(249e) Characterizing Confined Impinging Jet Reactor: Energy Dissipation Approach

Energy dissipation is often viewed as a measure of the degree of local turbulence in a mixing geometry. Impinging jets offer rapid mixing and can provide energy dissipation rates as large as 100,000 W/kg (Johnson et al., 2003), while stirred tanks typically offer only 10-12 W/kg. For a set of fast precipitation reactions, high local energy dissipation helps in achieving smaller length and time scales at which chemical reaction occurs. Local turbulence in Confined Impinging Jet Reactor (CIJR) is promoted by increasing the impinging jet flow rates. High local turbulence brings about fast micro-mixing. If micro-mixing is very fast, high local supersaturation (of chemically reactive species) is generated, which leads to a fast local nucleation rate and therefore small precipitate particle size with limited diffusional growth.

Johnson et al. (2003) mapped energy dissipation in CIJR through a chemical kinetics approach. In the present work, energy dissipation is estimated from a pressure drop approach for balanced and unbalanced flows. The pressure drop measurements and resulting estimates of dissipation are compared with reactive mixing experiments to define the limits of stable operation with unbalanced flows.

Reference: Johnson BK, Prud'homme RK. Chemical Processing and Micromixing in Confined Impinging Jets. AIChE Journal. 2003; 49(9)