Figure 1. Schematic illustration of the unstructured mesh of the reactor that comprises a plurality of process microchannels transferring heat from the process microchannels to a heat exchanger.
The computational domain of the microchannel reactor is illustrated schematically in Figure 2 in which the microchannel reactor comprises a plurality of process microchannels transferring heat from the process microchannels to a heat exchanger. Although the microchannel has a cross section that is circle, it is to be understood that the microchannel may have a cross section having any shape, for example, a square, circle, semi-circle, and trapezoid. The shape and size of the cross section of the microchannel may vary over its length. For example, the height or width may taper from a relatively large dimension to a relatively small dimension, or vice versa, over the length of the microchannel. The term adjacent channels when referring to the position of one channel relative to the position of another channel means directly adjacent such that a wall separates the two channels. This wall may vary in thickness. However, adjacent channels are not separated by an intervening channel that would interfere with heat transfer between the channels. In some cases, one channel may be adjacent to another channel over only part of the dimension of another channel. For example, a process microchannel may be longer than and extend beyond one or more adjacent heat exchange channels. The term fluid refers to a gas, a liquid, or a gas or a liquid containing dispersed solids or liquid droplets. The term contact time refers to the volume of the reaction zone within the microchannel reactor divided by the volumetric feed flow rate of the reactant composition at room temperature and a pressure of one atmosphere [53, 54]. The term residence time refers to the internal volume of a space occupied by a fluid flowing through the space divided by the average volumetric flowrate for the fluid flowing through the space at the temperature and pressure being used [55, 56]. The term reaction zone refers to the space within the process microchannels wherein the reactants contact the catalyst. The catalyst bed may be segregated into separate reaction zones in the process microchannels in the direction of flow through the process microchannels. In each reaction zone the length of one or more adjacent heat exchange zones may vary in their dimensions.