Modelling and simulation of counter-current reactors for continuous hydrothermal flow synthesis of nanoparticles

Numerical simulation using computational fluid dynamics is carried out to study the performance of a counter-current reactor in a continuous hydrothermal system for nanomaterial synthesis that is operated under supercritical water condition.Inlet flowrate and temperature are the key process variables and vary in the simulation.The predicted temperatures are in good agreement with measurements taken from a laboratory rig of identical design and under the same operating conditions.It is found that fast mixing in the reactor can be achieved by high inlet temperature,high inlet flowrate of the supercritical water and using unbalanced flow conditions,i.e.the supercritical water flowrate should not be equal to that of the precursor.The comparative simulation also reveals that the insertion length of the inner tube is a key factor dictating the reactor performance,and it needs to be less than 72.5 mm in order to achieve satisfactory mixing under the current reactor configuration.