In the last decade, many changes and regulations were applied in order to reduce the emissions out of diesel engines, which led to major changes in the chemical composition of the diesel by reducing its sulfur content. In addition, biodiesel fuel is of increasing importance in the automotive and energy sectors. These changes on the fuel helped to reduce hazardous emissions, but at the same time, they affected the performance of water-diesel separators due to their lower surface tension with water. Since water intrusion is inevitable due to transportation, storage, or clearances, it is important to improve the protection of the engines from moisture and to ensure efficient combustion processes (see e.g. , ). This in turn requires a good understanding of the transport and deposition of water droplets inside the coalescers. In order to use computer-aided engineering technology for the optimization of the separation process, reliable models for the prediction of the separation performance of the media are needed.
The fact that filtration and separation are by nature phenomena that connect several size scales imposes a challenge for both modeling and simulation. On the scale of the diesel fuel filter element, quantities like geometry of the medium, its (local) flow resistance and the (local) concentration of the water are relevant. On the other hand, properties of the separator material (e.g. wettability, contact angle), and microscale properties such as mesh geometry and local distribution of water droplets are influencing the deposition of water in/on the medium. This in turn changes the distribution of flow resistance and therefore, the transport of droplets towards the medium. It seems obvious that in order to obtain a macroscopic model, a detailed study of the separation process on the microscopic scale is mandatory.
The present work uses the Computational Fluid Dynamics (CFD) package OpenFOAM®, more precisely a variant of the module “interFoam”, to simulate the interaction of water droplets in a diesel fuel flow with a screen mesh. For the treatment of the liquid mixture, the module utilizes the Volume of Fluid method (VoF)...
Session: F11 - Numerical Methods for Filter Media Characterization and Improvement
Day: 24 October 2019
Time: 13:00 - 14:15 h