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Increasingly strict emission regulations and unfavorable economic climate bring severe challenges to the energy conservation of marine low-speed engine. Besides traditional methods, the energy and exergy analysis could acknowledge the losses of fuel from a global perspective to further improve the engine efficiency. Therefore, the energy and exergy analysis is conducted for a marine low-speed engine based on the experimental data. Energy analysis shows the exhaust gas occupies the largest proportion of all fuel energy waste, and it rises with the increment of engine load. The heat transfer consumes the second largest proportion, while it is negatively correlated to engine load. The energy analysis indicates that the most effective way to improve the engine efficiency is to reduce the energy wasted by exhaust gas and heat transfer. However, the latter exergy analysis demonstrates that there are other effective approaches to improve the engine efficiency.

The wedge clutch takes advantages of small actuation force/torque, space-saving and energy-saving. However, big challenge arises from the varying self-reinforced ratio due to the varying friction coefficient inevitably affected by temperature and wear. In order to improve the smoothness and synchronization time of the slipping process of the wedge clutch, this paper proposes a self-tuning PID controller based on Lyapunov principle. A new Lyapunov function is developed for the wedge clutch system. Simulation results show that the self-tuning PID obtains much less error than the conventional PID with fixed gains. Moreover, the self-tuning PID is more adaptable to the variation of the friction coefficient for the error is about 1/5 of the conventional PID.

High fuel injection pressure has been regarded as a key controlling factor for internal combustion engines to achieve good combustion performance with reduced emissions and improved fuel efficiency. For common-rail injection system (CRS) used in advanced diesel engines, fuel injection pressure can often be raised to beyond 200 MPa. Although characteristics of diesel spray has been thoroughly studied, little work has been done at ultra-high injection pressures. In this work, the characteristics of CRS diesel spray under ultra-high injection pressure up to 250 MPa was investigated. The experiments were conducted in an optically accessible high-pressure and high-temperature constant volume chamber. The injection pressure varied from 50 MPa to up to 250 MPa. Both non-evaporating condition and evaporating condition were studied. A single-hole injector was specially designed for this investigation.

The aim of this study is to evaluate the land requirement, energy consumption and GHG (greenhouse gases) emissions of microalgal biodiesel (M-BD) and Jatropha curcas seeds (J-BD) based biodiesel from the perspective of life cycle assessment (LCA). Mass and energy balance was used through the whole LCA calculation for each process. Two types of biodiesel (100% biodiesel: BD100, and 20% blends of biodiesel: BD20) were assumed to be combusted in the suitable diesel engine. Displacement method was adopted to measure the co-products credits. The results showed that the land requirement of producing 1 kg biodiesel from microalgae was about 1/31 of that from Jatropha curcas seeds. The well to pump (WTP) stage for microalgal biodiesel had higher fossil energy requirement but lower petroleum energy consumption and GHG emissions compared to Jatropha curcas and conventional diesel (CD). The WTP energy efficiency for J-BD100 and M-BD 100 were 26% and 17.4%, respectively.