Investigation on steady regimes in a X-shaped micromixer fed with water and ethanol

Microreactors are very attractive for intensifying chemical and biochemical reactions, as they enable a large heat transfer with high control of the operating conditions. These features allow improving the achievable reaction yield and selectivity. However, the mixing of reactants should be ensured, especially in simple designs, as the flow regime is laminar. This work aims at characterizing the flow regimes and degree of mixing in a X-shaped micromixer with two opposite inlets and at investigating how these regimes are affected by fluid properties. To this purpose we carry out numerical simulations of two different mixtures, i.e. Water-Water (W-W) and Water-Ethanol (W-E), for Reynolds numbers Re⩽200, to gain insight into the complex three-dimensional flow structures stemming from the impinging jets at the confluence. Besides, experimental flow visualizations from the W-W case provide a validation of the numerical model. The X-shaped reactor is observed to enable a superior mixing performance compared to T-, Y-, and Arrow-shaped microreactors, which are extensively employed.