Entropy generation in the intake pipe of an internal combustion engine

The significant pressure drop in the intake valves of the internal combustion engines is one of the problems in the automotive industry. From the point of view of the second law of thermodynamics, the entropy generation under ideal conditions should be zero. The generation of large amounts of local entropy at different locations means the loss of energy in these locations. Finding these locations can lead to the optimization of the intake pipe using the second law of thermodynamics. In this study, the Reynolds averaged Navier-Stokes equations are solved with the help of computational fluid dynamics in the intake pipe of an internal combustion engine. The sensitivity of the results to the computational mesh is evaluated. By comparing the pressure drop of different turbulence models with experimental results, the sensitivity of results to the turbulence modeling is evaluated. The dimensionless entropy generation rate is evaluated at various locations of the computational domain. By integrating the local entropy generation on the volume of the computational domain, the total entropy generation is calculated and the variations of this parameter with different turbulence models are evaluated. Results show that changing the turbulence model does not change the pressure drop significantly, but the entropy generation is sensitive to the turbulence model. Also, the entropy generation near the walls, near the entrance area, in the collision area of the flow with the valve and near the outlet area is high. In addition, the contribution of the main flow in entropy generation is greater than that of turbulence fluctuations.