Analysis of Thermal Efficiency Improvement of a Highly Boosted, High Compression Ratio, Direct-Injection Gasoline Engine with LIVC and EIVC at Partial and Full Loads

2015-01-1882

09/01/2015

Event
JSAE/SAE 2015 International Powertrains, Fuels & Lubricants Meeting
Authors Abstract
Content
The improvement mechanism of fuel consumption at partial and full loads of a boosted direction-injection gasoline engine with the elevated geometrical compression ratio and Miller cycle by either early or late intake valve closing (EIVC or LIVC) are analyzed based on the first law of thermodynamics and one dimensional engine simulation. An increase in geometric compression ratio increases the theoretical thermal efficiency for all the operating loads, but deteriorates the fuel economy at full loads, owing primarily to the full-load knock limit. Use of Miller cycle improves the fuel economy for both the partial and full load operations by reducing the pumping loss and optimizing the combustion phasing, respectively. A comparison between EIVC and LIVC on the influencing factors on the thermal efficiency at the partial load shows that EIVC leads to higher mechanical efficiency and less heat transfer loss than LIVC, and hence its efficiency improvement is superior over LIVC. In comparison with EIVC, the LIVC strategy performs better in reducing fuel consumption at the full load thanks to its more efficient burning and optimized combustion phasing in cylinder.
Meta TagsDetails
DOI
https://doi.org/10.4271/2015-01-1882
Pages
10
Citation
Zheng, B., Yin, T., and Li, T., "Analysis of Thermal Efficiency Improvement of a Highly Boosted, High Compression Ratio, Direct-Injection Gasoline Engine with LIVC and EIVC at Partial and Full Loads," SAE Technical Paper 2015-01-1882, 2015, https://doi.org/10.4271/2015-01-1882.
Additional Details
Publisher
Published
Sep 1, 2015
Product Code
2015-01-1882
Content Type
Technical Paper
Language
English