• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.2
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• pp.131-139
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• 2005

This study concerns the performance of boiling heat transfer in two-phase closed thermosyphons with various helical grooves. Distilled water, methanol, ethanol have been used as the working fluids. In the present work, a copper tube of the length of 1200 mm and 14.28 mm of inside diameter is used as the container of the thermosyphon. Each of the evaporator and the condenser section has a length of 550 mm, while the remaining part of the thermosyphon tube is adiabatic section. A experimental study was carried out for analyzing the Performances of having 50, 60, 70, 80 and 50 helical grooves. A Plain thermosyphon having the same inner and outer diameter as the grooved thermosyphons is also tested for comparison. The type of working fluid and the numbers of grooves of the thermosyphons with various helical grooves have been used as the experimental parameters. The experimental results have been assessed and compared with existing theories. The results show that the number of grooves and the type of working fluids are very important factors for the operation of thermosyphons. The helical grooved thermosyphons having 50 to 60 grooves in water, 60 to 70 grooves in methanol and ethanol shows the best heat boiling heat transfer coefficient.

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.62-62
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• 2003

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.239-244
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• 2003

This study concerns the performance of condensing heat transfer in two-phase closed thermosyphons with various helical grooves. Distilled water, methanol, ethanol have been used as the working fluid. In the present work, a copper tube of the length of 1200mm and 14.28mm of inside diameter is used as the container of the thermosyphon. Each of the evaporator and the condenser section has a length of 550mm, while the remaining part of the thermosyphon tube is adiabatic section. A experimental study was carried out for analyzing the performances of having 50, 60, 70, 80, 90 helical grooves. A plain thermosyphon having the same inner and outer diameter as the grooved thermosyphons is also tested for the comparison. The type of working fluid and the numbers of grooves of the thermosyphons with various helical grooves have been used as the experimental parameters. The experimental results have been assessed and compared with existing theories. The results show that the type of working fluids are very important factors for the operation of thermosyphons. And the maximum enhancement (i.e. the ratio of the heat transfer coefficients the helical thermosyphons to plain thermosyphons) is $1.5{\sim}2$ for condensation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.116-122
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• 2005

This study concerns the performance of condensing heat transfer in two-phase closed thermosyphons with various helical grooves. Distilled water, methanol, ethanol have been used as the working fluid. In the present work, a copper tube of the length of 1200mm and 14.28mm of inside diameter is used as the container of the thermosyphon. Each of the evaporator and the condenser section has a length of 550mm, while the remaining part of the thermosyphon tube is adiabatic section. A experimental study was carried out for analyzing the performances of having 50, 60, 70, 80, 90 helical grooves. A plain thermosyphon having the same inner and outer diameter as the grooved thermosyphons is also tested for the comparison. The type of working fluid and the numbers of grooves of the thermosyphons with various helical grooves have been used as the experimental parameters. The experimental results have been assessed and compared with existing theories. The results show that the type of working fluids are very important factors for the operation of thermosyphons. And the maximum enhancement (i.e. the ratio of the heat transfer coefficients the helical thermosyphons to plain thermosyphons) is $1.5{\sim}2$ for condensation.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1243-1249
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• 2004

This study is focused on the comparison between the internal saturation temperature of the working fluid and the surface temperature of adiabatic zone of two-phase closed thermosyphons with various helical grooves. Distilled water, methanol and ethanol have been used as the working fluid. In the present work, a copper tube of the length of 1200mm and 14.28mm of inside diameter is used as the container of the thermosyphon. Each of the evaporator and the condenser section has a length of 550mm, while the remaining part of the thermosyphon tube is adiabatic section. A experimental study was carried out for analyzing the performances of having 50, 60, 70, 80, 90 helical grooves. A plain thermosyphon having the same inner and outer diameter as the grooved thermosyphons is also tested for the comparison. The results show that the numbers of grooves and the type of working fluids are very important factors for the operation of thermosyphons. A good agreement between the internal saturation temperature of working fluid and the surface temperature of adiabatic zone of two-phase closed thermosyphons with various helical grooves is obtained.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.47-53
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• 2006

This study concerns the performance of condensation heat transfer in plain and grooved thermosyphons. Distilled water, methanol, ethanol have been used as the working fluids. In the present work, a copper tube of the length of 1200mm and 14.28mm of inside diameter is used as the container of the thermosyphon. Each of the evaporator and the condenser section has a length of 550mm, while the remaining part of the thermosyphon tube is adiabatic section. A study was carried out with the characteristics of heat transfer of the thermosyphon 50, 60, 70, 80, 90 helical grooves in which boiling and condensation occur. The liquid filling as the ratio of working fluid volume to total volume of thermosyphon, the kinds of working fluid, the inclination angle, grooves and operating temperature have been used as the experimental parameters. The experimental results show that the number of grooves, the amount of the working fluid, the kind of working fluid, angle of inclination angle are very important factors for the operation of thermosyphon. The maximum heat transfer was obtained when the liquid fill was about 20 to 25 % of the thermosyphon volume. The relatively high rates of heat transfer have been achieved in the thermosyphon with grooves. The helical grooved thermosyphon having 70 to 80 grooves in water, 60 to 70 grooves in methanol and 70 to 80 grooves in ethanol shows the best heat transfer coefficient in both condensation.