Prof. Srinivas Krishnaswamy's Talk

Mar 09, 2017 - 17:00

Mar 09, 2017 - 18:00

Rm. No. 118 Ground floor Chemical Engg. Dept.

Seminars

Prof. Srinivas Krishnaswamy Dept. of Chemical Engineering BITS Pilani K K Birla Goa campus

Abstract: Unmixed Combustion (UMC) a novel variant of combustion occurs when air and fuel alternately pass over an Oxygen Storage and Release Material (OSRM) mainly metal/metal oxides which undergo oxidation and reduction reactions. In this study the potential of UMC is demonstrated for heat transfer applications. A purpose-built test rig based on a dynamically operated Packed Bed Reactor (PBR) concept was designed fabricated and commissioned. Experiments were conducted using a representative Cu based OSRM along with methane (CH4) and zero air (21 mol% O2) as reactive gases. The energy generated in both oxidation and reduction due to exothermicity was radially transferred by conduction and convection to coolant air. For a specific loading of 1.25 kg of OSRM and fixed reaction cycle times the effect of varying zero air coolant and CH4 flowrate and reactive gas inlet temperature on the radial heat transfer was investigated. The radial heat transfer rate was maximized at 95 ± 2 % of total energy in the bed at an inlet temperature of 873.15 K and zero air coolant and CH4 flowrates of 15 LPM 150 LPM and 2 LPM (corresponding to 10 mol % concentration) respectively. Under “cyclic” steady state conditions the variation of bed temperature and coolant outlet temperature was restricted to within ± 30 K and ± 3 K respectively and the combustion process was observed to be self-sustaining. In addition a separate experimental investigation related to estimating kinetic parameters of oxidation of Cu and reduction of CuO encountered in UMC was carried out using a Pulsed Micro-reactor (PMR) technique. A simple generic methodology based on a uniform reaction model was adopted and has been validated for both reactions which were found to be surface reaction controlled. The estimated values of reaction orders and activation energies for both reactions and the pre-exponential factor for oxidation were found to be in good agreement with those obtained using Thermo Gravimetric Analysis (TGA). A lower value of pre-exponential factor for reduction however was obtained. The PMR approach offers a simple and effective alternative to quantitatively identify non-catalytic gas–solid reaction kinetics. A dynamic 2-D pseudo-homogeneous model for UMC based PBR integrated with heat transfer to a coolant has also been developed. A commercial software COMSOLTM was used for model implementation. The model predicts the axial and radial temperature profiles in the bed and total heat transfer for prescribed operating conditions used in the experimental runs. The model results obtained for one cycle comprising of oxidation and reduction were compared with experimental data and good agreement to within ± 9 % was obtained in all cases. No adjustment factors were incorporated in the model. The study also validates the use of a pseudo-homogeneous model in predicting the behaviour of dynamically operated UMC systems under relatively mild conditions. The results obtained present a strong argument for using UMC based reactor systems as an alternative to “premixed” combustion for process heat transfer applications subject to suitable combination of operating conditions inclusive of cycle time reactor material of construction and choice of OSRM.Bio-sketch: Dr. Srinivas is presently a Professor in the Department of Chemical Engineering at BITS Pilani K K Birla Goa campus. He obtained his Bachelor's Degree in Chemical Engineering from Shivaji University in 1991 and his Doctoral Degree from the University of London in 2004. After working as Trainee and Production Engineer at Vijay Kumar refractories and Oswal Petrochemicals from 1991 – 1993 he was selected to be part of 38th Batch of the one year Training school programme at Bhabha Atomic Research Centre (BARC). In 1994 he joined the Chemical Engineering Division at BARC as Scientific Officer and was successfully involved in the installation and commissioning of a 5TPA sulphur hexafluoride pilot plant (the first of its kind in India). In January 2000 he joined Queen Mary College University of London to study for a Ph.D. in the area of condensation heat transfer in the presence of a non-condensing gas with emphasis on fuel cell exhaust condensers proposed to be used in vehicles. In August 2003 he joined the University of Sheffield United Kingdom as a Post-doctoral Research Assistant and worked for a year in the area of thermo-chemical cycles for Hydrogen production. In January 2005 he joined the Chemical Engineering Group (presently Department of Chemical Engineering) at BITS Pilani K K Birla Goa campus as Assistant Professor. He was also a Visiting Professor at the Department of Chemical and Materials Engineering at Lunghwa University of Institute of Science and Technology Taiwan from May to July 2009. He became an Associate Professor in 2010 and a Professor in 2015. As a teacher Prof. Srinivas’ interests lie in Chemical Engineering Thermodynamics Chemical Reaction Engineering and Heat Transfer. His main focus of research involves addressing challenges posed in developing practical cost effective energy efficient and environment friendly systems from a commercialization point of view thereby attempting to bridge the gap between know-why and knowhow. He has received grants to the tune of approximately Rs. 9 crores from various funding agencies like Ministry of Fertilizers Aditya Birla Group DST-SERB Centre for High Technology (CHT) and GAIL India Ltd. Some of these projects have been in collaboration with Industries like GAIL India Aditya Birla Group Thermax Ltd. Bharat Petroleum Corporate R&D etc. His completed / ongoing projects involve studies in the area of Unmixed combustion Unmixed reforming Desalination Coke mitigation in refinery systems process condensate water treatment in ammonia plants etc. Besides teaching and research Prof. Srinivas has been associated with BITS Pilani administration assuming diverse responsibilities. More recently he has been appointed as Professor in Charge (University wide) of the Centre for Innovation Incubation & Entrepreneurship. He is also an Associate Member of the Institution of Chemical Engineers (IChemE) United Kingdom and Life Member of the Indian Institute of Chemical Engineers (IIChE). It is compulsory for CL702 and CL704 students.