Two-Phase Flow Instability of Boiling in a Double Microchannel System at High Heating Powers

The present work investigates experimentally the two-phase flow instability of convective boiling heat transfer in a system of two parallel microchannels at a given low mass flux and several different heating surface temperatures. The test section employed in this work is fabricated by silicon bulk micro machining and anodic bounding processes. Both channels are triangular with the channel-width of the topside of 100 i`m and hydraulic diameter of 51.7 i`m. The topside width of the central island between two channels is 20 i`m. The forced flow of de-ionized water is provided by a syringe pump. The two-phase flow visualization under boiling conditions is made possible by a high-speed digital video camera. The temperatures of inlet and outlet reservoirs, the inlet pressure as well as the pressure drop during the experiments are recorded and analyzed with flow visualization. The results of the study demonstrate clearly that two-phase flow instabilities with significant oscillations in two-phase flow properties can be developed in the system of double microchannels at high heating surface temperatures due to channel-to-channel interactions. Flow visualization confirms the presence of flow reversal during large amplitude oscillations. Such two-phase flow instabilities involving flow reversal should be of great concern for the design of a micro evaporator.