Han Yongqiang

Notice of Retraction Realization of the simulation platform of turbocharged diesel engine with EGR loop under transient conditions

Currently combustion and emission performance of diesel engine under transient conditions has become the researching focus. Its full of research challenges because of highly variability of engine operations and complexity of chemical reactions. A simulation platform of turbocharged diesel engine with EGR (exhaust gas recirculation) loop under transient conditions, based on the software coupling technique of GT-power and Matlab/Simulink, has been established. It simulated the EGR position step change transient operations and constant speed variable torque (CSVT) transient operation. Compared with the experimental results, it predicts the engine dynamics performance accurately. Based on this, the performance influences in three different kinds of fuel injection mass control strategies to the diesel engine under CSVT transient operation with EGR loop were discussed. It is shown that this simulation platform provides a new research method to improve transient diesel performance and explore control strategies of turbocharged diesel engine under transient conditions.

Simulation on Two-Stage Injection Combustion of Diesel Engine under Light Load

The objective of this paper was to simulate two-stage injection premixed spray combustion of common rail direct injection (CRDI) diesel engine using commercial CFD software code which called STAR-CD. Two-stage Injection with pilot and different injection dwell had been used to achieve premixed combustion. And different intake temperature had been considered to control emissions. The model in this paper had been validated by experimental data. Two-stage combustion with lower NO and soot emissions were achieved by means of well mixed fuel-air mixture. As analyzed, optimizing injection dwell of two split main injection with pilot is able to decrease NO emission without fuel and soot penalty. Second main injection of two-stage fuel injection with pilot was set to 5¡ãBTDC and 0¡ãBTDC. Delay 2cd main injection is meaningful to NO drop while make soot emissions higher.

Discussion of Transient Response Optimization Strategies of Turbocharged Diesel Engine under EGR Step Change Operation

Due to the high cost of engine bench test under transient operations, a transient simulation platform of turbocharged diesel engine with EGR (Exhaust Gas Recirculation) loop was established. Based on this simulation platform, in order to reduce NOx emissions and control the smoothness of combustion process organization of HCCI(Homogeneous Charge Compression Ignition£© combustion mode, four control strategies under EGR step change transient operation were discussed, which were the linear control strategy, the up cast control strategy, the sunken control strategy and the compositive control strategy. From the aspect of transient response of combustion boundary parameters, the up cast and the compositive control strategy are superior to the linear and the sunken. The response time of EGR mass flow rate of the up cast control strategy is 40% shorter than the linear, and it is 57% shorter than the sunken. In order to avoid torque ripple during transient process, the compositive and the linear control strategy are superior to the up cast and the sunken. The torque ripple of the compositive control strategy is 18% lower than the up cast. In terms of reducing NOx emissions during transient process, at one time, NOx emissions of the up cast and the compositive control strategy are 11% and 6% less than that of the linear. Reducing the same 12% of the NOx emissions, the up cast and the compositive control strategy can shorten 38% and 19%response time than that of the linear. From the purpose of reducing Soot emission during transient process, at one time, Soot emission of the linear and the compositive control strategy are 23% and 11% less than the up cast. Reach the same Soot emission value, the time of the linear and the compositive control strategy is slower by 36% and 17%relative to that of the up cast.

High pressure air spray assistant power supply control strategies and their effects on diesel engine under transient operations

In order to reduce smoke from direct-injection (DI) turbo-charged and after-cooled (TCA) diesel engines under transient operations, the real-time controlling and measuring system of a high pressure air spray assistant power supply (HPAS) was developed. Effects of HPAS on a DI TCA diesel engine under constant engine speed and increased torque (CSIT) transient operations were studied by using different control strategies. Pre-spray (PS) strategy, which means supplying highly pressurized air into the exhaust manifold two seconds before the accelerating-graph begins to rise and stopping spraying air when the accelerating-graph stops rising. Two other strategies—full-time-spray (FTS) and middle-time-spray (MTS)—were used to fully exploit HPAS potential. With the FTS and MTS strategies, the HPAS system can remarkably decrease smoke from DI TCA diesel engines under transient operations.