Transient conduction heat transfer simulation of a fuel heater

The reduction of the pollutant emissions of already consolidated technologies like internal combustion engines is one of the orders of the day. Even though rules have changed in Europe, internal combustion engines will continue in production and operation around the world for a considerable time to come. In view of the international efforts to reduce global warming, the pollutant emission rates of internal combustion engines must be urgently decreased. Several innovative strategies are envisaged to reach this objective. Among them, the flexibilization of fuels based on the use of biofuels, like ethanol and blends of biofuels with fossil fuels, in addition to the technique of fuel heating are of great potential. Along with the improvement of the cold phase performance of internal combustion engines, the heating prior to injection into the cylinders of either bio or fossil fuels, as well as of their mixtures, results in considerable decrease in the pollutant emission rates of gases like carbon oxide and non-burned hydrocarbons. Given the short heating time required as well as the high power input, boiling takes place during the fuel heating process. Thus, it is crucial to know in detail the thermal behavior of the heater structure during this process to ensure a safe working condition. Aiming at this objective, the present work presents transient heat conduction simulations of a commercial fuel heater using the software COMSOL. A heat transfer coefficient curve was applied as a boundary condition as if water was the working fluid. These simulations leading to temperature profile along the heater are qualitatively compared with experimental results using a dedicated experimental bench. The initial transient behavior of the current for a 10 V heating test and also the cooling process of the surface after a super-heating condition of the heater were analyzed. Good similarity of shape was found for the analyzed phenomena.