No single energy source, either conventional, or renewable, is self-sufficient to meet the energy
demand of any country. The intermittency in the supply of energy, as in the case of solar radiation,
creates a mismatch between the demand and the supply of the energy. This necessitates the
development of an efficient energy storage system that can be used as stand-by in case of unavailability
of the primary energy source. A properly designed thermal storage system may
overcome inherent intermittency of energy supply. In the present work, the charge-discharge
characteristics of the 5 MJ capacity storage system, based on latent heat storage, with paraffin
wax as a phase change substance, is numerically investigated. The performance of shell and tube
type device is evaluated using COMSOL®4.3a software. The results revealed that the paraffin
wax, as a Phase Change Material (PCM), charges more quickly (25% faster) as compared to
discharge. The PCM with a latent heat of 168 kJ/kg, was found suitable for effective heat storage
and does not undergo sub-cooling. This work suggests that the selection of the heat exchangers,
based on charging time, may be done by suitably designing the number of tubes. In this work, the
tubes in the heat exchanger were varied from 9 to 25 and through computational analysis, 17
tubes were found to be the most economical selection with better effectiveness. |
