Residence time distribution studies in microstructured plate reactors

Residence time distributions (RTDs) have been investigated experimentally for reactors with straight and zig-zag channels. The channels are formed by microstructured plates placed on top of each other and containing obstacles and holes to allow flow in 3 dimensions. Experimental RTD measurements were performed by monitoring the concentration of a tracer dye by means of a LED-photodiode system. The RTD was obtained for five different flowrates and four geometries containing straight and zig-zag channels. It was found that the zig-zag channel configuration gives a narrower distribution as compared to the straight channel ones. Secondary flows were thought to be present in the zig-zag channel even at small Reynolds numbers. Furthermore, as the flowrate increased, the variance of the distribution of all geometries increased. The RTD for a single rectangular cross section channel (with no 3-dimensional flow) was found to have the largest variance from all reactors investigated due to its largest hydraulic diameter. However, its variance was not far from those of microstructured reactors and this was attributed to its small aspect ratio (shallow, wide channel). The RTDs of all microstructured reactors, and in particular the zig-zag geometry, were less sensitive to flowrate increase than the RTDs of the rectangular channel, for the range of flowrates investigated.