Jia Yi Du

Simulation Research of the Effect of Compression Ratios on Combustion and Emission for Methanol/Diesel Dual Fuel Engine

This paper has studied the influence of the different ratio on combustion process and emissions of air premixed methanol/diesel dual fuel engine. The research was based on 4B26 diesel engine, and the 3-D numerical simulation on combustion process and emissions of the diesel engine with intake premixed methanol was carried out using AVL FIRE software. The study showed that,with the compression ratio reducing,the ignition delay period prolonged, and the ignition timing delayed, the maximum firing pressure, the peak of pressure rise rate and the maximum combustion temperature in cylinder decreased, the crank angle postponed, the NOX emission decreased and the Soot emission increased obviously.

Effect of Expansion Tube Structure on Regeneration of Diesel Particulate Filter

The regeneration process is simulated under the condition of different expansion tubes by the established model on CFD technology. It turns out that, increasing expansion angle of the expansion tube does good to lower the maximum wall temperature and the axial temperature gradient during the DPF regeneration, while it makes the uniformity of the wall regeneration temperature worse. At the same time, the regeneration rate becomes slower and the radial maximum temperature gradient increases. This study makes great significance to the design and optimization of DPF device structure and prolonging the service life of DPF.

Effect of Cetane Number Improver on Emission Characteristics of Methanol/Diesel Blend Fuel

The influence of cetane number improver on emission characteristics of diesel engine fueled with methanol/diesel blend fuel was investigated. Methanol/diesel blend fuel was prepared, in which the methanol content is 10%, different mass fraction (0%，0.5%) of cetane number improver were added to the blend fuel. Load characteristic experiments at maximum torque speed of the engine were carried out on 4B26 direct injection diesel engine. The results show that, compared with the engine fueled with diesel, the CO emission increases under low loads and reduces under medium and high loads, the HC emission increases, the NOx emission decreases under medium and low loads and increases under high loads, the soot emission reduces significantly when the diesel engine fueled with blends. When cetane number improver was added to blends, the CO and NOx emission reduces, the HC emission decreases, the soot emission increases to some extent compared with the methanol/dieselblend fuel without cetane number improver.

The Study on Control Strategy of Rail Pressure in the Starting Process for Common Rail Diesel Engine

The analysis on the characteristics of each period in the starting process for common rail diesel engine was carried out. Rail pressure simulation model in the starting process was set by Matlab/Simulink. And rail pressure was tested in 4JB1 high pressure common rail diesel engine. The experimental results showed that idle rail pressure and engine speed fluctuated severely. Solution to correction of duty of metering unit(MeUn) at initial period was proposed, and effect of dragged laps on duty of MeUn was added in control strategy. The improved experimental results showed that amplitude of rail pressure fluctuation was very small and idle speed was no longer overshoot. The performance of diesel engine in the starting process has been greatly improved.

Control Strategy and Realization of Dual Fuel Engine with Intake Premixed Methanol on Turbocharging Diesel Engine

Based on Methanol and diesel special combustion mode, a control strategy of methanol/diesel dual fuel engine on turbocharged DI diesel engine was introduced according to different operation conditions. A method of judging engine load by measuring intake manifold pressure was put forward. Bicubic interpolation method was adopted to optimize the control MAP for ensuring the coincidence between look-up table data and actual conditions. The feasibility of the control strategy is verified by bench test. And the results of test show that the economic performance of this dual fuel engine got a considerable improvement.

The Study of HEV Special Two-Stage TWC Characteristics

As there are many shortcomings for the traditional three-way catalyst (TWC),too large thermal inertia ,low heat capacity and poor thermal insulation properties .A new hybrid vehicles special two-stage TWC is designed.The experiment was carried out at drum test bench and frequent start/stop cycle condition.The result shows that the first-stage catalyst core temperature was maintained at 450°Cafter engine stop 200s, the peak value of HC emissions is only exist at the beginning 30 sec and the conversion efficiency of NOx up to 90% .The hybrid vehicles special two-stage TWC fully meet the frequent start / stop and transient cycle conditions requirment.

Analysis on Mean Value Model of Gasoline Engine in HEV Applications

A mean value model of the 1.5L gasoline engine was established. It mainly consists of fuel film model, transient fuel film compensation model and dynamic output model. After the validation of steady state, the power and economic performances were analyzed with NEDC drive cycle. Together with engine operating points, special attention was such key parameters as paid to engine speed, engine torque and fuel consumption. The dynamic model is validated. The air-fuel ratio fluctuation was studied to validate the fuel film model.

Research on Transient Fuel-Film Compensation Control Strategy for a Port-Fuel-Injected Engine

The fuel-film evaporation model and transient fuel-film compensator model were established. By virtue of Simulink, the validity of above models were verified. The square wave perturbation method was introduced. Basing numerous calibration, the fuel-film compensation strategy including zoned compensation and damping factors ware proposed. This new strategy can compensate in-cylinder fuel fluctuation effectively during transient conditions.

Transient Combustion and Hydrocarbon Emission Characteristics of a Port-Fuel-Injected Engine

An experimental paltform for simulating the starting process of a PFI engine was set up. The contrastive analysis of prototype engine between conventional start with starting motor and high-speed cranking start with ISG (Integrate Starter/Generator) was carried out. Variation regulation of the transient engine speed, the cylinder pressure, the fuel compensation factor, the intake manifold pressure and the transient HC emission were elaborated. The results show that, with the increase of cranking speed, the intake air pressure dropped, and the intake air quantity reduced as well. The duration of fuel evaporation was shortened, so the fuel atomization was insufficient. The possibility of misfire was increased and the transient HC emission was prominent. All these phenomena had a close relationship with ECT (Engine Coolant Temperature). Fuel compensation in the first few working cycles during starting process could make the original lean mixture more preferable in order to improve the combustion environment.

Development of Electronic Throttle Controller Based on LabVIEW Embedded Module

The mathematical model of electronic throttle was established in this paper, and a sliding mode control algorithm was designed based on the model. The simulation made to validate the control algorithm was achieved by LabVIEW Control and Simulation Toolkit. The control program was converted to C code and downloaded to the controller by LabVIEW embedded module. The simulation results showed that the controller met the ideal effect. There are many advantages of this kind of development mode, such as graphical programming, rich function module and code automatic generation. The development efficiency and quality can be increased.