Experimental analysis of a dual-fuel internal combustion engine

This thesis reports on the experimental analysis of a dual-fuel combustion cycle, which uses both diesel and hydrogen as fuel sources. The cycle deviates from a standard diesel cycle in that it has a very low compression ratio, which means less work is used during compression. The cycle instead uses the combustion of hydrogen gas to provide conditions suitable for diesel combustion. This approach means a higher power output should be possible, albeit at a lower efficiency, with the use of forced induction to retain the same peak pressure of the diesel cycle. A possible application for this cycle would be in a variable compression engine that has a range of power requirements. A high compression diesel engine would provide lower power outputs at high efficiency during normal operation, while the proposed low compression, dual-fuel cycle would fulfil the less frequent, high power requirements. This thesis details the repair, optimisation and experimental testing and analysis of a dual-fuel internal combustion engine, which operates on this proposed cycle. A prototype hydrogen-diesel engine, which had been built from an existing Yanmar single-cylinder diesel engine, was returned to full operational capacity through diagnosis, repair and replacement of failed components. The performance of the engine in naturally aspirated form was experimentally quantified, showing that it was returned to proper operation. The performance of the engine using simulated forced induction was also quantified. It was shown that the experimental cycle had superior power output to the standard diesel engine when used with forced induction.