Abstract
Diesel engines equipped with spark plug injection system refer to those engines in which the mixture of natural gas
and air enters the cylinder in the suction cycle and then a small amount of diesel fuel is sprayed into the cylinder during
the power cycle as ignition fuel or spark plug injection to be One of the main features of spark plug injection engines is
the drastic reduction of pollution caused by diesel burning. In this research, the investigation and analysis of these
engines have been done from the point of view of energy and exergy. For this purpose, the thermodynamic relationships
governing such an engine are coded by MATLAB software, and the program presents its performance parameters by
receiving the engine characteristics. The main goal of this research is to find the optimal point of the engine performance
in a state where both the efficiency of the first and second law is maximum and finding the main cause of exergy
destruction. The findings of this research show that with the increase in the amount of gas injection in the engine, the
efficiency of the first law of thermodynamics first decreases and then increases. Meanwhile, the efficiency of the second
law of thermodynamics increases as the amount of gas injection increases in the engine. If l the percentage of gas
injected into the engine, the results of optimization with the help of genetic algorithm show that the optimal point of
operation of such an engine in terms of the first and second law of thermodynamics will be in the condition that l ≥ 0.75
Also, the main cause of exergy destruction in engines equipped with spark plug injection system seems to be related to
diesel fuel combustion.
