Education

- B.S., Chemical Engineering, University of Roorkee (1987)
- M.E., Chemical Engineering, Indian Institute of Science (1989)
- Ph.D., Chemical Engineering, Indian Institute of Science (1993)

Courses

- CH 233 Interfacial and Colloidal Phenomena
- CH 235 Modelling in Chemical Engineering
- CH 245 Computational Transport Phenomena

Research

Our research interests are in the field of colloids and interfaces, specifically in nanoparticle synthesis, microfluidics, liquid-liquid dispersions, foams, and energy storage systems. We combine experimental investigations with process/phenomenological/CFD/population balance modelling in our research efforts. Discrete simulations and solution of population balance equations are allied interests.

Quantitative understanding of particle synthesis routes and using the insights obtained to devise processes/reactors for their continuous manufacture is an ongoing activity in the group. The first step of the synthesis process---nucleation of clusters that grow into seeds and then particles is of significant interest, in the context of the inability of the classical mechanisms to explain the observations. We have unraveled new pathways for gold nanoparticle synthesis and developed new contactors/reactors outside microfluidics framework for higher throughputs.

Energy storage in flow batteries and super-capacitors is receiving our significant attention. Our interest is in soluble lead redox flow battery. We find that the loss of lead ions to electrodes in the charge cycle and their release in the discharge cycle induces strong enough natural convection to even dominate over the effect of external flow on transport of ions near electrodes. Our focus is on developing battery designs that harness natural convection advantageously. Supercapacitors with high surface area in pores are promising for recovering energy wasted in bursts such as when a vehicle comes to a stop, and delivering it in bursts such as to crank an engine. The efforts are underway in the group to address the limiting factor---rapid transport of ions in porous materials.

Foams are encountered both in industrial processes, modern foods, and household products. Flow of foams is important. Additionally, a number of their attributes are yet not accessible quantitatively. Work is in progress in our group on both the fronts. We find through simulations that the bubbles lined up near a wall move forward similar to a procession of tanks on road, in bumper to bumper configuration, and explains how foam appears to slip past a wall, yet the observed pressure drops are quite low.
 

Awards & Honors

- Indian National Science Academy Young Scientist Medal, 1998
- Associate, Indian Academy of Science, Bangalore, 1997
- P S Narayana Medal, Best Thesis in Mechanical Sciences, IISc, 1993
- N R Kuloor Medal, IISc, 1989, 1993

Publications

1. MahendraNandanwar and SanjeevKumar (2016), Charge coup de fouet phenomenon in soluble lead redox flow battery, Chemcial Engineering Science, 154 61-71.

2. Ramana Reddy, S. Prakash and Sanjeev Kumar (2015), Phase Inversion of Agitated Liquid-Liquid Dispersions in the Presence of Micrometer-Sized Particles, Ind Eng Chem, 54 10502-10509.

3. Siva Rama Krishana Perala and Sanjeev Kumar (2014), On the two-step mechanism for synthesis of transition-metal nanoparticles, Langmuir, 30 12703-12711.

4. Mahendra Nandanwar and Sanjeev Kumar (2014), Modelling of effect of non-uniform current density on the performance of soluble lead redox flow batteries, Journal of The Electrochemical Society, 161 A1602--A1610.

5. Vibha Srivastava and Sanjeev Kumar (2014), Formation of hierarchical structures of Fe2O3 by liquid-liquid interface technique, CrystEngComm, 16 11122-11126.