Ph.D, M.E, BE

Dr. Mahendra Naktuji Nandanwar currently serves as Assistant Professor at the department of Chemical Engineering & Materials Science, School of Engineering, Coimbatore Campus.


  • 2016 : Ph. D.
    Indian Institute of Science, Bangalore
  • 2007 : ME (Chemical Engg)
    Indian Institute of Science, Bangalore


The work of Dr. Mahendra can be broadly classified into two: Energy and Water. His methodology of research includes experimental studies as well as modelling and simulation studies of the systems. He is actively involved in the development of flow battery systems for the large scale storage of energy. He is also involved in the development of safe drinking water systems and corrosion resistance materials.

Ongoing Funded Projects

  • Development of scaled-up, pump-less, free-convection-driven, soluble lead redox flow battery, Funded by DST, India. Duration 2021-2024.
  • Natural Convection Driven Flow-Through Soluble Lead Redox Flow Battery With inbuilt Sonication mechanism for Achieving Longer Cycle Life. Funded by SERB-DST, India. Duration 2017-2020.
  • Experimental Study on the Impact of Surface Micro-Structures and its Wetting Behavior on the Corrosive Nature of Solid Surfaces. Funded by BRNS, India, Duration 2018-2020.
  • Development of vibrating packed bed electrochemical reactor for heavy metals removal from groundwater and wastewater. Funded by SERB-DST.


Publication Type: Journal Article

Year of Publication Title


Mahendra Naktuji Nandanwar, Kumar, K. Santosh, Srinivas, S. S., and Dinesh, D. M., “Pump-less, free-convection-driven redox flow batteries: Modelling, simulation, and experimental demonstration for the soluble lead redox flow battery”, Journal of Power Sources, vol. 454, p. 227918, 2020.[Abstract]

A novel concept of pump-less, free-convection-driven redox flow battery (RFBs) is proposed. The concept is applicable to hybrid redox flow batteries in general. The concept is demonstrated for soluble lead redox flow battery (SLRFB) by developing a mathematical model. The model accounts for reaction kinetics at electrodes and ion transportation in electrolyte domain of the battery. It predicts existence of induced free convection which not only help overcome ion transfer resistance at electrode surfaces but also couples electrode compartment and reservoir compartment of the battery hydro-dynamically and capacitively. It also predicts electrode kinetics and ion transfer rate as cell voltage controlling mechanisms. Finally, cyclic performance of the pump-less SLRFB is demonstrated experimentally. The experiments shows faradaic efficiency and energy efficiency to be 93% and 65% respectively, in par with conventional pump-based SLRFB. The concept is also extended to other hybrid RFBs and their limiting performances are predicted.

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Mahendra Naktuji Nandanwar, “A modelling and simulation study of solublelead redox flow battery: Effect of presence of free convection on the batterycharacteristics”, Journal of Power Sources, 2018.


Mahendra Naktuji Nandanwar and Sanjeev Kumar, “Charge coup de fouet phenomenon in soluble lead redox flow battery”, Chemical Engineering Science, vol. 154, pp. 61 - 71, 2016.[Abstract]

The charge coup de fouet phenomenon, known in the context of lead-acid battery, refers to the presence of a voltage dip shortly after charging of a fully discharged battery begins. While the attempts to relate magnitude of coup de fouet phenomena with the state of health of battery have appeared in the literature, the phenomena continue to be poorly understood. The soluble lead redox flow battery (SLRFB), with potential for energy storage at large scale at low cost, also displays similar features. We report in this work our modeling and experimental efforts aimed at understanding charge coup de fouet phenomenon in natural convection driven SLRFB. We present a model that incorporates the presence of non-conducting PbO in deposits through a percolation type model for conductivity. The associated potential drop across the deposits is incorporated in the model through reduced overpotential available for driving Butler–Volmer kinetics. The complete model with coupled natural convection induced by non-uniform concentration of Pb ions in electrolyte successfully captures charge coup de fouet phenomenon, and explains the measured variation of its magnitude with the depth of discharge in the previous cycle. The model explains our earlier observation that during the discharge process, a receding zone of deposits is seen only on cathode but not on anode. The approach used is applicable to electrochemical systems in which solid conducting matrix evolves to non-conducting or poorly conducting and vice-versa, with a change in composition.

