The Influence of Thermal and Mechanical Loads on The Piston when the Engine Operates on CNG Fuel is Assessed

This study numerically simulates the mechanical and thermal durability of a diesel engine piston after conversion to compressed natural gas (CNG) operation. Combustion cycle simulations indicate that the peak pressure and temperature increase by 37.44% and 2%, respectively, when using CNG, thereby altering the piston’s operating conditions. The analysis results show a significant reduction in mechanical loading, with maximum stress and deformation decreasing by 45% and 43.75%, respectively, compared with diesel operation. In contrast, thermal loading increases, leading to a corresponding rise of 5% and 4% in thermal stress and thermal deformation, respectively. Under combined loading, the total stress decreases slightly by 5%, whereas the total deformation increases by 8%, reflecting the high-temperature but low-pressure combustion characteristics of CNG. Although the piston remains within allowable operating limits, thermal loading is identified as the dominant factor governing failure risk. These findings provide essential technical insights for optimizing piston design and cooling systems to enhance the reliability of CNG-converted engines.

CNG fuel; Internal combustion engine; Mechanical load; Thermal load

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