The current work focuses on the thermal efficiency of a horizontal concentric heat exchanger, which is investigated numerically by incorporating fins with various configurations to test the mechanism of heat transfer enhancement. As part of this study, from the start of phase shift to the offset involving natural convection physics in the PCM fluid tank, the melting process is simulated. ANSYS Fluent Code, an effective numerical analysis method for examining fluid flow and convective heat transfer phenomena during the melting phase of PCM, is conducting the investigation. The emphasis is mainly on extending the contact area between the PCM body and the cylindrical capsule by using longitudinal fins in the enclosed capsule to increase the rate of heat transfer to the PCM body during the melting process. Precise evaluation of heat transfer from the complex structure’s extended heat transfer region to PCM due to convection and conduction is a complicated problem, but crucial for thermal storage system design optimization. Two commercial PCMs: RT50 and C58, with their thermo-physical properties as input for modelling, are introduced in a 2D cylindrical pipe. With regard to the total enthalpy changes that qualify our model to run in the proceeding calculation, the selected modelling method is validated against experimental results. It is ensured that in the sequence of simulation cases, an isothermal boundary condition (373 K) is applied to the inner pipe and the corresponding Rayleigh number (Ra) ranges from 104 to 105 and Prandtl number (Pr) 0.05 to 0.07. Finally, parametric studies are carried out to determine the effect of longitude, thickness and number of longitudinal fins on the thermal efficiency of the PCM-LHTES (Latent Heat Thermal Energy Storage) device correlated with the physics of the mechanism of natural convection during PCM melting. In order to justify their applicability in the field of research, potential CFD analysis can be performed with other CFD codes such as CFX, OPENFOAM, STAR CCM+ or CFD++ and compared with the existing ANSYS Fluent code.

Author (s) Details

Mohammad Khan
Department of Physics, Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Stockholm, Sweden.

Nan Zhao
Department of Physics, Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Stockholm, Sweden.

Tianhao Xu
Department of Energy Technology, KTH Royal Institute of Technology (KTH), Stockholm, Sweden.

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