Effect of sinusoidal cylindrical surface of PCM on melting performance
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DOI 10.1007/s12206-020-0732-0
Journal of Mechanical Science and Technology 34 (8) 2020 Original Article DOI 10.1007/s12206-020-0732-0 Keywords: · Amplitude · Capsule shape · Number of sinusoids · PCM
Correspondence to: Jae Dong Chung [email protected]
Citation: Awasthi, A., Kumar, B., Nguyen, H. H., Lee, S. S., Chung, J. D. (2020). Effect of sinusoidal cylindrical surface of PCM on melting performance. Journal of Mechanical Science and Technology 34 (8) (2020) ?~?. http://doi.org/10.1007/s12206-020-0732-0
Received November 12th, 2019 Revised
Effect of sinusoidal cylindrical surface of PCM on melting performance Abhishek Awasthi, Binit Kumar, Huy Hai Nguyen, Seung Soo Lee and Jae Dong Chung School of Mechanical Engineering, Sejong University, Seoul 05006, Korea
Abstract
A numerical analysis was conducted to examine the effect of capsule shape on phase change material (PCM) melting speed. The surface parameters of the irregular capsule shape were amplitude a and the number of sinusoidal undulations n . Case studies were conducted: (1) with the same number of sinusoids but variable amplitude, (2) with the same amplitude but variable number of sinusoids, and (3) same PCM volume, i.e., the same irregular cylindrical capsule perimeter. Unlike observations with a convection-only inside capsule, the amplitude of irregularity in capsule shape a , rather than capsule area, was found to be the dominant factor in heat transfer enhancement. The capsule area was important only during the initial conduction-dominant period. The opposing influences of amplitude a and number of sinusoidal undulations n on the intensity of natural convection was observed. The result shows that only increasing the area does not increase the melting performance, it is the amplitude a which enhance the melting performance.
June 3rd, 2020
Accepted June 11th, 2020 † Recommended by Editor Yong Tae Kang
© The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature 2020
1. Introduction Energy storage systems are essential in conditions where energy demand fluctuates, which is commonly found in building applications and renewable energy sources. Among various energy storage methods, latent thermal energy storage (LTES) has the advantage of higher energy storage density than traditional sensible TES and is an effective means of shifting peak electrical loads in HVAC systems from on-peak hours to off-peak hours [1, 2]. LTES can be integrated either into the building envelope (passive LTES) or into ventilation systems (active LTES) to reduce cooling demand [3] or heating demand [4]. There are different types of LTES systems, such as ice-on-coil type, encapsulated type and shell and tube type LTES. By encapsulating phase change materials (PCM), it is possible to enhance heat transfer, which improves the dynamic performance of the LTES [5, 6]. For decades, researchers have been investigating ways to enhance heat transfer inside the capsule. The most widely used technique adds surface attachments such as fins
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