Heat transfer performance in 3D internally finned heat pipe
- Liao, Quan, Jen, Tien-Chien, Chen, Qing-hua, Li, Longjian, Cui, Wenzhi
- Authors: Liao, Quan , Jen, Tien-Chien , Chen, Qing-hua , Li, Longjian , Cui, Wenzhi
- Date: 2007
- Subjects: Heat pipes , Heat transfer , Finned tubes
- Type: Article
- Identifier: uj:5276 , http://hdl.handle.net/10210/14945
- Description: An experimental study of heat transfer performance in 3D internally finned steel-water heat pipe was carried out in this project. All the main parameters that can significantly influence the heat transfer performance of heat pipe, such as working temperature, heat flux, inclination angle, working fluid fill ratio (defined by the evaporation volume), have been examined. Within the experimental conditions (working temperature 40 C–95 C, heat flux 5.0 kw/m2–40 kw/m2, inclination angle 2–90 ), the evaporation and condensation heat transfer coefficients in 3D internally finned heat pipe are found to be increased by 50–100% and 100–200%, respectively, as compared to the smooth gravity-assisted heat pipe under the same conditions. Therefore, it is concluded that the special structures of 3D-fins on the inner wall can significantly reduce the internal thermal resistance of heat pipe and then greatly enhance its heat transfer performance.
- Full Text:
- Authors: Liao, Quan , Jen, Tien-Chien , Chen, Qing-hua , Li, Longjian , Cui, Wenzhi
- Date: 2007
- Subjects: Heat pipes , Heat transfer , Finned tubes
- Type: Article
- Identifier: uj:5276 , http://hdl.handle.net/10210/14945
- Description: An experimental study of heat transfer performance in 3D internally finned steel-water heat pipe was carried out in this project. All the main parameters that can significantly influence the heat transfer performance of heat pipe, such as working temperature, heat flux, inclination angle, working fluid fill ratio (defined by the evaporation volume), have been examined. Within the experimental conditions (working temperature 40 C–95 C, heat flux 5.0 kw/m2–40 kw/m2, inclination angle 2–90 ), the evaporation and condensation heat transfer coefficients in 3D internally finned heat pipe are found to be increased by 50–100% and 100–200%, respectively, as compared to the smooth gravity-assisted heat pipe under the same conditions. Therefore, it is concluded that the special structures of 3D-fins on the inner wall can significantly reduce the internal thermal resistance of heat pipe and then greatly enhance its heat transfer performance.
- Full Text:
A heat transfer correlation of flow boiling in micro-finned helically coiled tube
- Cui, Wenzhi, Li, Longjian, Xin, Ming-dao, Jen, Tien-Chien, Chen, Qinghua, Liao, Quan
- Authors: Cui, Wenzhi , Li, Longjian , Xin, Ming-dao , Jen, Tien-Chien , Chen, Qinghua , Liao, Quan
- Date: 2006
- Subjects: Convective boiling , Heat transfer , Helically coiled tubes , Nucleate boiling
- Type: Article
- Identifier: uj:5275 , http://hdl.handle.net/10210/14944
- Description: Two main mechanisms, nucleate boiling and convective boiling, are widely accepted for in-tube flow boiling. Since the active nuclei on the heated wall are dominant for nucleate boiling and flow pattern governs the convective boiling, the heat transfer coefficient is strongly influenced by the wall heat flux, mass flux and vapor quality, respectively. In practical industrial applications, for example, the evaporators in refrigeration, forced convective evaporation is the dominant process and high heat transfer efficiency can be obtained under smaller temperature difference between wall and liquid. Therefore, it is of importance to develop a correlation of convective boiling heat transfer with a good accuracy. In this paper, a new kind of micro-finned helically coiled tube was developed and the flow boiling heat transfer characteristics were experimentally studied with R134a. Based on the analysis of the mechanisms of flow boiling, heat transfer correlations of the specific micro-finned helically coiled tubes are obtained.
- Full Text:
- Authors: Cui, Wenzhi , Li, Longjian , Xin, Ming-dao , Jen, Tien-Chien , Chen, Qinghua , Liao, Quan
- Date: 2006
- Subjects: Convective boiling , Heat transfer , Helically coiled tubes , Nucleate boiling
- Type: Article
- Identifier: uj:5275 , http://hdl.handle.net/10210/14944
- Description: Two main mechanisms, nucleate boiling and convective boiling, are widely accepted for in-tube flow boiling. Since the active nuclei on the heated wall are dominant for nucleate boiling and flow pattern governs the convective boiling, the heat transfer coefficient is strongly influenced by the wall heat flux, mass flux and vapor quality, respectively. In practical industrial applications, for example, the evaporators in refrigeration, forced convective evaporation is the dominant process and high heat transfer efficiency can be obtained under smaller temperature difference between wall and liquid. Therefore, it is of importance to develop a correlation of convective boiling heat transfer with a good accuracy. In this paper, a new kind of micro-finned helically coiled tube was developed and the flow boiling heat transfer characteristics were experimentally studied with R134a. Based on the analysis of the mechanisms of flow boiling, heat transfer correlations of the specific micro-finned helically coiled tubes are obtained.
