Development And Experimental Study Of CNG / Diesel Dual Fuel Engine

Active promotion, development and utilization of natural gas as the primary clean substitutes, vigorously exploiting new alternative fuels engine, which have very important significance to achieve energy saving and emission reduction. Introduces the physicochemical properties of natural gas, expounds the characteristics of nature gas as alternative fuel, describes of the classification and characteristics of CNG engine in detail; Through the introduction of fuel supply system of CNG engine, introduces characteristics of gas supply mode in the outside of cylinder. Aiming at the deficiencies of single fuel engine, combining with the domestic and international research Situation, Analysis advantages of the CNG/diesel dual fuel engine. To clearly understand power performance, fuel economy, emission performance of the CNG/diesel dual fuel engine, developed a CNG/diesel dual fuel engine test system which based on electronic controlled high pressure common rail diesel engine.Determined the overall design scheme of CNG/diesel dual fuel engine, retained fuel supply system of the original engine, used the mufti-point sequential gas injection in intake manifold in the outside of the cylinder, Rely on self-designed electronic control system, in order to achieve different substitution rate, selected different amount of diesel and natural gas injection in different conditions. Introduced the working principle of high pressure common rail fuel injection system and electronically controlled gas injection system. The main components and functions of natural gas supply system, the modification design of the engine intake manifold and hot water circulatory system.Elaborated the development process of dual fuel engine electronic control system, Development of electronic control system including hardware platform, the design of control software and driver module. The hardware design of electric control system is mainly made up by sensors, NI PXI-1050 box, PXI-7833R board, power driver board, nature gas rail and nozzle. Depending on the Lab VIEW software FPGA module, developed sensor signal acquisition module、rapid cylinder detection module、gas injection drive module. Debugged Software and hardware, did cylinder detection and gas injection matching test on the dual fuel engine test bench. Finish the gas injection characteristics experiment of gas rail and nozzle.Conducted the experimental study of dual fuel engine, Studied the change trend of the dual fuel engine power performance, economy performance, exhaust temperature, exhaust emissions, the replacement rate etc. The test data showed that the power and the torque of CNG/diesel dual fuel engine were increased compared with the original engine in some extent; in middle and high load the fuel consumption rate was lower than burning pure diesel fuel, which is lower than burning pure diesel fuel in high load; the exhaust temperature increased with the increase of load, which was higher than that of using pure diesel with 10～20 ℃; Soot、NOx and CO2 emissions is lower than the original engine, HC and CO emissions is higher than the original engine, The fuel substitution rate was over 80%. Particularly analyzed main factors affecting the performance of the CNG/diesel dual fuel engine, also proposed corresponding parameters optimization and improvement measures.