Technical Breakthrough made in the field of Thermal Energy Storage (TES) system

The major technical breakthrough made in the field of TES system are listed below

1. Enhancement in thermal conductivity of PCM
a) 15 % enhancement in Water based PCM with Multi Wall Carbon NanoTubes (MWCNT) (For CTES application).

b) 40 to 45 % enhancement in liquid paraffin based PCM with MWCNT (For Free cooling application).

c) 12 % in liquid state and 56 % in solid state of water with Graphene nanoplatelets (For CTES application).

d) 22 % in liquid state and 29 % in solid state augmented in commercial paraffin with MWCNT (For Solar air heating).

Selected Publications
1. Kumaresan V, R Velraj, SK Das. Heat and Mass Transfer 48 (8), 1345-1355,2012

2. Kumaresan,V R Velraj, M Nanda, AK Maini, Proceedings of ICFMD 2011. Organized by DRDO [Received BEST POSTER AWARD]
2. Reduction in Subcooling
a) Subcooling reduction of 1.5°C in water by addition of surfactant.

b) Subcooling reduction of 2.19°C in RT 20 with respect to the heating/cooling rate.

c) Subcooling reduction of 4°C in water by addition of MWCNT.

d) Complete elimination of subcooling in water with pseudomonas.

e) Subcooling reduction in RT 20 with respect to radial location.

Selected Publications
1. P. Chandrasekaran, M. Cheralathan, V. Kumaresan, R. Velraj. Energy Vol 72, 636–642 2014.

2. GR Solomon, S Karthikeyan, R Velraj. Applied Thermal Engineering 52 (2), 505-511, 2013.
3. Enhanced Solidification & Melting Characteristics
a) 90 % reduction in solidification time at the cost of 20% reduction in storage.

b) 25 % and 20 % reduction in solidification time of water with MWCNT and CuO respectively (CTES).

c) 33 % reduction in solidification time of RT 20 (Free cooling) with MWCNT.

Selected Publications
1. R Velraj, R.V. Seeniraj, B Hafner, Christian Faber, Klemens Schwarzer. Solar energy 65 (3). 171-180. 1999

2. P Chandrasekaran, M Cheralathan, V Kumaresan, R Velraj Energy 72, 636-642, 2014

4. Numerical Modelling

a) Developed the generalised H-T relationship that accommodates the materials having either constant or a range of phase change
    temperatures for TES applications. This simplified the solving procedure by numerical methods for phase change problems.
b) Applicability of different mathematical models for the PCM based packed bed storage system – (Mapping).

c) Introduced Computational Fluid Dynamics model for Phase Change Material based free cooling application.

Selected Publications
1. R. Velraj, R. V. Seeniraj, B. Hafner, C. Faber and K. Schwarzer.. Solar Enegry Pii: S0038-092x (96) 1999

2. S. Karthikeyan, R. Velraj International Journal of Thermal Science. Vol. 60, 153-160. 2012.
5. Technical contributions made in various applications
a) Free cooling of buildings

Free cooling is one such concept through which building cooling demands can be met without compromising the indoor air quality. Our research group have been doing work in free cooling of buildings for the past 10 years. Further I have guided two Ph.D. research scholars who have completed their doctoral work and presently guiding two research scholars who are carrying out their research work in this particular application. We have achieved year round thermal management in a building using double layered PCM.

b) Cool Thermal Energy Storage System

Achieved Energy saving potential of 6 % – 9 % that leads to reduction in the chiller capacity by operating the evaporator at higher temperature (CTES).

c) Solar Air Heating

Solar air heater (SAH) is one of the promising solar thermal technologies which could be used for low and moderate temperature applications. The nominee has research experience in the field of solar air heaters. Interesting results were also obtained from the experiments conducted by our research group. It is also revealed that fluctuation of hot air in the solar air heater could be minimized through integration of TES system using HS 58 as PCM.

Vice Chancellor, Anna University, Chennai.

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