Lecturer in Chemical Engineering (June 1998 to June 2002)
Sr. Lecturer in Chemical Engineering (June 2002 to April 2007)
Reader in Chemical Engineering (April 2007 onwards)

Subjects Taught
Chemical Engineering Laboratory, Computer Programming Laboratory, Engineering Applications of Digital Computers, Environmental Engineering and Pollution Control, Heat Transfer, Momentum Transfer, Multiphase Reactors, Pharmaceutical Engineering

Research Interests
Gas - Liquid, Liquid - Liquid multiphase contacting in variety of multiphase contactors, such as mechanically agitated contactors, jet mixers, ejectors, etc. Mathematical modeling and experimental measurements of momentum, heat and mass transfer in multiphase systems

• Reliance Industries Ltd.
   
  
• Emmellen Biotech Pharmaceutical Ltd.
   
  
• Citurgia Biochemicals Ltd.
   
  
• Krebs Biochemicals Ltd.
   
  
• Voltas Limited
   
  
• NOCIL RCD
   
  
• National Peroxide Ltd.
   
  
• Geist Process Research
   
  

• Gold Medal from Mumbai University for scoring highest number of marks at B. Chem. Engg. Examination, 1993.
   
  
• Innovative Potential of Students Thesis Award for the Ph. D. thesis by the Indian National Academy of Engineering 2000
   
  
• Young Engineer Award of Indian National Academy of Engineering 2002
   
  
• SGSITS-ISTE National award for best research work done by Young Teachers of Engineering Colleges for the year 2003
   
  
• Indian National Science Academy Medal for Young Scientists, 2004
   
  
• Young Associate of the Indian Academy of Sciences 2004 - 2007
   
  
• Amar Dye-Chem Award of Indian Institute of Chemical Engineers (IIChE) for Excellence in Research and Development (Under the age of 35 Years) 2006
   
  

• Life member, I.I.Ch.E.
   
  

• Mechanically agitated Reactors: The emphasis of the research work in this area has been to review the currently available process design procedures, understand the relation between flow patterns produced by the impellers and the design objectives and thereby provide a rational basis for the design procedures.
   
  
• Dead End Systems: Dead end systems are employed when it is desirable to re-circulate the unreacted gas from the headspace back into the liquid phase. This is particularly important when the gases are pure, costly, toxic, hazardous, especially in hydrogenation, ammonolysis, alkylation, oxidation with pure oxygen etc. Self-inducing impellers and surface aerators are the two most commonly employed dead end systems. The previous literature on both the types of equipment has been critically reviewed. The limitations of the published literature have been brought out and suggestions have been provided for future work. The process design correlations useful for scale-up have been identified. A stepwise algorithm has been developed for the process design of these equipment. Experiments have been carried to investigate the applicability of self-inducing impeller in a conventional stirred reactor. These experiments have enabled optimization of the self-inducing impeller design to be used in stirred tanks along with a sparger. It has been shown that by proper choice of self-inducing impeller design, the productivity of the stirred tank reactor can be increased several-fold. A computational fluid mechanics (CFD) model has been developed to relate the shape of the blades of a self-inducing impeller and the local pressure field generated by the impeller. This work is expected to be helpful in optimization of the shape of the blade and the location of the orifices for the purpose of self-induction.
   
  
• Stirred Tank Reactors: A new CFD model for predicting the flow field and turbulence characteristics generated by impellers has been developed. This model is based on the forces acting on the impeller blades as a result of the blade shape, blade rotation and the re-circulating flows produced. The CFD model successfully predicts the flow field generated by a wide variety of axial flow impellers. The model ensures a balance between the energy supplied by the impeller and the energy dissipated within the reactor (a feature that is lacking in the present day CFD models). The relationship between the flow field generated by the impellers and blending in stirred reactors has been investigated with the help of CFD modeling. This relationship has been established by CFD modeling of the blending process for fifty different types of axial flow impellers. These investigations have clearly quantified the role of bulk diffusion and turbulent diffusion in the overall blending process. Strategies for improving the energy efficiency of the blending process have been formulated. A new correlation has been proposed to estimate the mixing time. CFD models have been developed to predict the residence time distribution of stirred reactors. The CFD model is successful in predicting the effect of impeller speed, location of the inlet and outlet nozzles etc. on the residence time distribution.
   
  A detailed computational and experimental program has been undertaken (as a part of the sponsored project from Huntsman Polyurethanes, Belgium) to investigate the hydrodynamic aspects of gas dispersion in stirred reactors. The aim of the project is to develop newer impeller designs that can handle gas at a very high rate. Experimental investigations have been carried out with superficial gas velocities up to 130 mm/s. The power characteristics, gas hold-up, impeller-operating regimes have been studied for a variety of commonly used impellers. The experimental and modeling investigations are now focused on the interaction of gas bubbles and impeller blades.
   
  
• Stirred Bioreactors: One of the key factors that govern the performance of a bioreactor is the level of hydrodynamic stresses that the microorganisms experience. The hydrodynamic stress can lead to damage / de-activation of microorganisms / enzymes. Therefore, the relationship between de-activation of enzymes, impeller geometry and the level of hydrodynamic stress has been investigated through a combination of CFD modeling and experimental measurements. It has been shown that the turbulent normal stresses are substantially larger than the turbulent shear stresses for axial as well as radial flow impellers. It has been observed that a strong correlation exists between the average normal stress within the reactor and the extent of de-activation. With this knowledge it is possible to determine the impeller geometry so as to minimize the shear damage and yet achieve the desired process results.
   
  
• Jet Mixed Tanks: CFD models have been developed and validated to study the hydrodynamic aspects of jet mixers. The CFD model has also been used to study the effects of nozzle geometry, location, and jet velocity on the mixing time in jet mixed tanks. This has enabled optimization of the nozzle geometry and the operating conditions so as to increase the energy efficiency of jet mixers. An experimental program was also undertaken to test out the predictions made with CFD models. Based on the CFD results and experimental investigations, guidelines have been developed for the design of jet mixers. It has been shown that under certain conditions jet mixers are much more energy efficient as compared to top entry or side entry mixers. The understanding developed in this process has enabled identification of rate controlling step in the blending process. This has been verified experimentally as well as with CFD modeling.
   
  
• Rotating Biological Contactor (RBC): RBCs are frequently used in wastewater treatment systems. Their advantages over the conventional activated sludge process are, ability to maintain high biomass loading without increasing the secondary clarifier load, high rate of oxygen transfer, larger interfacial area per unit reactor volume, low power consumption etc. A thorough literature review has been made on all the process design aspects of rotating biological contactors. It has been shown that the oxygen transfer capacity (amount of oxygen transferred per unit energy consumption) of the RBC system is substantially larger than the conventional equipment like surface aerators. Rotating biological contactors are being investigated for their efficacy as a gas - liquid contacting device. The hydrodynamic characteristics for RBC systems have not been studied in the past. Therefore, attempts are being made to characterize the hydrodynamics in terms of mixing time, dispersion coefficients, mass transfer coefficients, etc. These experiments are being carried out over a wide range of speeds of rotation, submergence levels, etc.
   
  
• Plasma Melting System: A CFD model is being developed to characterize the heat transfer and fluid flow aspects of a thermal plasma melting system. The model is being validated by comparison with the experimental data and further refinements are being made to improve the predictions. Attempts are also being made to make the computer program capable of running on parallel processing systems.