Truck & Off-Highway Engineering - June 2022 - 14

TECHNICAL INNOVATIONS
Kohler has noted that while HVO has less density than current diesel fuels, its higher cetane number
promotes better combustion characteristics.
Reduced emissions at sea
HVO has also been considered for use in
off-highway commercial applications
such as marine and agriculture. In 2019,
SAE published a technical paper from
researchers from the Norwegian
University of Science and Technology,
who performed a series of tests to verify
HVO's applicability as an alternative marine
fuel. The experiments measured
gaseous emissions (NOx, CO, THC and
CO2
) and particulate mass from the tested
marine gas oil (MGO) and HVO fuels.
The test engine for this measurement
was a Perkins 2506C-E15TAG1 inline-six
cylinder four-stroke diesel. This engine
displaces 15L with a compression ratio of
16:1 and is equipped with a turbocharger
as well as variable injection timing.
Emissions measurements were recordHVO
fuel can
drastically reduce
CO2
from Audi's
current-production
4- and 6-cylinder
diesel engines. The
automaker estimates
that HVO is available
in about 600 retail
stations in Europe.
Greenlighting HVO use
Kohler Engines recently approved use
of EN15940-compliant HVOs for its entire
diesel ICE lineup in Europe. The
company claims that the utilization of
HVO will enable a reduction in CO2
emissions of their diesel ICEs by up
90% ( " depending on the raw material
employed in HVO production " ) and that
no engine modifications are required
for their diesels to operate on pure or
blended HVO.
" We are witnessing a growing interest
from customers for use of synthetic
fuel (HVO) and other renewable
fuels, " said Luigi Arnone, Director of
Diesel Engine Engineering at Kohler.
" eFuels are especially interesting, not
only for their positive environmental
impact but also because they reach
performance levels comparable to
diesel fuels. "
The company clarified that even the
use of pure HVO still will necessitate the
use of exhaust aftertreatment systems
14 June 2022
where they are currently required.
However, Kohler also stated that use of
HVO fuels would not require any deviations
in required maintenance schedule
and that their standard European warranty
would be honored.
Kohler also noted that because HVO
fuel has a lower density than diesel, the
mass of fuel injected per cycle is lower
than that of EN590 diesel. The result is
a reduction of overall power and torque
by 1% and 5%, respectively. However,
this is offset by the higher cetane number
of HVO (75) compared to EN590
diesel (51), which promotes better combustion
characteristics.
Light-duty OEMs also have begun to
approve the use of HVO in their current
ICE offerings. Audi recently announced
that its diesel V6 production vehicles
soon will be capable of running on HVO.
The company claims a 70-90% reduction
in CO2
emissions on HVO, as well as
a 30% higher cetane rating than fossilbased
diesel.
ed from the engine exhaust pipe through
a J-shaped sampling probe located after
the turbocharger. The exhaust gas sampling
line, which was heated to a temperature
of 250°C (482°F), transported
the sampled gas to the exhaust gas analyzers
where the gaseous emissions were
measured in accordance with ISO 8178-1
(Reciprocating Internal Combustion
Engines Exhaust Emission Measurement).
The test concluded that the measured
gaseous emissions from HVO fuel
showed generally lower values of observed
CO2
emissions than MGO, despite
the higher registered volumetric fuel
consumption of HVO. One reason for this
is that the combustion process of HVO is
generally regarded as superior, which is
an important factor for CO emissions.
Meanwhile, NOx reduction was around
10-15%, depending on the load point,
and THC emissions were reduced by up
to 55%. There also was a 30% reduction
in PM mass observed on average for
HVO under certain test cycles.
There is evidence that the pure paraffinic
nature of green diesel with a corresponding
absence of aromatics and
other double-carbon chain structures
results in a reduced soot production.
Additionally, the shorter carbon chains
that HVO is composed of also are easier
to oxidize completely in contrast to that
for MGO.
Matt Wolfe
TRUCK & OFF-HIGHWAY ENGINEERING
FROM TOP: KOHLER; AUDI

Truck & Off-Highway Engineering - June 2022

Table of Contents for the Digital Edition of Truck & Off-Highway Engineering - June 2022