Karthik Nithyanandam

Research Project

Investigations on Latent Thermal Energy Storage for Concentrating Solar Power

Thermal energy storage (TES) in a concentrating solar power (CSP) plant allows for continuous operation even during times when solar radiation is not available, thus providing a reliable output to the grid. Energy can be stored either as sensible heat or latent heat, of which latent heat storage is advantageous due to its high volumetric energy density and the high Rankine cycle efficiency owing to the isothermal operation of latent thermal energy storage (LTES) system. Storing heat in the form of latent heat of fusion of a phase change material (PCM), in addition to sensible heat, significantly increases the energy density, thus potentially reducing the storage size and cost. However, a major technical barrier to the use of latent thermal energy of PCM is the high thermal resistance to energy transfer due to the intrinsically low thermal conductivity of PCMs, which is a particularly acute constraint during the energy discharge. Secondly, for integration of TES in CSP plants, it is imperative that the cyclic exergetic efficiency be high, among other requirements, to ensure that the energy extracted from the system is at the maximum possible temperature to achieve higher cycle conversion efficiency in the power block.

The first objective is addressed through computational modeling and simulation to quantify the effectiveness of two different approaches to reduce the thermal resistance of PCM in a LTES, viz. (a) developing innovative, inexpensive and passive heat transfer devices that efficiently transfer large amount of energy between the PCM and heat transfer fluid (HTF) and (b) increase the heat transfer area of interaction between the HTF and PCM by incorporating the PCM mixture in small capsules using suitable encapsulation techniques.

The second portion of the research focuses on numerical modeling of large scale latent thermal storage systems integrated to a CSP plant with the aforementioned enhancement techniques and cascaded with more than one PCM to maximize the exergetic efficiency. Based on systematic parametric analysis on the various performance metrics of the two types of LTES, feasible operating regimes and design parameters are identified to meet the U.S. Department of Energy SunShot Initiative requirements including storage cost < $15/kWht and exergetic efficiency > 95%, for a minimum storage capacity of 14 h, in order to reduce subsidy-free levelized cost of electricity (LCE) of CSP plants from 21¢/kWh (2010 baseline) to 6¢/kWh, to be on par with the LCE associated with fossil fuel plants.

