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Förslaget inkom 2006-02-10

An Experimental Investigation of Ignition Delay for Different Fuel Qualities

The human need and wish for transportation was and is constantly increasing. Especially cars with internal combustion engines are nowadays one of the major means for human transportation. However internal combustion engines have several drawbacks, like harmful exhaust emissions, e.g. in diesel engines: particles and nitric oxides (NOx), and the use of non-renewable energy sources. Thus ever stricter exhaust emissions regulation in combination with restricted oil reserves (thus even higher oil prices) increases the interest to improve the combustion process or/and use aftertreatment systems.

During the last years modern combustion systems like e.g. HCCI (Homogeneous Charge Compression Ignition) have drawn immense attention of the researchers all over the world since they have shown that it is possible to decrease both the emissions of soot particles and NOx, but with the negative trend to increase the hydrocarbon and carbon monoxide emissions. The main idea of HCCI is to inject the fuel into the combustion chamber and to mix it with the surrounding air, thus to obtain a homogenous mixture, before the combustion starts. The time between the start of fuel injection and the onset of the combustion is called ignition delay time and is dependent on various chemical and physical parameters, like e.g. temperature and pressure of the surrounding air, used fuel, and its cetane number. For HCCI the parameters End of Injection (EOI) and Start Of Combustion (SOC) is of important. Therefore it is very important to investigate the fuel effects (chemical composition) on the ignition delay

This master thesis is a combined constructional and experimental project and will be performed at the Department of Combustion and Multiphase flow at Chalmers University of Technology in a laboratory environment. The very much importance of this thesis is the construction and set-up of a state-of-art ignition delay measurement device and its functional testing. This device is of high importance for the combustion group and it is planned to use this device excessively for other projects after the finishing of the master thesis.
The Master thesis is divided into two parts. The first part of the thesis (the constructional part) consists out of the reconstruction of an existing combustion chamber. This existing combustion chamber (see Figure 1) was originally used on ships, to measure the cetane number of the fuel in order to adjust the injection timing. However in its current form it suffers from high variations of the injected fuel mass, negatively affecting the measurement accuracy. To reduce these high variations, the existing combustion chamber has to be equipped with a regular common rail fuel injection system and a pressure amplifier. The reconstruction work also includes the adaptation of a data acquisition system. The second part of the thesis is the experimental work. The reconstructed combustion chamber will be used to measure and analyse different ignition delay times of different fuels under various gas temperature, gas composition (to simulate EGR) and gas pressure conditions, and analyse the data points deviation


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