Microreactors & Flow Chemistry Group

Miniaturized devices are designed, fabricated and used for carrying out fast and exothermic reactions in an efficient manner. The devices are characterized for their hydrodynamics viz. mixing, heat transfer, mass transfer, RTD and pressure drop. Experimental and computational fluid dynamics are used understanding the flow in the devices in detail. The devices are used for carrying out homogeneous and heterogeneous catalytic and non-catalytic reactions. This is the first of this kind of the first such multipurpose laboratory in India. We have tested a series of micromixers and a few microreactors for different unit processes for carrying out single phase and multiphase reactions. Some of the reactions that we have demonstrated include selective aromatic nitration, oxidation of aromatic sulfides for API synthesis, continuous synthesis of dyes, nanoparticles, etc.

Joshi, R. A.; Joshi, R. R.; Tibhe, J.; Nivangune, N. T. and Kulkarni, A. A. (2012) Continuous flow synthesis of a-amino a,b-unsaturated esters in aqueous medium, Green. Proc. Synth. 1, 205–210
Kulkarni, A. A. and Kalyani, V. S. Two Phase Flow in Mini-channels: Hydrodynamics, Pressure drop and Residence Time Distribution, Ind. Eng. Chem. Res. (2009), 48, 8193–8204
Kulkarni A. A.; Nivangune, N. T.; Kalyani, V. S.; Joshi, R. A.; Joshi, R. R., Continuous Flow Nitration of Salicylic Acid, Organic Process Research and Development, (2008) 12(5), 995

EFD & CFD

Understanding flow in various process equipment is studied through experimental and computational fluid dynamics. The group has a state of the art Ultrasound Velocity Profiler (UVP), high resolution CSO Camera, Carl Zeiss Stereo Microscope with high speed imaging, digital manometers, syringe pumps, etc. The group has worked on flow in vortex diode, converging-diverging system with radial leakage (primary controller), multiphase flow in microchannels, flow of solids in microchannels, etc.

Kulkarni A. A., Ranade, V. V., Rajeev, R. Koganti, S. B., Vortex Diodes: Some Design Guidelines, Chemical Engineering Science, 64, (2009), 1285 - 1292
Kulkarni A. A., Mass Transfer in Bubble Column Reactors: Effect of Bubble Size Distribution, Industrial & Engineering Chemistry Research, 46, (2007) 2205-2211

In the stirred tank reactors, the energy is supplied in the form of a kinetic energy by rotating the impeller at desired speed. Usually, the distribution of energy dissipation is considerably heterogeneous and relatively low energy utilization is seen. A novel impeller has been designed that achieves uniformity throughout the stirred tank and helps achieve better mixing and low shear at relatively low power consumption. Both of these objectives are achieved using the principle of self-similarity, which helps generate a uniform randomness. The group also works on understanding the relevance of various time scales involved in a boiling reactor.

Kulkarni, A. A.; Singh A.; Bhatnagar, S.; Kulkarni, B. D. (2011) Fractal impeller for stirred tank reactor, Ind. Eng. Chem. Res., 50 (12), 7667–7676
Kulkarni A. A. and Ranade V. V. (2012) Evaporation Induced Transformation of L-L to G-L-L System: Direct Contact Heat Transfer and Rise Velocity in Partially miscible liquids (Accepted for GLS11, S-Korea)