Optimization methodology of operation of orifice-shaped micromixer based on micro-jet concept

Abstract

To establish an optimization methodology for the emulsification process in microchannels, we have investigated the relationship between the channel geometry of micromixers and the size of the formed droplets. We focus the channel geometry of orifice including the sudden contraction and expansion of the flow. The experimental results indicate that the channel geometry is effective in producing fine droplets, and that the mean droplet diameter is predicted on the basis of the pressure drop due to convection and the energy dissipation rate in the mixer chamber irrespective of the orifice geometry. In the orifice-shaped micromixer, the kinetic energy given to a fluid by contraction is dissipated within the order of milliseconds by the formation of a jet flow of the order of several hundreds of micrometers; we have named this jet-micro-jet.‖ On the basis of this mechanism, the energy dissipation rate in a micro-jet, ε jet , is quantified. The mean droplet diameter is proportional to ε jet −0.4 irrespective of the channel geometry of the mixer. Using this formulation, we have integrated the geometric parameters of the orifice and the physical properties of the fluids into the expression of ε jet to establish an optimization methodology of the droplet formation in the orifice-shaped micromixer.

Design method for micromixers considering influence of channel confluence and bend on diffusion length

“…where Q is the volume flow rate, P is the arbitrary pressure drop in the focused space, and V is the volume of the focused space [16,17].…”

Basic Design Concept of a Microreactor for Isothermal Operation Including Heat Conductivity

“…In this research, the isothermal control of a reaction was treated; therefore, the design method shown can be adapted to the design of a heat exchanger by replacing Q r with heat quantity J m À1 L T v in (14 This case is much easier, and the above arguments are also applicable.…”

“…Currently, few authors have discussed the suitable design of microreactors [12][13][14][15] because the designs are not well developed in comparison with large-scale macroplants, although, as previously stated, microreactors perform better than conventional macroscale reactors. One reason for the lack of available information regarding microreactors is that accurately measuring the distribution of temperature, density, pressure and so on in the minute space is challenging, because, for example, injecting a thermocouple into a microchannel to check the inner temperature causes a disturbance in its precise flow.…”

Continuous Synthesis of tert‐Butyl Peroxypivalate using a Single‐Channel Microreactor Equipped with Orifices as Emulsification Units

“…To deform or even to break up a droplet, a minimum of energy input is needed. This energy is introduced via the total flow velocity and, accordingly, the generated pressure drop over the system, and has to be released in a very short time (order of milliseconds) 34. A screening of flow velocities was undertaken to establish that needed to create an emulsion by the use of orifices.…”