System Design And Control Strategy Study On Integrated Closed Cycle Diesel Engine

The thesis is based on Chaoyang 4102BG industrial diesel engine working as power unit.Research on integration of the closed cycle diesel (CCD) system is carried out through analysis and experimental verification,from the perspective of control methods and structure optimization respectively, improving the level of engineering applications.The closed cycle diesel engine is different from that working under open loop. The absorption ratio of carbon dioxide, oxygen concentration and specific heat ratio of the intake gas are leading factors affecting the operation of CCD. According to basic requirements of affiliated system in closed loop,the corresponding control scheme is designed. The optimized parameters are determined based on the theory analysis and experiments. Control method is realized through programming the software. The thesis includes the following aspects:The integration design of CCD is carried out through designing the control system and optimizing the overall structure and placement of the system component. The system is divided into seven parts, including the power unit, gas distribution system, C02 processing unit, water management system, control system, gas storage and auxiliary system. On this basis, the control strategy of system operation and control loop is studied. In the aspect of system operation,issues including CCD start-up and shut down,open and closed loop transition, closed loop start-up are discussed to improve the automation,replacing the original manual operation. In the aspect of control loop, improvements are achieved on aspects including intake gas heat ratio control loop and pressure control loop, replacing the original control and monitoring method. The rack and the rotational speed signal are introduced to the programmable logic controller (PLC) to obtain the power of the diesel engine and set target operating parameters. The cylinder pressure measurement is replaced by the exhaust temperature measurement to simplify the system operation monitoring method. The sensor and actuator selection, debugging and installation are carried out according to the control system requirements and bench space layout. Advanced control method chosen, control program and monitoring interface written are according to the control strategy. The function of the improved parts is realized.The sensor and actuator selection, debugging and installation are carried out according to the control system requirements and bench space layout. Advanced control methods are chosen to write control program and monitoring interface according to the control strategy.The function of the improved parts is thus realized.Experiments are done based on the improved control loop. Venturi tube specific heat ratio measurement experiment, water level control experiment and power fitting verification experiments are carried out to verify the effectiveness of the control system.Through the above research, the automation of existing CCD engine bench is improved. The systems engineering process is boosted. And new ideas on monitoring methods and structure layout are proposed. This research can provide a reference for the further study of CCD.