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.
Solar Thermal Engineering
A.R. Shateri; I. Pishkar; Sh. Mohammad Beigi
Abstract
Trombe walls and solar chimneys have been widely used by the construction industry for many years to heat buildings. In this study, the heat conductance of a Trombe wall was simulated and studied. The equations related to energy and momentum were solved numerically by use of the technique of control ...
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Trombe walls and solar chimneys have been widely used by the construction industry for many years to heat buildings. In this study, the heat conductance of a Trombe wall was simulated and studied. The equations related to energy and momentum were solved numerically by use of the technique of control volume. The equations were solved simultaneously using the Simple algorithm. At first, a base case was defined and simulated. A sensitivity analysis study was then performed to investigate the parameters affecting the performance of the wall. Based on the results, an optimized geometry was suggested which maximized the performance of the Trombe wall. In addition, the effect of the presence of the fins on the surface of the absorber wall was studied. In order to obtain the best geometry, the fins were assumed to have different shapes but a constant area. The results showed that the Trombe wall with rectangular fins demonstrated the best performance compared to the other fin geometries studied in this paper. The presence of rectangular fins can increase the room temperature by 1.24% compared to other fin geometries.