- Full Text:
Heat transfer and pressure drop experimental correlations for air-water bubbly flow
- Cui, Wenzhi, Li, Longjian, Chen, Qinghua, Liao, Quan, Jen, Tien-Chien
- Authors: Cui, Wenzhi , Li, Longjian , Chen, Qinghua , Liao, Quan , Jen, Tien-Chien
- Date: 2006
- Subjects: Bubbly flow , Gas-liquid flow , Heat transfer , Pressure drop
- Type: Article
- Identifier: uj:5268 , http://hdl.handle.net/10210/14937
- Description: In this paper, a novel air–water bubbly flow heat transfer experiment is performed to investigate the characteristics of pressure drop of airflow and heat transfer between water and tubes for its potential application in evaporative cooling. The attempts to reduce the pressure drop while maintaining higher heat transfer coefficient have been achieved by decreasing the bubble layer thickness through the water pump circulation. Pressure drops of air passing through the sieve plate and the bubbling layer are measured for different height of bubble layer, hole–plate area ratio of the sieve plate and the superficial air velocity. Experimental data show that the increase of bubble layer height and air velocity both increase the pressure drop while the effect of the hole–plate area ratio of the sieve plate on the heat transfer coefficient is relatively sophisticated. A pressure drop correlation including the effects of all the tested parameters is proposed, which has a mean absolute deviation of 14.5% to that of the experimental data. Heat transfer coefficients of the water and the outside tube wall are measured and the effects of superficial air velocity, heat flux and bubble layer height are also examined. Through a dimensional analysis, a heat transfer correlation with a mean absolute deviation of 9.7% is obtained based on experimental data.
- Full Text:
- Authors: Cui, Wenzhi , Li, Longjian , Chen, Qinghua , Liao, Quan , Jen, Tien-Chien
- Date: 2006
- Subjects: Bubbly flow , Gas-liquid flow , Heat transfer , Pressure drop
- Type: Article
- Identifier: uj:5268 , http://hdl.handle.net/10210/14937
- Description: In this paper, a novel air–water bubbly flow heat transfer experiment is performed to investigate the characteristics of pressure drop of airflow and heat transfer between water and tubes for its potential application in evaporative cooling. The attempts to reduce the pressure drop while maintaining higher heat transfer coefficient have been achieved by decreasing the bubble layer thickness through the water pump circulation. Pressure drops of air passing through the sieve plate and the bubbling layer are measured for different height of bubble layer, hole–plate area ratio of the sieve plate and the superficial air velocity. Experimental data show that the increase of bubble layer height and air velocity both increase the pressure drop while the effect of the hole–plate area ratio of the sieve plate on the heat transfer coefficient is relatively sophisticated. A pressure drop correlation including the effects of all the tested parameters is proposed, which has a mean absolute deviation of 14.5% to that of the experimental data. Heat transfer coefficients of the water and the outside tube wall are measured and the effects of superficial air velocity, heat flux and bubble layer height are also examined. Through a dimensional analysis, a heat transfer correlation with a mean absolute deviation of 9.7% is obtained based on experimental data.
- Full Text:
Heat transfer augmentation in 3D internally finned and micro-finned helical tube
- Li, Longjian, Cui, Wenzhi, Liao, Quan, Mingdao, Xin, Jen, Tien-Chien, Chen, Qinghua
- Authors: Li, Longjian , Cui, Wenzhi , Liao, Quan , Mingdao, Xin , Jen, Tien-Chien , Chen, Qinghua
- Date: 2005
- Subjects: Helical tubes , Finned tubes , Heat transfer
- Type: Journal
- Identifier: uj:5263 , http://hdl.handle.net/10210/14932
- Description: Experiments are performed to investigate the single-phase flow and flow-boiling heat transfer augmentation in 3D internally finned and micro-finned helical tubes. The tests for single-phase flow heat transfer augmentation are carried out in helical tubes with a curvature of 0.0663 and a length of 1.15 m, and the examined range of the Reynolds number varies from 1000 to 8500. Within the applied range of Reynolds number, compared with the smooth helical tube, the average heat transfer augmentation ratio for the two finned tubes is 71% and 103%, but associated with a flow resistance increase of 90% and 140%, respectively. A higher fin height gives a higher heat transfer rate and a larger friction flow resistance. The tests for flow-boiling heat transfer are carried out in 3D internally micro-finned helical tube with a curvature of 0.0605 and a length of 0.668 m. Compared with that in the smooth helical tube, the boiling heat transfer coefficient in the 3D internally micro-finned helical tube is increased by 40–120% under varied mass flow rate and wall heat flux conditions, meanwhile, the flow resistance is increased by 18–119%, respectively.
