The shipping industry has reached a higher level of maturity in terms of its knowledge and awareness of decarbonization challenges. Carbon-free or carbon-neutralized green fuel, such as green hydrogen, green ammonia, and green methanol, are being widely discussed. However, little attention has paid to the green fuel pathway from renewable energy to shipping. This paper, therefore, provides a review of the production methods for green power (green hydrogen, green ammonia, and green methanol) and analyzes the potential of green fuel for application to shipping. The review shows that the potential production methods for green hydrogen, green ammonia, and green methanol for the shipping industry are (1) hydrogen production from seawater electrolysis using green power; (2) ammonia production from green hydrogen + Haber–Bosch process; and (3) methanol production from CO2 using green power. While the future of green fuel is bright, in the short term, the costs are expected to be higher than conventional fuel. Our recommendations are therefore as follows: improve green power production technology to reduce the production cost; develop electrochemical fuel production technology to increase the efficiency of green fuel production; and explore new technology. Strengthening the research and development of renewable energy and green fuel production technology and expanding fuel production capacity to ensure an adequate supply of low- and zero-emission marine fuel are important factors to achieve carbon reduction in shipping.
Dead-time element must be set into space vector pulsed width modulation signals to avoid short circuits of the inverter. However, the dead-time element distorts the output voltage vector, which deteriorates the performance of electrical machine drive system. In this paper, dead-time effect and its compensation control strategy are analyzed. Based on the analysis, the voltage distortion caused by dead-time is regarded as two disturbances imposed on dq axes in the rotor reference frame, which degenerates the current tracking performance. To inhibit the adverse effect caused by the dead-time, a control scheme using two linear extended state observers is proposed. This method provides a strong ability to suppress dead-time effects. Simulations and experiments are conducted on a permanent magnet synchronous motor drive system to demonstrate the effectiveness of the proposed method.
The high-pressure SCR system is suitable for low-speed marine engines that burn high-sulfur fuel, but it will cause the increase of the exhaust back pressure of main engine, which will affect the main engine’s performance and fuel consumption. At the same time, due to the large weight and size of the SCR reactor, the overall heat storage performance of the SCR reactor is large, which makes the temperature difference between the front and back of the turbine in the start-up and shutdown of the main engine and transient conditions, affecting the transient response performance of the turbine. In this paper, 6S46ME marine low-speed diesel engine and its high-pressure SCR system are taken as the research object, the co-simulation model is constructed by using GT-Suite coupled with a programming software, and the accuracy of the test model is verified. The influence of high-pressure SCR system on the performance of main engine is analyzed, and it finds that the fuel consumption of the main engine at low load increases significantly greater than that at high load, and the exhaust temperature of the main engine changes differently at different loads. On this basis, the co-simulation model was used to analyze the matching performance of high-pressure SCR system under the transient conditions such as the main engine Tier II/Tier III mode switching process, fast-loading, normal-loading and fast-unloading. The results show that the slow cut-in/cut-out of SCR reactor is beneficial to the stable operation of the main engine system, and the cut-in/cut-out time of high-pressure SCR system greatly affects the transient fuel consumption of the main engine, and the maximum increase of fuel consumption is about 3.6 g/kW·h; In addition, the thermal inertia of the reactor has a greater impact on the performance of the main engine at low load, but not at high load.
With the increasing awareness of global marine environmental protection, the emission of ship exhaust pollutants is strictly restricted. Selective catalytic reduction (SCR) technology is the mainstream technology to reduce ship NOx emission and make it meet IMO tier III regulations. A SCR reaction kinetic model based on Modelica language was established by Dymola software to predict the denitration efficiency, ammonia slip rate, and other parameters of SCR system. According to the functional structure of marine SCR system, the SCR system model is divided into urea injection module, mixer module, and SCR reactor module. The model was verified by SCR system bench test of WD10 diesel engine, which proved that the model can preferably reflect the actual situation. Using the established model, the effects of temperature, flow rate, NH3/NOx Stoichiometric Ratio (NSR), and cell density on the denitration performance of SCR system were analyzed. The results showed that the exhaust gas temperature and NSR have a great influence on the denitration efficiency. The injection amount of urea solution in marine SCR system should be based on the exhaust gas temperature and exhaust flow rate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.