scholarly journals The Use of Capsuled Paraffin Wax in Low-Temperature Thermal Energy Storage Applications: An Experimental and Numerical Investigation

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 538
Author(s):  
Agnieszka Ochman ◽  
Wei-Qin Chen ◽  
Przemysław Błasiak ◽  
Michał Pomorski ◽  
Sławomir Pietrowicz
Keyword(s):  
Phase Transitions ◽  
Energy Storage ◽  
Low Temperature ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Operating Conditions ◽  
Paraffin Wax ◽  
Temperature Phase ◽  
Maximum Heat

The article deals with the experimental and numerical thermal-flow behaviours of a low-temperature Phase Change Material (PCM) used in Thermal Energy Storage (TES) industrial applications. The investigated PCM is a composition that consists of a mixture of paraffin wax capsuled in a melamine-formaldehyde membrane and water, for which a phase change process occurs within the temperature range of 4 °C to 6 °C and the maximum heat storage capacity is equal to 72 kJ/kg. To test the TES capabilities of the PCM for operating conditions close to real ones, a series of experimental tests were performed on cylindrical modules with fixed heights of 250 mm and different outer diameters of 15, 22, and 28 mm, respectively. The module was tested in a specially designed wind tunnel where the Reynolds numbers of between 15,250 to 52,750 were achieved. In addition, a mathematical model of the analysed processes, based on the enthalpy porosity method, was proposed and validated. The temperature changes during the phase transitions that were obtained from the numerical analyses in comparison with the experimental results have not exceeded 20% of the relative error for the phase change region and no more than 10% for the rest. Additionally, the PCM was examined while using a Scanning Electron Microscope (SEM), which indicated no changes in the internal structure during phase transitions and a homogeneous structure, regardless of the tested temperature ranges.

Performance Comparison of Phase Change Materials for Thermal Energy Storage

2017 ◽  
Vol 909 ◽  
pp. 231-236
Author(s):  
Jagannath Korody ◽  
P. Dinesha
Keyword(s):  
Fatty Acids ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Operating Conditions ◽  
Paraffin Wax ◽  
Distinct Advantage

To use solar energy effectively and as a standalone source, the performance of thermal energy storage device is crucial. The quantity and quality of energy stored using these devices play an important role in the efficient operation of thermal engineering equipment in the area of Heating Ventilation and Air Conditioning (HVAC), Refrigeration and many other. The selection of storage system depends mainly on application considering quality of energy and cost of storage. Phase change materials (PCM) have played a vital role in the storage of thermal energy in various applications. Out of the various types of phase change materials, organic compounds have a distinct advantage of high latent heat per unit volume, high thermal conductivity, non-flammability and low cost compared to inorganic compounds. The present study compares the performance of two of the most commonly used phase change materials like Paraffin wax and Fatty acids which are organic. They are highly chemically stable, melt congruently and super-cooling does not pose as a significant problem. Moreover, they have been found to be compatible with various kinds of materials of common use. The various performance parameters like temperature variation during charging and discharging, heat absorbed and rejected and overall system efficiency are evaluated for these two materials and also for the combination of these two materials. From the experimental results it is concluded that fatty acids show better performance characteristics than paraffin wax under the same operating conditions. Combination of the two PCM does not give much advantage in terms of operating efficiency.

Thermal Energy Storage Through Melting of a Commercial Phase Change Material in an Annulus with Radially Divergent Longitudinal Fins

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Tonny Tabassum Mainul Hasan ◽  
Latifa Begum
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Operating Conditions ◽  
Melting Time ◽  
Bottom Part ◽  
Change Material

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.

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