Il comportamento del sistema urea del veicolo in climi freddi: sviluppo di un metodo di calcolo mediante CFD = Urea system in automotive and its behaviour in cold weather: development of a calculation method with CFD

Urea system in automotive and its behaviour in cold weather: development of a calculation method with CFD Nowadays is very important in engineering fields dealing with transport, as automotive, but also aerospace engineering, to control and to reduce polluting factors. In this work an urea based system for automotive purposes is analysed from a thermofluidodynamic point of view. This kind of solution is adopted in diesel engines in order to decrease the nytrogen oxides emissions and to comply new EU requirements for combustion cars. The problem of icing or deicing and its simulation in the CFD software STAR CCM+ in order to create a method to run the cases related to deicing of the urea system is considered in this work. The necessity of a software method for tests with a commercial script is clear if we think about the evolution of virtual means for engineering problems; as a matter of fact real tests as wind tunnel or on the road tests in order to assess performance or reliability of products are less used now than the artificial ones. This changement is necessary beacause of budgets reduction and ready availability of the instruments of simulation, but in this moment physical evidence has been fundamental for the modelling of the phenomenon and for further validation of the method. In this background this work is intended to create a new mean for analysis using existing software on FCA's vehicle equipped with urea system and it is intended to set a new prediction of wind tunnel tests, in order to avoid useless ones and select only the most important for certification process. The first part of the work has been the preparation of the model in ANSA software, in order to check the geometry and to create a mesh ready to use in CFD solver. Once finished all the required tests, as required for mesh procedure, the work became a research of the best solvers in STAR CCM+ in order to simulate the initial phases of icing and then de-icing of a mixture made of solid and liquid phases, starting from the state of art examples. Last part of the work has been the running of several cases and their analysis: there were several levels of precision during this phase, first guesses were primitive releases of the complete model. At this stage a thermal approach with TAITherm software was required, working in combined simulation with STAR CCM+. In the end proposals for further development followed. This work has been performed in FCA AeroThermal Buildings, located in Orbassano (TO).