Investigation of counter-current mixing in a continuous hydrothermal flow reactor

• Published in: The Journal of supercritical fluids 2012-02, Vol.62, p.165-172
• Main Authors: Tighe, Christopher J., Gruar, Robert I., Ma, Cai Y., Mahmud, Tariq, Wang, Xue Z., Darr, Jawwad A.
• Format: Article
• Language: English
• Subjects: Counter-current mixing; Hydrothermal synthesis; Nanoparticles; Supercritical water jet; Temperature profiles
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2011.11.027

[Display omitted] ► Counter-current mixing for the hydrothermal synthesis of nanoparticles was studied. ► Temperature profiles were measured at conditions near to the critical point of water. ► The superheated water temperature fell inside the mixer owing to heat lost to the cooler products. ► Rates of heat transfer and forces acting on the jet or plume of superheated water are estimated. Temperature profiles have been measured inside a counter-current mixer for the continuous hydrothermal synthesis of inorganic nanoparticles, at conditions (10–25mlmin−1 superheated water, referred to a density of 1gml−1, at 350–450°C and 24.1MPa, mixed with precursors at 10–20mlmin−1) used in work published by some of the authors and others. The superheated water cooled significantly before meeting the precursors, owing to internal transfer of heat through the wall of the inner tube to the products flowing around it. Consequently, the region immediately after the fluids had fully mixed was at a lower temperature than that determined from an overall heat balance. The flow of superheated water emerging from the inner pipe was characterised using the relevant dimensionless groups (Reynolds, Froude).