The opensource CFD (Computational Fluid Dynamics) software package OpenFOAM has been investigated in this projekt. OpenFOAM was evaluated against results obtained from the commercial CFD program Fluent. The comparison was conducted using geometry of a BFR (Burner Flow Reactor) as base. The BFR have previously been investigated with particle combustion. OpenFOAM has no solver for particle combustion so the comparison are done using two approaches; a cold-flow simulation using a turbulent incompressible solver, and a gas combustion simulation with methane as fuel. The cold-flow simulation showed similar results for both Fluent and OpenFOAM. The gas combustion simulation were done using both fuel-lean and fuel-rich environment. For the fuel-lean simulation, the two codes, were very similar, but in the fuel-rich simulation the temperature profile deviated. The gas combustion model in OpenFOAM is a transient model and significant calculation time were needed. To compensate for this, development of a steady-state gas combustion model have been initiated. The results of the developed combustion models still need some work, before they can compete with commercial software. Overall the OpenFOAM toolbox is considered a solid starting point for developing new code, although considerable time is needed to "reverse engineer" the code.