH = 50%, Ta=23°C

CCOPi-TC3

Cabin temperature

21

Test evaluation

COP-Correction factorsmultiplication of the single correction factors is simple and no loss in accuracy against detailed simulation

31 TCiCOPRHiCOPTiCOPiCOP CCCC

R2 = 0.9983

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C_COP directly simulated

Pro

du

ct

of

sin

gle

C_

CO

Ps

Suggested look-up table for type approvalt1 [°C] RH1 [%] t3 [°C] CCOPi_T1 CCOPi_RH CCOPi_TC3

25 50% 21 1.000 1.000 1.000

23.00 50% 21.00 1.285 1.000 1.000

24.00 50% 21.00 1.131 1.000 1.000

25.00 50% 21.00 1.000 1.000 1.000

26.00 50% 21.00 0.888 1.000 1.000

27.00 50% 21.00 0.793 1.000 1.000

28.00 50% 21.00 0.710 1.000 1.000

29.00 50% 21.00 0.637 1.000 1.000

30.00 50% 21.00 0.574 1.000 1.000

25.00 40% 21.00 1.000 1.242 1.000

25.00 45% 21.00 1.000 1.108 1.000

25.00 50% 21.00 1.000 1.000 1.000

25.00 55% 21.00 1.000 0.912 1.000

25.00 60% 21.00 1.000 0.838 1.000

25.00 65% 21.00 1.000 0.776 1.000

25.00 70% 21.00 1.000 0.722 1.000

25.00 50% 18.00 1.000 1.000 0.893

25.00 50% 20.00 1.000 1.000 0.962

25.00 50% 22.00 1.000 1.000 1.042

25.00 50% 24.00 1.000 1.000 1.136

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Some test results

ACEA (PSA) tested the method on 6 vehicles and found good repeatability:

TUG performed 3 repetitions with final test procedure and had one outlier:

Results with correction factor

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IDLE 50 kph 100 kph Cycle

l/h (

idle

) -

l/10

0

Additional fuel consumption diesel estate EURO 5

0.35

0.28

0.49

0.43

0.47

0.40

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FC MAC direct [kg/h] FC MAC COP-corrected [kg/h]

MA

C a

dd

itio

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l fu

el c

on

su

mp

tio

n [

kg

/h]

MAC-test 1

MAC-test 2

MAC-test 3

0%

2%

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18%

Stabwn test 1+3 Stabwn test 1+2+3

Tests considered

Sta

nd

ard

dev

iati

on

[%

]

Test 2 had a DPF regeneration during preconditioning but this hardly explains the difference

Option: define maximum standard deviation from >3 tests

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Utility parameters

• Possible need to relate additional fuel consumption to vehicle size

•Depending on outcome of a pilot period

•Depending on the final goal of the procedure

•If needed, a proxy for vehicle size will be required. This proxy should be:

•Easy to measure

•Unambiguous

•If possible already included in the vehicle type approval

•Encouraging to fuel efficient MAC technology

•Continuous to avoid optimisation at utility steps

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Utility parameters (2)

•Possible utility parameters could be:

•Glazing area and inclination

•Footprint

•Interior volume (possibly based on footprint X height)

•Pan area

•Etc

•Or a combination of the abovePan area

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Utility parameters (3)

Proposed approach:

Collect a multitude of vehicle parameters during the pilot phase to enable the calculation of the correlation between these parameters and the additional fuel consumption

This would of course need a means of correcting for various MAC technologies in some way MAC and powertrain parameters also needed during pilot phase

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Utility parameters (4)

Proposed parameters to be collected in the pilot phase:MAC component data

Compressor swept volume

Compressor type (piston, rotary vane, scroll, swash plate, swivel plate)

Compressor displacement control (fixed or variable displacement)

Compressor control type (internal control, external control)

Clutched compressor (yes / no)

Expansion valve type (fixed expansion valve (FXV), thermostatic expansion valve (TXV))

Receiver type (integrated / non integrated receiver)

Internal heat exchanger, IHX (yes / no)

Number of evaporators (single / double)

Cabin airflow fan control (PWM / dropping resistor)

Condenser airflow fan control (PWM / dropping resistor)

Refrigerant type

Refrigerant fill quantity

Cabin air recirculation strategy description[1]

MAC control strategy at low ambient temperatures (Auto MAC off at low ambient T/ MAC remains on at low ambient T)

Vehicle data

Vehicle body type (sedan, hatchback, stationwagon, SUV)

Number of seats

Interior volume[2]

Vehicle footprint

Vehicle height

Glazing data; for every pane of glass / transparent plastic

Size

Inclination

Thermal properties (Solar transmittance Tts according to ISO 13837)

Tire size[3]

Powertrain data

Engine fuel type (petrol, diesel, CNG, LPG, etc.)

Engine maximum power

Engine displacement

Engine number of cylinders

Compressor drive method (belt, electric)

Compressor drive ratio if belt driven (crank / compressor pulley ratio)3

Gearbox type (manual, automatic with torque converter, dual clutch, robotized manual)3

Base idle speed3

Gearbox ratios3

Final drive ratio3

[1] Possibly, in a follow-up project a control system strategy checklist could be defined which can be used in a “tick-box” manner to describe the control strategy. This would ensure that the control system strategy descriptions would all be in a similar format which should enable easier data handling and analysis.

[2] Possibly calculated from a CAD model, (in or excluding seats and trim?)

[3] This influences the time-speed pattern of the compressor over the test cycle as well as provide an estimate of the difference in CAP at idle and during the other phases of the test.

List will

be included in

the

final re

port

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Main open options•Best preconditioning before soaking (NEDC?)

•Test low temperature behavior?

•How to handle battery SOC?

•Use cabin temperature or vent outlet temperatures as target?

•Which tolerances are reasonable for T’s and RH?

•How many test repetitions are necessary for stable result? (>2)

•Take glazing quality into consideration by correction factor or by change in MAC air mass flow?

•Start a pilot phase?

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0

0.1

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0.5

0.6

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0.8

Idling 50 100 Mix

Test Sub-cycle

kg

/h

Thank you for your attention and for the support in this project!

Tk1

Tk3

Tk4

Tk2

s [kJ/kgK]

h [k

J/kg

]

t1tk3

tk1t2

4 1

23

TC3

Ta, a

To CVS, exhaust gas analyser g CO2/km

Chassis dynamometer

blower

ma

ml

330 mm to roof

30 mm

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Time [sec]

Velo

cit

y [

km

/h]

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Ge

ar

[-]

Velocity [km/h]

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MAC test cycle