Flow Basics

Mixing

In SYRRIS micro reactors, reagent flows are laminar and not turbulent - reagents do not mix by turbulence (as in a round bottom flask) but instead, they mix by diffusion. This means there is essentially no back mixing of materials in the reactor –flow in the reactor is basically “plug flow”. Because the distance across the channel is ~200µm, the time taken for reagents to completely diffuse is in the order of seconds. At typical AFRICA flow rates, this corresponds to less than 10mm of flow along reaction channel. Note that the total length of the reactors is ~1m

Click here to see the AFRICA flow system.

Click here to see the FRX flow system.

Residence Time

In a flow reactor, the residence time of the reagents in the reactor chip (i.e. the amount of time that the reaction is heated or cooled) is calculated from the volume of the reactor and the flow rate through it.

Therefore, to achieve a longer residence time, you can either pump more slowly and/or use a reactor with a larger volume. In this way, both AFRICA and FRX are able to operate with reaction times from a few tens of seconds to a few hours. The AFRICA software automatically calculates and delivers the total flow rate required to give the desired residence time. The software also indicates when the calculated flow rate is either too high or too low for the pumps to supply, and therefore when it is necessary to use a larger or smaller chip or to fit larger or smaller syringes to the pumps. For the same given residence time, one can either choose to use a larger reactor (and therefore larger flow rate) or a smaller reactor (and therefore smaller flow rate). The key difference is that with a large reactor, more material will be synthesised/consumed in a given time. In practice, this means AFRICA and especially FRX can be used to synthesise milligram to gram quantities.

Heating & Cooling

The surface area to volume ratio of the reaction mixture in an Syrris flow reactor is very large. This means that heat can be added to or removed from the reaction mixture more rapidly than in a batch reactor. It also means a constant temperature can be easily maintained for reactions which are exo- or endothermic.

Syrris Microreactor

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The Dolomite Centre provides design, development and manufacture of glass microfluidic devices and systems.