Thermal storage characteristics for rectangular cavity with partially active walls

• Published in: International journal of heat and mass transfer Vol. 126; pp. 683 - 702
• Main Authors: Hong, Yuxiang, Ye, Wei-Biao, Huang, Si-Min, Yang, Minlin, Du, Juan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2018
• Subjects: Aspect ratio; Discrete heat source; Inclination angle; Latent heat storage; Partially active wall; Rectangular cavity; Discrete heat source; Inclination angle; Partially active wall; Aspect ratio; Latent heat storage; Rectangular cavity
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2018.05.005

Dynamic latent-heat thermal storage behaviors in partially active rectangular cavity are numerically solved and optimized under the foundational factors of aspect ratio AR (0.5 ≤ AR ≤ 2), number of discrete heat source N (1 ≤ N ≤ 4), and inclination angle (0° ≤  ≤ 90°). It is found that the best overall thermal characteristics are reached as aspect ratio AR = 0.5 (Fig. a). The corresponding physical model with employed boundary conditions (Fig. b) is depicted in detail, as well as the location of solid-liquid interface (Fig. b) at time t = 720 s. Furthermore, the streamlines and isotherms (Fig. c) are presented at the corresponding time. [Display omitted] •A partially thermal active rectangular storage cavity is investigated.•Heat source separated is an efficient approach for enhancement energy storage.•Optimized thermal behaviors are reached at θ = 0°, AR = 0.5, and N = 4.•Multiple convection cells are formed firstly and then merged into larger ones. The work is directed at the numerical simulation of latent-heat thermal energy storage in a two-dimensional rectangular cavity with partially thermally active parts. The detailed transient computations are performed for the inclination angle varies from 0 to 90° based on horizontal ground, for the aspect ratio of the rectangular cavity varies from 0.5 to 2, and for the number of discrete heat source located in the heated wall varies from 1 to 4. Numerical results indicated that thermally active part heated by discrete heat sources is a promising alternative for high-efficient thermal energy storage, as the vector direction between gravitation and overall heat flux is opposite, and that the aspect ratio has significantly sensitized for the thermal behavior as the inclination angle is 90°. It is demonstrated that the optimized thermal storage behaviors are reached for the inclination angle of 0°, the aspect ratio of 0.5, and the number of discrete heat source of 4, with the requested thermal storage time reduced more than 40%. It is found that the formation of the multicellular flow structure during the early stage of melting process, while a merging of the small recirculating cells into larger ones is observed during the following stage.