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.