Evaluation of multi-branch fin inserts for improved thermal response in latent heat storage systems: A numerical approach
Tuqa Abdulrazzaq, Hussein Togun, Jasim M. Mahdi, Hayder I. Mohammed, Farhan Lafta Rashid, Abbas Fadhil Khalaf, Ali E. Anqi, Abdellatif M. Sadeq
Abstract
Latent heat thermal energy storage (LHTES) offer a promising solution, but the inherently low thermal conductivity of their storage materials, known as phase change materials (PCMs), impedes thermal response rates. This study numerically explores the impact of multi-branch fin configurations on melting and solidification performance in a fixed-volume LHTES system, aiming to optimize the trade-off between increased fin surface area for improved heat transfer and potential flow constraints from excess fins obstructing convective PCM motion. A transient Two-dimensional (2D) model using the enthalpy-porosity approach simulates the phase change of the PCM around cylindrical tube-fin arrangements. Four cases are compared: plain fins, two-branch fins, four-branch fins, and five-branch fins, all with constant total fin volumes. Results show that multi-branch fins initially enhance melting rates due to increased heat transfer area, but declining returns arise beyond a threshold. At 325 K inlet temperature, the PCM with two-branch, three-branch, and four-branch fins melted completely within 60 minutes versus 90 minutes for plain fins, reducing melting time by 33.9%, 37.1%, and 44.9%, respectively. However, the five-branch case provided marginal further improvement due to excessive fin crowding restricting molten PCM flow. Similar trends occurred during solidification, with multi-branch fins reducing solidification times by 18.3-29.0%. This work guides identifying an optimal fin configuration that balances heat transfer enhancement and unimpeded convection. This approach prevents diminishing returns typically observed when implementing excessive fin volume arrangements.