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IEA AMF Annex 57: HDV Performance Evaluation -Intermediate update of Finnish subproject

26/05/2020 VTT – beyond the obvious

Petri Söderena & Nils-Olof NylundVTT Technical Research Centre of Finland

HDV Performance Evaluation


Key findings

Heavy-duty truck engines operating with diesel process (i.e. compression ignition and diffusion

combustion) have a clear advantage in efficiency compared to powertains with spark-ignition engines• Up to - 17 % ... - 25 % less consumed energy vs. SI-engines depending on the average loading of the

cycle/mission – the higher the loading the lower difference

In tailpipe CO2 emissions spark-ignited methane HDV engines provide slightly lower to slightly higher

emissions depending on the engine loading in the specific cycle/mission• - 6 %...+3 % vs diesel in chassis dynamometer and even up to 9 % lower emissions in the measured on-road

routes

• Typically for spark-ignited engines the engine efficiency decrease sharper when engine loading reduces from high

load to low load compared to diesels – smaller difference in high load and less transient cycles/missions

New engine options, dual-fuel LNG-diesel and ED95 ethanol, provide interesting options for the

future• Dual-fuel LNG-diesel powertain can provides up to 19 % less CO2 tailpipe emissions compared to diesel

• ED95 ethanol powertrain provides similar efficiency and CO2 emissions compared to diesel

Paraffinic renewable HVO diesel (EN15940) improved the efficiency of diesel trucks 0.7 % … 1.5 %



Key findings

Regarding local emissions, all the powertrain options are capable of low emissions• Powertrains equipped with SCR are capable of ultra low NOx emissions in hot operation conditions,

even as low as 1 mg/kWh on powertrain basis

• Engines equipped with particulate filter are capable on PN and PM emissions clearly under the

emission limit values

• In best case, SI-methane engines without particulate filter are also capable on PN and PM emissions

under the limit value

• Other SI-methane truck measured gave PN emissions under and another clearly over the limit value

N2O emissions in CO2 equivalence basis can be relative high in engines equipped with

SCR – adding up to 7 % compared to CO2 emissions• Not dependent on the fuel, but the chemistry used in the SCR and the exhaust gas temperature

temperature

CH4 tailpipe emissions are not a problem for the new generation methane powertrains,

spark-ignited and direct injection dual-fuel• Adds less than 1 % to CO2 equivalence basis compared to CO2 emissions


Combines experimental work, modelling and forecasting

Partners within AMF are:• Canada

• Finland (VTT as coordinator for the project)

• Chile

• Japan

• Korea

• Sweden

Each participating country performs research independently within commonly agreed

reseach plan and methodology• Outcome: consolidated research report and summary with key message of how well are current HD

vehicles performing and what can be expected in the future

Duration 10/2018-10/2020

Estimated overall budget for the six partners is app. 610,000 €

HDV Performance Evaluation – A project within IEA Advanced Motor Fuels TCP*)

*) Technology Collaboration Programme


The duration of the Finnish

subproject is 01/2019-10/2020

Project partners within Finland are• Gasum (energy company)

• Neste (energy company)

• Posti (Finnish Post)

• Proventia (supplier of HDV EAT

systems)

• St1 (energy company)

• Traficom (Transport authority)

• VTT (coordinator)

HDV Performance Evaluation –Finnish subproject

*Portable Emission Measurement System

** ISC = In-service conformity, Euro VI legislative in-service testing method


HDV’s energy consumption

Emissions with different technologies

Information supporting decision making

Publicity for new tehnologies

HDV (incl. HCT) energy consumption

HDV emissions

Information for reporting (EU and

national)

Information on emissions from

alternative technologies (WTW)

Todays status for decisions making

IEA AMF TCP

TransDigi reseachplatform

International and national

publicity

Climate impact

Impacts on stakeholders

Impacts on authorities

Main details of the tested trucks


Id Emission

class

Chassis Engine and EATa Fuel Transmission Curb

mass [kg]

