Heat and mass transfer of laminar jets impinging a heated surface*

The features of catalytic reactors result from the interplay of catalyst properties and the heat and mass transfer near the active surface. The last one has an important effect on the reaction rate and thus on the reactor efficiency. A multi impinging jet configuration is studied here. The resulting flow dynamics are analyzed with the scope of enhancing the surface heat and mass transfer and thus improving the catalytic reactor efficiency.

Laminar twin impinging jets and a matrix of four impinging jets are computed by 3D numerical simulations with the CFD software OpenFOAM. The influence of the Reynolds number, jet-to-jet spacing and the temperature gradient between jets and the catalytic sample are characterized. Mass transfer near the sample is then investigated by injecting a passive scalar. Jet interactions are classified and a topological diagram is established for both the twin-jet and the matrix of four impinging jets. Between the jets, a fountain flow emerging from the collision of two counter wall-jets is observed for a given range of parameters, affecting the heat and mass transfer on the active surface and a fortiori in the whole domain. A chemical reaction model is then added to the solver where the reaction rate follows a Langmuir Hinshelwood model. The objective being to characterize as a function of different above parameters, the global production of such a system.