Abd Rashid Abd Aziz

Effect of injection timing on combustion, performance and emissions of lean-burn syngas (H2/CO) in spark-ignition direct-injection engine

This article is aimed at exploring syngas as an alternative fuel for the modern gas engines. It presents the experimental results on the effect of start of injection on combustion, performance and emissions of a direct-injection spark-ignition engine powered by syngas of H2/CO composition. The engine was operated with wide open throttle at minimum advance to achieve maximum brake torque. Two different start of injections were selected to represent before and after inlet valve closing and the excess air ratio (λ) was set at 2.3. The engine operation at start of injection = 120° before top dead center was found to be best for combustion and performance at speed up to 2100 r/min. At engine speed higher than 2100 r/min, this start of injection does not permit maximum performance due to injection duration limitation. Hence, early injection at start of injection = 180° before top dead center was adopted at higher speed with better combustion and performance. Therefore, best performance of syngas in direct-injection spark-ignition engine could be attained by setting start of injection at 120° before top dead center for lower speeds and at 180° before top dead center for speed greater than 2100 r/min. Even though fast combustion of syngas suggested late injection for better combustion, performance and emissions, its lower calorific value resulted in operational limitations for direct-injection system particularly at higher speeds maintaining air–fuel ratio close to the stoichiometry.

Low and Medium Calorific Value Gasification Gas Combustion in IC Engines

Higher hydrogen to carbon ratio of gasification gases produced from solid fuels has been utilized in internal combustion engines (ICE) since long ago. Advancements in the conversion technologies and the abundant availability of solid fuels added with advancements in the technology of gas engines and their fuelling system have renewed the interest and are believed to be transition fuels from carbon based to hydrogen based. Over the past 30 years, there were many trials to bring back the gasification gas technology in ICE. This study is mainly focused on the investigation of technical challenges with lower and medium calorific value gasification gases in IC engines The range of operation of these fuels is found to be influenced by available injection duration and injector pulse width in direct-injection spark-ignition engines. The lower calorific value of these gases also make them less competitive to CNG and H2 in the dual fueling in CI engine even though they have better advantage in the emissions. Furthermore, red glow color deposit was spotted on the surface of the combustion chamber after short running on all fuels that was resulted from decomposition of iron pentacarbonyl (Fe(CO)5) contaminants.

The effect of spray angles of the injector on the power of compressed natural gas direct injection (CNGDI) engine

A study was carried out on the new design of fuel injectors for Compressed Natural Gas Direct Injection (CNGDI) engine. There are two injectors designed with 30° and 70° spray angle was developed and tested. The tests on the injectors were carried out using Single Cylinder Research Engine SCRE with compression ratio of 14:1. The SCRE test bed used computerized data acquisition system. There are two main parameters for the selection of the best injector i.e. the spray angle (30° and 70°) and the operating pressure is set at 2.0 MPa. From the study, the engine performance and the emission were recorded from the test. The results indicated that the injector with 70° spray angle achieved higher performance than the other injector.