Truck A Euro VI step C Tractor 4x2 Spark ignited 13 L

EGRb+TWCcCNG Automatic / Robot 8540

Truck B Euro VI step C Tractor 6x2 Spark ignited 13 L

TWC

LNG Automatic / Robot 8257

Truck C Euro VI step D Tractor 4x2 Compression ignition 13 L

EGR+DOCd+DPFe+SCRfDiesel Automatic / Robot 7510

Truck D Euro VI step D Tractor 4x2 Direct injection dual-fuel 13 L

EGR+DOC+DPF+SCR

LNG-diesel Automatic / Robot 7960

Truck E Euro VI step C Rigid 6x2 Compression ignition 13 L

EGR+DOC+DPF+SCR

ED95 Automatic / Robot 9090

Truck F Euro VI step D Tractor 4x2 Compression ignition 11 L

EGR+DOC+DPF+SCR

Diesel Automatic / Robot 7202

a = Exhaust aftertreatmentb = Exhaust gas resirculation

d = Diesel oxidation catalyste = Diesel particulate filterf = Selective catalytic reduction

c = Three-way catalyst

Test fuels


Fuel LHV Density CHO m-% Other

Pump CNG 49.1 MJ/kg

- -

Methane number approx. 90, (CH4: ~96.8 mol-%,

C2H6: ~1.8 mol-%, C3H8: ~0.4 mol-%, N2: 0.7

mol-%) Avg. values of grid gas

Low methane

number (MN)

CNG

49.5 MJ/kg

- -

Methane number approx. 77, (CH4: 94 mol-% and

C3H8: 6 mol-%)

Pump LNG 49.7 MJ/kg (Truck B)

49.8 MJ/kg (Truck D)- -

CH4: ~95 mol-%, C2H6: ~5.3 mol-%, C3H8: ~0.4

mol-%

EN590 diesel 43.0 MJ/kg 835 kg/m3 H: 13.6 m-%,

C: 86.4 m-%

Cetane index 54.5

EN15940 HVO 43.8 MJ/kg 780 kg/m3 H: 14.6 m-%,

C: 83.4 m-%

Cetane index 82.8

ED95 24.5* MJ/kg 828 kg/m3

-

Hydrous ethanol content ~95 Vol% (incl. ~5 wt%

H2O)

~5 Vol% ignition improver, lubricant and other

volatiles*Average value of two different samples analysed October 2019 and April 2020. LHV of ED95 can vary by estimation 24.1…25.0 MJ/kg depending on water content.


WHVC* provides a link to Euro VI type approval cycle WHTC**• Cold and hot start

HDV PerE is a tailor made cycle for comparison of the results

on chassis dyno and on-road produced with PEMS• Hot start cycle

With vehicles loaded, both cycles require full engine power

output in acceleration• App. 270 kW (367 hp) wheel power / 90 % of maximum (410 hp)

Test cycles on chassis dynamometer HDV PerE route/cycle

*World harminized vehicle cycle **World harminized transient cycle

WHVC 30

tons (halfpayload)

WHVC 44

tons (fullpayload)

HDV PerE(chassis dyno,

30 tons)

HDV PerE(PEMS, 30 tons)

Euro VI ISC (30 tons)

Length [km] ~20 ~20 ~30 ~31.5 ~140

Duration [s] ~1800 ~1800 ~1900 ~2160 ~8400

Average

speed [km/h]

~40 ~40 ~58 ~53 ~60

Cumulative

work [kWh]

~26 ~35 ~49 Truck B: 41.7

Trucks C: 36

Truck D: 35.7(engine / ECU

based, engine -

auxiliaries)

Truck B: 163

Trucks C: 123

Truck D: 122(engine / ECU

based, engine -

auxiliaries)

Relative work

[kWh/km]

~1.3 ~1.8 ~1.6 1.1 – 1.3 0.9 – 1.2


ISC** route according to Euro VI step C regulation

ISC test route developed and verified with truck B • Trucks C and D did not produce enough work, roughly 3.7 – 3.9 x WHTC work (requirement in Step C is min. 5 x WHTC

Engine loading on HDV PerE was higher in chassis dyno vs. on-road -> has some effect on comparability

Test cycles on-road with PEMS* device

* Portable emission measurement system

** In-service conformity test, Euro VI HDV’s on-road test required during the engine type approval and in-use period


Overall, the powertains which worked based on diesel process (i.e. compression ignition

and diffusion combustion) gave the lowest energy consumption

Powertains with spark-ignition engines and stoichiometric combustion gave lower efficiency• Nevertheless, the difference is reduced with increased load i.e. WHVC 44 tons vs. 30 tons

• Engine high efficiency operation area is smaller for spark-ignited engines compared to diesels

