Heat transfer in a direct contact turbulent exchanger/reactor

Transport of thermal energy between two co-current flows of immiscible liquids is of interest for the improvement of cooling or heating processes, in terms of characteristic time, compactness, and energy cost. The major benefit lays in the dramatic increase of the specific contact area between the two fluids, due to the dispersion of the internal phase in the main flow under the turbulent stresses, compared with a classical double-jacket heat exchanger. Moreover, the thermal resistance of the wall is eliminated, and the diffusive transfer in the drops is linked to the particle size. Hence, turbulence governs the heat transfer both in the dispersion process, and by the heat transfer mechanism at the interface. In this work, the dispersion is realized in a static mixer, namely HEV (High Efficiency Vortex, see figure 1). The study will be carried with the aim of comparing the efficiency of the direct contact system with two reference configurations: wall-transfer in the HEV and direct contact in a simple duct of the same hydraulic diameter, so that both dispersion and geometric advantages could be quantified. Experimental results will be confronted with the classical model of Whitaker to predict the global performance of the device. Moreover, an algebraic 1D model for the axial development of the specific area and the temperature profile will be developed in order to optimize the heat exchanger dimensions. (authors)