Development and thermal performance of a wall heat collection prototype

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This study experimentally investigates the natural convection heat transfer performance of a rectangular thermosyphon with an aspect ratio of 3.5. The experimental model is divided into a loop body, a heating section, a cooling section, and two adiabatic sections. The heating section and the cooling section are located in the vertical legs of the rectangular loop. The length of the vertical heating section and the length of the upper and lower horizontal insulation sections are 700 mm and 200 mm, respectively, and the inner diameter of the loop is 11 mm. The relevant parameters and their ranges are as follows: the input thermal power is 30–60 W (with a heat flux in the range of 60–3800 W/m2); the temperature in the cooling section is 30, 40, or 50 °C; and the potential difference between the hot and cold sections is 5, 11, or 18 for the cooling section lengths of 60, 45, and 30 cm, respectively. The results indicate that the value of the dimensionless heat transfer coefficient, the Nusselt number, is generally between 5 and 10. The heating power is the main factor affecting the natural convection intensity of the thermosyphon.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Observation of Natural Convection Heat Transfer Performance of a Rectangular Thermosyphon

Huang

Chen

et al. 2019

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“…Lai et al [7] explored the thermal performance of a rectangular natural circulation loop. The results showed that the average velocity of the fluid increases with an increase in the heating power and aspect ratio or a decrease in the length of the cooling section.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Aspect Ratio of a Rectangular Thermosyphon on Its Thermal Performance

Huang

Tzeng

et al. 2019

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The natural convection behaviors of rectangular thermosyphons with different aspect ratios were experimentally analyzed in this study. The experimental model consisted of a loop body, a heating section, a cooling section, and adiabatic sections. The heating and cooling sections were located in the vertical portions of the rectangular loop. The length of the vertical cooling section and the lengths of the upper and lower adiabatic sections were fixed at 300 mm and 200 mm, respectively. The inner diameter of the loop was fixed at 11 mm, and the cooling end temperature was 30 °C. The relevant parameters and their ranges were as follows: The aspect ratios were 6, 4.5, and 3.5 (with potential differences of 41, 27, and 18, respectively, between the cold and hot ends), and the input thermal power ranged from 30 to 60 W (with a heat flux of 600 to 3800 W/m2). The results show that it is feasible to obtain solar heat gain by installing a rectangular thermosyphon inside the metal curtain wall and that increasing the height of the opaque part of the metal curtain wall can increase the aspect ratio of the rectangular thermosyphon installed inside the wall and thus improve the heat transfer efficiency.

“…Such a loop can serve as a low-cost and highly reliable passive heat transfer device. Studies of the performance of single-phase natural convection loops and the effects of various parameters can be found in the existing literature [1][2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Thermal Performance of a Vertical U-Shaped Thermosyphon Containing a Phase-Change Material Suspension Fluid

Hsu

et al. 2017

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This study investigated the thermal performance of a vertical U-shaped thermosyphon containing a phase-change material (PCM) suspension fluid via experimentation. The heating and cooling sections were located at the top and bottom of the loop, respectively. The lengths of the heating and cooling sections each accounted for one fifth of the height of the loop. Pure water and a PCM (octadecane) suspension fluid were used to fill the loop to compare the thermal performance of the thermosyphon under different heating power, cooling temperature, and PCM suspension concentration conditions. The results showed that, when the PCM suspension concentration was higher than a critical value, the addition of the PCM suspension had no positive effect on reducing the highest temperature of the fluid in the loop but instead resulted in an increase in fluid temperature. More detailed experiments are needed to observe the phenomena and decide critical values under different experimental parameters.