Investigation on the characteristics of an advanced rotational hydrodynamic cavitation reactor for water treatment

In the present study, the characteristics of a representative advanced rotational hydrodynamic cavitation reactor (ARHCR) in pilot scale were experimentally investigated. The cavitation generation mechanism was analyzed with respects to experimental flow visualization. The variation regularity of the thermal performance under a full range of operational conditions (i.e., various rotational speeds (2600 to 4200 rpm) and flow rates (1 to 2.6 m(3)/h)) was analyzed by establishing polynomial model and response surface. A critical flow rate of 1.2 (<= 2800 rpm) or 1.4 m(3)/h ( 2800 rpm) was found out for the present ARHCR for the first time, the thermal performance can be greatly enhanced when the critical flow rate was reached. The achieved heat generation rate and thermal efficiency can be as high as 57.21 MJ/h and 79.99%, respectively. The effects of the operational conditions on the thermal performance were evaluated and discussed. Finally, the thermal and disinfection performance of the present ARHCR was compared with that of previous devices. The ARHCR achieved a disinfection rate of 100% for Escherichia coli with an expense of $2.72/m(3) at the optimal condition. The disinfection result indicated that the treatment rate of the present ARHCR was approximately 140 times higher than that of the recently reported ARHCR, with 50 times lower expenses. The findings of this work can strongly contribute to the fundamental understanding, design, and application of ARHCRs in water treatment.