Forecasting of thermal energy storage performance of Phase Change Material in a solar collector using soft computing techniques

2010 ◽  
Vol 37 (4) ◽  
pp. 2724-2732 ◽  
Author(s):  
Yasin Varol ◽  
Ahmet Koca ◽  
Hakan F. Oztop ◽  
Engin Avci
Author(s):  
Benkadour Ayman ◽  
Mustapha Faraji

Abstract Sensible thermal energy storage systems can reduce energy environmental fluctuation dependency with the nocturnal energy needs usage in maintaining the building's comfort levels. In the present paper, Phase Change Material (PCM) is introduced to improve the thermal energy storage capacity of a solar collector integrating a novel composite Phase Change Material (PCM)/concrete wall. A mathematical model based upon the conservation and heat transfer equations has been developed using the enthalpy method. The Numerical investigation has been implemented into a personal FORTRAN code. Many series of simulation runs were executed. The position of the PCM layer within the wall and the PCM melting temperature are varied in the range 0 cm ≤ xm ≤ 7.5 cm and 15 °C ≤ Tm ≤ 35 °C, respectively. The objective is to let inner temperature Tin swing close to a comfort threshold. The position of PCM close to the absorber improves the efficiency of the room heating with good nocturnal use of latent heat stored during the day. PCM melting temperature affects deeply the composite PCM/concrete wall/solar collector behavior. Lastly, PCM gained the system an important benefit which is the solar collector high-Temperature isolation as to not reach the room and disturb the inside comfort zone by melting and solidifying. Those parameters can be considered as the primary pointers for PCM/wall integrated solar collector design. Also, a Daily Heating Potential, Qh, and Thermal Load Leveling, TLL, are introduced to evaluate the system performance.


Author(s):  
Tonny Tabassum Mainul Hasan ◽  
Latifa Begum

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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