Performance enhancement of a bubble pump with multiple divergent channels

• Main Authors: Hung, Chao-Chin, 洪兆進
• Other Authors: Pan, Chin
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/egu8x5

碩士 === 國立清華大學 === 工程與系統科學系 === 105 === The bubble pump is a critical component of a diffusion absorption refrigeration system, which is driven mainly by heat and buoyancy effect. This paper continues to study bubble pump of previous study and improves the design of bubble pump. The outlet liquid position is moved to the top of bubble pump and connect with separator. In this way, it can reduce the heat loss. The vapor flow rate, outlet liquid flow rate and efficiency etc. are important parameters to the bubble pump. Therefore, this information are record and analyze to enhance the bubble pump performance. The present study investigates experimentally the performance of a bubble pump with multiple diverging lift channels operating with a binary mixture (ethanol/water) as working fluids. The bubble pump contains generator, lift tube and separator. The heating area of the generator is 27mm×50mm with depth 2mm and the generator is connected with 6 lifting tubes. The depth of the lifting tube at the inlet is same as the generator and is 3.3mm at the outlet and diverging angle of 0.5ﾟ. The separator is a 23mm×28mm×12.5mm space to separator vapor and liquid. Three concentration of molar fractions ( =0.1, 0.2 and 0.3) and two driving head (H=10cm and 15cm) are tested and compared with the uniform lifting tubes. Moreover, a visualization window is placed on the surface of channel for flow visualization using a high speed video camera with 500 frame rate. The results indicate that the vapor mass flow rate raises with increasing the concentration and heating power. Similarly, the outlet liquid mass flow rate increases to a maximum and then decreases with increasing heating power. This is due to the transition of flow pattern. The mass efficiency increases with increasing heating power. The energy efficiency increases with increasing power and concentration and it seems to reach an asymptotic value if the heating power get high. The flow pattern observed in the experiment is most slug flow and it changes to annular flow at the high heating power. The outlet liquid flow rate and vapor flow rate of the diverging channels is higher than the uniform design. Therefore, the energy efficiency of the diverging design is high than the uniform.