Numerical Optimization of Compression Ratio for a PPC Engine running on Methanol
Svensson, Erik LU and Verhelst, Sebastian LU
(2019)
2019 JSAE/SAE Powertrains, Fuels and Lubricants International Meeting, JSAE 2019
In SAE Technical Papers
- Abstract
Partially premixed combustion (PPC) has shown to produce high gross indicated efficiencies while yielding lower pollutant emissions, such as oxides of nitrogen and soot, than conventional diesel combustion. Gasoline fuels with a research octane number (RON) of 60-70 have been proposed as optimal for PPC as they balance the trade-off between ensuring good combustion stability at low engine loads and avoiding excessive peak pressure rise rates at high loads. However, measures have to be taken when optimizing the engine operating parameters to avoid soot emissions. In contrast, methanol has a much lower propensity for soot formation. However, due to a higher RON of methanol the required intake temperature is higher for the same engine... (More)
Partially premixed combustion (PPC) has shown to produce high gross indicated efficiencies while yielding lower pollutant emissions, such as oxides of nitrogen and soot, than conventional diesel combustion. Gasoline fuels with a research octane number (RON) of 60-70 have been proposed as optimal for PPC as they balance the trade-off between ensuring good combustion stability at low engine loads and avoiding excessive peak pressure rise rates at high loads. However, measures have to be taken when optimizing the engine operating parameters to avoid soot emissions. In contrast, methanol has a much lower propensity for soot formation. However, due to a higher RON of methanol the required intake temperature is higher for the same engine compression ratio to ensure auto-ignition at an appropriate timing. Increasing the compression ratio allows a lower intake temperature and improves combustion stability as well as engine brake efficiency. Nevertheless, a higher compression ratio generally increases in-cylinder heat losses and peak pressure. These effects were investigated in a simulation study, which combined 0-D and 1-D models, of a multi-cylinder heavy-duty Scania D13 engine operated in PPC mode and running on methanol. Engine experiments from a single-cylinder engine at different compression ratios were used to validate the simulation models. The optimal compression ratio from a brake efficiency perspective was found for four operating conditions from the 12 mode non-idle European stationary cycle supplemental emissions test points. This compression ratio was then used for optimizing key engine parameters. The results showed that a 21.6:1 compression ratio was optimal instead of the original 17.3:1 compression ratio. Especially at lower engine loads, a significant increase in brake efficiency was found. The main reason was a lower intake temperature which increased the average ratio of specific heats and allowed for a lower boost pressure.
(Less)
- author
- Svensson, Erik
LU
and Verhelst, Sebastian
LU
- organization
- publishing date
- 2019-12-19
- type
- Chapter in Book/Report/Conference proceeding
- publication status
- published
- subject
- host publication
- 2019 JSAE/SAE Powertrains, Fuels and Lubricants
- series title
- SAE Technical Papers
- article number
- 2019-01-2168
- publisher
- Society of Automotive Engineers
- conference name
- 2019 JSAE/SAE Powertrains, Fuels and Lubricants International Meeting, JSAE 2019
- conference location
- Kyoto, Japan
- conference dates
- 2019-08-26 - 2019-08-29
- external identifiers
-
- scopus:85084439531
- ISSN
- 0148-7191
- DOI
- 10.4271/2019-01-2168
- language
- English
- LU publication?
- yes
- id
- 050fc786-ee30-431e-afb7-7a987c7f952c
- date added to LUP
- 2020-05-26 11:08:23
- date last changed
- 2022-04-18 22:43:38
@inproceedings{050fc786-ee30-431e-afb7-7a987c7f952c,
abstract = {{<p>Partially premixed combustion (PPC) has shown to produce high gross indicated efficiencies while yielding lower pollutant emissions, such as oxides of nitrogen and soot, than conventional diesel combustion. Gasoline fuels with a research octane number (RON) of 60-70 have been proposed as optimal for PPC as they balance the trade-off between ensuring good combustion stability at low engine loads and avoiding excessive peak pressure rise rates at high loads. However, measures have to be taken when optimizing the engine operating parameters to avoid soot emissions. In contrast, methanol has a much lower propensity for soot formation. However, due to a higher RON of methanol the required intake temperature is higher for the same engine compression ratio to ensure auto-ignition at an appropriate timing. Increasing the compression ratio allows a lower intake temperature and improves combustion stability as well as engine brake efficiency. Nevertheless, a higher compression ratio generally increases in-cylinder heat losses and peak pressure. These effects were investigated in a simulation study, which combined 0-D and 1-D models, of a multi-cylinder heavy-duty Scania D13 engine operated in PPC mode and running on methanol. Engine experiments from a single-cylinder engine at different compression ratios were used to validate the simulation models. The optimal compression ratio from a brake efficiency perspective was found for four operating conditions from the 12 mode non-idle European stationary cycle supplemental emissions test points. This compression ratio was then used for optimizing key engine parameters. The results showed that a 21.6:1 compression ratio was optimal instead of the original 17.3:1 compression ratio. Especially at lower engine loads, a significant increase in brake efficiency was found. The main reason was a lower intake temperature which increased the average ratio of specific heats and allowed for a lower boost pressure.</p>}},
author = {{Svensson, Erik and Verhelst, Sebastian}},
booktitle = {{2019 JSAE/SAE Powertrains, Fuels and Lubricants}},
issn = {{0148-7191}},
language = {{eng}},
month = {{12}},
publisher = {{Society of Automotive Engineers}},
series = {{SAE Technical Papers}},
title = {{Numerical Optimization of Compression Ratio for a PPC Engine running on Methanol}},
url = {{http://dx.doi.org/10.4271/2019-01-2168}},
doi = {{10.4271/2019-01-2168}},
year = {{2019}},
}