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Mahendra Naktuji Nandanwar and Sanjeev Kumar, “Modelling of effect of non-uniform current density on the performance of soluble lead redox flow batteries”, Journal of the Electrochemical Society , vol. 161, no. 10, pp. A1602-A1610, 2014.[Abstract]

Soluble lead acid redox flow battery (SLRFB) offers a number of advantages. These advantages can be harnessed after problems associated with buildup of active material on electrodes (residue) are resolved. A mathematical model is developed to understand residue formation in SLRFB. The model incorporates fluid flow, ion transport, electrode reactions, and non-uniform current distribution on electrode surfaces. A number of limiting cases are studied to conclude that ion transport and electrode reaction on anode simultaneously control battery performance. The model fits the reported cell voltage vs. time profiles very well. During the discharge cycle, the model predicts complete dissolution of deposited material from trailing edge side of the electrodes. With time, the active surface area of electrodes decreases rapidly. The corresponding increase in current density leads to precipitous decrease in cell potential before all the deposited material is dissolved. The successive charge-discharge cycles add to the residue. The model correctly captures the marginal effect of flow rate on cell voltage profiles, and identifies flow rate and flow direction as new variables for controlling residue buildup. Simulations carried out with alternating flow direction and a SLRFB with cylindrical electrodes show improved performance with respect to energy efficiency and residue buildup.

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Mahendra Naktuji Nandanwar and Sanjeev Kumar, “A new discretization of space for the solution of multi-dimensional population balance equations”, Chemical Engineering Science, vol. 63, no. 8, pp. 2198 - 2210, 2008.[Abstract]

In this work, a novel radial grid is combined with the framework of minimal internal consistency of discretized equations of Chakraborty and Kumar [2007. A new framework for solution of multidimensional population balance equations. Chemical Engineering Science 62, 4112–4125] to solve n-dimensional population balance equations (PBEs) with preservation of (n+1) instead of 2n properties required in direct extension of the 1-d fixed pivot technique of Kumar and Ramkrishna [1996a. On the solutions of population balance equation by discretization-I. A fixed pivot technique. Chemical Engineering Science 51, 1311–1332]. The radial grids for the solution of 2-d PBEs are obtained by intersecting arbitrarily spaced radial lines with arcs of arbitrarily increasing radii. The quadrilaterals obtained thus are divided into triangles to represent a non-pivot particle in 2-d space through three surrounding pivots by preserving three properties, the number and the two masses of the species that constitute the newly formed particle. Such a grid combines the ease of generating and handling a structured grid with the effectiveness of the framework of minimal internal consistency. A new quantitative measure to supplement visual comparison of two solutions is also introduced. The comparison of numerical and analytical solutions of 2-d PBEs for a number of uniform and selectively refined radial grids shows that the quality of solution obtained with radial grids is substantially better than that obtained with the direct extension of the 1-d fixed pivot technique to higher dimensions for both size independent and size dependent aggregation kernels. The framework of Chakraborty and Kumar combined with the proposed 2-d radial grid, which offers flexibility and achieves both reduced numerical dispersion and the ease of implementation, appears as an effective extension of the widely used 1-d fixed pivot technique to solve 2-d PBEs.

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Mahendra Naktuji Nandanwar and Sanjeev Kumar, “A new discretization of space for the solution of multi-dimensional population balance equations: Simultaneous breakup and aggregation of particles”, Chemical Engineering Science, vol. 63, no. 15, pp. 3988 - 3997, 2008.[Abstract]

n this work, we show that straight forward extensions of the existing techniques to solve 2-d population balance equations (PBEs) for particle breakup result in very high numerical dispersion, particularly in directions perpendicular to the direction of evolution of population. These extensions also fail to predict formation of particles of uniform composition at steady state for simultaneous breakup and aggregation of particles, starting with particles of both uniform and non-uniform compositions. The straight forward extensions of 1-d techniques preserve 2n properties of non-pivot particles, which are taken to be number, two masses, and product of masses for the solution of 2-d PBEs. Chakraborty and Kumar [2007. A new framework for solution of multidimensional population balance equations. Chemical Engineering Science 62, 4112–4125] have recently proposed a new framework of minimal internal consistency of discretization which requires preservation of only (n+1) properties. In this work, we combine a new radial grid [proposed in 2008. part I, Chemical Engineering Science 63, 2198] with the above framework to solve 2-d PBEs consisting of terms representing breakup of particles. Numerical dispersion with the use of straight forward extensions arises on account of formation of daughter particles of compositions different from that of the parent particles. The proposed technique eliminates numerical dispersion completely with a radial distribution of grid points and preservation of only three properties: number and two masses. The same features also enable it to correctly capture mixing brought about by aggregation of particles. The proposed technique thus emerges as a powerful and flexible technique, naturally suited to simulate PBE based models incorporating simultaneous breakup and aggregation of particles.

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  • Mathematics (Transforms and Partial Differential Equations, Numerical Methods)
  • Heat Transfer
  • Mass Transfer
  • Mechanical Operations