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In the present investigation, experiments were conducted in wide open throttle condition (WOT) for different speed ranging from 1400 rpm to 1800 rpm at an interval of 200 on a single-cylinder four-...

This article experimentally investigates the effect of spark timing on performance and emission characteristics of high-speed spark-ignition (SI) engine operated with different hydrogen–gasoline fuel blends. For this purpose, the conventional carbureted SI engine is modified into an electronically controllable engine, wherein an electronically controllable unit was used to control the ignition timings and injection duration of gasoline. The tests were conducted with different spark timings at the wide open throttle position and 3000 rpm engine speed. The experimental results demonstrated that brake mean effective pressure and engine brake thermal efficiency increased first and then decreased with the increase in spark advance. Peak cylinder pressure, temperature and heat release rate were increased until 20% hydrogen addition and with increased spark timings. NOx emissions were continuously increased with the increment in both spark timings and hydrogen addition, whereas hydrocarbon emissions were...

In this study, the effects of 15% methanol + 85% gasoline blend (M15) on cold start HC emissions and performance of an spark ignition engine at idle and wide open throttle (WOT) conditions were investigated when using a thermal barrier layer (TBL) coated piston under various compression ratios (CRs). The performance tests were implemented at three CRs of 8·2, 7·2 and 6·2 for both standard (STD) and TBL piston. When M15 blend was used in the engine with TBL piston at idle, cold start HC emissions decreased considerably at the CR of 7·2. Maximum decreases of 49·45, 47·05 and 32·2% in HC emissions of the engine with TBL piston at WOT were found at the CRs of 8·2, 7·2 and 6·2 respectively. It was observed that the brake power increased at all CRs without knocking, compared to that of the STD engine. Maximum increases of 5·8, 7·56 and 2·55% in the brake power were reached at the CRs of 6·2, 7·2 and 8·2 respectively. Specific fuel consumption of TBL piston engine was found 3·4% lower than that of the ST...

In this study, in order to decrease cold start HC emission at idle and the wide open throttle (WOT) conditions, a thermal barrier layer (TBL) was deposited on the top surface of a piston. The engine was tested at three compression ratios of 8˙2, 7˙2 and 6˙2 and for two different conditions for each compression ratio. At the first stage, cold start HC emission was measured for the first 180 s. Second, the performance and exhaust characteristics were measured at WOT. Cold start HC emission in the engine with TBL decreased compared to the standard engine at the compression ratios tested. While observing an increase in brake power up to 3 and 5% at the compression ratio of 7˙2 and 6˙2 respectively, the brake power decreased up to 6% at the compression ratio of 8˙2 compared to that of the standard engine. Maximum decreases in HC emissions of the engine with TBL piston at WOT were found to be 43˙18, 47˙05 and 32˙12% at the compression ratios of 8˙2, 7˙2 and 6˙2 respectively.

The effects of throttle body injection on fuel spray atomization are examined in terms of their impact on fuel/air distribution in multi-cylinder engines. From exhaust product measurements of individual cylinders in a four cylinder engine, cylinder-to-cylinder uniformity of fuel/air ratio is shown to vary substantially with engine operating conditions. For example, cylinder-to-cylinder variations in fuel/air ratio ranged from 3% at light loads to nearly 15% at wide open throttle. In contrast, substantially different fuel injectors had little impact on the fuel/air distribution. These trends correlated well with previous measurements of throttle body injection systems where throttle position and air flowrate were shown to dominate the spray quality (in terms of drop size and spatial uniformity) and injector effects were of secondary importance. The improved uniformity of fuel/air distribution for light load conditions can be directly attributed to increased air velocity past the nearly closed thro...