Correlation of Single-Cylinder to Multi-Cylinder Performance for a Medium Speed Diesel Engine

Single-cylinder research engines are valuable tools in the development of multi-cylinder reciprocating engines. The financial advantages of single-cylinder testing increases with engine size offering even larger benefits for medium-speed engines than light-duty automotive or heavy-duty truck engines. While testing on a single-cylinder engine provides a number of economic and technical advantages [1], careful planning and setup are required to maximize the usefulness of single-cylinder results as predictive of multi-cylinder performance. This paper describes the methodology used to set up and operate a single-cylinder medium speed diesel engine for combustion performance testing. An overview of the test cell design, infrastructure and instrumentation is provided, along with detailed specifications of the engine. There is good correlation between the single-cylinder and multi-cylinder performance when the gas-exchange-and frictional loss differences are taken into account. The strategy and results for this correlation effort are presented and discussed. The apparent rate of heat release was very consistent between the MCE and the SCE for the same load and injection timing. For other parameters, it was found that the single-cylinder engine contains biases relative to the absolute values observed from a full multi-cylinder engine, but the single-cylinder results are very useful in identifying relative performance trends and in performing in-cylinder optimization.