e-POWER's internal combustion engine achieves 50% thermal efficiency
Efficient, fixed-point operation is achieved by restricting the engine's operating range, which is only possible for an engine that is dedicated to electricity generation
Improving
engine
efficiency
is
an
issue
that
is
common
to
automobile
manufacturers,
and
a
maximum
of
approx.
40%
thermal
efficiency*1
is
being
achieved.
However,
it
took
almost
30
years
to
improve
thermal
efficiency
from
30%
to
40%.
With
e-POWER,
Nissan
specializes
the
role
of
the
engine
for
electricity
generation,
and,
furthermore,
achieves
a
thermal
efficiency
of
50%
through
lean
combustion*2
based
on
the
unique
STARC*3
concept
and
waste
heat
recovery
technology.
This
makes
it
possible
to
further
improve
fuel
efficiency
and
to
reduce
CO2.
- Thermal Efficiency: Ratio of the fuel's energy that can be extracted as power
- Lean Combustion: Combustion with an air-fuel mixture ratio that has more air than the theoretical air-fuel ratio (wherein the fuel and oxygen reaction have perfect proportions; that is, the ratio of completely burned air to fuel). Lean combustion with an excess air ratio of λ = 2 is assumed.
- STARC: Strong Tumble & Appropriately stretched Robust ignition Channel
System Mechanism
By specializing the engine for electricity generation, it can be operated in its most efficient range. Furthermore, Nissan will continue to develop its battery technology to achieve fixed-point driving to achieve the most efficient driving possible. Through this, fuel economy can be improved.
Based on the unique STARC concept, the intake manifold, combustion chamber, and piston shape are optimized for the fixed-point operating range of the electricity generation engine and form a stable and extended spark plug discharge channel*4 by maintaining a strong tumble flow in the center of the cylinder. This enables stable combustion under highly diluted conditions, such as high EGR*5 and lean combustion, and improves thermal efficiency.
- Discharge Channel: The flow of electricity through the air discharged for ignition.
- EGR (Exhaust Gas Recirculation): Technology that recirculates a portion of the exhaust gases after combustion, intaking them again. Although combustion of the air-fuel mixture diluted via EGR improves thermal efficiency, ensuring combustion is a challenge.
Measures to Achieve 50% Thermal Efficiency
For
conventional
engine
technologies,
basic
thermal
efficiency
was
improved
by
lengthening
the
stroke
and
reducing
friction.
Furthermore,
by
restricting
the
engine's
operating
range
utilize
e-POWER,
it
is
possible
to
improve
the
theoretical
thermal
efficiency
using
high
EGR
combustion
under
the
STARC
concept,
reducing
intake
and
exhaust
losses
via
the
dedicated
turbo,
achieving
a
net
thermal
efficiency
of
43%.
Additionally,
due
to
the
evolution
of
battery
technologies
in
the
future,
through
the
shift
to
fixed-point
operation,
the
engine
will
achieve
50%
thermal
efficiency
through
lean
combustion
based
on
the
STARC
concept,
even
further
reductions
in
friction,
and
efficient
recovery
of
waste
heat.
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