Publications

1. R.M. Stoddard, K. Nithyanandam and R. Pitchumani, “Fabrication and Durability Characterization of Superhydrophobic and Lubricant-Infused Surfaces,” Journal of Colloid and Interface Science, 608, 662–672, 2022.
2. R.M. Stoddard, K. Nithyanandam and R. Pitchumani, “Steam Condensation Heat Transfer on Lubricant Infused Surfaces,” Invited Article, iScience, 24(4), 102336, 2021.
3. K. Kant, K. Nithyanandam, and R. Pitchumani, “Analysis and Optimization of a Novel Hexagonal Waveguide Concentrator for Solar Thermal Applications,” Energies, 14, 2146, 2021.
4. K. Nithyanandam, P. Shoaei and R. Pitchumani, “Technoeconomic Analysis of Thermoelectric Power Plant Condensers with Nonwetting Surfaces,” Invited Article, Energy, 227, 120450, 2021.
5. S. Hatte, K. Nithyanandam and R. Pitchumani, “Quantification of Laminar Drag Reduction on Liquid-Infused Structured Non-Wetting Surfaces,” Paper Q23.00007, 72nd Annual Meeting of the APS Division of Fluid Dynamics, Seattle, Washington, November 2019. 
6. K. Nithyanandam, A. Narayan and R. Pitchumani, “Analysis and Design of a Radial Waveguide Concentrator for Concentrated Solar Thermal Applications,” Energy, 151, 940–953, 2018.
7. K. Nithyanandam, J. Stekli, and R. Pitchumani, High Temperature Latent Heat Storage for Concentrating Solar Thermal (CST) Systems, Chapter 10 in Advances in Concentrating Solar Thermal Research and Technology, M. Blanco, ed., pp. 213–246, 2017 (ISBN: 978-0-0810-0516-3).
8. J. Deshpande, K. Nithyanandam and R. Pitchumani, “Analysis of a Direct Contact Membrane Distillation System for Desalination,” Journal of Membrane Science, 523C, 301–316, 2017.
9. K. Nithyanandam, J. Deshpande and R. Pitchumani, “Coupled Thermal and Optical Analysis a Planar Waveguide Concentrator-Receiver,” Applied Energy, 208, 1576–1589, 2017.
10. K. Nithyanandam and R. Pitchumani, “Thermal and Structural Investigation of Tubular Supercritical Carbon Dioxide Power Tower Receivers,” Solar Energy, 135, 374–385, 2016.
11. K. Nithyanandam, R. Pitchumani and A. Mathur, “Analysis of a Latent Thermocline Storage System with Encapsulated Phase Change Materials for Concentrating Solar Power,” Applied Energy, 113, 1446–1460, 2014.
12. K. Nithyanandam and R. Pitchumani, “Computational Modeling of Dynamic Response of a Latent Thermal Energy Storage System with Embedded Heat Pipes,” ASME Journal of Solar Energy Engineering, 136(1), 011010, 9 pp., 2014.
13. K. Nithyanandam and R. Pitchumani, “Cost and Performance Analysis of Concentrating Solar Power Plants with Integrated Thermal Energy Storage,” Energy, 64(1), 793–810, 2014.
14. K. Nithyanandam and R. Pitchumani, “Computational Studies on Metal Foam and Heat Pipe Enhanced Latent Thermal Energy Storage,” ASME Journal of Heat Transfer, 136(5), 051503, 10 pp., 2014.
15. K. Nithyanandam and R. Pitchumani, “Design of a Latent Thermal Energy Storage System with Embedded Heat Pipes,” Applied Energy, 126, 266–280, 2014.
16. K. Nithyanandam and R. Pitchumani, “Optimization of an Encapsulated Phase Change Material Thermal Energy Storage System,” Solar Energy, 107, 770–788, 2014.
17. K. Nithyanandam and R. Pitchumani, “Computational Studies on a Latent Thermal Energy Storage System with Integral Heat Pipes for Concentrating Solar Power,” Applied Energy, 103, 400—415, 2013.
18. K. Nithyanandam and R. Pitchumani, “Thermal Energy Storage with Heat Transfer Augmentation using Thermosyphons,” International Journal of Heat and Mass Transfer, 67, 281–294, 2013.
19. K. Nithyanandam and R. Pitchumani, “Techno-Economic Analysis of Concentrating Solar Power Plants with Integrated Latent Thermal Storage Systems,” Paper No. ES-FuelCell2013-18213, 7^th International Conference on Energy Sustainability, 2013.
20. K. Nithyanandam and R. Pitchumani, “Design and Optimization of Latent Thermal Energy Storage with Embedded Metal Foams for Concentrating Solar Power Plants,” Paper No. ES-FuelCell2013-18211, 7^th International Conference on Energy Sustainability, 2013.
    
21. K. Nithyanandam and R. Pitchumani, “Analysis and Design of a Dye-Sensitized Solar Cell,” Solar Energy, 86(1), 351–368, 2012.
22. K. Nithyanandam, R. Pitchumani and A. Mathur “Analysis of a Latent Thermocline Energy Storage System for Concentrating Solar Power Plants,” Paper No. ESFuelCell2012-91389, 6^th International Conference on Energy Sustainability, 2012.
    
23. K. Nithyanandam and R. Pitchumani, “Numerical Analysis of Latent Thermal Energy Storage System with Embedded Thermosyphons,” Paper No. ESFuelCell2012-91416, 6^th International Conference on Energy Sustainability, 2012.
    
24. K. Nithyanandam and R. Pitchumani, “Analysis and Optimization of a Latent Thermal Energy Storage System with Embedded Heat Pipes,” International Journal of Heat and Mass Transfer, 54(21–22), 4596–4610 2011.
25. K. Nithyanandam and R. Pitchumani, “Computational Modeling of Dynamic Response of a Latent Thermal Energy Storage System With Embedded Heat Pipes,” Paper No. ESFuelCell2011-54501, 5^th International Conference on Energy Sustainability, 2011.
26. K. Nithyanandam and R. Pitchumani, “Analysis and Design of Dye Sensitized Solar Cells,” Paper No. IHTC14-23101, Proceedings, 14^th International Heat Transfer Conference, Washington D.C., 2010, ISBN 978-0-7918-3879-2.
    
27. K. Nithyanandam and R. Pitchumani, “Computational Modeling of Latent Thermal Energy Storage System With Embedded Heat Pipes,” Paper No. IMECE2010-38682, ASME International Mechanical Engineering Congress & Exposition, 2010.

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