复合循环系统辅助低压缩比柴油发动机压燃工作的可行性研究

A single-cylinder four-stroke diesel engine with a compression ratio of 9.5 was used to simulate a rotary engine, and an intake air heating system based on compound cycle was proposed, an experimental study on the effect of this system on cold start and stable operation of low compression ratio diesel engine was carried out, which verified the feasibility of diesel rotary engine working in compression ignition mode by increasing the intake air temperature, explored the optimal operation strategy of compound circulation system in the warm-up process, and determined the optimal intake air temperature for stable operation of the engine. The results show that the use of compound circulation system to heat the intake air can achieve stable cold start of low compression ratio diesel engine, and the minimum intake air temperature required for cold start is 373 K; when the engine speed is 2 000 r/min, there is an optimal intake air temperature under different loads, which maximizes the engine output torque, and the optimal intake air temperature under high load conditions is 363 K; the total energy consumption and time spent in the warm-up phase decrease with the increase of the intake air temperature at the time of electric heating exit. Considering the energy consumption, time consumption and practicability, the optimal intake air temperature for electric heating exit is 393 K. After the warm-up operation for a long time, the intake air temperature can be maintained at a high level only through the exhaust waste heat recovery device, thus ensuring the stable compression ignition operation of the engine.