Flow-Through Reactor Chambers (Flow Cells)
Continuous Ultrasonic Liquid Processing
With the use of reactor chambers (flow cells), ISM's ultrasonic systems can be configured for continuous liquid processing in "flow-through" and "batch-continuous" modes. When large amounts of materials need to be processed, these arrangements are preferable to "batch" mode because they result in a much higher processing capacity, greater ultrasonic exposure uniformity and better temperature stability. During continuous ultrasonic processing, the use of a properly designed reactor chamber ensures that all working liquid is directed through the active cavitation zone(s) created by an incorporated Barbell horn, resulting in homogeneous processing and high-quality product. ISM's reactor chambers commonly include water-cooling jackets which help maintain the temperature of the working liquid at a desired level.
Batch-continuous mode (illustrated on the left), where the material is recirculated through the reactor chamber, is recommended for challenging processes, such as nanocrystallization, nanoemulsification, deagglomeration, etc. Recirculation results in multiple passes through the chamber, increasing cumulative exposure time and practically eliminating any possibility of active cavitation zone bypass. Total required exposure times are largely determined by the nature of the process, as well as by ultrasonic exposure parameters - ultrasonic amplitude, temperature, pressure, etc.
Flow-through mode is commonly used as part of multistep processing involving different modalities. In this mode, the working liquid coming from a previous processing step passes through the reactor chamber, where it gets exposed to high-intensity ultrasonic cavitation, after which it is either collected as the final product or continues down the line. This arrangement is more common for faster processes requiring a single pass through the system. Multi-reactor arrangement is also possible, which combines the advantages of both configurations.
Internal structures of reactor chamber assemblies with (left to right) FBH, HBH and HBHO Barbell horns are provided on the left. The same reactor chamber may be used with all Barbell horn types. Commonly, the working liquid is supplied through "main inlet" at the bottom and comes out through "main outlet" at the top. Depending of the required process temperature, chilled water, propylene glycol or another cooling liquid may be used for temperature control. "Cooling inlet" and "cooling outlet" may be placed on the same side of the reactor chamber's jacket, as shown in the figure at the top, or on opposite sides, as shown in the figures on the left.
When 
elevated processing pressures are required, flanged Barbell horns may be utilized. Penetration of the horn into the chamber, in this case, is arranged such that the flange is "sandwiched" between the body of the chamber and its lid, which ensures a reliable, pressure-resistant seal. The same arrangement may be used when penetration is set up into a pipe. For a large-diameter pipe, multiple horns may be positioned at different angles, such that the entire cross-section on the pipe becomes an active cavitation zone.