Operational Profile Based Optimization Method for Maritime Diesel Engines

This paper presents an approach to a new engine calibration method that takes the engine’s operational profile into account. This method has two main steps: modeling and optimization. The Design of Experiments method is first conducted to model the engine’s responses such as Brake Specific Fuel Consumption (BSFC) and Nitrogen Oxide ( N O x ) emissions as the functions of fuel injection timing, common rail pressure and charged air pressure. These response surface models are then used to minimize the fuel consumption during a year, according to a typical load profile of a ferry, and to fulfill the N O x limits set by International Maritime Organization (IMO) regulations, Tier II, test cycle E2. The Sequential Quadratic Programming algorithm is used to solve this minimization problem. The results showed that the fuel consumption can be effectively reduced with the flexibility to trade it off with the N O x emissions while still fulfilling the IMO regulations. In general, this method can decrease the manual calibration effort and improve the engine’s performance with a tailored setting for individual operational profiles.

The Investigation of Geometric Parameters on the Injection Characteristic of the High Pressure Common-Rail Injector

According the actual structure and working principle of a fuel injector to build a model of the common-rail injector, including the control valve, the solenoid valve, and the needle valve of the injector. The model includes the leakage model for the control piston and needle valve that takes into account increasing leakage at high pressure. The performance of the fuel injector is investigated using a one-dimensional numerical model. Analyzing the effect of the system and structure parameters including common-rail pressure, injection pulse width, inlet and outlet hole diameter, and the injection nozzle on the injection characteristics of the fuel injector. Results show that the geometric parameter is the main property affecting the flow characteristic of the injector, which includes the flow rate of inlet and outlet hole, pressure waves in the control chamber and injection rate. The common-rail pressure, injection pulse width and the geometric parameters mainly affect the injection performance, such as the injection rate and injected volume. The investigation result can provide some useful information to improve the injection characteristic in follow-up studies.