Search Results

Due to the rising price of crude oil, biofuel is being considered as a global alternative for fossil fuels to reduce the emission of greenhouse gases. Diesel blended with bio fuel is currently being widely adopted in many countries. The Taiwanese government has been enforcing the adoption of B2 since 2010. However, there have remained consistent concerns about engine durability related to the use of biofuel, especially regarding after-treatment systems. A selective catalytic reduction system (SCR) has been utilized recently to reduce NOX emission in order to meet the Euro IV and V emission standards. To evaluate the impact of biodiesel on the durability of engines equipped with the SCR system, a long-term testing program was organized for the purposes of this study. The results can be used as a reference for the development of marketing promotion strategies as well as government policies in Taiwan.

To formulate a computer model for a two-stroke engine, the boundary conditions have to be solved for cylinder or crankcase to pipe flow, pipe flow to atmosphere. The models to deal with the former and the latter are often called partially open end model and open end model respectively. In this paper, two types of models for partially open end and two for open end are investigated by comparing the predicted pressure data in the exhaust pipe. Also, two different ways to model transfer pipe are considered. One treats the flow in transfer pipes as quasi-steady flow while the other simulates that with an one-dimensional gas dynamic model. The simulation is based on a zero-dimensional thermodynamic model for cylinder as well as crankcase and an one-dimesional gas dynamic model for pipes. The former uses 4th-order Runge-Kutta method and the latter uses a combined 4th-order Runge-Kutta and two-step Lax-Wendroff (4RK/2LW) method.