Comparing the performance of a CI engine after replacing the mechanical injector with a common rail solenoid injector

In this investigation, the mechanical injector (four orifices in nozzle) in a compression ignition single-cylinder engine (Daedong with the maximum power of 11 hp) was replaced with a common rail fuel injection system with a solenoid injector (eight orifices in nozzle) and the operation of the engine with both of these injectors was experimentally studied and compared. To do so, the operation of the solenoid injector in two different start of injection timings was analyzed. At first, the injection control system for the common rail solenoid injector system was designed and the ability to control direct injection of the fuel into the combustion chamber in terms of injection pressure, injection duration and the start of injection timing was achieved. After that, the function of the engine in combustion characteristics and emission aspects was investigated. The tests were performed in the fixed speed of 1150 rpm, in idle condition and in the low-load operation with a brake power of 1.22 kW on the engine. With the pressure data from the experiments, the heat release rate, total released energy, start of combustion, ignition delay, combustion duration, combustion efficiency and fuel conversion efficiency were calculated. The results showed that with replacing the mechanical injector with common rail solenoid injector system, in the same injection timing, in order to reach the same brake work in low-load operation, the combustion duration was extended, and also the combustion and fuel conversion efficiencies were increased by 7% and 3%, respectively. Besides, particulate matter (PM) and NOx emissions were reduced.