Technical and economic assessment of phase change and thermochemical advanced thermal energy storage (TES) systems. Final report. Volume II. Phase change TES sizing computer program

This study reports on the unsteady two-dimensional numerical investigations of melting of a paraffin wax (phase change material, PCM) which melts over a temperature range of 8.7oC. The PCM is placed inside a circular concentric horizontal-finned annulus for the storage of thermal energy. The inner tube is fitted with three radially diverging longitudinal fins strategically placed near the bottom part of the annulus to accelerate the melting process there. The developed CFD code used in Tabassum et al., 2018 is extended to incorporate the presence of fins. The numerical results show that the average Nusselt number over the inner tube surface, the total melt fraction, the total stored energy all increased at every time instant in the finned annulus compared to the annulus without fins. This is due to the fact that in the finned annulus, the fins at the lower part of the annulus promotes buoyancy-driven convection as opposed to the slow conduction melting that prevails at the bottom part of the plain annulus. Fins with two different heights have been considered. It is found that by extending the height of the fin to 50% of the annular gap about 33.05% more energy could be stored compared to the bare annulus at the melting time of 82.37 min for the identical operating conditions. The effects of fins with different heights on the temperature and streamfunction distributions are found to be different. The present study can provide some useful guidelines for achieving a better thermal energy storage system.

Thermal stability, latent heat and flame retardant properties of the thermal energy storage phase change materials based on paraffin/high density polyethylene composites

Renewable Energy ◽

10.1016/j.renene.2009.01.017 ◽

2009 ◽

Vol 34 (10) ◽

pp. 2117-2123 ◽

Cited By ~ 113

Author(s):

Yibing Cai ◽

Qufu Wei ◽

Fenglin Huang ◽

Shiliang Lin ◽

Fang Chen ◽

...

Keyword(s):

Thermal Stability ◽

Energy Storage ◽

Phase Change ◽

Flame Retardant ◽

Latent Heat ◽

Thermal Energy ◽

Thermal Energy Storage ◽

High Density Polyethylene ◽

Phase Change Materials ◽

Flame Retardant Properties

Latent Heat Phase Change Heat Transfer of a Nanoliquid with Nano–Encapsulated Phase Change Materials in a Wavy-Wall Enclosure with an Active Rotating Cylinder

Sustainability ◽

10.3390/su13052590 ◽

2021 ◽

Vol 13 (5) ◽

pp. 2590

Author(s):

S. A. M. Mehryan ◽

Kaamran Raahemifar ◽

Leila Sasani Gargari ◽

Ahmad Hajjar ◽

Mohamad El Kadri ◽

...

Keyword(s):

Heat Transfer ◽

Energy Storage ◽

Phase Change ◽

Latent Heat ◽

Thermal Energy ◽

Thermal Energy Storage ◽

Wavy Wall ◽

Governing Equations ◽

Stefan Number ◽

Change Material

A Nano-Encapsulated Phase-Change Material (NEPCM) suspension is made of nanoparticles containing a Phase Change Material in their core and dispersed in a fluid. These particles can contribute to thermal energy storage and heat transfer by their latent heat of phase change as moving with the host fluid. Thus, such novel nanoliquids are promising for applications in waste heat recovery and thermal energy storage systems. In the present research, the mixed convection of NEPCM suspensions was addressed in a wavy wall cavity containing a rotating solid cylinder. As the nanoparticles move with the liquid, they undergo a phase change and transfer the latent heat. The phase change of nanoparticles was considered as temperature-dependent heat capacity. The governing equations of mass, momentum, and energy conservation were presented as partial differential equations. Then, the governing equations were converted to a non-dimensional form to generalize the solution, and solved by the finite element method. The influence of control parameters such as volume concentration of nanoparticles, fusion temperature of nanoparticles, Stefan number, wall undulations number, and as well as the cylinder size, angular rotation, and thermal conductivities was addressed on the heat transfer in the enclosure. The wall undulation number induces a remarkable change in the Nusselt number. There are optimum fusion temperatures for nanoparticles, which could maximize the heat transfer rate. The increase of the latent heat of nanoparticles (a decline of Stefan number) boosts the heat transfer advantage of employing the phase change particles.