Abstract The high energy density of some fossil fuels makes them attractive to power portable devices through the use of thermoelectric conversion elements. The idea explored here is the fabrication of a ceramic combustor using Low Temperature Co- Fired Ceramics tapes. A simultaneous experimental effort is underway and might help us eventually in calibrating the model. Although, before any fabrication, we would like to optimize through simulations the pre-mixing of the fuel (Hydrogen gas) and oxidizer (Oxygen from Air), and the temperature profiles once the flame is active. In order to aid on the design of the mixer, we have simulated the turbulent and laminar flow behavior of three converging streams on a device fabricated using LTCC. The turbulent flow is solved using the k-ε model and the laminar flow using Navier-Stokes. A tracer species is then introduced in the inlets and its journey followed using a mass transport model that includes convective and diffusive components. Various geometries are considered in order to explore which one will yield the best performance. We obtained temperature profiles for an assumed heat source when considering conduction and convection. Profiles are modeled using energy balance and the solution to Fourier equation and its boundary problems.