Photovoltaic Systems
Mousa Farhadi; Arash Mahdavi; Mofid Gorji Bandpy; Amirhoushang Mahmoudi
Abstract
Regulating the operating temperature of photovoltaic (PV) systems is essential for their longevity. An efficient passive cooling method involves the incorporation of Phase Change Materials (PCMs). In this study, a novel nonlinear analytical solution is employed to investigate the melting and solidification ...
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Regulating the operating temperature of photovoltaic (PV) systems is essential for their longevity. An efficient passive cooling method involves the incorporation of Phase Change Materials (PCMs). In this study, a novel nonlinear analytical solution is employed to investigate the melting and solidification processes within the PV-PCM system, which operates continuously for 24 hours each day. The analytical approach significantly reduces computational time to a few seconds compared to over three months required by CFD techniques. The transformation of the partial differential energy equation into a nonlinear ordinary differential energy equation facilitates precise observation of both melting and solidification processes of the PCM material. The analytical approach is further applied to assess the performance of the PV-PCM system during two typical summer days in 2020 and 2021. Additionally, the impact of PCM thickness on the PV-PCM system is examined as a variable input. Results indicate that increasing PCM thickness from 1 cm to 5 cm reduces the peak temperature of the PV module by approximately 7 . This temporal shift is significant, enabling the PV module to operate at cooler temperatures during peak solar intensity, resulting in higher power output. The analytical solution proves instrumental in determining the optimal PCM thickness for a PV-PCM system in any location within seconds. Findings reveal that a 5 cm PCM thickness leads to a 13% decrease in maximum temperature and a 3.4% increase in minimum electrical efficiency. The integration of thermal energy storage enhances the overall efficiency and performance of the PV system.
Solar Thermal Engineering
Seyed Younes Afshoon; Rouzbeh Shafaghat; Mofid Gorji Bandpy
Abstract
This paper investigates the melting behavior of phase-change material (PCM) in an evacuated tube solar collector. The outer tube was made of borosilicate glass with a diameter of 60 mm, and the inner tube was made of copper with a diameter of 10 mm and length of 1500 mm. The heat transfer problem in ...
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This paper investigates the melting behavior of phase-change material (PCM) in an evacuated tube solar collector. The outer tube was made of borosilicate glass with a diameter of 60 mm, and the inner tube was made of copper with a diameter of 10 mm and length of 1500 mm. The heat transfer problem in heat pipe was investigated in four cases: finless, full fin, half fin, and third fin. The fins were cut from a 35 mm diameter copper tube and installed concentrically with the outer tube. The inner space between the absorber tube and the heat pipe was filled with stearic acid as the PCM. The numerical simulation was conducted using the Ansys Fluent 2022 for the laminar incompressible Newtonian fluid flow in the transient state via the enthalpy-porosity model. The initial temperature of PCM was 27°C, and liquid fraction was zero at the beginning of the simulation. After validating the numerical results with experimental ones, the collector performance was evaluated by considering the four temperatures of 68, 72, 76, and 80°C for the fin and heat pipe at three different times t = 22, 55, and 110 s. The results showed that by increasing the fin area in three cases of third fin, half fin, and full fin, the melting and storage time of PCM were reduced by 6%, 44%, and 87%, respectively. Also, as the Estefan number increased from 0.007 to 0.05, 0.09, and 0.13, the process of PCM melting decreased by 75%, 85%, and 92%, respectively.