Alternative fuel type engines based on diesel type combustion (direct-injection dual-fuel

LNG-diesel and ED 95 ethanol) performed well• Dual-fuel almost as well as diesel

• Ethanol powertrain similar and

in some condition even

better than diesel

Energy consumption

WHVC hot start 30 tons WHVC hot start 44 tons


Spark-ignited trucks A and B consumed more energy than conventional diesel trucks C and F• Roughly 24 % more energy on high load cycle

• Roughly 34 % more on medium load cycle

Dual-fuel truck D consumed a bit more than diesel trucks C and F • Roughly 4 % - 7 % depending on a load and cycle

Ethanol truck E delivered diesel-like or even better efficiency• Up to 5 % less energy consumption than diesels depending on cycle

EN 15940 HVO gave small advantage in

energy consumption vs. regular diesel• 0.7… 1.5 % less energy consumption than with regular diesel

depending on truck

Energy consumption

HDV PerE


Principally, the tailpipe CO2 emission is a result of powertrain efficiency and the fuel carbon

intensity

Eventhough methane has lower carbon intensity (theor. approx. 25 % less CO2 / kg,fuel) than

diesel, the tailpipe CO2 emission with spark-ignited engines varied from slightly lower to slightly

higher (- 6 %...+3 %) compared to powertrains with diesel engines• On-road conditions spark-ignited engine performed even better with up to – 9 % lower tailpipe CO2 emission

vs. diesel

Truck with ED95 ethanol engine produced roughly similar tailpipe CO2 emission as diesel, - 4 %

… + 1% compared to diesel

Dual-fuel LNG-diesel truck produced the lowest tailpipe CO2 emissions, even up to 19 % less

compared to diesel

CH4 tailpipe emissions (23xGHG factor vs. CO2) are not anymore a problem with CNG and LNG

trucks independet of engine type i.e. spark-ignited or dual-fuel direct-injection

N2O emissions can play substantial role in CO2 equivalence emissions basis (298xGHG factor vs.

CO2).• Even up to 7 % addition to CO2 equivalence emissions with trucks equipped with SCR

• Fuel is not the decisive factor form N2O emissions, instead the sensitivity for N2O emissions originates from the

SCR chemistry used and exhaust gas temperature

CO2 equivalence emissions


Dual-fuel truck D had the lowest CO2 eqv. emissions• Pure CO2 emissions roughly 19 % less than diesel trucks C and F

• CH4 slip emissions are marginal (roughly under 1 % of CO2 emissions)

• N2O emissions in CO2 eqv. 16 – 42 g/kWh (3 %…7 % of CO2 emissions) depending on hot cycle

Ethanol truck E had CO2 emissions in similar level or a bit lower vs. diesel, , - 4 % … + 1% compared to

diesel

Diesels are not that sensitive to load, whereas for SI gas engines efficiency increases and specific CO2emission decreases with increasing load

Better efficiency of diesel truck C compared to diesel truck F was seen also in CO2 eqv. emissions

CO2 equivalence emissions

WHVC hot start 44 tonsWHVC hot start 30 tons


Truck A performs better on HDV PerE cycle than in WHVC vs. diesel trucks C and F -> The efficiency

difference of SI-engine and diesel engine is reduced in higher loadings• In the HDV PerE, SI truck A delivers roughly 6 % lower CO2 eqv. emissions as diesel trucks C and F

LNG trucks B and D give 7 %…9 % lower CO2 emissions in PEMS route vs. diesel truck C• NOTE: Engine power and work defined by the ECU (comparability?)

CO2 emissions

HDV PerE 30 tons On-road PEMS


Type approval limit value for Euro VI engines in WHTC cycle for NOx is 460 mg/kWh (engine

work specific) • Weighted avg. value (0.14xcold cycle + 0.86xhot cycle)

• In this study, all the work specific emissions are based on the powertrain work. In engine basis they would

be lower depending on the each truck transmission efficiency.

