An experimental investigation to study the performance and the emission characteristics of a spark ignition engine operating on a natural gas-air mixture with a partial injection of liquid spray has been carried out. A light kerosene has been injected into the combustion chamber of the engine through an adopted injection system.
Measurements of power output and fuel consumption as well as concentrations of CO , HC NO in the exhaust gas have been made for a range of gas-air mixture ratios and different values of injected liquid spray mass fraction. The pressure variations in the combustion chamber have been detected and recorded by a piezo type transducer and a dual channel oscilloscope respectively.
The obtained results show that a partial injection of liquid kerosene into the spark ignition engine working on a natural gas-air mixture leads to improve engine performance for lean mixture ratios.
The region of engine stable operation is extended by 20 – 30 percent, while the maximum power output is increased by 5 – 10 percent for constant operating conditions. This is due to the fact that the injected liquid particles will improve both volumetric efficiency and burning velocity for gas-air lean mixtures. Also, a significant reduction in the emission of the nitric oxide compared to the case without a partial injection of kerosene has been obtained.