22-May-2013
02:35:37 IST
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NISCAIR ONLINE PERIODICALS REPOSITORY (NOPR) >
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Indian Journal of Engineering and Materials Sciences (IJEMS) >
IJEMS Vol.13 [2006] >
IJEMS Vol.13(4) [August 2006] >
| Title: | Optimization of inlet valve closure timing and clearance volume of a SI engine for better performance at part loads A numerical and experimental approach |
| Authors: | J M Mallikarjuna, J M
V Ganesan, V |
| Issue Date: | Aug-2006 |
| Publisher: | CSIR |
| IPC Code: | F01L1/34 |
| Abstract: | In this paper, a computer simulation and experimental
investigations on a single cylinder, four-stroke, spark ignited engine are
carried out to optimize inlet valve closure timing and clearance volume for
better part-load performance. The simulation procedure involves thermodynamic
and global modeling techniques. Many sub-models have been used for predicting
heat transfer, friction and gas exchange processes. Unburned hydrocarbons,
carbon monoxide and nitric oxide emissions are also predicted.
Experiments
have been conducted on a single cylinder, air-cooled, four-stroke,
spark-ignited engine. In this work, by varying inlet valve closure timing (IVCT)
and clearance volume, geometric expansion ratio (GER) of engine alone is
varied, while effective compression ratio (ECR) is kept constant, thereby
GER/ECR ratio is altered. For modified engine, GER/ECR ratio is varied from
1.25 to 2. Experiments have been conducted for two effective compression
ratios, viz., 7 and 8 at a speed of 1200 rpm. Performance and exhaust emission
characteristics have been measured at different loads and GER/ECR ratios. The
predicted performance and emission characteristics are compared with measured
values and the agreement between the two is found to be good. It is observed
that, for modified engine, considerable improvements have been found in the
reduction of pumping losses (about 25.8 to 56%), increase in the brake thermal
efficiency (about 13.6 to 25%), and reduction in unburned hydrocarbon emissions
(about 18.5 to 58%). Finally, for modified engine, it is found that GER/ECR
ratio of 1.5 gives the best performance compared to standard engine for both
compression ratios. |
| Page(s): | 307-321 |
| ISSN: | 0975-1017 (Online); 0971-4588 (Print) |
| Source: | IJEMS Vol.13(4) [August 2006]
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