Saving Fuel - Improving main engine efficiency at reduced ship speed by optimising engine operating characteristics

Abstract

The conditions for the shipping industry are changing dramatically with increasing fuel prices and more stringent emission regulations. As a result, ship owners are often forced to operate their ships at reduced speed to cut fuel costs. This trend has led to an increasing demand in propulsion plant operational flexibility. This study will therefore investigate the possibility of optimising main engine specific fuel consumption at reduced ship speed by comparing certain operational modes that enable different loading conditions for the main engine. The broad scientific knowledge that is already available in the area, is complemented by the case study of a product tanker, addressing the above mentioned research question. The case study provides a useful reality check of the reviewed diesel engine theory and is aimed to examine specific fuel consumption in different operational modes of the case study ship propulsion plant. Case study results indicate that combinator mode operation is markedly advantageous in comparison with fixed engine speed operation, in the lower main engine output region; a conclusion that turns out to have a scientific foundation.