Akademik Veri Yönetim Sistemi
International Journal of Automotive Engineering and Technologies, cilt.9, sa.2, ss.94-104, 2020 (Hakemli Dergi)
As a consequence of the emissions-cheating scandals and more strict
emission regulations enforce researchers to reduce emissions out and
find alternative fuels for SI engines. For this purpose, various spark
plugs are available in the market with different electrode materials.
However, they have not been tested together with different engine
parameters. Hence, emissions out from a variable compression
spark-ignited engine with different spark plugs and hydrogen enrichment
were the scope of this study. The tests were conducted with a
four-stroke, single-cylinder, naturally aspirated, variable compression
ratio (VCR) engine. Two different compression ratios (CR) of 8.5:1 and
10:1 at maximum brake torque (MBT) spark timing applied to assess the
effects of different spark plugs and hydrogen usage at different engine
loads. Copper, iridium and platinum spark plugs were tested for each
experiment condition. Also, hydrogen was added through the intake
manifold with flow rates of 0, 2 and 4 l/min to enhance the combustion
of the VCR engine. Carbon monoxide (CO), carbon dioxide (CO2), nitrogen
oxides (NOx) and unburned hydrocarbons (UHC) emission values were
measured in this study. According to test results, with iridium and
platinum spark plug usage, hydrogen addition and higher CR, the engine
emitted lower CO and UHC at all engine loads. However, a higher amount
of CO2 was emitted because of increased completeness of the combustion
and the amount of NOx emissions rose due to increment in-cylinder
temperatures. These variances were more apparent with platinum spark
plug usage compared to the iridium spark plug. As a result, the usage of
iridium and platinum spark plugs were shown lower incomplete emissions
products out, except NOx emissions.