Investigation of Semi-arc/circular wicklsee heat pipe of solar collector

• Main Authors: De-Tang Chen, 陳德堂
• Other Authors: Chien-Yuh Yang
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/94394818331453126499

碩士 === 國立中央大學 === 機械工程研究所 === 91 === This paper presents an experimental analysis of the heat transfer performance of a semi-arc/circular wickless heat pipe. Methanol was filled as the working fluid with 20%, 35%, 50% and 65% filling ratios of the evaporating section volume. Owing to the action of surface tension drainage in the sharp corner, it keeps the evaporating of the heat pipe wet and cause the higher evaporating thermal conductivity than that of circular tube. It also can reduce the effect of thermal conductivity. Evaporating and condensing space of circular condensing section was larger hence the condensing liquid film become thinner and improved the performance. The total length of all heat pipe are 1380mm. For evaporating section is 1000mm、adiabatic section is 80mm and condensing section is 300mm. The heat transfer mechanism and effect of filling ratio and inclination angle were measured and discussed. The situation of start up difficult was occurred at filling ratio 65%, 50% and 35%. However it’s startable at 20% for low power support with good performance. The disadvantages of start up difficult at low insolation and low incline angle for solar water heater would be improve by semi-arc/circular wickless heat pipe. Natural convection heat transfer was found in water tank section and caused the higher heat resistance compared to heat pipe section. The heat resistance of water tank section was higher than heat pipe section, since the heat transfer was natural convection. Future work is necessary to improve the heat transfer performance of water tank section. It’s believed that the performance will be improved by inserting the heat pipe into bottom of water tank.