Aug 23 2015 10:30 AM
Aug 23 2015 12:00 PM
On Sunday, August 23, 2015, CCRC organized a seminar titled 'Towards 60% Fuel Efficient Engine'
by Prof. Bengt Johansson. The semianr discussed in detail the potential
that the internal combustion engine has for high fuel effeciency. Read
more about the talk abstract and the bio of the speaker below.
The internal combustion engine has great potential for high
fuel efficiency. The ideal otto and diesel cycles can easily achieve more than
70% thermodynamic efficiency. The problems come when those cycles should be
implemented in a real engine. Extreme peak pressure during the cycle will call
for a very robust engine structure that in turn will increase friction and
hence reduce mechanical efficiency. A very high compression ratio also increase
the surface to volume ratio and promote heat losses, taking away much of the
benefits from the theoretical cycle.
The presentation will start with a standard SI engine
and it’s efficiency as a function of load. Then a high compression ratio SI
with be introduced and compared with the same engine operated in HCCI mode. The
four efficiencies of SI as well as HCCI will be discussed and variations like
HCCI with negative valve overlap and higher mean piston speed will be shown.
A next step is the results with Partially Premixed
Combustion. With PPC the indicated efficiency was shown to be up to 57%, thus
10% up from the best HCCI engine of 47%. However, to get the very high
efficiency a high dilution level is needed. This is a challenge for the gas
management system and hence gas exchange and mechanical efficiencies can
The final part of the presentation is giving an engine
concept that can enable the conditions for PPC combustion but with much
improved gas exchange and mechanical efficiency. It enables an effective
compression ratio in excess of 60:1 but with much less cylinder surface area.
The concept also enables low friction and hence high mechanical efficiency. The
basic concept will be explained and initial simulation results will be
Bengt Johansson is Professor in Internal Combustion
Engines at Lund University since 2001 and head of the combustion engine group
since 2004. He is also director of the Centre of Competence Combustion
Processes with a number of international industry partners since 2003. His
group is among the leaders in low temperature combustion research and has
published more than 250 papers within HCCI. He is also part time professor at
TU Eindhoven, the Netherlands 2011-2015. He was chairman of the SAE Engine
Combustion Committee 2012-2015 and since 2006 chair for the HCCI fuels
collaborative task within the International Energy Agency, IEA.