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On Reduction of Nitrogen Oxides in Heavy-Duty Engines : with NOx Model Feedback, PPC and SNCR

Muric, Kenan LU (2018)
Abstract (Swedish)
European emission legislation has in recent years put a strict limit on NOx emissions
from heavy-duty truck engines. EGR and selective catalytic reduction are the two most
common technologies applied in a modern heavy-duty diesel engine to fulfill the legislation.
The scope of this thesis is to explore other ways of reducing NOx emissions emitted
by a heavy-duty engine. Several technology options are studied with this particular task
in mind. First, a NOx model was developed and implemented for fast execution on a
field-programmable gate array (FPGA). Model validation showed that a good fit to data
could be achieved with the NOx modeling approach suggested in this thesis. The model
was then used for split... (More)
European emission legislation has in recent years put a strict limit on NOx emissions
from heavy-duty truck engines. EGR and selective catalytic reduction are the two most
common technologies applied in a modern heavy-duty diesel engine to fulfill the legislation.
The scope of this thesis is to explore other ways of reducing NOx emissions emitted
by a heavy-duty engine. Several technology options are studied with this particular task
in mind. First, a NOx model was developed and implemented for fast execution on a
field-programmable gate array (FPGA). Model validation showed that a good fit to data
could be achieved with the NOx modeling approach suggested in this thesis. The model
was then used for split fuel injection control strategy in a Scania D13 to reduce NOx
formation during combustion by defining a threshold value. In order to obtain controllability
with this type of strategy, the net indicated load had to be above 20 bar with a
fuel injection pressure of 700 bar. Still, very little could be done to reduce the formation
of nitrogen oxides with this strategy.

If exhaust temperatures are above 700 ◦C it is possible to obtain thermal reduction
(SNCR) when an ammonia based reductant is added to the exhaust gases. The cylinder
head of the Scania D13 was modified to inject AUS 32 directly into the combustion
cylinder, using the FPGA NOx model as input. However, in most cases only a 15 %
reduction was achieved with SNCR. The SNCR was then tested in a novel split-cycle
engine concept where a large tank is used between the combustion cylinder and expander.
The gas temperature in the tank is high enough for SNCR to occur. In this case, both experiments
and simulations showed high reduction of 40 % to 50 % when the normalized
stoichiometric ration (NSR) is 1. The experiments were run on a modified Volvo HD13
single-cylinder engine. For NSR = 2 and 3, above 85 % reduction of NOx was obtained in
both simulations and experiments. A problem with the strategy was that large amounts
of NH3 would be released into the air. The results suggest that an SCR and ammonia slip
catalyst would still be needed in the final design of the double compression expansion
engine.

Lastly, partially premixed combustion (PPC) was studied in a multi-cylinder VGT Volvo
HD13 engine with respect to soot-NOx trade-off using PRF70 fuel and a novel piston
design. A brake specific NOx emission of approximately 0.4 g/kWh could be achieved
at 1000 Nm with 0.07 g/kWh soot. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Associate Professor Mulone, Vicenzo, Università di Roma, Tor Vergata, Rome, Italy
organization
publishing date
type
Thesis
publication status
published
subject
keywords
aftertreatment, emissions, Engine simulation, engine modeling, SNCR, PPC Engine
pages
212 pages
publisher
Department of Energy Sciences, Lund University
defense location
M:B, Building M, Ole Römers väg 1, Lund University, Faculty of Engineering LTH.
defense date
2018-11-01 10:15
ISBN
9789177538479
9789177538462
language
English
LU publication?
yes
id
9197506d-613f-406c-8415-ba5d42882f36
date added to LUP
2018-10-03 15:02:31
date last changed
2018-11-21 21:41:58
@phdthesis{9197506d-613f-406c-8415-ba5d42882f36,
  abstract     = {European emission legislation has in recent years put a strict limit on NOx emissions<br/>from heavy-duty truck engines. EGR and selective catalytic reduction are the two most<br/>common technologies applied in a modern heavy-duty diesel engine to fulfill the legislation.<br/>The scope of this thesis is to explore other ways of reducing NOx emissions emitted<br/>by a heavy-duty engine. Several technology options are studied with this particular task<br/>in mind. First, a NOx model was developed and implemented for fast execution on a<br/>field-programmable gate array (FPGA). Model validation showed that a good fit to data<br/>could be achieved with the NOx modeling approach suggested in this thesis. The model<br/>was then used for split fuel injection control strategy in a Scania D13 to reduce NOx<br/>formation during combustion by defining a threshold value. In order to obtain controllability<br/>with this type of strategy, the net indicated load had to be above 20 bar with a<br/>fuel injection pressure of 700 bar. Still, very little could be done to reduce the formation<br/>of nitrogen oxides with this strategy.<br/><br/>If exhaust temperatures are above 700 ◦C it is possible to obtain thermal reduction<br/>(SNCR) when an ammonia based reductant is added to the exhaust gases. The cylinder<br/>head of the Scania D13 was modified to inject AUS 32 directly into the combustion<br/>cylinder, using the FPGA NOx model as input. However, in most cases only a 15 %<br/>reduction was achieved with SNCR. The SNCR was then tested in a novel split-cycle<br/>engine concept where a large tank is used between the combustion cylinder and expander.<br/>The gas temperature in the tank is high enough for SNCR to occur. In this case, both experiments<br/>and simulations showed high reduction of 40 % to 50 % when the normalized<br/>stoichiometric ration (NSR) is 1. The experiments were run on a modified Volvo HD13<br/>single-cylinder engine. For NSR = 2 and 3, above 85 % reduction of NOx was obtained in<br/>both simulations and experiments. A problem with the strategy was that large amounts<br/>of NH3 would be released into the air. The results suggest that an SCR and ammonia slip<br/>catalyst would still be needed in the final design of the double compression expansion<br/>engine.<br/><br/>Lastly, partially premixed combustion (PPC) was studied in a multi-cylinder VGT Volvo<br/>HD13 engine with respect to soot-NOx trade-off using PRF70 fuel and a novel piston<br/>design. A brake specific NOx emission of approximately 0.4 g/kWh could be achieved<br/>at 1000 Nm with 0.07 g/kWh soot.},
  author       = {Muric, Kenan},
  isbn         = {9789177538479},
  keyword      = {aftertreatment,emissions,Engine simulation,engine modeling,SNCR,PPC Engine},
  language     = {eng},
  month        = {10},
  pages        = {212},
  publisher    = {Department of Energy Sciences, Lund University},
  school       = {Lund University},
  title        = {On Reduction of Nitrogen Oxides in Heavy-Duty Engines : with NOx Model Feedback, PPC and SNCR},
  year         = {2018},
}