475796 Modeling Multiphysics Transport Phenomena and Device Design for Solar-Fuel Technologies

Sunday, November 13, 2016
Continental 4 & 5 (Hilton San Francisco Union Square)
Rohini Bala Chandran, Energy Storage and Distributed Resources, Lawrence Berkeley National Laboratory, Berkley, CA

2ndyear Postdoctoral Fellow

Research Motivation and Interests:

Imagine if we could take a leaf from nature’s book to convert and store available sunlight, water and carbon dioxide in stable chemical bonds of hydrogen and hydrocarbon compounds. These solar-fuels could provide carbon-neutral alternatives to the fossil fuel dominated energy sector with enormous potential for large-scale storage and long-term transportation. Ingenious fundamental science and device-scale engineering advancements are needed to efficiently harness, convert and store solar energy along with favorable economic drivers to facilitate global technological adoption. My research interests and strengths are to develop mathematical models and high fidelity computational simulations closely connected with experimental investigations to design scalable, stable and cost-effective integrated solar energy conversion and storage devices. Specifically, I am interested in probing the complex interactions of the various physical phenomena – optical absorption, heat and mass transfer, heterogeneous chemical reactions and interfacial electron transport to optimize the materials-to-device scale performance of high- and low- temperature solar fuel generators.

Awards:Doctoral Dissertation Fellowship awarded by the Graduate School at the University of Minnesota for 175 Ph.D. candidates from a campus wide competition.

Postdoctoral Project:  “Design of a Particle-Suspension Reactor for Photoelectrochemical Solar Water Splitting”

Supervised by Dr. Adam Z. Weber, Lawrence Berkeley National Laboratory, and Prof. Shane Ardo, University of California, Irvine.

PhD Dissertation: Transport and Chemical Phenomena in a Solar Reactor to Split Water and Carbon Dioxide to Produce Synthesis Gas

Supervised by Prof. Jane H. Davidson, Christenson Chair in Renewable Energy, University of Minnesota, Twin Cities

Research Interests:  

My graduate and postdoctoral research work has helped me acquire an interdisciplinary background in the areas of thermal sciences and fluid mechanics, semiconductor device physics and electrochemistry. I have gained substantial expertise in developing numerical transport models using in-house codes as well as commercial softwares to simulate interdependent transport processes for device-scale performance optimization. I am adept at parallelizing computational codes to implement them on high performance computers (HPCs), which is especially beneficial for three-dimensional and transient problems. Beyond continuum modeling approaches, I am also experienced with Monte Carlo simulations for radiative transport and meso-scale Lattice-Boltzmann approaches to simulate sedimentation of bacterial swimmers. As part of the reactor design team at the University of Minnesota, we designed and tested a 4 kW, high-temperature solar reactor integrated with gas phase heat recovery to operate at 1500 °C. The reactor implements an isothermal ceria redox cycle to split water and carbon dioxide to produce synthesis gas. The prototype development and reactor operation has given me an opportunity to view a heat and mass transfer, reaction-engineering problem from the eyes of materials scientists and structural mechanics researchers. In my current research, I am trying to understand the intricacies involved in semiconductor physics and interfacial electrochemical reactions in particulate suspensions. All my research projects so far have had a significant experimental and prototyping component, which has taught me the value of exploiting combined numerical-experimental approaches to connect the dots in multi-physics problems with varying length and time scales. This experience has also provided me with a versatile knowledge of experimental toolkits – thermocouple instrumentation and control, gas analysis equipment (RLGA and mass spectrometer), UV-VIS spectrophotometer, dynamic light scattering and cyclic voltammetry, to name a few.

Teaching Interests:

I have been a Teaching Assistant for over three years of my graduate study in undergraduate physics (statics and mechanics, electricity and magnetism) and mechanical engineering core courses (fluid mechanics, heat transfer, thermodynamics and measurements laboratory). I have particularly benefited from my experiences of running laboratory classes that involved designing experimental test stations and control devices for teaching fundamental transport phenomena concepts. I’ve also had the opportunity to mentor graduate students in my research lab to train them on performing numerical simulations and have worked closely with them to write and orally present scientific results. Outside of professional work, I strive to encourage younger students’ participation in science and mathematics by volunteering in high schools to help students with basic algebra, geometry and physical sciences.

Future Direction: 

As faculty I would like to apply my expertise in transport modeling for designing solar-fuel generators and other energy conversion systems to further the fundamental understanding of the interactions between various physical phenomena, and use this knowledge to offer device-scale engineering solutions. I hope to integrate my experiences from my PhD and postdoctoral work to more closely investigate full-spectrum utilization and heat management in integrated photoelectrochemical devices subjected to concentrated solar radiation. Concentrated solar power provides the benefit of higher power input per unit area of the device but also causes excess heating that could deteriorate the performance of the semiconductor materials. However, intelligent material selection and device design could potentially redirect the ultraviolet and visible portions of the solar spectrum towards water and carbon-dioxide splitting and channel the high-quality heat in the infrared wavelengths for heat storage.

Besides renewable solar fuel applications, I am also interested in solar gasification of biomass and other-waste materials, redox flow batteries, water treatment and pollution abatement with photocatalysts, thermal energy storage in phase change materials and modeling heat and air flow to optimize building energy requirements. I envision that developing numerical models of varying complexity and length scales along with carefully designed experiments can result in optimized performances, irrespective of the end application.

Selected Publications 

[1] Bala Chandran R., and Davidson J. H., 2016, “Model of transport and chemical kinetics in a solar thermochemical reactor to split carbon dioxide,” Chem. Eng. Sci., 146, pp. 302–315.

[2] Bala Chandran R., De Smith R. M., and Davidson J. H., 2015, “Model of an integrated solar thermochemical reactor/reticulated ceramic foam heat exchanger for gas-phase heat recovery,” Int. J. Heat Mass Transf., 81, pp. 404–414.

[3] Hathaway B. J., Bala Chandran R., Sedler S., Thomas D., Gladen A., Chase T., and Davidson J. H., 2015, “Effect of Flow Rates on Operation of a Solar Thermochemical Reactor for Splitting CO2 Via the Isothermal Ceria Redox Cycle,” J. Sol. Energy Eng., 138(1), p. 011007.

[4] Bala Chandran R., Bader R., and Lipiński W., 2015, “Transient heat and mass transfer analysis in a porous ceria structure of a novel solar redox reactor,” Int. J. Therm. Sci., 92, pp. 138–149.

[5] Bader R., Bala Chandran R., Venstrom L. J., Sedler S. J., Krenzke P. T., De Smith R. M., Banerjee A., Chase T. R., Davidson J. H., and Lipinski W., 2015, “Design of a Solar Reactor to Split CO2 Via Isothermal Redox Cycling of Ceria,” J. Sol. Energy Eng., 137(3), p. 031007.

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