A novel mixing insert for static mixers in building services installations – CFD and experimental inv

Abstract

The paper presents a new structural solution for a mixing insert intended for static mixers installed in cylindrical pipes. Based on a review of the literature and patent solutions in the field of static mixers, as well as on CFD calculations, three variants of inserts were developed: a twisted lattice baffle, a twisted solid baffle, and a composite insert combining both concepts. 
In the experimental part, a prototype test installation was built and the pressure drop in the mixer was measured for various insert configurations, as well as for a Kenics-type insert and for an empty pipe. On this basis, the friction factor f and the pressure drop coefficient Z were determined as functions of the Reynolds number. The results indicate that the composite insert with counter-rotating solid and lattice sections provides pressure drops comparable to a classical Kenics insert, while ensuring favourable velocity and pressure fields in the near-wall region. The potential applications of the new insert in central heating installations, domestic hot water systems, refrigeration installations and renewable energy systems are discussed.