Two kinds of heat exchangers combining heat and mass transfer are studied: a new falling film gasliquid contactor with spiral fins and a rotating multiple-disc compact exchanger applied to a polymerisation reaction. The studies will produce new and more efficient design concepts. These designs will also ensure smaller residence times suitable for processing of thermally sensitive materials.
Heat exchangers combining heat and mass transfer during evaporation and during chemical reaction are studied. To this effect, a falling film evaporator and a rotating disc reactor heat exchanger are examined.
Falling film evaporators are rarely used in industry due to their lack of reliability. The proposed technique of spiral finned tubes combines high efficiency with stable operation. Two types of spiral finned tubes are tested: graphite tubes with external spiral fins and graphite or metal tubes with internal spiral fins. In parallel, the improvement of heat exchanger geometry (improved tubes and plates) and the evaporation process of relevant mixtures is studied. This is the basis and prerequisite to improve the heat exchange technique for recycling diluted mixtures of water and alcohol. The main steps are : the determination of the industrial fields where this technique may be used, modelling of heat and mass transfer, laboratory experiments to validate the model, full scale experiments to adjust the model with size effect and a techno-economic evaluation for some industrial applications. Rotating disc multifunctional reactor heat exchangers are a good way to enhance heat and mass transfer during pre-polymerization reactions. This reduces the spread in residence time and increases mixing; the consequence is significant energy savings and production of a polymer with a narrow molecular weight distribution. Two linked aspects are studied: the film flow hydrodynamic of a viscous melt and the shear mixing in a double disc arrangement, and the effect of enhanced heat and mass transfer, mixing and shorter residence time while polymerisation. For this, two experimental units are designed, built and tested, one is used for hydrodynamic characterisation and the other as prepolymeriser. Various parameters are studied such as the geometry, the type of fluids, the speed of rotation, the temperature (for polymerisation) and the flow rate.
An evaluation of the results and an estimate of the energy savings will conclude this work.
Funding SchemeCSC - Cost-sharing contracts
19009 Pikermi Attiki
54530 Pagny Sur Moselle
NE2 4AA Newcastle Upon Tyne