Modelling
Our work focuses on the development of validated models able to predict the behaviour of reacting flows at the resolution necessary to achieve precision chemistry in microchannel devices. We are active with both pressure driven and electrosomotic flows.
Electro Osmotic Flows in glass chips are being studied both theoretically and experimentally. The objective is to subdivide the flow in each channel into small slugs, of volume analogous to a biological cell, to enhance the precision of the resulting chemistry and to create opportunities for simultaneous reaction and electrophoretic separation of reagents and products.
As part of the Ionic Liquids work and elsewhere we have looked in some depth at the problems of mixing. Although the length scale of microchannels is small, in liquid systems at the low Reynolds Numbers involved, it is still large in comparison with likely diffusion lengths. Mixing is thus surprisingly difficult to achieve. This becomes particularly important, for example when measuring chemical kinetics on a chip since it introduces considerable measurement uncertainty into t = 0.
Gas phase flows and reactions have also being modelled in stacked microchannel reactors consisting of alternating reaction and heat transfer channels. Relationships between the reaction rate per unit volume and the reaction kinetics and the design of the heat transfer channels have been derived.
Further gas flow work has concentrated on deepened understanding of the very low Re flows involved in the channels. A novel analysis approach, applicable at vanishingly small fluid inertia is being developed. It has generally been found that there are experimental anomalies in certain regions in these micro-channel systems.