- Full Text:
- Authors: Li, Longjian , Cui, Wenzhi , Liao, Quan , Mingdao, Xin , Jen, Tien-Chien , Chen, Qinghua
- Date: 2005
- Subjects: Helical tubes , Finned tubes , Heat transfer
- Type: Journal
- Identifier: uj:5263 , http://hdl.handle.net/10210/14932
- Description: Experiments are performed to investigate the single-phase flow and flow-boiling heat transfer augmentation in 3D internally finned and micro-finned helical tubes. The tests for single-phase flow heat transfer augmentation are carried out in helical tubes with a curvature of 0.0663 and a length of 1.15 m, and the examined range of the Reynolds number varies from 1000 to 8500. Within the applied range of Reynolds number, compared with the smooth helical tube, the average heat transfer augmentation ratio for the two finned tubes is 71% and 103%, but associated with a flow resistance increase of 90% and 140%, respectively. A higher fin height gives a higher heat transfer rate and a larger friction flow resistance. The tests for flow-boiling heat transfer are carried out in 3D internally micro-finned helical tube with a curvature of 0.0605 and a length of 0.668 m. Compared with that in the smooth helical tube, the boiling heat transfer coefficient in the 3D internally micro-finned helical tube is increased by 40–120% under varied mass flow rate and wall heat flux conditions, meanwhile, the flow resistance is increased by 18–119%, respectively.
- Full Text:
Heat transfer augmentation in 3D inner finned helical pipe
- Li, Longjian, Cui, Wenzhi, Liao, Quan, Mingdao, Xin, Jen, Tien-Chien, Chen, Qinghua
- Authors: Li, Longjian , Cui, Wenzhi , Liao, Quan , Mingdao, Xin , Jen, Tien-Chien , Chen, Qinghua
- Date: 2004
- Subjects: Heat transfer , Helical tubes
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16052 , uj:15733 , Citation: • Li, L. et al. 2004, “Heat transfer augmentation in 3D inner finned helical pipe,” ASME Heat Transfer/Fluids Engineering Conference, July 11-15, 2004, Charlotte, North Carolina, Vol. 3, pp. 139-143. HT-FED2004-56430. ISSN: 0-7918-4692-X.
- Description: Abstract: Experiments were performed to investigate the performance enhancement of single-phase flow and boiling heat transfer in the 3D inner finned helical tubes. The tests for single-phase flow and heat transfer were carried out in the helical tubes with a curvature of 0.0663 and a length of 1.15m, the range of the Reynolds number examined varies from 1000 to 8500. In comparison to the smooth helical tube, the experimental results of two finned helical tubes with different inner fin geometry showed that the heat transfer and flow resistance in the 3D inner finned helical tube gains greater augmentation. Within the measured range of Reynolds number, the average augmentation ratio of heat transfer of the two finned tubes are 71% and 103%, compared with the smooth helical tube, and 90% and 140% for flow resistance, respectively. The tests for flow boiling heat transfer was carried out in the 3D inner finned helical tube with a curvature of 0.0605 and a length of 0.668m.Compared with that in the smooth helical tube, the boiling heat transfer coefficient in the 3D inner finned helical tube is increased by 40%~120% under varied mass flow rate and wall heat flux conditions, meanwhile, the flow resistance coefficient increased by 18%~119%.
- Full Text:
- Authors: Li, Longjian , Cui, Wenzhi , Liao, Quan , Mingdao, Xin , Jen, Tien-Chien , Chen, Qinghua
- Date: 2004
- Subjects: Heat transfer , Helical tubes
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16052 , uj:15733 , Citation: • Li, L. et al. 2004, “Heat transfer augmentation in 3D inner finned helical pipe,” ASME Heat Transfer/Fluids Engineering Conference, July 11-15, 2004, Charlotte, North Carolina, Vol. 3, pp. 139-143. HT-FED2004-56430. ISSN: 0-7918-4692-X.
- Description: Abstract: Experiments were performed to investigate the performance enhancement of single-phase flow and boiling heat transfer in the 3D inner finned helical tubes. The tests for single-phase flow and heat transfer were carried out in the helical tubes with a curvature of 0.0663 and a length of 1.15m, the range of the Reynolds number examined varies from 1000 to 8500. In comparison to the smooth helical tube, the experimental results of two finned helical tubes with different inner fin geometry showed that the heat transfer and flow resistance in the 3D inner finned helical tube gains greater augmentation. Within the measured range of Reynolds number, the average augmentation ratio of heat transfer of the two finned tubes are 71% and 103%, compared with the smooth helical tube, and 90% and 140% for flow resistance, respectively. The tests for flow boiling heat transfer was carried out in the 3D inner finned helical tube with a curvature of 0.0605 and a length of 0.668m.Compared with that in the smooth helical tube, the boiling heat transfer coefficient in the 3D inner finned helical tube is increased by 40%~120% under varied mass flow rate and wall heat flux conditions, meanwhile, the flow resistance coefficient increased by 18%~119%.
- Full Text:
- «
- ‹
- 1
- ›
- »