scholarly journals Optimizing the shape of PCM container to enhance the melting process

2022 ◽  
Author(s):  
Bingkun Huang ◽  
Shimi Yang ◽  
Jun Wang ◽  
Peter D Lund

Abstract The shape of container influences natural convection inside a latent heat storage with a phase change material (PCM). Often the geometrical design of a PCM container is based on empirical observations. To enhance convection and melting of the PCM, authors propose here new design guidelines for an improved container. Using the so-called Co-factor method as the optimized basis, which is defined as the vector product of the velocity and temperature gradient, the new design method strives to raise the velocity of natural convection in liquid PCM, increase the amount of PCM in the direction of the convective flow, and reduce the amount of PCM far from the heating surface. Following these guidelines and Co factor, an optimized PCM container with an elongated and curved shape is proposed and compared to a rectangular container. Numerical simulations indicated that the total melting time of the PCM in the optimized container could be reduced by more than 20% compared to the rectangular one. The higher natural convection velocity and the better use of it to melt the PCM in the optimized container space attributed to the better performance than that in rectangular container. The results can be used to design more effective PCM storage systems.

A numerical simulation study was performed on shell and tube configuration for latent heat storage applications where a Phase Change Material “PCM” - N-eicosane -was used to fill the shell side. The effects of smooth tube eccentricity from the shell center were investigated first, two values of eccentricity (ε=0.267, ε=0.533) were compared to the concentric case (ε=0). It was found out that increasing the eccentricity reduces the melting time by 5% and 10% for ε=0.267 and 0.533 respectively. Then the combined effects of eccentricity and attaching fins to the tube within the shell side were investigated for two fin types: straight rectangular fins and flipped triangular fins. The fin addition to the concentric tube reduced the melting time by about 36%, whereas combining the fins - of either type - to the tube of eccentricities of 0.267 and 0.533 reduced the melting by almost 41 % and 48% respectively, when compared to the smooth concentric tube case


Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4091
Author(s):  
Bin Huang ◽  
Lin-Li Tian ◽  
Qing-Hua Yu ◽  
Xun Liu ◽  
Zu-Guo Shen

Latent thermal energy storage is regarded as an effective strategy to utilize solar energy and recover automotive waste heat. Based upon an enthalpy-porosity method, the influence characteristics and mechanism of fin location on phase change material melting behavior in vertical rectangular enclosures were explored numerically. The results show that as fin location increases, the melting time decreases before attaining the minimum at the fin location of 0.20 after which it increases and finally surpasses the no fin case, because (1) the influence range of fins for conduction is limited by the bottom surface when putting fins next to this surface, (2) the liquid flow resistance increases with moving fins up, and (3) mounting fins near the top surface accelerates melting at the upper part, facilitating thermal stratification formation and weakening natural convection. Nu is higher than the no fin case, i.e., Nu enhancement factor is a positive value, in the melting process for a lower fin location, while for other fin locations, a transition to a negative value takes place. The higher the fin location is, the earlier the transition that arises. Finally, a strategy of increasing the maximum liquid flow velocity is proposed to reinforce melting for cases with considerable natural convection.


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