An experimental investigation on optimized manifold injection in a direct-injection diesel engine with various hydrogen flowrates

摘要

In recent days, the importance of environment and energy have been emphasized and, among various energy sources, the fuels for automotive use are attracting attention as they are closely related to day-to-day life. The fossil fuels that are widely used have some serious problems. One of these problems is the limit in reserves, the second problem is that they cannot be recycled, and another problem is that they produce many exhaust emissions. Therefore, various research studies on alternative fuels have been carried out to find a substitute for fossil fuels. Hydrogen, a non-carbon fuel, can meet zero-emission vehicles standards in the future and can be commercially used as a fuel, even though it has a number of technical and economical barriers. For this paper, experiments were conducted to determine the optimized injection timing, injection duration, and injection quantity of the fuel for a manifold injected hydrogen-operated engine using diesel fuel as an ignition source for hydrogen. In the manifold injection technique, the optimized condition is the start of injection at gas exchange top dead centre (TDC) with an injection duration of 30° crank angle (CA) with a hydrogen flowrate of 7.5 l/min. The brake thermal efficiency is found to increase by 9 per cent compared with diesel fuel. Smoke is found to be lower for all hydrogen flowrates at all the load conditions owing to the absence of carbon in hydrogen. CO emissions vary from 0.03 to 0.12 vol % compared with from 0.08 to 0.14 vol % in a diesel fuel investigation. The exhaust gas temperature is found to be slightly higher by 7 per cent for the hydrogen operation compared with diesel fuel. Manifold injection systems with diesel fuel as the ignition source operate smoothly, show improved performance, and emit less pollution than diesel fuel does. It is possible to operate the direct-injection diesel engine smoothly using hydrogen in dual-fuel mode for the entire load spectrum.