Mechanical Engineering / Makina Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4129

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Access Right: Closed AccessAuthor: search.filters.author.Manca, Oronzio

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  • Article
    Citation - WoS: 36
    Citation - Scopus: 37
    Numerical Investigation of Melting Process for Phase Change Material (pcm) Embedded in Metal Foam Structures With Kelvin Cells at Pore Scale Level
    (Elsevier, 2023) Sabet, Safa; Buonomo, Bernardo; Sheremet, Mikhail A.; Manca, Oronzio
    The present numerical study analyzes the melting process of phase change material (PCM) embedded in a metallic foam structure at pore scale level. The computational domain consists of two different sizes of 3D cubic boxes. The analyzed domain is filled with Kelvin cell-structures with different Cell Per Length (CPL) and constant porosity of 0.956. A constant temperature, higher than the melting temperature of PCM, is assigned to one external surface of the enclosure, while the other surfaces are adiabatic. The conjugate problem for the heat transfer between the PCM and the solid structure with Kelvin cells is developed. Enthalpy-porosity method is used to describe the PCM melting process. The finite volume method is used to solve the conjugate heat transfer problem at pore scale level by Ansys-Fluent code. A comparison of different CPL values is reported in terms of liquid fraction, average temperature of the PCM, and energy storage. The comparison is also considered between the two different volumes of the cubic boxes. The presence of the metallic structured Kelvin cells increases the overall heat transfer rate and decreases the melting time. Results for smaller cavity indicates that as the CPL number increases, the time required for the PCM melting process decreases. Furthermore, the total heat accumulation process takes a shorter time to reach the maximum value. The melting time and the duration of heat accumulation are worsened for the large cubic box (L = 4 inch) at CLP>6. This is due to the dominant viscous effect, which decreases the velocity induced by the buoyancy forces because of higher contact surface area. In these cases, heat transfer between liquid and solid phases of the PCM decreases substantially. © 2023 Elsevier Ltd
  • Article
    Citation - WoS: 6
    Citation - Scopus: 6
    Numerical Study on Thermal Behaviors of Parallel Plate Systems for Sensible Thermal Energy Storage With Heat Loss
    (Elsevier, 2023) Sabet, Safa; Buonomo, Bernardo; Xie, Gongnan; Manca, Oronzio
    A numerical study on thermal energy storage systems with parallel plates to collect sensible heat is conducted with porous and direct model approaches. The simulations in a two-dimensional domain are performed with COMSOL Multiphysics commercial software. For the equivalent porous medium, the permeability and effective thermal conductivity as well as the specific area, and interfacial convective coefficient are numerically evaluated, considering a thermally and hydrodynamically fully developed flow. A stack of parallel plates is the system with assigned length and height, and the external heat losses effect is considered. The analysis allows to evaluate an optimized configuration as Channels Per Length (CPL) by means of a balance in the channels between pressure drop and heat transfer. Moreover, the effect of CPL values and heat loss from the parallel plate system is esti-mated in terms of charging time and heating capacity. The results exhibit that as the CPL increases, the time required for the charging process decreases while heat accumulation inside the system increases significantly. In fact, at the highest CPL, charging time is 2.7 times faster and the amount of heat accumulation is approximately 20% higher in adiabatic case. It is illustrated that the amount of heat accumulation inside the system varies considerably for different heat loss values. Ultimately, this study shows that porous model is more practical and accurate to be used for higher CPL cases.