Characterization of the performances of an innovative heat-exchanger/reactor

Abstract

International audienceThe use of heat exchanger/reactors (HEX/reactors) is a promising way to overcome the barrier of poor heat transfer in batch reactors. However to reach residence time long enough to complete the chemistry,low Reynolds number has to be combined with both a plug flow behaviour and the intensification of heat and mass transfers. This work concerns the experimental approach used to characterize an innovative HEX/reactor. The pilot is made of three process plates sandwiched between five utility plates. The process stream flows in a 2 mm corrugated channel. Pressure drop and residence time distribution characterizations aim at studying the flow hydrodynamics. Identified Darcy correlations point out the transition between laminar and turbulent flow around a Reynolds number equal to 200. Moreover the flow behaves like a quasi-plug flow (Pe > 185). The heat transfer and mixing time have also been investigated. The ratio between the reaction kinetics and the mixing time is over 100 and the intensification factor ranges from5000 to 8000 kW m−3K−1. As a consequence, no limitations were identified which allows the implementation of an exothermic reaction. It has been successfully performed under severe temperature and concentration conditions, batchwise unreachable. Thus, it highlights the interest of using this continuous HEX/reactor

Implementation of ‘chaotic’ advection for viscous fluids in heat exchanger/reactors

“…This is interesting to promote heat and mass transfer intensification while working with low Reynolds numbers. Similar trends have been observed by Theron et al [6] in the corrugated channel.…”

“…The implemented experimental set-up and procedure are similar to the ones described by Theron et al [6]. The oxidation reaction involves two aqueous solutions of sodium thiosulfate and hydrogen peroxide as reactants.…”

“…The performances of the previous SAR patterns are compared with a classical 2D corrugated one which design is based on the one studied by [5,6]. The manufacturing process of the 2D HEX reactor is the same and the cooling system is based on isothermal walls (with cooling plates).…”

“…This device combines the benefits of a large heat transfer performance and a plug-flow regime allowing an intensive radial mixing, as a result of the specific design of process channels [4][5][6][7][8][9]. These geometries generate instabilities even in laminar flow regime (50 < Re < 2000).…”

“…Then, a case study in reactive conditions is implemented with the continuous oxidation of sodium thiosulfate with hydrogen peroxide. Finally, the whole performances of the SAR geometries have been compared with the ones of a corrugated pattern plate-type heat exchanger/reactor [6].…”