Different camshaft profile analyses for natural gas engine performance and emission

Recently, the environmental crisis and the negative influence of gasoline and diesel fuels on it, together with these fuels high cost persuaded manufacturing companies to use natural gas as substitute fuel. Considering the same volumetric efficiency and fuel penetration, natural gas needs more space because of its much lower density in comparison to liquid fuels. In this regard, the Miller cycle as the fifth-thermodynamic cycle in internal combustion engines is discussed. Increasing the expansion ratio along with the compression by changing in the intake valve closure is the main characteristic of this cycle. In this study, AVL FIRE software is used to simulate D87 gas engine. Since the close cycle cannot examine valve lifting effectively as well as turbo charging, one-dimensional simulation by GT Power software is used. After their parallelism with each other, four camshaft timing was used as well as Otto cycle. Results show that there is a reduction in the maximum pressure and temperature with slight increment in power. Also due to decrease in peak temperature, NOx diminishes obviously.