Flow pattern characterization for R-245fa in minichannels: Optical measurement technique and experimental results |
| |
| Institution: | 1. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China;2. Department of Chemical Engineering, Tsinghua University, Beijing 100084, China |
| |
| Abstract: | An optical measurement method using image processing for two-phase flow pattern characterization in minichannel is developed. The bubble frequency, the percentage of small bubbles as well as their velocity are measured. A high-speed high-definition video camera is used to measure these parameters and to identify the flow regimes and their transitions. The tests are performed in a 3.0 mm glass channel using saturated R-245fa at 60 °C (4.6 bar). The mass velocity is ranging from 100 to 1500 kg/m2 s, the heat flux is varying from 10 to 90 kW/m2 and the inlet vapor quality from 0 to 1. Four flow patterns (bubbly flow, bubbly–slug flow, slug flow and annular flow) are recognized. The comparison between the present experimental intermittent/annular transition lines and five transition lines from macroscale and microscale flow pattern maps available in the literature is presented. Finally, the influence of the flow pattern on the heat transfer coefficient is highlighted. |
| |
| Keywords: | Minichannel Flow patterns Two-phase flows Optical measurement technique |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