All technologies tested provided combined NOx emission value under the legislative limit

value

Emissions performance in cold and hot cycle depends on technology• In general, trucks equipped with spark-ignited engine and three-way catalyst performed better on cold

start cycle

• Trucks equipped with SCR provided better result in hot start cycle

NOTE: Best performing trucks were Euro VI step D which might also be the effecting factor

not the technology (SCR vs. three-way catalyst) itself

Gaseous emissions


In cold start cycle, NOx emissions were

multiple times higher vs. hot start cycle

depending of the truck

NOx emissions on a really low level in

hot start cycle• Trucks C, D and F had lowest emissions –

even below 30 mg/kWh and with truck F even

under 5 mg/kWh

CNG/LNG trucks A and B also capable of low

NOx emissions – comb. cycle below 300

mg/kWh

• Truck E had the highest NOx emissions

• However on average well below the Euro VI

limit value of 460 mg/kWh (engine work

specific)

Gaseous emissionsWHVC combined


Current HD powertrains are capable on providing really low NOx emissions• Both SI-engines with TWC and engines with SCR are capable on well under 200 mg/kWh NOx emissions

Trucks D and F equipped with SCR produced NOx emissions even below 10 mg/kWh in

high loading WHVC

• Diesel truck F produced NOx emissions even low as 1 mg/kWh

Gaseous emissions



NOx emissions were extremely low also on chassis dyno in HDV PerE cycle

• Trucks C, D and especially F had NOx concentration in the range of couple ppm’s

On-road emissions with PEMS device were on the same level with all the trucks• In exception, truck D had really low NOx emissions on the ISC route

• Also high variation in NOx emission on HDV PerE route with trucks C and D depending on drive

Gaseous emissions

On-road PEMSHDV PerE 30 tons


PM emissions are in really low level – limit value in Euro VI engines type

approval cycle WHTC is 10 mg/kWh

Particulate emissions

WHVC hot start 44 tonsWHVC hot start 30 tons HDV PerE 30 tons

No data

Type approval limit value for Euro VI engines in WHTC cycle is 6x1011 particulate/kWh

Particulate emissions are not a problem for Euro VI trucks independent of the fuel• In direct injection compression ignition engines (diesel, ED 95 ethanol, dual-fuel LNG-diesel) particulate filter takes

care of PN emissions

• Due to the premixed homogenious charge and high H/C ratio of methane, stoichiometric spark-ignited engines without

particulate filter are as well capable for low PN emissions

PN emissions were on a low level with compression ignition

trucks C-F equipped with particulate filter• No difference between cold and

hot start cycles

• However, LNG Truck D had a bit higher

PN emissions vs. diesel and ethanol trucks

SI methane truck B produced also PN

emissions under the limit value

SI methane Truck A had really high

PN emissions with low MN gas both in

cold and hot start cycle• Reason might be party the low MN gas



WHVC combined


On hot start cycles the PN emissions of compression ignition trucks C, E and F on similar or lower level

Dual-fuel Truck D had clearly higher PN emissions vs. trucks C, E and F eventhough it has also

particulate filter

Spark-ignited methane trucks A and B had difference in PN emissions• Truck A had really high PN emissions, especially with low MN gas – well above the limit value

• Truck B had low PN emissions, below the Euro VI limit – however higher than compression ignition diesel and ethanol

trucks




Low PN emissions with trucks B, C and E also in HDV PerE cycle

Trucks A and D had higher emissions

Also in PEMS measurements, trucks B and C had low PN emissions

In PEMS measurements, truck D had deviation in PN emissions depending on the cycle/route – possibly

EAT thermal management / regeneration that nevertheless was not detected?

Particle emissions

On-road PEMSHDV PerE 30 tons


Chassis dynamometer

Overall, the powertains which worked based on diesel process (i.e. compression ignition

and diffusion combustion) gave the lowest energy consumption

Powertains with spark-ignition engines and stoichiometric combustion gave lower efficiency• Nevertheless, the difference was smaller the higher the loading i.e. WHVC 44 tons vs. 30 tons

• Engine high efficiency operation area is smaller for spark-ignited engines compared to diesels

Alternative fuel type engines based on diesel type combustion (direct-injection dual-fuel LNG-diesel and

ED 95 ethanol) performed well• Dual-fuel almost as well as diesel

• Ethanol powertrain similar and in some condition even better than diesel

Regarding CO2 tailpipe emissions, powertrains with diesel process performed best• Diesel and ED95 ethanol engines on similar level

• Dual-fuel LNG-diesel performed the best with advantage from fuel chemistry and almost diesel-like efficiency

Powertrains with spark-ignition methane engines produced slightly lower or slightly higher CO2emissions compared to diesel depending on loading• The higher and less transient the loading the better CO2 result for SI-methane trucks

