In this paper we experimentally investigated the pressure drop fluctuation and liquid/vapour interface behaviours during flow boiling in a single rectangular micro-channel with high aspect ratio. An integrated testing system including syringe pump, pressure sensors, thermocouples, micro-channel and high speed camera was mounted in a 1 m x 1 m x 1 m plexiglass box, the ambient temperature inside of which was controllable. A micro-channel with the hydraulic diameter of 727 mu m was chosen, the aspect ratio of which was 10. FC-72 was used as the working liquid, with a saturation temperature of 56 C at atmospheric pressure.
The present study concentrated on the transition from single-phase flow to two-phase flow (including single-phase friction losses and onset of nucleation) and flow instabilities and liquid vapour interface behaviors during two-phase flow. Pressures at inlet (P-in) and outlet (P-out) of the channel were measured and pressure drop (P-in - P-out) was then obtained. The pressure drop fluctuation was discussed. Besides, various liquid vapour interface behaviors including interface deformation, recoiling and re-wetting as well as bubble nucleation, bubble growth and bubble geometry were captured and analyzed with the aid of a high speed camera. Additionally, evaporation rates of bubble nose and bubble tail at different mass fluxes and heat fluxes were compared. (C) 2010 Elsevier Ltd. All rights reserved.
|Number of pages||9|
|Journal||Applied Thermal Engineering|
|Publication status||Published - Apr 2011|