Summary


Chassis dynamometer

In transient operation with medium loading spark-ignited methane trucks A and B did not

have CO2 benefit over the diesel trucks C and F

On higher loading cycles / operation (HDV PerE simulating long haulage) spark-ignited

methane trucks A and B had some small benefit in CO2 emissions, around 1 – 6 %

On high loading and less transient operation (i.e. long haulage) spark-ignited methane

Trucks may have higher benefit vs. diesel because the engine efficiency difference is not

that high (SI around 40 % vs. CI around 45 %) in high load operation

Dual-fuel Truck D had 5 – 7 % lower efficiency vs. diesel trucks C and F

Ethanol Truck E had the best efficiency, up to 4 % better than the diesel trucks C and F

• However, the difference depended on the cycle, changing between -1.7 % (aggerated

WHVC) … 4 % (HDVPere)

EN15940 HVO improved the efficiency slightly, 1.5 % for truck C and 0.7 % for truck F vs.

regular diesel

Summary


Chassis dynamometer

Regarding CO2 equivalence emissions, truck D (direct-injection dual-fuel) had the lowest

emissions• Roughly 8 – 18 % lower than diesel truck C depending on loading and cycle

N2O emissions (GHG factor 298) may be rather significant source for CO2eqv emissions for

trucks equipped with SCR:• Truck C: 12 – 18 gCO2,eqv /kWh depending on the cycle

• Truck D: 16 – 48 gCO2,eqv /kWh depending on the cycle

• Truck F: 14 – 24 gCO2,eqv /kWh depending on the cycle

The CO2 emissions of ethanol truck E were on similar level as truck C or slightly lower• However, in cold start WHVC truck E had higher CO2 emissions vs. truck C, also lower efficiency

In case of CO2 emissions, results are presented TtW basis -> TtW is not telling the

complete truth, but giving a comparison basis for powertrain level comparisons -> Bio

content is not considered which however have a big effect in global CO2 emissions

perspective• Biomethane, renewable diesel and ED95 ethanol each have much lower CO2 emissions in life cycle

analysis basis vs. fossil fuels CNG, LNG and diesel

Summary


Chassis dynamometer

NOx emissions of new Euro VI trucks are really low• Compression ignition trucks C, D and F with SCR had the lowest emissions, even low as 1 mg/kWh

with truck F

• In hot start WHVC with 30 tons, truck E had the highest emissions of all tested trucks around 370

mg/kWh in powertrain basis, but still well below the limit value (and even lower in engine basis)

Both three-way catalyst and SCR systems are capable of really low tailpipe NOxemissions, even less than 100 mg/kWh when in normal operation temperature

Summary


Chassis dynamometer

PM emissions were in a relly low level with all the trucks tested - well below the Euro VI

limit value of 10 mg/kWh• Spark-ignited methane engine and compression ignition engine with particulate filter are capable of

really low PM emissions

Spark-ignited methane engine (in the best case) and compression ignition engine with

particulate filter are capable of really low PN emissions – well below the Euro VI limit value

of 6x1011 particulate/kWh• PN emissions were in a really low level with compression ignition diesel trucks C and F and ethanol

truck E

• Spark-ignited methane truck A had very high PN emissions – well above the Euro VI limit value of

6x1011 particulate/kWh

• Spark-ignited methane truck B had low PN emissions

• Dual-fuel truck D with particulate filter had clearly higher PN emissions vs. diesel trucks C and F

• Clear reason not yet known - there might have been EAT thermal management or regeneration

active

Summary


On-road PEMS

In engine work basis, trucks B (SI LNG engine) and D (compression ignition dual-fuel) had

the same CO2 emissions• Roughly 7 – 9 % lower than the diesel truck C

In HDV PerE route, dual-fuel LNG-diesel truck D had the lowest CO2 emissions• Around 11 % lower than trucks B and C

New Euro VI trucks are capable for really low on-road NOx emissions• Around 200 mg/kWh for trucks B and C

• Truck D had really low emissions in ISC route, around 30 mg/kWh

Exhaust aftertreatment regeneration or heat mode may cause during short term high

variation in PN emissions as was observed with truck D

Summary

26/05/2020

@VTTFinland www.vtt.fiPetri Söderena

[email protected]

+358 403573420

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